Renesas RTKA271082DE0000BU User manual

Evaluation Board Manual
R33UZ0006EU0100 Rev.1.00 Page 1
Jul 25, 2022 © 2022 Renesas Electronics
The RTKA271082DE0000BU evaluates the
performance of the RAA271082 Automotive PMIC
with three synchronous buck regulators and one low
dropout linear regulator. The evaluation board is
intended for use in point-of-load automotive
applications, including camera systems, with 4.5V to
42V input supply range.
In addition to four output voltages, the evaluation
board also contains an I2C interface, a RSTB status
indicator, and a general purpose I/O (GPIO) signal.
The RAA271082 is offered in a 4mm×4mm 24-lead
Step Cut QFN (SCQFN) package with an exposed
pad. The RAA271082 is qualified to AEC-Q100,
Grade1.
Features
▪VIN operating range from 4.0 to 42V
▪Start range 4.5 to 42V
▪Three synchronous bucks with internal
compensation and one LDO
▪Fixed Frequency 2.2MHz
▪Over-temperature, overcurrent, overvoltage and
negative overcurrent protection
Specifications
▪VIN range: 4V to 42V
▪VOUT1 range 2.8V to 5.05V, up to 1A
▪VOUT2 range 0.85V to 3.3V, up to 1A
▪VOUT3 range 0.85V to 3.3V, up to 1A
▪LDO4 range 2.87V to 3.4V, up to 300mA
▪I2C interface
▪RSTB and GPIO signals
Figure 1. Block Diagram
RAA271082
PHASE1
FB1
EN
VIN1
PGND1
PHASE2
FB2
LDOIN4
PHASE3
FB3
LDOOUT4
PGND2/3
LDOOUT4
BOOT1
VOUT1
3.8V at 1A
(2.8V – 5.05V)
VOUT2
1.8V at 1A
(0.85V - 3.3V)
VOUT3
1.2V at 1A
(0.85V - 3.3V)
VIN2/3
RSTB
EN_LV
BYP
CFG1
BYP
Enable From System,
or EN tied to VIN1 pin
LV Enable From System
or EN_LV tied to BYP
_
SDA
SCL
GPIO
I
2
C Serial
Interface
4.7µH
10µF
0.1µF
0.1µF
1µF
1.5µH
1.5µH
2x10µF
2x10µF
3.3V at 300mA
VIN
(4-42V, 45V max)
0.22µF
4.7µF
(2.7V – 3.4V)
RTKA271082DE0000BU

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RTKA271082DE0000BU Evaluation Board Manual
Contents
1. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Manual Output Control using EN and EN_LV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 GUI (Graphical User Interface) Control of EN and EN_LV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Testing the Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.1 Input and Output Connections and Test Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. GUI Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Changing Programming Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Fault Status Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1 Displaying Detected Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3 Fault Response Mask Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.4 Fault to GPIO Control Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.5 GPIO Pin Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.6 RSTB Pin / WWDT Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6.1 RSTB Operation and Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6.2 WWDT Operation and Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.7 Misc Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.7.1 Misc1 Options – Register 0x7B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.7.2 Misc2 Options – Register 0x7C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.7.3 Misc3 Options – Register 0x7D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.8 Reg Map Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.9 REA Dongle tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.10 Log Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3. Board Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1 Layout Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.3 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.4 Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4. Typical Performance Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5. Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6. Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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RTKA271082DE0000BU Evaluation Board Manual
1. Functional Description
The evaluation board with connections, headers, and test points is shown in Figure 2.
The EN and EN_LV pins can be manually controlled by installing jumpers J1 (top left) and J3 (top right) as shown
in Figure 2. This allows manual control of the Buck1 and Buck2/Buck3/LDO4 regulators.
For EN control, a 2-pin jumper should be installed on either J1 or J2, but not both. Installing both could damage
the USB interface board.
For EN_LV control, a 2-pin jumper should be installed on either J3 or J6, but not both. Installing both could
damage the USB interface board or the RAA271082 IC.
Figure 2. RAA271082 Evaluation Board: Connections, Headers, and Test Points
J1: 3-Pin Header
for Manual EN Control
TP11:
EN Test Poin t
TP14:
EN_LV
Test Point
VIN1 Input Vout1 Output
TP16: SCL TP17: RSTB
TP7
(GND)
TP5
(+)
TP1
(+)
TP3
(GND)
TP10 (GND)
TP6 (+)
TP8 (GND-)
TP15: SDA TP13: GPIO
Digital Test Points
TP2 (+)
TP4 (GND)
J2: 2-pin Header
for I
2
C Control
of EN
TP9 (+)
USB Interface Board
J4: 3-pin CFG1
Configuration Header
J3: 3-Pin Header for
Manual EN_LV Control
J6: 2-pin Header
for I
2
C Control
of EN_LV
LDO4 Output
VOUT3 Output
Vout2 Output
TP12:
BYP
USB 2.0 Mini-B
Connector

