Texas Instruments UCD90320 User manual

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User's Guide
SLVUAW9C–September 2016–Revised February 2020
UCD90320 Sequencer and System Health Controller
PMBus Command Reference
The UCD90320 Power Supply Sequencer and Monitor supports a wide range of commands that allow an
external host to configure, control, and monitor voltage rails and fans. Communication between the
sequencer and the host is via an I2C electrical interface using the PMBus™ command protocol.
The PMBus specification describes the command protocol in general terms. This document describes
implementation details that are specific to the UCD90320 Power Supply Sequencer and Monitor. If a
command is not described in this document and it is supported by a UCD90320 device (see Table 2), it
functions exactly as described in the PMBus specification. In which case, refer to PMBus specification for
more details.
See the device-specific data sheet for a complete description of the features.
This document makes reference to "Fusion". The TI Fusion Digital Power Designer (SLVC223) is provided
for device configuration. This Microsoft®Windows®based, graphical user interface (GUI) offers an intuitive
interface for configuring, storing, and monitoring all system operating parameters.
Note: This document does not apply to any other UCD90xxx devices
Contents
1 PMBus Specification ........................................................................................................ 5
1.1 Manufacturer Specific Status (STATUS_MFR_SPECIFIC) ................................................... 7
2 Data Formats................................................................................................................. 7
2.1 Data Format for Output Voltage Parameters.................................................................... 7
2.2 Data Format for Other Parameters............................................................................... 7
2.3 Distinguishing Between Linear Data Formats................................................................... 8
2.4 Translation, Quantization, and Truncation....................................................................... 8
2.5 8-Bit Time Encoding................................................................................................ 8
3 Memory Model ............................................................................................................... 9
4 Alert Response Address Support.......................................................................................... 9
5 Supported PMBus Commands ........................................................................................... 10
6 Implementation Details for PMBus Core Commands.................................................................. 19
6.1 (00h) PAGE ........................................................................................................ 19
6.2 (01h) OPERATION................................................................................................ 19
6.3 (11h) STORE_DEFAULT_ALL .................................................................................. 19
6.4 (12h) RESTORE_DEFAULT_ALL............................................................................... 20
6.5 (1Bh) SMBALERT_MASK........................................................................................ 20
6.6 (20h) VOUT_MODE............................................................................................... 20
6.7 (38h) IOUT_CAL_GAIN .......................................................................................... 21
6.8 (41h – 69h) xxx_FAULT_RESPONSE ......................................................................... 21
6.9 (62h) TON_MAX_FAULT_LIMIT ................................................................................ 22
6.10 (66h) TOFF_MAX_WARN_LIMIT ............................................................................... 22
6.11 (80h) STATUS_MFR_SPECIFIC................................................................................ 22
6.12 (81h) STATUS_FAN_1_2 and (82h) STATUS_FAN_3_4 ................................................... 22
6.13 (8Dh) READ_TEMPERATURE_1............................................................................... 23
6.14 (8Eh) READ_TEMPERATURE_2............................................................................... 23
6.15 (90-93h) FAN_SPEED_1 Through FAN_SPEED_4.......................................................... 24
6.16 (ADh) IC_DEVICE_ID ............................................................................................ 24
6.17 (AEh) IC_DEVICE_REV.......................................................................................... 24

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7 Input and Output Pin Configuration...................................................................................... 25
8 PWM Configuration ........................................................................................................ 28
9 Implementation Details for User Data Commands..................................................................... 29
9.1 (B5h) BLACK_BOX_FAULT_INFO (USER_DATA_05)...................................................... 29
9.2 (B6h) BLACK_BOX_FAULT_RAILS_WARNING(USER_DATA_06)....................................... 30
9.3 (B7h) BLACK_BOX_LOG_RAILS_VALUE(USER_DATA_07).............................................. 31
9.4 (B8h) RAIL_PROFILE(USER_DATA_08)...................................................................... 31
9.5 (B9h) RAIL_STATE (USER_DATA_09)........................................................................ 33
10 Implementation Details for Manufacturer-Specific Commands....................................................... 34
10.1 (D0h) FAULT_PIN_CONFIG (MFR_SPECIFIC_00).......................................................... 34
10.2 (D1h) VOUT_CAL_MONITOR (MFR_SPECIFIC_01)........................................................ 35
10.3 (D2h) SYSTEM_RESET_CONFIG (MFR_SPECIFIC_02)................................................... 36
10.4 (D3h) SYSTEM_WATCHDOG_CONFIG (MFR_SPECIFIC_03)............................................ 38
10.5 (D4h) SYSTEM_WATCHDOG_RESET (MFR_SPECIFIC_04) ............................................. 40
10.6 (D5h) MONITOR_CONFIG (MFR_SPECIFIC_05)............................................................ 40
10.7 (D6h) NUM_PAGES (MFR_SPECIFIC_06) ................................................................... 43
10.8 (D7h) RUN_TIME_CLOCK (MFR_SPECIFIC_07)............................................................ 43
10.9 (D8h) RUN_TIME_CLOCK_TRIM (MFR_SPECIFIC_08).................................................... 43
10.10 (D9h) ROM_MODE (MFR_SPECIFIC_09) .................................................................... 43
10.11 (DAh) USER_RAM_00 (MFR_SPECIFIC_10) ................................................................ 44
10.12 (DBh) SOFT_RESET (MFR_SPECIFIC_11).................................................................. 44
10.13 (DCh) RESET_COUNT (MFR_SPECIFIC_12) ............................................................... 44
10.14 (DDh) PIN_SELECTED_RAIL_STATES (MFR_SPECIFIC_13)............................................ 44
10.15 (DEh) RESEQUENCE (MFR_SPECIFIC_14)................................................................. 47
10.16 (DFh) CONSTANTS (MFR_SPECIFIC_15) ................................................................... 47
10.17 (E0h) PWM_SELECT (MFR_SPECIFIC_16).................................................................. 48
10.18 (E1h) PWM_CONFIG (MFR_SPECIFIC_17).................................................................. 48
10.19 (E2h) PARM_INFO (MFR_SPECIFIC_18) .................................................................... 48
10.20 (E3h) PARM_VALUE (MFR_SPECIFIC_19).................................................................. 49
10.21 (E4h) TEMPERATURE_CAL_GAIN (MFR_SPECIFIC_20)................................................. 49
10.22 (E5h) TEMPERATURE_CAL_OFFSET (MFR_SPECIFIC_21)............................................. 49
10.23 (E9h) FAULT_RESPONSES (MFR_SPECIFIC_25) ......................................................... 49
10.24 (EAh) LOGGED_FAULTS (MFR_SPECIFIC_26) ............................................................ 52
10.25 (EBh) LOGGED_FAULT_DETAIL_INDEX (MFR_SPECIFIC_27).......................................... 54
10.26 (ECh) LOGGED_FAULT_DETAIL (MFR_SPECIFIC_28) ................................................... 54
10.27 (EDh) LOGGED_PAGE_PEAKS (MFR_SPECIFIC_29)..................................................... 56
10.28 (EEh) LOGGED_COMMON_PEAKS (MFR_SPECIFIC_30)................................................ 57
10.29 (EFh) LOGGED_FAULT_DETAIL_ENABLES (MFR_SPECIFIC_31)...................................... 57
10.30 (F0h) EXECUTE_FLASH (MFR_SPECIFIC_32) ............................................................. 58
10.31 (F1h) SECURITY (MFR_SPECIFIC_33)....................................................................... 58
10.32 (F2h) SECURITY_BIT_MASK (MFR_SPECIFIC_34)........................................................ 59
10.33 (F3h) MFR_STATUS (MFR_SPECIFIC_35) .................................................................. 59
10.34 (F4h) GPI_FAULT_RESPONSES (MFR_SPECIFIC_36) ................................................... 61
10.35 (F5h) MARGIN_CONFIG (MFR_SPECIFIC_37).............................................................. 63
10.36 (F6h) SEQ_CONFIG (MFR_SPECIFIC_38)................................................................... 63
10.37 (F7h) GPO_CONFIG_INDEX (MFR_SPECIFIC_39)......................................................... 68
10.38 (F8h) GPO_CONFIG (MFR_SPECIFIC_40) .................................................................. 69
10.39 (F9h) GPI_CONFIG (MFR_SPECIFIC_41).................................................................... 80
10.40 (FAh) GPIO_SELECT (MFR_SPECIFIC_42) ................................................................. 83
10.41 (FBh) GPIO_CONFIG (MFR_SPECIFIC_43) ................................................................. 83
10.42 (FCh) MISC_CONFIG (MFR_SPECIFIC_44) ................................................................. 83
10.43 (FDh) DEVICE_ID (MFR_SPECIFIC_45)...................................................................... 84
11 Range Checking and Limits............................................................................................... 85
12 Glossary ..................................................................................................................... 90
List of Figures

