Texas Instruments bq24187 User manual

User's Guide
SLUUAI5 –April 2014
bq24187 Evaluation Module User's Guide
The bq24187 evaluation module is a complete charger module for evaluating compact, flexible, high-
efficiency, USB-friendly, switch-mode charge management solution for single-cell, Li-ion and Li-polymer
batteries used in a wide range of portable applications.
Contents
1 Introduction ................................................................................................................... 2
1.1 BQ24187 IC Features.............................................................................................. 2
1.2 bq24187EVM Features ............................................................................................ 2
1.3 Schematic............................................................................................................ 3
1.4 I/O Description ...................................................................................................... 4
1.5 Test Points to IC Pins.............................................................................................. 4
1.6 Control and Key Parameters Setting............................................................................. 4
1.7 Recommended Operating Conditions............................................................................ 5
2 Test Summary................................................................................................................ 5
2.1 Definitions............................................................................................................ 5
2.2 Recommended Test Equipment .................................................................................. 5
2.3 Recommended Test Equipment Setup .......................................................................... 7
2.4 Recommended Test Procedure................................................................................... 9
3 Printed-Circuit Board Layout Guideline.................................................................................. 10
4 Bill of Materials and Board Layout ...................................................................................... 11
4.1 Bill of Materials .................................................................................................... 11
4.2 Board Layout....................................................................................................... 12
List of Figures
1 bq2418xEVM Schematic.................................................................................................... 3
2 BAT_Load (PR1010) Schematic........................................................................................... 6
3 Connections of HPA172 Kit ................................................................................................ 7
4 Recommended Initial Test Setup for bq24187EVM-625 ............................................................... 8
5 Main Window of BQ24187SW Evaluation Software..................................................................... 8
6 Top Assembly Layer....................................................................................................... 12
7 Top Layer ................................................................................................................... 13
8 First Internal Layer ......................................................................................................... 14
9 Second Internal Layer ..................................................................................................... 15
10 Bottom Layer................................................................................................................ 16
List of Tables
1 Bill of Materials - PWR625A ............................................................................................. 11
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Introduction www.ti.com
1 Introduction
1.1 BQ24187 IC Features
The BQ24187 family integrates a synchronous PWM controller, power MOSFETs, input-current sensing,
high-accuracy current and voltage regulation and charge termination into a small WCSP package. The
charge parameters can be programmed through an I2C interface. Key IC features include:
• High-efficiency, fully integrated, NMOS-NMOS, synchronous buck charger with 1.5-MHz frequency
• Charge time optimizer
• Integrated power FETs for up to 2-A charge rate
• 5-V, 1-A on-the-go (OTG) VBUS supply
For details, see the bq24187 data sheet (SLUSBM0).
1.2 bq24187EVM Features
The bq24187 evaluation module (EVM) provides a complete charger module for evaluating compact,
flexible, high-efficiency, USB-friendly, switch-mode battery charge solutions for single-cell, Li-ion and Li-
polymer battery-powered systems used in a wide range of portable applications. Key EVM features
include:
• Terminal blocks and standard headers for IN, BAT, TS; USB connector for IN
• Programmable battery voltage, charge current, input current, and status via I2C interface
• IN operating up to 6.0 V
• LED indication for status signals
• Test points for key signals available for testing purposes. Easy probe hook-up
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1
2
J10
BAT
DRV
1
2
3
JP6
HIGH
up to 4.44V, 2A
PSEL
PSEL
BAT
LOW
Open
C6 1
2
J11
GND
BAT
GND
1
2
J5
BQ24187YFF
PGND
A1 PGND
A2 PGND
A3 PGND
A4 PGND
A5 PGND
A6
PMID
B1
SW B2
SW B3
SW B4
SW B5
SW B6
IN
C1
IN
C2
IN
C3
IN
C4
CD
C5
BOOT C6
SDA
D1
SCL
D2
NC D3
TS D5
DRV D6
STAT
E1
INT
E2
CS+ E3
CS+ E4
CS+ E5
CS+ E6
AGND
F1 NC F2
BAT F3
BAT F4
BAT F5
BAT F6
PSEL
D4
U1
BQ2418XYFF
1.0uF
C4
GND
GND
1
2
3
4
5
6 7
8 9
J2
GND
DM
1
2
JP1
USB R9
GND
PSEL
1.0uF
C9
GND
GND
22uF
C5
up to 6V, 2.5A
1
2
J4
GND
INT
IN
STAT
DRV
1.0uF
C2
4.7uF
C1
TS
IN
Open
C8
PSEL
1
2
J1
GND
GND
GND
DM
SCL
GND
1
2
J8
SDA
GND
0.033uF
C3
GND
1
2
J6
DRV
SW
1.5 uH
L1
DRV
1
2
3
JP4
HIGH
CD
DRV 1
2
J7
LOW
DRV
DRV
GND
GND
GND
EXT
1
2
J3
1
2
J9
5.62k
R5
TP9
TS
GND
TS
DRV
GND
1
2
3
JP5
EXT
D2
12
JP2
12
JP3
D1
TP10
TS
SCL
SIM
1
2
3
4
5
6
7
8
9
10
J12
12.4k
R6
STAT
GND
INT TP1TP2 TP3TP4 TP5 TP7
GND
SW
GND 200
R2
TP11
BAT SDA
GND
CS+
50K
R7
GND
1.50k
R3
1.50k
R4
TP6 TP8
IN
INTSTAT 200
R1
CS+
GND
IN
GND
1
1 1
1
1 See BOM for values
www.ti.com Introduction
1.3 Schematic
Figure 1 illustrates the bq2418x EVM schematic.