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1.1 Manual Output Control using EN and EN_LV
For manual control of EN, install a jumper on J1 and ensure that J2 jumper is not installed.. The upper position of
J1 connects EN to the VIN1 supply and enables the IC. The lower position connects EN to GND and disables the
IC. EN can be controlled directly by removing the jumpers from J1 and J2 completely and connecting a DC source
to TP11, the EN test point.
The following are the states of the EN:
▪EN = GND. The IC is off and in its lowest power state.
▪EN = 1.5V. The IC is in Standby Mode. It will communicate through I2C but all outputs are off. This state cannot
be entered using jumpers; removing the jumper and driving EN to 1.5V will enable Standby mode.
▪EN > 1.8V. The IC is on and Buck1 (high voltage regulator) is enabled. The low voltage regulators are then
enabled/disabled using the EN_LV input.
For manual control of EN_LV, install a jumper on J3 and ensure that J6 jumper is not installed. EN_LV controls
outputs Buck2, Buck3, LDO4. The J3 upper position connects EN_LV to the BYP supply and enables the outputs.
The J3 lower position connects EN_LV to GND and disables the outputs. EN_LV can also be driven directly by
removing the jumper from J3 and J6 and connecting a DC source to TP14, the EN_LV test point.
Note: EN_LV is a low-voltage input limited to 5.5V maximum.
The following are states of the EN_LV:
▪EN_LV = GND. The low voltage (Buck2, Buck3, LDO4) outputs are off.
▪EN > 1.5V. The low voltage outputs are enabled.
When using manual control of EN and EN_LV, the GUI cannot be used to select options such as output voltage
setting, UV and OV thresholds. The GUI is still able to do operations that do not involve option selections, such as:
▪Read and clear fault status bits (registers 0x80 – 0x83)
▪Enable and disable the IC response to various faults (registers 0x85 – 0x87)
▪Enable and disable GPIO and RSTB response to various faults (registers 0x8A – 0x8D)
▪Configure and use the Windowed Watchdog Timer (WWDT) (registers 0xA0 – 0xA3)
▪Configure the GPIO and RSTB pin functions (registers 0xA4, 0xA5)
1.2 GUI (Graphical User Interface) Control of EN and EN_LV
GUI control of EN and EN_LV is enabled by removing the 2-pin jumpers from J1 and J3, and installing the jumpers
on J2 and J6. With GUI control of EN and EN_LV enabled, the GUI provides control of EN and EN_LV and
provides added capabilities:
Change option settings for
▪Output voltage
▪UV and OV thresholds,
▪Power-up sequencing, startup delay, shutdown delay
See the I2C Programming Options section in the RAA271082 Datasheet for the full list of available options.
1.3 Testing the Outputs
When the EN and EN_LV inputs have been configured, the outputs can be loaded to perform tests such as load
regulation, startup and shutdown, and load transients.

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1.3.1 Input and Output Connections and Test Points
The input and output connections are shown in Figure 1 and Table 1
The following are more test points (see Figure 1):
▪GPIO and RSTB test points located at the bottom edge of the board, TP13 and TP17.
▪EN test point at the upper left corner of the board, TP11.
▪EN_LV test point at the upper right corner of the board, TP14.
▪BYP regulator test point at the right side of the board roughly half way down, TP12.
2. GUI Operation
Before starting the GUI software:
▪The USB interface cable must be connected between the host computer and the EVB.
▪The VIN1 supply to the EVB must be 4.5V minimum.
For GUI control of EN and EN_LV
▪Do not install the jumpers on J1 (top left) and J3 (top right) of the EVB
• The GUI operates with J1 and J3 installed, but the GUI cannot change options.
▪Jumpers must be installed on J2 (top left) and J6 (top right)
• This allows all the GUI capabilities to operate.
Figure 3 shows the list of the GUI files to be downloaded.
Double-click the RAA271082_GUI_V1.00.exe file to start the GUI software.
Table 1.
(+) Test Point GND Test Point Default Value (V)
VIN1 (input) TP5 TP7 12 (4V to 42V, 4.5V to start)
Vout1 TP1 TP3 3.8
Vout2 TP2 TP4 1.8
Vout3 TP6 TP8 1.2
LDO4 TP9 TP10 3.3
Figure 3. GUI Files