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1 PMBus Status Supported by the UCD90320 ............................................................................ 6
2 Factors Determining the State of a GPO ............................................................................... 70
3 Ignore Inputs On ........................................................................................................... 72
4 Ignore Inputs Off ........................................................................................................... 73
5 Ignore Inputs On with Delay .............................................................................................. 73
6 State Machine .............................................................................................................. 74
7 Example of State Machine................................................................................................ 74
List of Tables
1 8-Bit Time Encoding......................................................................................................... 8
2 PMBus Commands ........................................................................................................ 11
3 Relationship Between PAGE and Rail .................................................................................. 19
4 Exponent Influence on Voltage Range and Resolution ............................................................... 21
5 Example Settings for Voltage Monitoring Ranges ..................................................................... 21
6 Replaced Fault Response Commands.................................................................................. 22
7 STATUS_FAN_1_2 Support.............................................................................................. 22
8 STATUS_FAN_3_4 Support.............................................................................................. 22
9 STATUS_FAN_1_2 Support With More Than Four Fans............................................................. 23
10 STATUS_FAN_3_4 Support With More Than Four Fans............................................................. 23
11 UCD90320 Pin ID Definitions............................................................................................. 25
12 PWM-Supported Frequencies............................................................................................ 28
13 BLACK_BOX_FAULT_INFO Command Format ...................................................................... 29
14 Fault Info Format........................................................................................................... 30
15 BLACK_BOX_FAULT_WARNING Command Format ................................................................ 30
16 BLACK_BOX_FAULT_WARNING Command Format ................................................................ 31
17 Rail N Value................................................................................................................. 31
18 RAIL_PROFILE Command Format (Write) ............................................................................. 31
19 RAIL_PROFILE Command Format (Read)............................................................................. 32
20 Number Profile (write) ..................................................................................................... 32
21 RAIL_STATE Command Format......................................................................................... 33
22 Rail State.................................................................................................................... 33
23 FAULT_PIN_CONFIG Command Format............................................................................... 34
24 SYSTEM_RESET_CONFIG Command Format ....................................................................... 36
25 GPI Tracking Configuration............................................................................................... 38
26 SYSTEM_WATCHDOG_CONFIG Command Format ................................................................ 38
27 Reset Period Configuration for UCD90320............................................................................. 40
28 Monitor Types............................................................................................................... 40
29 MONITOR_CONFIG Command Format ................................................................................ 41
30 Monitor Type and Page Byte ............................................................................................. 42
31 ADC Monitor Pin Definitions.............................................................................................. 42
32 RUN_TIME_CLOCK Command Format ................................................................................ 43
33 Changes to the OPERATION Command ............................................................................... 44
34 GPI Selection of System States.......................................................................................... 45
35 PIN_SELECTED_RAIL_STATES Command Format ................................................................. 45
36 RESEQUENCE Command Format ...................................................................................... 47
37 CONSTANTS Command Format ........................................................................................ 47
38 CONSTANTS for Each Device........................................................................................... 48
39 Valid PWM Pin IDs......................................................................................................... 48
40 PWM_CONFIG Command Format ...................................................................................... 48

