Test Setup and Results
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8
SLVUB31A – September 2017 – Revised March 2018
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bq25910EVM-854 Evaluation Module
2.2.4
Measuring bq25910 Charge Efficiency
This section details how to evaluate the bq25910 charge efficiency.
1. Apply 9 V on VBUS at the
J3
port on the EVM.
2. Apply 3.8 V on BAT at the
J4
port on the EVM.
3. Follow the steps in
section 2.2.3.1
, to place the master charger in HIZ mode.
4. Follow the steps in
section 2.2.2
, to enable charge on the bq25910.
5. In order to calculate efficiency, the input voltage, battery voltage and charge current must be set
correctly.
•
On bqStudio, navigate to the bq25910 device tab and select
3000mA
from the
Fast Charge
Current Limit
drop-down menu.
•
Using a multimeter, measure the voltage at the
BAT_s
testpoint with respect to the
GND_s
testpoint and modify the battery emulator voltage until 3.8 V is measured.
•
Using a multimeter, measure the voltage at the
VBUS2_s
testpoint with respect to the
GND_s
testpoint and modify the power supply until 9 V is measured.
•
At this point, the device should be providing 3 A of charge current. Input current and charge
current can be measured either by an ammeter in series with VBUS and BAT or measuring the
voltage across the sense resistors,
R20
and
R21
, and converting the voltage to current.
•
Once input voltage, battery voltage, charge current and input current are measured, efficiency can
be calculated.