Figure 1. bq2418xEVM Schematic
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1.4 I/O Description
Header/Terminal Block Description
J1– IN/GND Input power positive and negative terminal
J2 – USB USB miniconnector
J3 - GND DRV linear regulator negative header
J4 - IN Input power positive header
J5 - GND Battery negative header
J6 - DRV DRV linear regulator positive output
J7 - DRV/GND DRV linear regulator positive and negative terminals
J8 - GND Input power negative header
J9 - EXT TS/GND External thermistor terminal
J10 - GND Battery positive header
J11 - BAT/GND Battery positive and negative terminal
J12 - USB-TO-GPIO USB-TO-GPIO box keyed connector
1.5 Test Points to IC Pins
Test Point Description
TP1 BAT
TP2 SW
TP3 GND
TP4 CS+
TP5 GND
TP6 STAT
TP7 GND
TP8 INT
TP9 TS
TP10 SCL
TP11 SDA
1.6 Control and Key Parameters Setting
Jumper Description Default Factory Setting
JP1 N/A Not installed
JP2 Shorting jumper to connect DRV to annode of D1 STAT LED SHORTED
JP3 Shorting jumper to connect DRV to annode of D1 INT LED SHORTED
CD = LO: Charge disable low for normal operation
JP4 CD = LO
CD = HI: Charge disable high to disable the buck converter and enter Hi-Z mode
TS = SIM: Connects a potentiometer to the TS pin so that the potentiometer can
simulator a thermistor. The potentiometer is preset per R5 and R6 so that the TS
voltage is 0.5 x V (DRV).
JP5 TS=SIM
TS = EXT: Connects the TS pin to an external thermistor through J9. The resistor
divider formed by R5 and R6 is sized to accommodate a 10-kΩthermistor. If a different
thermistor is used, R5 and R6 must be resized.
PSEL = LOW: Input current limit is set to 1.5 A until changed by I2C.
JP6 PSEL = HIGH: Default mode input current limit is set to 100 mA until changed by I2C. PSEL = LOW
Default mode input current limit is set to 1.5 A until changed by I2C.
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www.ti.com Introduction
1.7 Recommended Operating Conditions
Min Typ Max Unit
Supply voltage, VIN Input voltage from ac adapter (bq24262) 4.2 6.0 V
Battery voltage, VBAT Voltage output at VBAT terminal (registers set via I2C 3.5 4.2 4.44 V
communication)
Supply current, IIN(MAX) Maximum input current from ac adapter input (registers set 0.1 2.0 A
via I2C communication)
Fast charge current, Battery charge current (registers set via I2C communication) 0.500 2.0 A
ICHRG(MAX)
Operating junction temperature range, TJ-40 125 °C
2 Test Summary
This procedure describes one test configuration of the HPA721 evaluation board for bench evaluation.
2.1 Definitions
The following naming conventions are followed.
VXXX : External voltage supply name (VADP, VBT, VSBT)
LOADW: External load name (LOAD1, LOAD2)
V(TPyyy): Voltage at internal test point TPyyy. For example, V(TP12) means the voltage at
TP12.