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41 PARM_INFO Command Format ......................................................................................... 49
42 FAULT_RESPONSES Command Format .............................................................................. 50
43 Fault Response Byte Format ............................................................................................. 50
44 LOGGED_FAULTS Command Format.................................................................................. 52
45 Non-Paged Fault Log Bit Definitions..................................................................................... 52
46 GPI Fault Log Bit Definitions.............................................................................................. 53
47 Page-Dependent Fault Log Bit Definitions.............................................................................. 54
48 LOGGED_FAULT_DETAIL_INDEX Command Format............................................................... 54
49 LOGGED_FAULT_DETAIL Command Format......................................................................... 55
50 Number of Log Entries in Each Device Type........................................................................... 55
51 Fault Identification + Days ................................................................................................ 56
52 Fault Value.................................................................................................................. 56
53 LOGGED_PAGE_PEAKS Command Format.......................................................................... 57
54 LOGGED_FAULT_DETAIL_ENABLES Command Format........................................................... 57
55 Manufacturer Specific Status ............................................................................................. 59
56 GPI_FAULT_RESPONSES Command Format ........................................................................ 61
57 Rail Profile Pin Selection.................................................................................................. 62
58 MARGIN_CONFIG Command Format .................................................................................. 63
59 SEQ_CONFIG Command Format ....................................................................................... 64
60 Sequencing Timeout Configuration Byte................................................................................ 66
61 Relationship Between GPO_CONFIG_INDEX and the Actual GPO Number...................................... 69
62 GPO_CONFIG Command Format ....................................................................................... 70
63 Status Types................................................................................................................ 76
64 GPI_CONFIG Command Format ........................................................................................ 80
65 GPI Pin Configuration ..................................................................................................... 80
66 Fault Enable Bits ........................................................................................................... 81
67 GPI Selection ............................................................................................................... 81
68 MISC_CONFIG Command Format ...................................................................................... 83
69 Miscellaneous Configuration Byte........................................................................................ 84
70 Range and Limits for PMBus Commands............................................................................... 85
Trademarks
Microsoft, Windows are registered trademarks of Microsoft Corporation.
PMBus is a trademark of SMIF, Inc.

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1 PMBus Specification
This document makes frequent mention of the PMBus specification, specifically, the PMBus Power
System Management Protocol Specification Part II – Command Language, Revision 1.2. The specification
is published by the Power Management Bus Implementers Forum and is available from http://pmbus.org.
The types of status supported by the UCD90320 are shown in Figure 1. Whenever any of these bits are
set, the PMBALERT# line is asserted. Unsupported types are denoted with grayed-out text.

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Figure 1. PMBus Status Supported by the UCD90320

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1.1 Manufacturer Specific Status (STATUS_MFR_SPECIFIC)
The standard STATUS_MFR_SPECIFIC command does not have enough bits to implement UCD90320’s
functionalities. This command has been replaced by the MFR_STATUS command (see Section 10.33).
2 Data Formats
Sections 7 and 8 of the PMBus standard provides for five different data formats: three for parameters
related to output voltage and two for all other commands. Each PMBus device is expected to support only
one of these formats.
2.1 Data Format for Output Voltage Parameters
For parameters related to output voltage, the UCD90320 supports the linear format defined in Section
8.3.1 of the PMBus specification. The linear format uses a 16-bit unsigned mantissa for each parameter,
along with an exponent that is shared by all the voltage-related parameters. The exponent is reported in
the bottom 5 bits of the VOUT_MODE parameter.
The voltage value is calculated using the equation
Voltage = V × 2X(1)
Where:
Voltage is the parameter of interest, in volts,
V is a 16-bit unsigned binary integer mantissa, and
X is the signed 5-bit twos-complement binary integer exponent from VOUT_MODE.
Exception: The PMBus standard assumes that all output voltages are expressed as positive numbers;
therefore, all parameters related to output voltage are unsigned integers, with a few notable exceptions.
The VOUT_CAL_OFFSET, and VOUT_CAL_MONITOR values are intended for making fine adjustments
to the output voltage and may take on small negative values. As such, these parameters are treated as
signed twos-complement binary integers.
2.2 Data Format for Other Parameters
For parameters not directly related to output voltage, the UCD90320 supports the linear data format
described in section 7.1 of the PMBus specification. This linear format is a two-byte value that contains an
11-bit, twos-complement mantissa and a 5-bit, twos-complement exponent.
The relationship between the PMBus parameter and the real-world value is given by the formula:
R = Y × 2X(2)
Where:
R is the real-world value,
Y is an 11-bit, signed twos-complement binary integer mantissa, and
X is the signed 5-bit, `twos-complement binary integer exponent.
This pseudo floating-point notation allows values as large as ≈33E6 down to ≈15E-6 to be sent over the
PMBus. The internal variables used by the UCD90320 firmware are mostly 16 bits wide and do not
support such a wide range of values. The resolution of a PMBus setting depends strongly on both the
exponent of the PMBus value (larger values have coarser resolution) and the scaling of the internal
variables.

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2.3 Distinguishing Between Linear Data Formats
The PMBus specification uses the same term, linear, to describe both the 16-bit+exponent format used for
the voltage-related parameters as well as the 11-bit+exponent format used for other parameters. In cases
where it is necessary to distinguish between these two data formats, this document uses the term
LINEAR16 or LINEAR11.
2.4 Translation, Quantization, and Truncation
The internal variables used by the UCD90320 are often scaled to take optimal advantage of the
hardware’s native units such as ADC or DAC counts rather than volts or amperes. As a result, values that
are written and read via PMBus must undergo mathematical translations. These translations, with their
inherent quantization, may result in very slight differences between the setting that was written to the
UCD90320 and the value that was later read back from it. This is normal and compliant, described in
section 7.4 of the PMBus specification.
In some cases, a value written to the device may cause it to exceed the range of its internal variable. In
some cases, the device reports this as an error; in other cases it saturates the variable at a safe value. In
all cases, the value read back via the PMBus reflects as accurately as possible the internal variable
actually being used by the UCD90320.
2.5 8-Bit Time Encoding
To save memory when precision is not needed, several commands will encode a time parameter in 8-bits.
The 8 bits are separated into two fields. Bits 6 and 7 are the index for the multiplier field and bits 0 to 5 are
the mantissa (0x00 to 0x3F). The two are multiplied together to derive the time. A mantissa of 0 will result
in a time of 0 regardless of the multiplier value.
Table 1. 8-Bit Time Encoding
Multiplier Index Multiplier
(ms) Resulting Range
b’00 1 0 to 63 ms
b’01 8 8 to 504 ms
b’10 64 64 ms to 4.032 s
b’11 512 512 ms to 32.256 s

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3 Memory Model
Section 6 of the PMBus specification describes the memory model for PMBus devices. Values used by the
PMBus device are loaded into volatile Operating Memory from one or more of the following places:
• Values hard coded into an integrated circuit (IC) design (if any)
• Values programmed from hardware pins (if any)
• A nonvolatile memory called the Default Store
• A nonvolatile memory called the User Store (not supported by the UCD90320)
• Communications from PMBus
The UCD90320 contains RAM that is used as Operating Memory. Embedded Data Flash memory is used
to implement the hard-coded values and the Default Store values. Hard-coded values require a new
firmware revision. Values in the Default Store may be changed using the STORE_DEFAULT_ALL
command described in Section 6.3.
Section 6.1 of the PMBus specification describes the ordering of memory loading and precedence. In
general, the hard-coded parameters are loaded into Operating Memory first. Second, any pin-
programmable settings take effect. Third, values from the Default Store are loaded. Later, commands
issued from the PMBus take effect. In all cases, an operation on a parameter overwrites any prior value
that was already in the Operating Memory.
4 Alert Response Address Support
UCD90320 supports using the PMBALERT# line to notify the host of warning or fault conditions, but it
does not support the Alert Response Address protocol.