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When powered up, the GUI should initially appear as shown in Figure 4.
The GUI functions are grouped into rows or columns as explained.
The tab shown in Figure 4 is the Configure tab. This tab and the other tabs such as Fault Status, Fault Response
Mask are discussed later.
On the right side of the picture, the red arrows point to various functions grouped into rows. Note: These rows are
shown for the Configure tab; other tabs show different options. The rows are explained as follows:
▪Tab select row: This row contains buttons for the different tabs in the GUI. Each tab controls a set of functions.
When the tab is selected, the GUI displays the drop-downs and options associated with that tab.
▪Output Voltage: This row shows the four outputs listed, Buck1, Buck2, Buck3, LDO4.
▪Output Voltage select: This row contains the drop-downs selecting the output voltages.
▪Output OV Threshold: This row contains drop-downs for selecting the OV thresholds. Each output can select
an independent OV threshold.
▪Output UV Threshold: This row contains drop-downs for selecting the UV thresholds. Each output can select
an independent UV threshold.
▪Soft-Start Ramp Rate selection: This row contains drop-downs for selecting Soft-Start Ramp Rate.
• Buck1, Buck2, and LDO4 have independent ramp rate selections.
• The Buck3 ramp rate is the same as for Buck2.
▪Spread Spectrum: This contains drop-downs for selecting spread spectrum options.
The following are the areas on the GUI going down the left side:
▪Dongle Found counter: This indicates how many Dongles (USB interface boards) the GUI recognizes. If the
count is zero (0), the GUI is not connected to the USB interface board.
Figure 4. Configure Tab with Labels
Tab Select
Output Voltage
Select
Output OV
Threshold
Output UV
Threshold
Soft-Start Ramp
Rate Select
Output Pulldown
Select
Select for Power Sequence, tOFF delay, and tON delay
Spread Spectrum
Select
EN (Buck1)
Control
EN_LV
Control
ReCalculat e
CRC
Refresh All: Reads all registers in the IC.
Output Voltage
VIN ULVO
Select
Device ID
Information
Dongle Found
Counter
Configure Tab is Active

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▪VIN UVLO drop-down: Selects the VIN UVLO threshold.
▪Device ID information: Reads the device ID and silicon revision.
▪EN control: Controls the Buck1 output and Standby operation.
▪EN_LV control: Controls the LV outputs (Buck2, Buck3, LDO4).
▪ReCal button: Reads all pertinent registers and perrforms a CRC calculation.
▪Refresh All button: Reads all pertinent registers and updates the current tab displayed. This button can be
used at any time on any tab.
Other tabs are updated automatically after a Refresh All when they are selected.
▪Power Sequence: Contains drop-downs for selecting the startup and shutdown order.
▪tOFF delay: Contains drop-downs for selecting the delay between outputs shutting down.
▪tON delay: Contains drop-downs for selecting the delay between outputs starting up.
When powered up, the GUI should initially appear as in Figure 4.
The EN and EN_LV controls are at the left side of the display. The EN control has the IC in the Standby position,
and the EN_LV control has the LV outputs (Buck2/Buck3/LDO4) in the Off state.
To turn Buck1 on, click the On button in the EN (HV) control. Vout1 should power up with the factory-set voltage.
To turn the LV outputs on, click the On button in the EN_LV control. Buck2, Buck3, and LDO4 should power up
with their factory-set voltages.
2.1 Changing Programming Options
Complete the following steps to make changes in the options on this tab such as Output Voltage and VOUT OV
Threshold:
1. Use the EN control to place the IC in Standby. All the options on the Configure tab can be changed only when
the device is in Standby mode (the EN_LV control can be placed in either the Off or On state).
2. Select the desired options by using the specific drop-down menus.
a. Note: There are options not shown on this Configure tab, which can only be selected while the device is
in Standby mode. These other options are located on the Misc tab. Changes on that tab can be made by
moving to that tab and selecting the required options.
3. Use the Refresh All button to verify the selections.
4. When satisfied that the selections are correct, click the ReCal CRC button.
a. The GUI automatically reads the new CRC calculation result from registers 0xB6, 0xB7
b. The GUI copies these values into registers 0x7E, 0x7F.
5. Click the Refresh All button.
6. Set EN control to EN.
The device should now power up with the selections chosen. Note: When EN control is On, the Buck1 output is
powered up and you cannot make any changes to the selections on the Configure tab. If you try to change a
selection, the drop-down may change but a Refresh All shows that the device settings have not changed.
Note: If selections are made with the device in Standby and ReCal CRC is not performed, if EN is set to On, the
outputs start up but quickly shut down because of a CRC Recheck error. If this occurs, place the device in
Standby, click ReCal CRC, click Refresh All, and then place EN to the On setting. The outputs should come up
with the selected options.
The limitation of making selections only during Standby operation does not apply to any of the bits related to: fault
status, fault response, fault reporting to GPIO or RSTB, set-up of the Windowed Watchdog Timer, or set-up of the
GPIO and RSTB pins. These parameters are shown on the other tabs in the GUI.

