Texas Instruments bq24720 EVM User manual

User's GuideSLUU237 – January 2006
bq24720/21 EVM (HPA104) for Multi-Cell SynchronousSwitch-Mode Charger With System Power Selector andSMBus SBS-Like Interface
Contents1 Introduction .......................................................................................... 22 Test Summary ...................................................................................... 43 Circuit Design and Layout Guideline ........................................................... 214 Bill of Materials, Board Layout, and Schematics .............................................. 22
List of Figures
1 Connections of the EV2300 Kit ................................................................... 52 Original Test Setup for bq24720 EVM ........................................................... 63 Original Test Setup for bq24721 EVM ........................................................... 74 The Main Window of the bq2472x SMB Evaluation Software ................................ 85 The Software Main Window ....................................................................... 96 The Software Main Window ..................................................................... 107 The Software Main Window ..................................................................... 118 The Waveforms at No Load ..................................................................... 129 Test Setup for bq24720 EVM .................................................................... 1310 Test Setup for bq24721 EVM .................................................................... 1311 The Software Main Window ..................................................................... 1412 The Waveforms at I
(bat)
= 3 A .................................................................... 1513 The Software Main Window ..................................................................... 1614 The Software Main Window ..................................................................... 1715 The Waveforms at I
(bat)
= 300 mA ............................................................... 1816 The Software Main Window ..................................................................... 1917 The Software Main Window ..................................................................... 2018 Top Assembly ..................................................................................... 2419 Bottom Assembly .................................................................................. 2520 Layer 1.............................................................................................. 2621 Layer 2.............................................................................................. 2722 Layer 3.............................................................................................. 2823 Layer 4.............................................................................................. 2924 Top Silk ............................................................................................. 30
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 1Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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1 Introduction
1.1 EVM Features
1.2 General Description
1.3 I/O Description
Introduction
•Evaluation Module For Both bq24720 and bq24721•High Efficiency NMOS-NMOS Synchronous Buck Charger With User-Selectable 300 kHz or 500 kHzFrequency
•Battery/Adapter to System Power Selector Function•SBS-Like SMBus Interface for Control and Status Communications With Host•Programmable Battery Voltage, Charge Current, and AC Adapter Current via SBS-Like SMBusInterface
•Battery Pack Voltage Regulation Range up to 19.2 V•AC Adapter Operating Range 13 V–24 V•Charge and Adapter Overcurrent Protection•Charge Peak Current up to 14 A. Charge Average Current up to 7 A•LED Indication for AC Adaptor Connection, Power Path Conduction, Charge Enable and Alarm Signal•Test Points for Key Signals Available for Testing Purpose. Easy Probe Hook-up•Jumpers Available. Easy to Change Connections and Enable (or Disable) Charge•May Be Used with TI bq2472x SMB Evaluation Software
The bq24720/21 evaluation module is a complete charger module for evaluating a multi-cell synchronousnotebook charge and path selection solution using the bq24720/21 devices. It is designed to deliver up to9 A of charge current to Li-Ion or Li-Pol applications.
The bq24720/21 has a highly integrated battery charge controller designed to work with external hostcommands. The battery voltage, charge current, and other system parameters are programmable viaSBS-like SMBus interface.
The dynamic power management (DPM) function SMBus Interface modifies the charge current dependingon system load conditions, avoiding ac adapter overload.
High accuracy current sense amplifiers enable accurate measurement of either the charge current or theac adapter current, allowing termination of nonsmart packs and monitoring of overall system power.
The adapter isolation diode can be bypassed with external an MOSFET using a control signal provided bythe bq24720/21, thus reducing overall power dissipation.
For details, see the bq24720 data sheet (SLUS668 ) and the bq24721 data sheet (SLUS683 ).