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5 Supported PMBus Commands
Table 2 lists the PMBus commands. Commands 00h through CFh are defined in the PMBus specification
and are considered to be core commands that are standardized for all manufacturers and products.
Commands D0h through FEh are manufacturer specific and may be unique for each manufacturer and
product.
The device columns (UCD90120, and so forth) indicate if a command is supported by a given device. The
command is supported if a check mark (√) appears in that column. Commands that are not supported by
any device are grayed out.
Most commands support writing and reading. Exceptions are indicated in the Comments column.
The Data Format column indicates the format of the data:
Byte 8-bit binary value. See the PMBus specification for details for each command.
LINEAR16 16-bit linear format used for output voltage parameters. Described in Section 2.1.
LINEAR11 11-bit linear format used for parameters other than output voltage. Described in Section 2.2.
n/a Command does not have a data field.
String ASCII string. Described in Section 22.2 of the PMBus specification.
Byte Array A block of data in binary format.
The Scope column indicates how each command is affected by the PAGE setting.
Common This command does not depend on the PAGE setting. It is a common variable used by all pages.
PAGE This command applies to the page(s) set by the most recent PAGE command. See Section 6.1 for details.
The Page column in Table 2 points to additional detail about the command. A number that is not in
parenthesis corresponds to the page in the PMBus Power System Management Protocol Specification
Part II – Command Language, Revision 1.1, dated 5 February 2007. The number in parenthesis is the
page number in this document.
The Data Flash column indicates if the parameter is stored in the Default Store in Data Flash. If an x
appears in that column, it is not stored. See Section 6.3 for more information.
Most commands are used for device configuration which is often only done once with the assistance of the
TI provided GUI (Fusion). In normal operation, only a subset of the commands are used frequently. Those
commands are highlighted in bold font.

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(1) There is a chance that a write to this command will receive a NACK. Once the firmware starts a periodic or commanded update of data flash, it may take up to 100 ms to complete. During
that time, writes to these commands will receive a NACK. If this occurs, wait 100 ms and retry the command. This note only applies if the brownout feature is not enabled (see Brownout
Enable in MISC_CONFIG).
Table 2. PMBus Commands
Code
(hex) Command Transaction Type Data Format [Units] Scope Page
UCD90124
UCD9090
UCD90910 UCD90160
UCD90120A UCD90124A
UCD90240 UCD90320
Data Flash
Comments
00 PAGE R/W Byte Byte Common 46
(19) √ √ √ √ √ √ √ √ x
01 OPERATION R/W Byte Byte PAGE 49(1
9) √ √ √ √ √ √ √ √ x
02 ON_OFF_CONFIG R/W Byte Byte PAGE 51 √ √ √ √ √ √ √ √
03 CLEAR_FAULTS Send Byte n/a Common 60 √ √ √ √ √ √ √ √ Write Only
04 PHASE
05-0F Reserved
10 WRITE_PROTECT 43
11 STORE_DEFAULT_ALL Send Byte n/a Common 43
(20) √ √ √ √ √ √ √ √ Write Only(1)
12 RESTORE_DEFAULT_ALL Send Byte n/a Common 44
(20) √Write Only
13 STORE_DEFAULT_CODE 44
14 RESTORE_DEFAULT_CODE 44
15 STORE_USER_ALL 45
16 RESTORE_USER_ALL 45
17 STORE_USER_CODE 46
18 RESTORE_USER_CODE 46
19 CAPABILITY Read Byte Byte Common 48 √ √ √ √ √ √ √ √ Read Only
1A QUERY 49
1B SMBALERT_MASK R/W Word Byte
1C-1F Reserved
20 VOUT_MODE R/W Byte Byte PAGE 24
(21) √ √ √ √ √ √ √ √ The mode is fixed at 000 (Linear Mode), but the
exponent may be modified. See Section 2.1 and
Section 6.6 for details.
21 VOUT_COMMAND R/W Word LINEAR16 [V] PAGE 52 √ √ √ √ √ √ √ √
22 VOUT_TRIM 52
23 VOUT_CAL_OFFSET 52
24 VOUT_MAX 53
25 VOUT_MARGIN_HIGH R/W Word LINEAR16 [V] PAGE 53 √ √ √ √ √ √ √ √
26 VOUT_MARGIN_LOW R/W Word LINEAR16 [V] PAGE 53 √ √ √ √ √ √ √ √
27 VOUT_TRANSITION_RATE 53
28 VOUT_DROOP 54
29 VOUT_SCALE_LOOP 54
2A VOUT_SCALE_MONITOR R/W Word LINEAR11 [V/V] PAGE 54 √ √ √ √ √ √ √ √
2B-2F Reserved