V(Jxx): Voltage at header Jxx
V(TP(XXX)): Voltage at test point XXX. For example, V(ACDET) means the voltage at the test
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 header XX
Jxx(BBB): Terminal or pin BBB of header xx
JPx ON : Internal jumper Jxx terminals are shorted
JPx OFF: Internal jumper Jxx terminals are open
JPx (-YY-) ON: Internal jumper Jxx adjacent terminals marked as YY are shorted
Measure: →A,B Check specified parameters A, B. If measured values are not within specified limits,
the unit under test has failed.
Observe →A,B Observe if A, B occur. If they do not occur, the unit under test has failed.
Assembly drawings have locations for jumpers, test points, and individual components.
2.2 Recommended Test Equipment
2.2.1 Power Supplies
1. A power supply #1 (PS #1) capable of supplying 5 V at 2.5 A, is required.
2. If not using a battery as the load, then power supply #2 (PS #2) capable of supplying up to 5 V at 5 A
is required to power the circuit shown in Figure 2.
2.2.2 Load #1 Between BAT and GND
Testing with an actual battery is the best way to verify operation in the system. If a battery is not available,
then a circuit similar to the one shown in Figure 2 can simulate a battery when connected to a power
supply. Alternatively, a sourcemeter, capable of sourcing and sinking current can be used to simulate a
battery.
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Figure 2. BAT_Load (PR1010) Schematic
2.2.3 Meters
Four equivalent voltage meters (VM #) and two equivalent current meters (CM #) are required. The current
meters must be able to measure 3-A current.
2.2.4 Computer
A computer with at least one USB port and a USB cable is required. The BQ24187 evaluation software
must be properly installed.
2.2.5 HPA172 Communication Kit (USB TO GPIO)
An HPA172 USB-to-I2C communication kit is required.
2.2.6 Software
Download BQ24187SW.zip from the charger's product folder, unzip the file, and double-click on the
SETUP.EXE file. Follow the installation steps.
Because the bq24187 has a watchdog timer, it is recommended that you set the software's Reset
Watchdog Timer to reset every 5 seconds. Otherwise, after 30 seconds of operation, the IC enters
Default mode. Note that the 27-minute safety timer is not reset by this function and eventually times out if
charging does not complete, unless the Safety Timer Time Limit is expanded or disabled via the GUI.
One way to reset the safety timer is to allow the 30-second watchdog timer to expire. See Figure 3 in the
data sheet for more information about the timers.
Also, it is generally helpful to activate the Write On Change functions, in the upper left of the GUI window,
to ON. The Write On Change function writes any changes to the GUI's check boxes, drop-down boxes,
and registers to the IC. Otherwise, the user must click the WRITE button to write changes to the software.
It is recommended that the user periodically click the READ button to find the IC's instantaneous status.
Alternatively, the AutoRead function can be activated to periodically update the GUI with the IC's status.
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To
Computer
USB port
USB Interface
Adapter
I/O
USB
Texas Instruments
© 2006
10-pin
Ribbon
Cable
To EVM
www.ti.com Test Summary
2.3 Recommended Test Equipment Setup
1. For all power connections, use short, twisted-pair wires of appropriate gauge wire for the amount of the
current.
2. Set PS #1 for 5-V, 2.5-A current limit and then turn off supply.
3. Connect the output of PS #1 in series with a current meter (CM #1) to J1 (IN).
4. Connect a voltmeter (VM #1) across J4 and J3 (IN and GND).
5. If BAT_Load as shown in Figure 1 is used, connect PS #2, set to approximately 3.7 V, to the input side
(PS #2+/-) of BAT_Load, then turn off PS #2.
6. Connect the output side of the battery or BAT_Load in series with current meter (multimeter) #2 (CM
#2) to J11 and J10 or J5 (BAT, GND). Ensure that a voltage meter (VM #2) is connected across J10 or
TP1 and J5 or TP7 (BAT and GND).
7. Connect VM #3 across J6 and J8 (DRV and GND).
8. Connect the HPA172 kit to J12 by the 10-pin ribbon cable. Connect the USB port of the HPA172 kit to
the USB port of the computer. The connections are shown in Figure 3.
Figure 3. Connections of HPA172 Kit
9. Ensure jumpers are at the settings highlighted in yellow (except for JP1 which is not installed) per
Section 1.6.