Jack Description
J1–POS AC adapter, positive outputJ1–GND AC adapter, negative outputJ2–POS External power supply, positive outputJ2–GND External power supply, negative outputJ3–REF VREF5 pin (11) outputJ3–CHGEN CHGEN pin (1) outputJ3–SDA SDA pin (13) output, SMBus data lineJ3–SCL SCL pin (14) output, SMBus clock lineJ4–ALARM ALARM pin (25) outputJ4–IOUT IOUT pin (17) outputJ4–GND Ground
2bq24720/21 EVM (HPA104) for Multi-Cell Synchronous SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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1.4 Controls and Key Parameters Setting
1.5 Recommended Operating Conditions
Introduction
Jack Description
J5–REF IC reference voltage VREF5 (pin 11)J5–VPUP Pull-up voltage sourceJ5–EXT External power supplyJ6–CHGEN CHGEN pin (1) outputJ6–GND GroundJ7–VPUP Pull-up voltage sourceJ7–LEDPWR LED Pull-up power lineJ8–ACGD/TS ACGOOD pin (15) output for bq24720, TS pin (15) output for bq24721J8–GND GroundJ8–VBAT Connected to battery packJ8–VSYS Connected to systemJ9–BYPASS BYPASS pin (6) outputJ9–LED LED driveJ10–ACDRV ACDRV pin (2) outputJ10–LED LED driveJ11–BATDRV BATDRV pin (24) outputJ11–LED LED driveJ12–ACGD ACGOOD pin (15) outputJ12–LED LED drive
Jack or Resistor Description Factory Setting
Pull-up power source setting
1-2 (pin 1 and 2J5 1-2: Use external power supply as the pull-up source
are short-circuited)2-3: Use REF5 as the pull-up sourceJ6 Enable charge process when ON. OffThe pull-up power source supplies the LEDs when ON. LED has no power source whenJ7 OnOFF.J9 The conduction of the bypass MOSFET is indicated by D8 when ON. OnJ10 The conduction of the AC MOSFET is indicated by D10 when ON. OnJ11 The conduction of the battery MOSFET is indicated by D11 when ON. On
SYMBOL DESCRIPTION MIN TYP MAX UNIT
V
I
Supply voltage Input voltage from ac adapter input 13 19.5 24 VV
(BAT)
Battery voltage Voltage applied at VBAT terminal of J8 9–16.8 20 VI
O
Supply current Maximum input current from ac adapter input 5 7 AI
(chrg)
Charge current Battery charge current 2 4 7 AT
J
Operating junction temperature range 0 125 °C
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 3Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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2 Test Summary
2.1 Definitions
2.2 Equipment
Test Summary
This procedure details the configure of the HPA104 evaluation board. On the test procedure, the followingnaming conventions are followed. See the HPA104 schematic for details.
VXXX : External voltage supply name (VADP, VBT, VSBT)LOADW: External load name (LOADR, LOADI)V(TPyyy): Voltage at HPA104 internal test point TPyyy. For example, V(TP12) means thevoltage at TP12.V(Jxx): Voltage at HPA104 jack terminal Jxx.V(TP(XXX)): Voltage at test point XXX. For example, V(ACDET) means the voltage at thetest point which is marked as ACDET.V(XXX, YYY): Voltage across point XXX and YYY.I(JXX(YYY)): Current going out from the YYY terminal of jack XX.Jxx(BBB): Terminal or pin BBB of jack xxJxx ON : HPA104 internal jumper Jxx terminals are shortedJxx OFF: HPA104 internal jumper Jxx terminals are openJxx (-YY-) ON: HPA104 internal jumper Jxx adjacent terminals marked as YY are shortedMeasure →A,B Check specified parameters A, B. If measured values are not within specifiedlimits, the unit under test has failed.Observe →A,B Observe if A, B occurs. If they do not occur, the unit under test has failed.
The assembly drawings have locations for jumpers, test points, and individual components.
2.2.1 POWER SUPPLIES•Power Supply Number 1 (PS1): a power supply capable of supplying 20-V at 5-A is required.•Power Supply Number 2 (PS2): a power supply capable of supplying 5-V at 1-A is required.•Power Supply Number 3 (PS3): a power supply capable of supplying 5-V at 1-A is required. (bq24721EVM only).