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Table 2. PMBus Commands (continued)
Code
(hex) Command Transaction Type Data Format [Units] Scope Page
UCD90124
UCD9090
UCD90910 UCD90160
UCD90120A UCD90124A
UCD90240 UCD90320
Data Flash
Comments
(2) These values are only applied when associated voltage is in regulation. If there is not an associated voltage monitor, these values are applied after the rail is enabled and after
TON_DELAY.
30 COEFFICIENTS 54
31 POUT_MAX 55
32 MAX_DUTY 55
33 FREQUENCY_SWITCH 56
34 Reserved
35 VIN_ON 56
36 VIN_OFF 56
37 INTERLEAVE 56
38 IOUT_CAL_GAIN R/W Word LINEAR11
[mV/A = mΩ]PAGE 57 (22) √ √ √ √ √ √ √ Current sense gain
39 IOUT_CAL_OFFSET R/W Word LINEAR11 [A] PAGE 58 √ √ √ √ √ √ √
3A FAN_CONFIG_1_2 58 See FAN_CONFIG command, E8h
3B FAN_COMMAND_1 R/W Word LINEAR11 [%] Common 58 () √√√x % Duty cycle (0-100%) RPM Command mode
3C FAN_COMMAND_2 R/W Word LINEAR11 [%] Common 60 √√√x See FAN_COMMAND_1
3D FAN_CONFIG_3_4 59 See FAN_CONFIG command, E8h
3E FAN_COMMAND_3 R/W Word LINEAR11 [%] Common 60 √√√x See FAN_COMMAND_1
3F FAN_COMMAND_4 R/W Word LINEAR11 [%] Common 60 √√√x See FAN_COMMAND_1
40 VOUT_OV_FAULT_LIMIT R/W Word LINEAR16 [V] PAGE 60 √ √ √ √ √ √ √ √
41 VOUT_OV_FAULT_RESPONSE R/W Byte Byte PAGE 61
(23) See FAULT_RESPONSES command
42 VOUT_OV_WARN_LIMIT R/W Word LINEAR16 [V] PAGE 61 √ √ √ √ √ √ √ √
43 VOUT_UV_WARN_LIMIT R/W Word LINEAR16 [V] PAGE 61 √ √ √ √ √ √ √ √
44 VOUT_UV_FAULT_LIMIT R/W Word LINEAR16 [V] PAGE 62 √ √ √ √ √ √ √ √
45 VOUT_UV_FAULT_RESPONSE R/W Byte Byte PAGE 62
(23) See FAULT_RESPONSES command
46 IOUT_OC_FAULT_LIMIT R/W Word LINEAR11 [A] PAGE 62 √ √ √ √ √ √ √ See (2)
47 IOUT_OC_FAULT_RESPONSE R/W Byte Byte PAGE 62
(23) See FAULT_RESPONSES command
48 IOUT_OC_LV_FAULT_LIMIT 63
49 IOUT_OC_LV_FAULT_RESPONSE 63
4A IOUT_OC_WARN_LIMIT R/W Word LINEAR11 [A] PAGE 63 √ √ √ √ √ √ √ See (2)
4B IOUT_UC_FAULT_LIMIT R/W Word LINEAR11 [A] PAGE 63 √ √ √ √ √ √ √ See (2)
4C IOUT_UC_FAULT_RESPONSE R/W Byte Byte PAGE 64
(23) See FAULT_RESPONSES command
4D Reserved
4E Reserved
4F OT_FAULT_LIMIT R/W Word LINEAR11 [°C] PAGE 64 √ √ √ √ √ √ √

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Table 2. PMBus Commands (continued)
Code
(hex) Command Transaction Type Data Format [Units] Scope Page
UCD90124
UCD9090
UCD90910 UCD90160
UCD90120A UCD90124A
UCD90240 UCD90320
Data Flash
Comments
50 OT_FAULT_RESPONSE R/W Byte Byte PAGE 64
(23) See FAULT_RESPONSES command
51 OT_WARN_LIMIT R/W Word LINEAR11 [°C] PAGE 64 √ √ √ √ √ √ √
52 UT_WARN_LIMIT 64
53 UT_FAULT_LIMIT 64
54 UT_FAULT_RESPONSE 64
55 VIN_OV_FAULT_LIMIT 66
56 VIN_OV_FAULT_RESPONSE 66
57 VIN_OV_WARN_LIMIT 66
58 VIN_UV_WARN_LIMIT 66
59 VIN_UV_FAULT_LIMIT 67
5A VIN_UV_FAULT_RESPONSE 67
5B IIN_OC_FAULT_LIMIT 68
5C IIN_OC_FAULT_RESPONSE 68
5D IIN_OC_WARN_LIMIT 68
5E POWER_GOOD_ON R/W Word LINEAR16 [V] PAGE 69 √ √ √ √ √ √ √ √
5F POWER_GOOD_OFF R/W Word LINEAR16 [V] PAGE 69 √ √ √ √ √ √ √ √
60 TON_DELAY R/W Word LINEAR11 [ms] PAGE 70 √ √ √ √ √ √ √ √ This does not apply to retries
61 TON_RISE 70
62 TON_MAX_FAULT_LIMIT R/W Word LINEAR11 [ms] PAGE 71
(23) √ √ √ √ √ √ √ √ Maximum time to reach POWER_GOOD_ON
63 TON_MAX_FAULT_RESPONSE R/W Byte Byte PAGE 71
(23) See FAULT_RESPONSES command
64 TOFF_DELAY R/W Word LINEAR11 [ms] PAGE 71 √ √ √ √ √ √ √ √
65 TOFF_FALL 71
66 TOFF_MAX_WARN_LIMIT R/W Word LINEAR11 [ms] PAGE 72 √ √ √ √ √ √ √ √
67 Reserved
68 POUT_OP_FAULT_LIMIT 69
69 POUT_OP_FAULT_RESPONSE 69
6A POUT_OP_WARN_LIMIT 70
6B PIN_OP_WARN_LIMIT 70
6C-77 Reserved
78 STATUS_BYTE Read Byte Byte Common 72 √ √ √ √ √ √ √ √ x Read Only
79 STATUS_WORD Read Word Word Common 74 √ √ √ √ √ √ √ √ x Read Only
7A STATUS_VOUT Read Byte Byte PAGE 75 √ √ √ √ √ √ √ √ x Read Only
7B STATUS_IOUT Read Byte Byte PAGE 75 √ √ √ √ √ √ √ x Read Only
7C STATUS_INPUT 76
7D STATUS_TEMPERATURE Read Byte Byte PAGE 76 √ √ √ √ √ √ √ x Read Only