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Note: While options can be selected, the accuracy of the selected options may be slightly outside the datasheet
specifications. Datasheet accuracy limits are assured only for the factory-programmed settings. As an example, if
Vout1 is selected to the default value of 3.8V, the output value is finely adjusted at the factory for Vout1 set to 3.8V.
If Vout1 is later changed to a different voltage setting, the new Vout1 voltage may be slightly less accurate than
the default setting. However, the change in accuracy is minor and should not significantly affect system or board
level testing. After the required options have been chosen, the device then can be ordered and factory-adjusted
with those specific options, to provide the tightest accuracy available.
If any option is set to a value other than the factory-programmed value, this creates a CRC Recheck fault, see
Displaying Detected Faults. This CRC Recheck error is ignored if the steps ReCal CRC and Refresh All are
followed before setting EN to On. The CRC Recheck still occurs and is detected and shown as a fault but the fault
is ignored, and the device operates as intended.
2.2 Fault Status Tab
The Fault Status tab is selected by clicking the Fault Status button in the Tab row. The Fault Status tab is shown
on the next page. Note: The left side of the GUI, with EN and EN_LV control, and the ReCal and Refresh All
buttons, did not change. This is true for all tabs.
The Fault Status tab is arranged as follows: The output-related faults are arranged in columns. The first column at
left, Output-related faults (in blue background) lists fault types related to an output voltage: such as OV, UV, OC. It
also shows the Over-Temp or Over-temperature fault.
The remaining columns moving to the right show the faults which can be detected for Buck1, Buck2, Buck3, and
LDO4. LDO4, for instance, has drop-downs shown in the Overcurrent, Overvoltage, and Undervoltage faults. It
Figure 5. Fault Status Tab with Labels
Output-Related
Faults
Vout1
Faults
Vout2
Faults
LDO4
Faults
Vout3
Faults
Clear Faults for
Buck1
Buck2/3
LDO4
(row)
WWDT Faults: Restart, Too-Slow, Too-Fast DAC Compare Faults Sequence Fault
CRC Recheck
Fault
I2C CRC
Fault

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does not show drop-downs for NOC (Negative Overcurrent) fault or for Severe UV fault; these faults cannot be
detected.
At the bottom of the Fault Status tab are fault indicators for the Watchdog Timer (WWDT), DAC Compare faults,
Sequence faults, I2C CRC faults, and CRC Recheck faults.
2.2.1 Displaying Detected Faults
To see what faults are detected, click the Refresh All button. Faults detected should highlight as yellow text with
red background, as shown in Figure . Here the faults detected are Overcurrent and Undervoltage on Buck1.
Note: If a fault is detected, the fault status bit for that fault is set to logic 1 and stays at logic 1 until the bit is
cleared.
To clear a fault, go to the fault detected drop-down and select no fault detected/clear fault. The drop-down
should read no fault detected/clear fault and the text should now appear as black text with light blue
background.
It is possible to clear all faults for Buck1 by clicking on the CLEAR Buck 1 (HV) button at the bottom of the Buck1
fault list.
Faults for Buck2, Buck3, and LDO4 are displayed and handled in the same manner as faults for Buck1. There are
also CLEAR B2/B3 (LV) and CLEAR LDO4 (LV) buttons. These can be used to clear faults for Buck2/Buck3 and
LDO4 respectively, or each fault can be cleared individually by selecting the drop-down.
After clearing faults, click Refresh All. If the fault condition is removed, the drop-down reads no fault
detected/clear fault. If the fault condition persists or reoccurs, the drop-down shows the fault detected.
As shown in Figure 7, at the bottom of the Fault Status tab are drop-downs for the Windowed Watchdog Timer
(WWDT), DAC compares, I2C CRC, CRC Recheck, and Sequence faults. These drop-downs operate the same
as fault drop-downs for Buck1. A fault condition is displayed as fault detected in yellow text with red background.
Figure 6. Vout1 Faults

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In the example, the CRC Recheck fault is detected. In this case, there is no button to clear all these faults at once;
each fault must be cleared individually using the drop-downs.
In Figure 7, the CRC Recheck fault (far right) shows a fault detected. Any change to the factory programmed
options causes a CRC Recheck fault. If the device options are changed, the device detects the change within 5ms
and sets the CRC Recheck fault bit high. If changes are done correctly using ReCal CRC and Refresh All, the fault
is still detected but it is ignored, which allows users to test various configurations. The fault cannot be cleared
because the device does CRC Recheck every 5ms. Even if the fault is cleared, the fault is re-detected within 5ms.
2.3 Fault Response Mask Tab
The Fault Response Mask tab shown in Figure 8 is selected by clicking the Fault Response Mask button in the
Tab row. This tab controls the response of the device (shut down or ignore) for various faults. The fault response
selections for Buck1, Buck2, Buck3, and LDO4 are laid out similarly to the Fault Status tab, with fault response
grouped into columns by output and into rows by fault type.
Figure 7. Fault Status Tab – WWDT and Other Faults
Figure 8. Fault Response Mask Tab with Labels
Output-Related
Faults
Vout1
Fault
Responses
Vout2
Fault
Responses
LDO4
Fault
Responses
Vout3
Fault
Responses
Latchoff Faults: (HV), (LV)