2.2.2 ELECTRONIC LOAD•A 30-V, 5-A electronic load
2.2.3 KEPCO LOAD•A Kepco bipolar operational power supply / amplifier, 0 V ±20 V (or above), 0 A ±6 A (or above).
2.2.4 METERS
•Eight Fluke 75, (equivalent or better)– Or: Five equivalent voltage meters and three equivalent current meters. The current meters mustbe able to measure 5A+ current.
2.2.5 OSCILLOSCOPES
•An oscilloscope, a single voltage probe, and a single current probe are required.
bq24720/21 EVM (HPA104) for Multi-Cell Synchronous4 SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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2.3 Equipment Setup
2003
EV2300
HPA002
VCC
HDQ
VOUT
GND
VOUT
SDA
SCL
GND
NC
SMBD
SMBC
GND
HDQI2C
SMB
USB
ToComputer
USBport
SDA
SCL
GND
ToEVM
2003
EV2300
HPA002
VCC
HDQ
VOUT
GND
VOUT
SDA
SCL
GND
NC
SMBD
SMBC
GND
HDQI2C
SMB
USB
ToComputer
USBport
SDA
SCL
GND
ToEVM
Test Summary
2.2.6 COMPUTER
•A computer with at least one USB port and a USB cable. The EV2300 USB driver and the bq2472xSMB evaluation software must be properly installed.
2.2.7 EV2300 SMBUS COMMUNICATION KIT•An EV2300 SMBUS communication kit.
2.2.8 SOFTWARE
•Driver(USB EV2300) Installer XP2K-Last updated Jan 28-04.zip: This is the EV2300 USB driver. Saveand unzip to c:\temp (or other directory). Double click on the setup.exe file. Follow the installationsteps.
•bq24720SMBEVSW2_10.zip: This is the bq2472x SMB evaluation software. Save and unzip to c:\temp(or other directory). Double click on the SETUP.EXE file. Follow the installation steps. This softwareneeds to be installed after the EV2300 USB driver.
1. Set the power supply number 1 for 0 V ±100 mVDC, 5 A ±0.1 A current limit and then turn off thesupply.
2. Connect the output of power supply number 1 in series with a current meter (multimeter) to J1 (POS,GND).
3. Connect a voltage meter across J1 (POS, GND).4. Set the power supply number 2 for 3.3 V ±100 mVDC, 1 A ±0.1 A current limit and then turn off thesupply.
5. Connect the output of the power supply number 2 to J2 (POS, GND).6. Set the Kepco load for 10 V ±100 mVDC and then turn it off.7. Turn off the electronic load.8. Connect a voltage meter across J8 (VBAT, GND).9. Connect a voltage meter across J8 (VSYS, GND).10. Connect J3 (SDA, SCL) and J4 (GND) to the EV2300 kit SMB port. Connect the USB port of theEV2300 kit to the USB port of the computer. The connections are shown in Figure 1 .
Figure 1. Connections of the EV2300 Kit
11. Turn on the oscilloscope.12. Insert the voltage probe into TP30 (PH) and connect it to the oscilloscope.13. Hook up the current probe to the wire connected to L1, and connect to the oscilloscope. Set up thecurrent probe so that the current direction is from the floating pad to the pad on the right-hand side.14. J5 (VPUP, EXT): ON, J6: OFF, J7: ON, J9: ON J10: ON, J11: ON.15. J12: ON ( For bq24720 only), J12: OFF ( For bq24721 only).
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 5Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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V
POS
J1
GND
VSYS
J8
GND
VBAT
IOUT
GND
REF
J3
J2
J11J10J9
J7
Power
supply#2
ACGD
J4
GND
ALARM
CHGEN
SDA
SCL
POS
J6
J5
D8D10D11D7D9
D18
J12
APPLICATIONCIRCUIT
V
USB
V
EV2300
Iin
I
Power
supply#1
BQ24720EVM
Oscilloscope
L1
PH
V
POS
J1
GND
VSYS
J8
GND
VBAT
IOUT
GND
REF
J3
J2
J11J10J9
J7J7J7
Power
supply#2
ACGD
J4
GND
ALARM
CHGEN
SDA
SCL
POS
J6J6J6
J5
D8D10D11D7D9
D18
J12
APPLICATIONCIRCUIT
V
USB
V
EV2300
Iin
I
Power
supply#1
BQ24720EVM
Oscilloscope
L1
PH
Test Summary
16. ( For bq24721 only) Set the power supply number 3 for 2.5 V ±100 mVDC, 1 A ±0.1 A current limitand then turn off the supply.17. ( For bq24721 only) Connect the output of the power supply number 3 to J8 (ACGD, GND).