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Table 2. PMBus Commands (continued)
Code
(hex) Command Transaction Type Data Format [Units] Scope Page
UCD90124
UCD9090
UCD90910 UCD90160
UCD90120A UCD90124A
UCD90240 UCD90320
Data Flash
Comments
7E STATUS_CML Read Byte Byte Common 76 √ √ √ √ √ √ √ √ x Read Only
7F STATUS_OTHER 77
80 STATUS_MFR_SPECIFIC 78 See MFR_STATUS
81 STATUS_FANS_1_2 Read Byte Byte Common 78
(23) √√√x Read Only
82 STATUS_FANS_3_4 Read Byte Byte Common 79
(23) √√√x Read Only
83-87 Reserved
88 READ_VIN 80
89 READ_IIN 80
8A READ_VCAP 80
8B READ_VOUT Read Word LINEAR16 [V] PAGE 80 √ √ √ √ √ √ √ √ x Read Only
8C READ_IOUT Read Word LINEAR11 [A] PAGE 80 √ √ √ √ √ √ √ x Read Only
8D READ_TEMPERATURE_1 Read Word LINEAR11 [°C] Common 80
(24) √ √ √ √ √ √ √ x Read Only
8E READ_TEMPERATURE_2 R/W Word LINEAR11 [°C] PAGE 80
(24) √ √ √ √ √ √ √ x UCD90120 and UCD90124: Read Only
8F READ_TEMPERATURE_3 80
90 READ_FAN_SPEED_1 Read Word LINEAR11 [RPM] Common 81
(25) √√√x Read Only (Only valid when the fan is enabled.)
91 READ_FAN_SPEED_2 Read Word LINEAR11 [RPM] Common 81
(25) √√√x Read Only (Only valid when the fan is enabled.)
92 READ_FAN_SPEED_3 Read Word LINEAR11 [RPM] Common 81
(25) √√√x Read Only (Only valid when the fan is enabled.)
93 READ_FAN_SPEED_4 Read Word LINEAR11 [RPM] Common 81
(25) √√√x Read Only (Only valid when the fan is enabled.)
94 READ_DUTY_CYCLE 81
95 READ_FREQUENCY 81
96 READ_POUT 81
97 READ_PIN 81
98 PMBUS_REVISION Read Byte Byte Common 82 √ √ √ √ √ √ √ √ Read Only
99 MFR_ID R/W Block
(18 bytes) String Common 83 √ √ √ √ √ √ √ √
9A MFR_MODEL R/W Block
(12 bytes) String Common 83 √ √ √ √ √ √ √ √
9B MFR_REVISION R/W Block
(12 bytes) String Common 83 √ √ √ √ √ √ √ √
9C MFR_LOCATION R/W Block
(12 bytes) String Common 83 √ √ √ √ √ √ √ √
9D MFR_DATE R/W Block
(6 bytes) String Common 83 √ √ √ √ √ √ √ √

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Table 2. PMBus Commands (continued)
Code
(hex) Command Transaction Type Data Format [Units] Scope Page
UCD90124
UCD9090
UCD90910 UCD90160
UCD90120A UCD90124A
UCD90240 UCD90320
Data Flash
Comments
9E MFR_SERIAL R/W Block
(12 bytes) String Common 83 √ √ √ √ √ √ √ √
9F Reserved
A0 MFR_VIN_MIN 84
A1 MFR_VIN_MAX 84
A2 MFR_IIN_MAX 84
A3 MFR_PIN_MAX 84
A4 MFR_VOUT_MIN 84
A5 MFR_VOUT_MAX 84
A6 MFR_IOUT_MAX 84
A7 MFR_POUT_MAX 84
A8 MFR_TAMBIENT_MAX 84
A9 MFR_TAMBIENT_MIN 84
AA-AC Reserved
AD IC_DEVICE_ID Block Read String Common (25) √ √ PMBus 1.2
AE IC_DEVICE_REV Block Read String Common (25) √ √ PMBuS 1.2
AF Reserved
B0-B4 MFR_STATUS_0-MFR_STATUS_4 √ √ Must be used with SMBALERT_MASK (0x1B) to
write/read MFR_STATUS SMB alert mask
B5 BLACK_BOX_LOG_FAULT_INFO
(USER_DATA_05) B/W Block Byte Array Common √ √ X Block Box First Fault log
B6 BLACK_BOX_LOG_RAILS_WARNING
(USER_DATA_06) Block Read Byte Array Common √ √ X All rails warning when first fault was present
B7 BLACK_BOX_LOG_RAILS_VALUE
(USER_DATA_07) Block Read Byte Array Common √ √ X All rails value when the first fault was present
B8 RAIL_PROFILE(USER_DATA_08) Block Read Byte Array PAGE (33) √
B9 RAIL_STATE(USER_DATA_09) Block Read Byte Array PAGE (35) √
BA-BF USER_DATA_05-USER_DATA_0F
C0-CF Reserved
D0 SEQ_TIMEOUT / FAULT_PIN_CONFIG(UCD90240/320)
(MFR_SPECIFIC_00)
R/W Word/ R/W
Block LINEAR 11[ms]/ Byte Array Page/Comm on (37) √ √ √ Must be configured along with GPI_CONFIG
which selects the external pin to use for the input
source
D1 VOUT_CAL_MONITOR
(MFR_SPECIFIC_01) R/W Word LINEAR16 [V] PAGE (39) √ √ √ √ √ √ √ √ Offset calibration value for the sensor used in READ_VOUT. Signed.
D2 SYSTEM_RESET_CONFIG
(MFR_SPECIFIC_02) R/W Block (4, 6, or 9 bytes) Byte Array Common (39) √ √ √ √ √ √ √ √ Configures the System Reset function
D3 SYSTEM_WATCHDOG_CONFIG
(MFR_SPECIFIC_03) R/W Block (4 bytes) Byte Array Common (43) √ √ √ √ √ √ √ √ Configures the System Watchdog function
D4 SYSTEM_WATCHDOG_RESET
(MFR_SPECIFIC_04) Send Byte n/a Common (45) √ √ √ √ √ √ √ √ Resets the System Watchdog timeout counter
D5 MONITOR_CONFIG
(MFR_SPECIFIC_05) R/W Block Byte Array Common (45) √ √ √ √ √ √ √ √ Configure pins for monitoring (voltage, temperature, and so forth)