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Each of the output-related fault responses can be enabled or disabled by selecting the drop-down. Selecting no
response to fault causes the device to not respond (not shut down any outputs) if the fault is detected.
Selecting fault response hiccup options causes the device to respond to a fault (shut down an output) in
accordance with the hiccup option selected. (Hiccup options are selected on the Misc tab.) These fault response
selections can be changed whenever EN is not in the Off state. However, the hiccup options on the Misc tab do
require the EN pin to be in Standby to be selected, along with a ReCal CRC/Refresh All cycle.
At the bottom of the Fault Response Mask tab (Figure 8) are the Latchoff (HV) and Latchoff (LV) drop-downs.
Unlike the other drop-downs on this tab, these act also as fault indicators. If a Latchoff event occurs on the HV
(Buck1) regulator, the (HV) drop-down reads latchoff detected in yellow text with red background. This indicates
that the HV Buck1 output is in a latched-off state, which prevents Buck1 from restarting. This state can be cleared
by selecting no fault detected/clear fault from the drop-down, which allows Buck1 to restart from a latch-off
condition.
The Latchoff (LV) drop-down does the same function for the LV outputs. If a fault on a LV output (Buck2, Buck3,
LDO4) results in a latchoff state, this drop-down indicates a latchoff detected fault, which prevents the LV
outputs from restarting. This state can be cleared by selecting no fault detected/clear fault from the drop-down,
which allows the LV outputs to restart from a latch-off condition.
Clicking on Refresh All updates the Fault Response settings for the device.
2.4 Fault to GPIO Control Tab
The Fault to GPIO Control shown in Figure 9 is selected by clicking the Fault to GPIO Control button in the Tab
row. This tab controls which faults are directed to the GPIO pin. The faults for Buck1, Buck2, Buck3, and LDO4
are arranged similarly to the Fault Status tab, with fault response grouped in columns by output and in rows by
fault type.
Figure 9. Fault to GPIO Tab with Labels
Output-Related
Faults
Vout1
Fault Responses
Vout2
Fault Responses
LDO4
Fault Responses
Vout3
Fault Responses
WWDT Faults: Restart, Too-Slow, Too-Fast CRC Recheck Fault I2C CRC Fault

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All drop-downs on this tab are configured to display ignore GPIO on fault or assert GPIO pin low on fault. Use
the drop-downs to select which, if any, faults cause the GPIO pin to assert low when the fault is detected. These
selections can be made whenever EN is at Standby or On and have no effect on the ReCal CRC operation.
Note: If the GPIO pin is used as a fault indicator (assert GPIO pin low on fault), the GPIO pin also needs to be
configured as a fault indicator. This is selected on the GPIO Pin tab. See the GPIO Pin Tab for how to configure
GPIO as a fault indicator.
At the bottom of the Fault to GPIO tab are drop-downs for the Watchdog timer faults, the I2C CRC fault, and the
CRC recheck fault.
2.5 GPIO Pin Tab
The GPIO Pin tab shown in Figure 10 is selected by clicking the GPIO Pin button in the tab row. This tab controls
the use of the GPIO pin. Note: All functions on this tab are controlled by the GPIO_CTRL register, register 0xA4.
The following are the GPIO options explained in more detail.
▪Read status of GPIO: This box shows the current logic state of the GPIO pin, whether the GPIO pin is
configured as input or output (The value is reflected in register 0xA4, Bit 7). If GPIO is configured as an input,
connected for example to an interrupt signal or fault monitor, the input value can be read by a microcontroller
using I2C and used to make fault response decisions at the system level.
Figure 10. GPIO Pin Tab with Labels
Read status of GPIO pin
GPIO Pin function select:
1) GPIO drives high during initialization, then low when outputs start up.
2) GPIO as fault indicator (active low on fault detection)
3) GPIO as logic output, controlled by GPIO Write Data
4) GPIO connected to internal 2.2MHz clock
Note: The GPIO pin can also be configured as an input.
GPIO Write Data (for GPIO configured as output pin)
GPIO Pin direction select:
-Open Drain Output
- Input: Used as an input for the Watchdog
Timer or as an input that can be
polled using an external microcontroller.