After the steps above, the test setup for bq24720 EVM is shown in Figure 2 . The test setup for bq24721EVM is shown in Figure 3 .
Figure 2. Original Test Setup for bq24720 EVM
6bq24720/21 EVM (HPA104) for Multi-Cell Synchronous SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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V
POS
J1
GND
VSYS
J8
GND
VBAT
IOUT
GND
REF
J3
J2
J11J10J9
J7
Power
supply#2
ACGD
J4
GND
ALARM
CHGEN
SDA
SCL
POS
J6
J5
D8D10D11D7D9
D18
J12
APPLICATIONCIRCUIT
V
USB
V
EV2300
Iin
I
Power
supply#1
BQ24721EVM
Oscilloscope
L1
PHVPower
supply#3
V
POS
J1
GND
VSYS
J8
GND
VBAT
IOUT
GND
REF
J3
J2
J11J10J9
J7J7J7
Power
supply#2
ACGD
J4
GND
ALARM
CHGEN
SDA
SCL
POS
J6J6J6
J5
D8D10D11D7D9
D18
J12
APPLICATIONCIRCUIT
V
USB
V
EV2300
Iin
I
Power
supply#1
BQ24721EVM
Oscilloscope
L1
PHVPower
supply#3
Test Summary
Figure 3. Original Test Setup for bq24721 EVM
Turn on the computer. Open the bq2472x SMB evaluation software. The main window of the software isshown in Figure 4 .
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 7Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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2.4 Procedure
Test Summary
Figure 4. The Main Window of the bq2472x SMB Evaluation Software
2.4.1 AC Adapter Detection Threshold
Make sure EQUIPMENT SETUP steps are followed. Turn on PS2
(For bq24721 only) Turn on PS3
Turn on PS1Measure→V(J8(VSYS)) = 0 V ±500 mVMeasure→V(TP(VREF5)) = 0 V ±500 mV
Increase the output voltage of PS1 until the D8 (BYPASS) is on. The threshold is approximately 13 V. Donot exceed.
Measure→V(TP(ACDET)) = 1.2 V ±0.1 VMeasure→V(J1(POS)) = 13 V ±1 VMeasure→V(J8(VSYS)) = 13 V ±1 VMeasure→V(TP(VREF5)) = 5 V ±500 mVMeasure→V(TP20) = 6 V ±200 mV (TP20 is a through-hole test point above the IC)Observe→D18 (ACGOOD) on ( for bq24720 only)Observe→D10 (ACSW) ON, D9 (ALARM) ON
bq24720/21 EVM (HPA104) for Multi-Cell Synchronous8 SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
2.4.2 Charge Parameters Setting
Increase the voltage of PS1 until V(J1(POS)) = 19 V ±0.1 V.Measure→V(J8(VBAT, GND)) = 0 V ±1 V
In the software main window, click Read All on the top part of the window. The window is shown inFigure 5 .
Figure 5. The Software Main Window
Type 12600 (mV) in the Battery Voltage Register on the lower right part of the window and click Write.This sets the battery voltage regulation threshold.
Type 1000 (mA) in the Charge Current Register on the lower right part of the window and click Write. Thissets the battery charge current regulation threshold.
Type 5000 (mA) in the Input Current Register on the lower right part of the window and click Write. Thissets the input current regulation threshold.
The window should be like Figure 6 .
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 9Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 6. The Software Main Window
Install J6.Observe→D7 (CHG EN) ON.
Change the B0 bit (CHGEND) of Control Register to 0. (Enable the charging). Click Write.Measure→V(J8(VBAT)) = 12.6 V ±200 mVObserve→D9 (ALARM) ON.