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Table 2. PMBus Commands (continued)
Code
(hex) Command Transaction Type Data Format [Units] Scope Page
UCD90124
UCD9090
UCD90910 UCD90160
UCD90120A UCD90124A
UCD90240 UCD90320
Data Flash
Comments
D6 NUM_PAGES
(MFR_SPECIFIC_06) Read Byte Byte Common (48) √ √ √ √ √ √ √ √ READ-ONLY Returns the number of active pages
D7 RUN_TIME_CLOCK
(MFR_SPECIFIC_07) R/W Block Byte Array Common (49) √ √ √ √ √ √ √ √ Time in milliseconds and days (4 bytes each)
D8 RUN_TIME_CLOCK_TRIM
(MFR_SPECIFIC_08) R/W Word LINEAR11 [%] Common (49) √ √ √ √ √ √ √ √ Percent adjustment for calibrating the Run-Time Clock
D9 ROM_MODE
(MFR_SPECIFIC_09) Send Byte n/a Common (50) √ √ √ √ √ √ √ √ WRITE-ONLY
This command sends the device back into ROM
mode.
DA USER_RAM_00 (MFR_SPECIFIC_10) R/W Byte Byte Common (50) √ √ √ √ √ √ √ √
RAM value that is set to 0 during device reset.
By writing a nonzero value to this variable and
then monitoring its value, a host may determine
that a device reset has occurred.
DB SOFT_RESET (MFR_SPECIFIC_11) Send Byte n/a Common (50) √ √ √ √ √ √ √ √ WRITE-ONLY
This command restarts the controller firmware.
DC RESET_COUNT (MFR_SPECIFIC_12) R/W Word (a) 2 Bytes(a) Common (50) √ √ √ √ √ √ √ √
The number of times that the device has been
reset.
√
DD PIN_SELECTED_RAIL_STATES
(MFR_SPECIFIC_13) Read Block (18 bytes) Byte Array Common (51) √ √ √ √ √ √ Allows encoding on input pins to decide into what state each of the rails should be.
DE RESEQUENCE
(MFR_SPECIFIC_14) Write Word 2 Bytes Common (54) √√√√√√√xCommands selected rails to resequence. (Write Only)
DF CONSTANTS
(MFR_SPECIFIC_15) Read Block (8 bytes) Byte Array Common (51) √ √ √ √ √ √ √ √ Fixed information about the device
E0 PWM_SELECT
(MFR_SPECIFIC_16) R/W Byte Byte Common (56) √ √ √ √ √ √ √ √ xDetermines which PWM the PWM_CONFIG command applies to
E1 PWM_CONFIG
(MFR_SPECIFIC_17) R/W Block (8 bytes) Byte Array Common (56) √ √ √ √ √ √ √ √ Configures a PWM (frequency, duty cycle, and phase)
E2 PARM_INFO
(MFR_SPECIFIC_18) R/W Block (5 bytes) Byte Array Common (56) √ √ √ √ √ √ √ √ x
Parm Info
<parm base>
<parm offset low byte>
<parm offset high byte>
<parm count>
<parm size>
This command sets the parameters used by the
Parm Value command.
E3 PARM_VALUE
(MFR_SPECIFIC_19) R/W Block Byte Array Common (57) √ √ √ √ √ √ √ √ xValue transferred to memory location chosen by the PARM_INFO command
E4 TEMPERATURE_CAL_GAIN
(MFR_SPECIFIC_20) R/W Word LINEAR11 [°C/V] PAGE (57) √ √ √ √ √ √ √ Gain calibration for the external sensors used by the READ_TEMPERATURE_2 command
E5 TEMPERATURE_CAL_OFFSET
(MFR_SPECIFIC_21) R/W Word LINEAR11[°C] PAGE (58) √ √ √ √ √ √ √ Offset calibration for the external sensors used by the READ_TEMPERATURE_2 command
E6 TEMPERATURE_BIAS_PIN
(MFR_SPECIFIC_22)
E7 FAN_CONFIG_INDEX
(MFR_SPECIFIC_23) R/W Byte Byte Common ( ) √√√xSelects to which fan the FAN_CONFIG command applies
E8 FAN_CONFIG
(MFR_SPECIFIC_24) R/W Block (15 Bytes) Byte Array Common ( ) √ √ √ Fan configuration – fault detection, auto adjust, and so forth

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Table 2. PMBus Commands (continued)
Code
(hex) Command Transaction Type Data Format [Units] Scope Page
UCD90124
UCD9090
UCD90910 UCD90160
UCD90120A UCD90124A
UCD90240 UCD90320
Data Flash
Comments
E9 FAULT_RESPONSES
(MFR_SPECIFIC_25) R/W Block (9 Bytes) Byte Array PAGE (58) √ √ √ √ √ √ √ √ Defines the response to all supported faults
EA LOGGED_FAULTS
(MFR_SPECIFIC_26) R/W Block Byte Array Common (62) √ √ √ √ √ √ √ √ Flags in Data Flash that are set when each fault type occurs on each page(1)
EB LOGGED_FAULT_DETAIL_INDEX
(MFR_SPECIFIC_27) R/W Word 2 bytes Common (64) √ √ √ √ √ √ √ √ xNumber of LOGGED_FAULT_DETAIL entries and a read/write index into those entries
EC LOGGED_FAULT_DETAIL
(MFR_SPECIFIC_28) Read Block Byte Array Common (65) √ √ √ √ √ √ √ √ Detail information about the faults that have occurred
ED LOGGED_PAGE_PEAKS
(MFR_SPECIFIC_29) R/W Block Byte Array Byte [°C],
LINEAR16 [V],
LINEAR11 [amp] PAGE (66) √ √ √ √ √ √ √ √ Peak temperature, voltage, and current for a
given page, stored in Data Flash(1)
EE LOGGED_COMMON_PEAKS
(MFR_SPECIFIC_30) R/W Byte Byte [°C] Common (68) √ √ √ √ √ √ √ Peak internal temperature(1)
EF LOGGED_FAULT_DETAIL_ENABLES
(MFR_SPECIFIC_31) R/W Block Byte Array Common (69) √ √ √ √ √ √ √ √ Selectable fault logging by rail and by fault type
F0 EXECUTE_FLASH
(MFR_SPECIFIC_32) Send Byte n/a Common (70) √ √ √ √ √ √ If in ROM mode, starts the device executing in
FLASH mode. If already in FLASH mode,
command has no effect.
F1 SECURITY
(MFR_SPECIFIC_33) R/W Block (6 bytes) Binary Array Common (70) √ √ √ √ √ √ Sets the password used to secure the unit against unauthorized modification of its settings
F2 SECURITY_BIT_MASK
(MFR_SPECIFIC_34) R/W Block (32 bytes) Binary Array Common (71) √ √ √ Configures which commands are password protected
F3 MFR_STATUS
(MFR_SPECIFIC_35) Read Block (2 or 4 or 5 bytes) Byte Array PAGE (72) √ √ √ √ √ √ √ √ xReplaces the STATUS_MFR_SPECIFIC command
F4 GPI_FAULT_RESPONSES
(MFR_SPECIFIC_36) R/W Block Byte Array PAGE 75 √ √ GPI fault responses per page
F5 MARGIN_CONFIG
(MFR_SPECIFIC_37)
UC90240:
R/W Word
All others:
R/W Byte
UC90240: R/W Word
All others: R/W Byte PAGE (77) √ √ √ √ √ √ √ √ Selects the margining pin and other margining configuration
F6 SEQ_CONFIG
(MFR_SPECIFIC_38) R/W Block (6-12 bytes) Byte Array PAGE (78) √ √ √ √ √ √ √ √ Configures sequencing dependencies and enable pin
F7 GPO_CONFIG_INDEX
(MFR_SPECIFIC_39) R/W Byte Byte Common (84) √ √ √ √ √ √ √ √ xSelects to which GPO the GPO_CONFIG
command applies. On UCD90240, also selects
AND-Path.
F8 GPO_CONFIG
(MFR_SPECIFIC_40) R/W Block (20 or 29 bytes) Byte Array Common (84) √ √ √ √ √ √ √ √ Configures output pins and their dependencies
F9 GPI_CONFIG
(MFR_SPECIFIC_41) R/W Block (13 bytes) Byte Array Common (100) √ √ √ √ √ √ √ √ Configures input pins
FA GPIO_SELECT
(MFR_SPECIFIC_42) R/W Byte Byte Common (104) √ √ √ √ √ √ √ √ xDetermines to which GPIO the GPIO_CONFIG command applies
FB GPIO_CONFIG
(MFR_SPECIFIC_43) R/W Byte Byte Common (104) √ √ √ √ √ √ √ √ Set or get the state of a GPIO
FC MISC_CONFIG
(MFR_SPECIFIC_44) R/W Block 2 Bytes Common (105) √ √ √ √ √ √ √ √ Miscellaneous configuration settings
FD DEVICE_ID
(MFR_SPECIFIC_45) Read Block (up to 32 bytes) String Common (104) √ √ √ √ √ √ √ √ Returns ASCII string with hardware and firmware version information of the controller