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AVVM#2
CM#2
ICHRG
PS
#1 A
V
VM#3
CM#1
IIN
V
+
-
VM#1
+
-
+
-
-
-+
+
Windows
PC
USB-TO-
GPIO
BAT_Load
PS#2
Test Summary www.ti.com
10. After the preceding steps have been performed, the test setup for bq24187EVM-625 is configured as
is shown in Figure 4
Figure 4. Recommended Initial Test Setup for bq24187EVM-625
11. Turn on the computer. Open the BQ24187 evaluation software. Figure 5 shows the main window of
the software.
Figure 5. Main Window of BQ24187SW Evaluation Software
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www.ti.com Test Summary
2.4 Recommended Test Procedure
The following test procedure may be useful for evaluating the charger IC outside of a real system, if no
battery is available to connect to the output and a simulated battery, if needed.
2.4.1 Charge Voltage and Current Regulation of IN
1. Ensure that the steps in Section 2.3 are followed.
2. Move JP4 to LO.
3. Turn on PS #1.
4. Enable PS #2 and adjust PS #2 so that the voltage measured by VM #2, across BAT and GND,
measures 3.2 V ±50 mV.
5. Adjust the power supply so that VM #1 still reads 5 V ±100 mV, if necessary, then
Measure on CM #2 →ICHRG < 120 mA
Measure on CM #1 →IIN = 90–100 mA
6. Software setup:
• Press the READ button to obtain the current settings.
• Set Write On Change to ON, if not already set.
• Set Safety Timer to Disabled.
• Set Reset Watchdog Timer to update every 5 seconds.
• Uncheck Disable Charging if checked.
• Check Enable STAT/INT Outputs.
• Set Battery Regulation Voltage to 4.20 V.
• Set IN Input Current Limit to 2.0 A.
• Set Charge Current to 1000 mA.
• Click the READ button at the top of the window and confirm that the previous settings remain.
7. Enable PS #2 and adjust PS #2 so that the voltage measured by VM #2, across BAT and GND,
measures 3.8 V ±50 mV.
8. Adjust the power supply so that VM #1 still reads 5 V ±100 mV, if necessary, then
Measure on CM #2 →ICHRG = 1000 mA ±50 mA
Measure on CM #1 →IIN < 750 mA
9. Turn off PS #1 and PS #2.
2.4.2 Helpful Hints
1. To observe the taper current as the battery voltage approaches the set regulation voltage, allow the
battery to charge or, if using BAT_Load (PR1010), slowly increase the PS #2 voltage powering
BAT_Load (PR1010). Use VM #2 across BAT and GND to measure the battery voltage seen by the IC.
2. To observe the VIN-DPM feature, lower the current limit on PS #1.
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Printed-Circuit Board Layout Guideline www.ti.com
3 Printed-Circuit Board Layout Guideline
1. To obtain optimal performance, the power input capacitors, connected from the PMID input to PGND,
must be placed as close as possible to the IC.
2. Place 4.7-µF input capacitor as close to PMID pin and PGND pin as possible to make the high-
frequency current loop area as small as possible. Place 1-µF input capacitor GNDs as close to the
respective PMID capacitor GND and PGND pins as possible to minimize the ground difference
between the input and PMID.
3. The local bypass capacitor from CS+ to GND must be connected between the CS+ pin and PGND of
the IC. The intent is to minimize the current path loop area from the SW pin through the LC filter and
back to the PGND pin.
4. Place all decoupling capacitors close to their respective IC pins and as close as possible to PGND (do
not place components such that routing interrupts power stage currents). All small control signals must
be routed away from the high-current paths.
5. The PCB must have a ground plane (return) connected directly to the return of all components through
vias (two vias per capacitor for power-stage capacitors, one via per capacitor for small-signal
components). It is also recommended to put vias inside the PGND pads for the IC, if possible. A star
ground design approach is typically used to keep circuit block currents isolated (high-power/low-power
small-signal) which reduces noise-coupling and ground-bounce issues. A single ground plane for this
design gives good results. With this small layout and a single ground plane, no ground-bounce issue
exists, and having the components segregated minimizes coupling between signals.
6. The high-current charge paths into IN, USB, BAT, and from the SW pins must be sized appropriately
for the maximum charge current in order to avoid voltage drops in these traces. The PGND pins must
be connected to the ground plane to return current through the internal low-side FET.
7. For high-current applications, the balls for the power paths must be connected to as much copper in
the board as possible. This allows better thermal performance because the board conducts heat away
from the IC.
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