In the software main window, click Read All on the top part of the window.Observe→D9 (ALARM) off.Observe→The B2 bit (NoVreg) of the Status Register turns green (voltage loop active). The windowshould be like Figure 7 .
10 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 7. The Software Main Window
Observe →Make sure the phase node voltage (PH) and the inductor current waveforms look likeFigure 8 .
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 11Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 8. The Waveforms at No Load
2.4.3 Charge Current and AC Current Regulation (DPM)
Change the B0 bit (CHGEND) of Control Register to 0. (Enable the charging). Click Write.
Connect the output of the Kepco load in series with a current meter (multimeter) to J8 (VBAT, GND).Make sure a voltage meter is connected across J8 (VBAT, GND). Turn on the Kepco load. Connect theoutput of the electronic load in series with a current meter (multimeter) to J8 (VSYS, GND). Make sure avoltage meter is connected across J8 (VSYS, GND). Turn on the power of the electronic load. Set the loadcurrent to 2.5 A ±50 mA, but disable the output. The setup is now like Figure 9 for bq24720 and likeFigure 10 for bq24721. Make sure I
(bat)
= 0 A ±10 mA and I
(sys)
= 0 A ±10 mA.
12 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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BQ24720EVM
Ibat
V
I
POS
J1
GND
VSYS
J8
GND
VBAT
IOUT
GND
REF
J3
J2
J11J10J9
J7
Power
supply#2
ACGD
J4
GND
ALARM
CHGEN
SDA
SCL
POS
J6
J5
D8D10D11D7D9
APPLICATIONCIRCUIT
Isys
V
I
USB
V
EV2300
Electr.
Load
Kepco
Load
Iin
I
Power
supply#1
D18
J12
Oscilloscope
L1
PH
BQ24720EVM
Ibat
V
I
POS
J1
GND
VSYS
J8
GND
VBAT
IOUT
GND
REF
J3
J2
J11J10J9
J7J7J7
Power
supply#2
ACGD
J4
GND
ALARM
CHGEN
SDA
SCL
POS
J6J6J6
J5
D8D10D11D7D9
APPLICATIONCIRCUIT
Isys
V
I
USB
V
EV2300
Electr.
Load
Kepco
Load
Iin
I
Power
supply#1
D18
J12
Oscilloscope
L1
PH
BQ24721EVM
Ibat
V
I
POS
J1
GND
VSYS
J8
GND
VBAT
IOUT
GND
REF
J3
J2
J11J10J9
J7
Power
supply#2
ACGD
J4
GND
ALARM
CHGEN
SDA
SCL
POS
J6
J5
D8D10D11D7D9
APPLICATIONCIRCUIT
Isys
V
I
USB
V
EV2300
Electr.
Load
Kepco
Load
Iin
I
Power
supply#1
D18
J12
Oscilloscope
L1
PHVPower
supply#3
BQ24721EVM
Ibat
V
I
POS
J1
GND
VSYS
J8
GND
VBAT
IOUT
GND
REF
J3
J2
J11J10J9
J7J7J7
Power
supply#2
ACGD
J4
GND
ALARM
CHGEN
SDA
SCL
POS
J6J6J6
J5
D8D10D11D7D9
APPLICATIONCIRCUIT
Isys
V
I
USB
V
EV2300
Electr.
Load
Kepco
Load
Iin
I
Power
supply#1
D18
J12
Oscilloscope
L1
PHVPower
supply#3
Test Summary
Figure 9. Test Setup for bq24720 EVM
Figure 10. Test Setup for bq24721 EVM
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 13Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Change the B0 bit (CHGEND) of Control Register to 0. (Enable the charging). Click Write.Measure→I
(bat)
= 1000 mA ±200 mA
Type in 3000 (mA) in the Charge Current Register and click Write.Measure→I
(bat)
= 3000 mA ±200 mA
Make sure the B3 bit (IOUTBT) of the Control Register is 1. (charge current output). If not, change it to 1.Click Write.
Measure→V(J4(IOUT)) = 600 mV ±30 mV
Click Read All.Observe→The B3 bit (NoIreg) of the Status Register turns green (charge current loop active). Thewindow should be like Figure 11 .