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▪GPIO Write Data: If GPIO is selected as a logic output, this bit dictates which logic state (1 or 0) is sent to the
pin.
▪GPIO Pin function select: For all options in this selection (see Figure 10, bottom left), the GPIO pin is
configured as an open-drain output and an external pull-up resistor is required. On initial power-up, the GPIO
pin defaults to option 1, drives high (open-drain) during initialization and then drives low when initialization is
completed. Selecting any other Pin function must be done after initialization is completed. This is also true for
setting the pin direction as an input.
▪GPIO Pin direction select: The GPIO pin can be configured as an output or input, after the initialization is
completed at power-up. All the selections in the GPIO Pin function select (Figure 10, bottom left) require the
GPIO pin to be configured as an output. If the GPIO pin direction is selected as an input, this overrides the
GPIO Pin function selection, and the pin operates as input-only.
2.6 RSTB Pin / WWDT Tab
The RSTB Pin / WWDT tab shown in Figure 9 is selected by clicking the RSTB Pin / WWDT tab in the Tab row.
This tab controls operation of the RSTB pin. This tab also controls configuration of the Windowed Watchdog Timer
(WWDT).
2.6.1 RSTB Operation and Options
The RSTB pin is a general fault indicator for the device with an active-high/active-low output. In normal operation,
RSTB will drive low when any of the outputs falls outside the Undervoltage or Overvoltage threshold selected for
that output (which causes the internal PGood signal for that output to be logic low = power not good).
However, it is possible to configure RSTB so that it will ignore one or more PGood signals. The outputs which are
ignored depend on the Power Sequence order selected from the Configure tab, as shown in Table 2:
Note: PGood for Vout1 is never ignored. If Vout1 falls outside the UV or OV threshold the RSBT pin is asserted
low. Also , there are programmable delays for the detection and assertion of PGood on UV and OV faults, see the
Misc Tab for details.
The RSTB pin can also be programmed to be driven low by a Watchdog Timer fault, or by a Sequence fault (the
fault in the internal startup sequencer).
RSTB also generally drives low during any fault which later causes output shutdown. For example, if a DAC
Compare fault is detected, RSTB immediately drives low, even though the outputs are still in tolerance. When
RSTB drives low as a fault indication, it drives low for 200ms and then returns to a logic high state. This is true for
all UV and OV faults. For Watchdog timer and Sequence faults, there is a 20ms pulse option that can be selected
from the Misc tab.
2.6.2 WWDT Operation and Options
Many options on this tab are related to the WWDT (Windowed Watchdog timer).
The WWDT has many options:
▪The WWDT can be enabled or disabled.
▪The WWDT features three faults that can trigger a shutdown (restart, too slow, too fast)
▪The WWDT fault timing is independently programmable for too-slow and too-fast faults.
Table 2. Ignored Outputs
Option Power Sequence = Buck2 -> Buck3 -> LDO4 Power Sequence: LDO4 -> Buck2 -> Buck3
0 no PGood signal ignored no PGood signal ignored
1 LDO4 PGood ignored Buck3 PGood ignored
2 LDO4, Buck3 PGood ignored Buck3, Buck2 PGood ignored
3 LDO4, Buck3, Buck2 PGood ignored Buck3, Buck2, LDO4 PGood ignored

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▪WWDT lockout, a feature that locks the WWDT settings and prevents any future changes.
▪Which WWDT faults are sent to the RSTB pin as fault indicators.
▪If a WWDT fault occurs, the response can be to shut down all outputs or shut down only LV outputs.
Note: When the count drop-downs are loaded with non-zero values, the WWDT fault detector is armed when it
receives a valid WWDT kick. If a WWDT fault is detected, the fault status bit is set high and the fault appears on
the Fault Status tab. However, if the WWDT is not enabled (using wwdt_enable), the outputs continue to operate
normally.
For the outputs to shut off from a WWDT fault, these steps must be taken:
1. The tick and count for the desired WWDT fault must be selected.
2. One or more fault response masks for the required WWDT must be selected, which allows the device to shut
down the outputs. Selection of each fault response is optional.
3. Select which outputs to shut down using the wwdt_reg_dis_sel drop-down. Choices are all outputs or only the
LV outputs Buck2/Buck3/LDO4.
4. Choose a Kick Select (GPIO and/or I2C kick).
5. Select which WWDT, if any, asserts the RSTB pin low. Each selection is optional. Note: In many cases, RSTB
is driven low on a WWDT fault because the outputs are forced to shut down. Enable the WWDT using the
wwdt_enable drop-down.
6. Initiate the WWDT by issuing a valid WWDT kick.
After these steps, the WWDT is actively armed and detects and respond to a WWDT fault.
The RSTB Pin/WWDT tab is shown in Figure 11.
Figure 11. RSTB Pin/WWDT Tab with Labels
Power Good to RSTB Select
WWDT Enable/disable
WWDT Fault Response
Enable/disables:
Restart Fault
Too-Slow Fault
Too-Fast Fault
Manual Register Kick
WWDT Kick S el ect
Too-Slow Tick
Too-slow count
Too-Fast Tick
Too-Fast Count
WWDT Fault:
Output Disabl e
Select
WWDT:
Programming
Lockout Select
RSTB Pulse Width,
200ms/20ms indicator,
selected on Misc tab.
(Applies to WWDT and
Sequence Faults only)
Restart Fault
to RSTB select
Too-Slow Fault to
RSTB Select
Too-Fast Fault
to RSTB Select
Sequence Fault to
RSTB Select
RSTB (click to
force a single
RSTB pulse)

