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Test Summary
5
SLUUBL3A – June 2017 – Revised October 2017
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Copyright © 2017, Texas Instruments Incorporated
bq25606 PWR772 Evaluation Module
2.3
Test Procedure
2.3.1
Charger Mode Verification
1. Enable Load #1 from
Section 2.2
, Step 4.
2. Measure the voltage across J4 and J5 as follows:
•
Measure
→
V(TP8(SYS), TP17(GND)) = 3.65 V (typical)
•
Measure
→
V(TP9(BAT), TP17(GND)) = 2.5 V (typical)
•
Measure
→
IBAT ( = pre-charge current)
3. Change Load #1 to 3.7 V
•
Measure
→
V(TP8(SYS), TP17(GND)) = 3.8 V (typical)
•
Measure
→
V(TP9(BAT), TP17(GND)) = 3.7 V (typical)
•
Measure
→
IBAT ( = fast charge current)
4. Adjust R10 to change charging current.
5. Adjust R11 to change input current limit.
6. Turn off and disconnect Load #1.
7. Turn off and disconnect PS#1.
2.3.2
Boost Mode Verification
1. Do not install JP3.
2. If the constant voltage load connected from BAT to GND is not a four-quadrant supply (sources
current), remove the load and use the power source disconnected in step 1, set to 3.7 V and 2-A
current limit and connect between BAT and GND.
3. Apply 10
Ω
(5 W or greater) across J1 VAC(+) to GND(–).
4. Verify V
VBUS
to GND since VBUS is the actual boost mode output voltage.
Measure
→
V
VBUS
= 5.15 V (Typical)
5. Turn off and disconnect power supply.
6. Remove 10-
Ω
resistor at VAC.
2.3.3
Helpful Tips
•
The leads and cables to the various power supplies, batteries, and loads have resistance. The current
meters also have series resistance. The charger dynamically reduces charge current depending on the
voltage sensed at its VBUS pin (using the VINDPM feature), BAT pin (as part of normal termination),
and TS pin (through its battery temperature monitoring feature via battery thermistor). Therefore,
voltmeters must be used to measure the voltage as close to the IC pins as possible instead of relying
on the digital readouts of the power supply. If a battery thermistor is not available, make sure shunts
JP6 and JP7 are in place.
•
When using a source meter that can source and sink current as your battery simulator, TI highly
recommends adding a large (1000+
μ
F) capacitor at the EVM BAT and GND connectors in order to
prevent oscillations at the BAT pin due to mismatched impedances of the charger output and source
meter input within their respective regulation loop bandwidths. Configuring the source meter for 4-wire
sensing eliminates the need for a separate voltmeter to measure the voltage at the BAT pin.
When using 4-wire sensing, always ensure that the sensing leads are connected in order to prevent
accidental overvoltage by the power leads.
•
For precise measurements of charge current and battery regulation near termination, the current meter
in series with the battery or battery simulator should not be set to auto-range and may need be
removed entirely. An alternate method for measuring charge current is to either use an oscilloscope
with Hall effect current probe or place a 1% or better, thermally capable (for example, 0.010
Ω
in 1210
or larger footprint) resistor in series between the BAT pin and battery and measure the voltage across
that resistor. The bq25606EVM has the sensing resistors onboard.