Figure 11. The Software Main Window
Observe→Make sure the phase node voltage and the inductor current waveforms look like Figure 12 .
14 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 12. The Waveforms at I
(bat)
= 3 A
Enable the output of the electronic load.Measure→I
(sys)
= 2500 mA ±200 mA, I
(bat)
= 3000 mA ±200 mA, I
I
= 4300 mA ±300 mA
Disable the output of the electronic load.Type 3000 (mA) in the Input Current Register and click Write.
Enable the output of the electronic load.Measure→I
(sys)
= 2500 mA ±200 mA, I
(bat)
= 500 mA ±300 mA, I
I
= 3000 mA ±400 mAMeasure→V(J4(IOUT)) = 100 mV ±80 mV
Change the B3 bit (IOUTBT) of the Control Register to 0. (adapter current output). Click Write.Measure→V(J4(IOUT)) = 600 mV ±30 mVClick Read AllObserve→The B4 bit (NoDPM) of the Status Register turns green (DPM loop active). The windowshould be like Figure 13 .
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 15Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 13. The Software Main Window
Turn off the electronic load.Measure→I
(sys)
= 0 ±100 mA, I
(bat)
= 3000 mA ±200 mA.
2.4.4 Charger Cut-Off by Thermistor (bq24721 ONLY)
Slowly increase the output voltage of PS3 until I
(bat)
= 0 A ±10 mA.Measure→V(J8(ACGD)) = 3.675 V ±300 mV
Slowly decrease the output voltage of PS3. Charge resumes. Continue to decrease the output voltage ofPS3 until I
(bat)
= 0 A ±10 mA.Measure→V(J8(ACGD)) = 1.465 V ±300 mV
Slowly increase the output voltage of PS3 to 2.5 V ±100 mVMeasure→I
(bat)
= 3000 mA →200 mA.
2.4.5 Voltage Regulation and NonSynchronous Operation at Light Load
Slowly increase the output voltage of the Kepco load until I
(bat)
= 300 mA ±20 mAMeasure→V(J8(VBAT, GND)) = 12.6 V ±200 mV
In the Software main window, click Read All.Observe →The B2 bit (NoVreg) of the Status Register turns green (voltage loop active). The windowshould be like Figure 14 .
16 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 14. The Software Main Window
Observe→The inductor current waveform is like Figure 15 . The inductor current does not drop below0 A.
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 17Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 15. The Waveforms at I
(bat)
= 300 mA
2.4.6 Learn Cycle
Measure→V(J8(VSYS)) = 19 V ±1 V (adapter connected to system)Observe→D10 (ACSW ON) ON, D11 (BATDRV ON) OFF.
Change the B0 bit (CHGEND) of the Control Register to 1(disable the charging). Click Write.
Change the B4 bit (LEARN) of the Control Register to 1. (learn cycle). Click Write.Measure→V(J8(VSYS)) = 12.3 V ±300 mV (battery connected to system).Observe→D10 (ACSW ON) off, D11 (BATDRV ON) ON.Click Read All.Observe→The window should be like Figure 16 .
18 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 16. The Software Main Window
2.4.7 Power Path Selection
Change the B4 bit (LEARN) of the Control Register to 0. (no learn). Click Write.Measure→V(J8(VSYS)) = 19 V ±1 V (adapter connected to system)Observe→D10 (ACSW ON) ON, D11 (BATDRV ON) OFF.
Turn off PS1.Measure→V(J8(VSYS)) = 12.3 V ±300 mV (battery connected to system)Observe→D10 (ACSW ON) OFF, D11 (BATDRV ON) ON, D8 (BYPASS ON) OFF.Observe→The B1 bit (CHGOFF) of the Status Register turns red (charger is not on). The windowshould be like Figure 17 .
SLUU237 – January 2006 bq24720/21 EVM (HPA104) for Multi-Cell Synchronous 19Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface

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Test Summary
Figure 17. The Software Main Window
bq24720/21 EVM (HPA104) for Multi-Cell Synchronous20 SLUU237 – January 2006Switch-Mode Charger With System Power Selector and SMBus SBS-Like Interface