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The explanations for the drop-downs in Figure 11 are shown below.
From the right side:
▪Power Good selections for RSTB. The default setting for RSTB is that any output below its UV threshold will
generate a RSTB low fault indication. This opt_pg_rstb drop-down allows RSTB to ignore some outputs based
on drop-down selection. The options available are determined by the Power Sequence option which is selected
on the Configure tab.
▪Enable for the WWDT.
▪Masks (to prevent or allow shutdown upon fault) for the three WWDT faults (restart, too slow, too fast)
▪Kick select for WWDT (I2C register kick and/or GPIO input kick).
▪Manual kick. Clicking this button sends a WWDT kick to register 0xA3 (KICK_REG).
▪WWDT parameter settings for too-slow and too-fast faults. Note: The restart fault is simply a too-slow fault
with the period set at 2x of the too-slow timing. The tick selects the time interval used for the counter (100usec,
1ms, etc). The count sets the number of ticks used by the WWDT timer.
Example: Set the too-slow tick to 1ms and the too-slow count to 6. The Watchdog timer detects a fault if a time
period of 1ms × 6 = 6ms passes without a valid WWDT kick. The too-fast tick and count settings operate in the
same manner as too-slow.
From the bottom:
▪WWDT fault output disable select. This drop-down selects which outputs are shut down due to a WWDT
fault. The choices are all outputs shut down or only the LV outputs are shut down (Buck1 remains on).
▪WWDT programming lock-out. If WWDT locked out is selected, this locks all WWDT programming
parameters from further changes. The WWDT options remain locked out until the device goes through a
power-on reset. This option is prevents a malfunctioning microcontroller from accidentally changing the WWDT
parameters.
▪WWDT faults to RSTB, three options: Restart fault to RSTB, too-slow fault to RSTB, and too-fast fault to
RSTB. These drop-downs select whether the RSTB pin drives low when the selected WWDT fault is detected.
Each of the three faults can be independently routed or not routed to the RSTB pin.
▪Sequence fault to RSTB: If selected, the RSTB pin drives low if a sequence fault is detected.
▪RSTB button: Click this button to force a single RSTB pulse at the RSTB pin. This is equivalent to writing a 1 to
Bit 3 of register of 0xA5.
▪RSTB Pulse Width 20ms/200ms indicator. This display is an indicator only, controlled by the
opt_short_fault_wait bit on the Misc tab, in the Misc2 Opt column, which controls register 0x7C (MISC2_OPT),
bit 3.

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2.7 Misc Tab
The Misc tab shown in Figure 12 is selected by clicking the Misc tab in the tab row. This tab controls
miscellaneous options that are found in registers 0x7B, 0x7C, and 0x7D of the RAA271082. Note: All options on
this tab are CRC checked and therefore can be changed only when the device is in Standby mode. After options
are selected, a ReCal CRC and Refresh All operation is needed to enable the device to start up with the selection
options.
The options available on this tab are explained in the following sections.
Figure 12. Misc Tab with Labels
Power-Good to RSTB Select
LV Output Discharge Drop-Downs
Hiccup/Latchoff Options Pre-Filter on UV Detect Buck3 Phase Selection
Optional I2C Address
Optional Regulator
Manual Control
Optional 30ms
OV/UV Filter
Optional I2C CRC
Checking
Optional 20ms on RSTB
Optional Buck1 NOC Limit
Optional Buck1 OC1 Limit
Optional Buck3 OC Limit
Optional Buck3 OC Limit
Optional NOC Behavior
Misc1 Options
Misc2 Options
Misc3 Options

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2.7.1 Misc1 Options – Register 0x7B
Misc1 options are shown in Figure 12 in the Misc1 Options box at the top.
▪Hiccup/latchoff options: The device has four selections for hiccup/shutdown for response per register 0x7B
bits 7,6.
▪Optional pre-filter for UV detection: The device has four selections for a pre-filter delay on UV detection per
register 0x7B bits 5,4. The same delay is applied to all four outputs. Note: There is an internal fixed delay of 2
to 3µs for UV detection. The below selections are in addition to this fixed delay.
These delays affect only the UV detection. OV detection is not affected by this selection.
▪Buck3 Phase selection: Default operation for the Buck3 switching cycle is to be 180 degrees out of phase with
both Buck1 and Buck2. There is an option for have the Buck3 switching cycle to be in phase with Buck2, per
register 0x7B bit 0.
The options previously described are all contained in register 0x7B. The remaining options in register 0x7B, the
output discharge drop-down for Buck2, Buck3, and LDO4, are in the same register but they are not listed on this
tab. The output discharge options for these outputs are shown on the Configure tab.
2.7.2 Misc2 Options – Register 0x7C
Misc2 options are shown in Figure 12, in the Misc2 Options box at the right side.
▪Optional I2C address: The device has an option for an I2C address of either 0x4D or 0x4E (register 0x7C
Bit 7). However, the GUI presently supports only the address 0x4D and the 0x4E option is disabled. Future
versions of the GUI may support this feature. Register 0x7C, Bit 7.
▪Optional manual control of outputs: This option allows users the ability to control the startup and shutdown
of outputs using direct I2C control instead of using the EN and EN_LV pins. This feature is enabled only through
factory programming and is disabled from GUI. Register 0x7C, Bit 6.
▪Optional UV/OV filter: This is an optional 30ms filter applied to UV and OV, both detection and response. The
same filter is applied to all outputs and applies to both UV and OV faults. Register 0x7C, Bit 5.
▪Optional I2C CRC checking: The device supports CRC checking on I2C transactions, but it is not supported
by the GUI at this time. Register 0x7C, Bit 4.
▪Optional short (20ms) RSTB pulse: The length of the RSTB pulse can be selected for 20ms instead of the
default 200ms by this drop-down. This affects only the WWDT and Sequence faults. For other faults such as
OV and UV, the RSTB pulse width is fixed at 200ms. Register 0x7C, Bit 3.
▪Optional NOC1 limit: This option selects a higher NOC (Negative Overcurrent) limit for Buck1. The default
value is 800mA, the optional value is 1A. Register 0x7C, Bit 2.
▪Optional OC1 current limit: This option selects different Overcurrent (OC1) levels for Buck1. The default value
is 1.50A, with options of 1.20A and 1.75A. Register 0x7C Bits 1,0.
0 Hiccup and retry continuously
1 Hiccup and retry for 10 attempts, then latch off.
2 Hiccup and retry for 5 attempts, then latch off.
3 Latch off on first fault.
0 Disable filter: no additional filter delay added.
1 Enable 10µs filter: an additional 10µs delay is added
2 Enable 25µs filter: an additional 25µs delay is added
3 Enable 40µs filter: an additional 40µs delay is added.