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Table 2. PMBus Commands (continued)
Code
(hex) Command Transaction Type Data Format [Units] Scope Page
UCD90124
UCD9090
UCD90910 UCD90160
UCD90120A UCD90124A
UCD90240 UCD90320
Data Flash
Comments
FE Mfr_Specific_Extended_Command
FF PMBUS_Extended_Command

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6 Implementation Details for PMBus Core Commands
The following PMBus core commands are defined in the PMBus specification. This section describes
details that are unique to the UCD90320 implementation.
6.1 (00h) PAGE
The PAGE command provides the ability to configure, control, and monitor multiple outputs on one unit
using a single PMBus physical address. When the PAGE command is sent, all subsequent commands are
applied to settings for the rail selected by the PAGE command.
The Fusion Digital Power Designer software uses the term Rail to refer to a voltage output. Rails are
numbered starting with one, whereas pages are numbered starting at zero. The relationship between the
PMBus PAGE value and the Rail number is shown in Table 3.
Setting PAGE = 0xFF means that the following write commands are to be applied to all outputs. A page
setting of 0xFF is invalid for all read commands, with the exception of the PAGE command.
(1) The maximum number of rails on the UCD90320 is 24.
Table 3. Relationship Between PAGE and Rail
Page Output Rail
0 1
1 2
2 3
... ...
23(1) 24
24 – 254 Invalid
255 (0xFF) All
Section 11.10 of the PMBus specification describes the PAGE command in more detail.
6.2 (01h) OPERATION
This command is used to turn outputs on and off along with input from the CONTROL pin. Section 12.1 of
the PMBus specification describes this command in more detail.
The UCD90320 supports the following modes for the Operation command:
• Immediate Off (No Sequencing)
• Soft Off (With Sequencing)
• On Nominal (No Margining)
• On Margin High (Ignore Faults)
• On Margin High (Act on Fault)
• On Margin Low (Ignore Faults)
• On Margin Low (Act on Fault)
6.3 (11h) STORE_DEFAULT_ALL
The STORE_DEFAULT_ALL command saves the PMBus parameters from Operating Memory into the
Default Store in Data Flash. The UCD90320 uses the most recently written set of Default Store values at
startup or after a RESTORE_DEFAULT_ALL command. If the Default Store has never been written,
values from the hard-coded memory are used.

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NOTE: The device configuration will be corrupted if a power cycle or a reset occurs before this save
operation is completed. To ensure a successful save operation, after writing the
STORE_DEFAULT_ALL command, wait for the STORE_DEFAULT_ALL_DONE bit to be set
(see the MFR_STATUS). Once that bit is set, check the STORE_DEFAULT_ALL_ERROR
bit. If the STORE_DEFAULT_ALL_DONE bit is set and the STORE_DEFAULT_
ALL_ERROR is not set, the operation was successful.
NOTE: Monitoring and other tasks (including PMBus communication) are not performed during this
save operation which may take up to 100 milliseconds.
6.4 (12h) RESTORE_DEFAULT_ALL
The RESTORE_DEFAULT_ALL command restores the PMBus parameters from the Default Store into
Operating Memory. If the Default Store has never been written, values from the hard-coded memory are
used
NOTE: Resetting the device is a better (more thorough) way to perform this operation.
6.5 (1Bh) SMBALERT_MASK
This command is added in PMBUS specification 1.2 and is described in section 15.38. It is used to block a
status bit(s) from causing the SMBALERT# signal to be asserted. Refer to PMBUS specification document
for format details. This command has to be used together with status command codes in order to write or
read the mask of a specific status bit. The status command codes that can be used with this command
include:
• STATUS_VOUT
• STATUS_IOUT
• STATUS_TEMPERATURE
• STATUS_CML
• STATUS_FANS_1_2
• STATUS_FANS_3_4
Another status command code, MFR_STATUS, also needs to work with the SMBALERT_MASK
command. However, SMBALERT_MASK can only write/read one byte mask at a time. Since
MFR_STATUS contains 40 bits, it is split into 5 sub-commands to work with the SMBALERT_MASK
command:
• MFR_STATUS_0: for MFR_STATUS bit 7 to 0
• MFR_STATUS_1: for MFR_STATUS bit 15 to 8
• MFR_STATUS_2: for MFR_STATUS bit 23 to 16
• MFR_STATUS_3: for MFR_STATUS bit 31 to 24
• MFR_STATUS_4: for MFR_STATUS bit 39 to 32
6.6 (20h) VOUT_MODE
This command, described in Sections 8.1 and 8.2 of the PMBus specification, indicates the data format
used for all commands related to output voltage (all LINEAR16 commands). The command includes a 3-
bit Mode field and a 5-bit Parameter field. In UCD90320, the Mode field is a read-only and is fixed to
000b(linear data format, described in Section 2.1). The Parameter field is the exponent value and can be
modified.
NOTE: This exponent field must be updated before modifying any value that is affected by this
setting (all LINEAR16 commands).