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2.7.3 Misc3 Options – Register 0x7D
Misc3 options are shown in Figure 12, in the Misc3 Options box at the bottom right side.
▪Optional Buck3 OC: This option selections different Overcurrent (OC) levels for Buck3. The default value is
1.20A, with options of 0.96A and 1.56A. Register 0x7D Bits 7,6.
▪Optional Buck3 OC: This option selections different Overcurrent (OC) levels for Buck3. The default value is
1.20A, with options of 0.96A and 1.56A. Register 0x7D Bits 5,4.
▪NOC option for soft-start: This option selects different behaviors for the NOC detector. The default behavior is
that the NOC detector (which truncates the low-side on-time) is always active. The optional behavior is that
NOC truncates the low-side on-time only during the soft-start interval. Register 0x7D Bit 2.
2.8 Reg Map Tab
The Reg Map (register map) tab shown in Figure 13 is selected by clicking the Reg Map tab in the tab row. This
tab displays the names, addresses, and bit names of the registers in the RAA271082. The window area at the left
contains a list of all available registers that can be opened or collapsed to view the bit names and assignments.
See the RAAA271082 Datasheet for more detail on register and bit names and definitions. When the GUI is first
powered up, the Reg Map tab has all registers expanded. Each register can be collapsed by clicking the - box to
the left of each register name.
Figure 13. Reg Map Tab with Labels
Register and bit list
Click the - or + to expand or collapse
the contents of a register

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2.9 REA Dongle tab
The REA Dongle tab shown in Figure 12 below is selected by clicking the REA Dongle tab in the tab row. This tab
can be used to perform direct read and write operations on specific registers.
The following are the explanations of the various drop-downs and text boxes in the Reg Map tab.
▪To perform a READ operation on a register: Type the hexadecimal address of the register in the Offset box,
and then click the READ button. The register contents (value) are displayed in the R-data box.
▪To perform a WRITE operation on a register: Type the hexadecimal address of the register in the Offset box,
then type the required write value of the register (in hexadecimal) in the W-data box, then click the Write button.
This writes the required value to the register. Click on READ to verify that the WRITE operation was successful,
by checking the value in the R-data box. If the READ operation does not show the required value in the
selected register, this indicates one of three possibilities:
• The register selected is non-writeable under all conditions.
• The register selected is writeable only when EN has the device placed in Standby mode.
• The device is not on. (EN is set to Off, or VIN supply is not present).
2.10 Log Tab
The Log tab shown in Figure 13 is selected by clicking the Log tab in the tab row. This tab maintains a log of
read/write operations done between the GUI and the RAA271082, which is useful for analyzing and
understanding the register read/write operations used to configure the device options. For example, clicking
Refresh All at any time initiates a read of many registers, and this series of register reads is displayed in the Log
window. This Log feature can useful when tracking the relationship between selecting device options and the
registers associated with those options.
Figure 14. Reg Map tab with Labels
Protocol: Use the option
I2C_Standard_Byte_RW
I2C Clock Rate:
Use deFault value of 400
Slave ID: Use deFault
value of 0x4D
Offset: This is the
hexadecimal address of the
register you want to access
W-Data box: This is to enter
data that you wish to WRITE
to a register.
R-Data box: This displays
data being READ from a
register.
Click on this to WRITE the
data in the W-data field to the
register in the Offset box.
Click on this to READ the data
from the register in the Offset
box. The value read from the
register is displayed in the R-data
box.

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The Log tab also contains a Clear Log button which clears away all previous read/write information. This is helpful
in tracking individual register operations.
Figure 15. Log Tab with Labels
Running log of read/write
transactions between the GUI
and the RAA271082.
Clear Log button:
Click this to clear all
Log entries.