BQ24081 Datasheet, PDF (3/10 Pages) Texas Instruments – bq24081EVM 1-A Single-Chip Li-Ion and Li-Pol Charge Management IC Evaluation Module

www.ti.com
Test Summary
1. Turn on the power supply, which is preset to 5 Vdc, and 1 A for the current limit setting.
2. The bq24081 enters preconditioning mode if the battery is below the V_(LOWV) threshold. In this mode,
the bq24081 precharges the battery with a low current, typically:
I_{O(CHG) = 0.7 A = 70 m A}
10
10
(2)
until the battery voltage reaches the V_(LOWV) threshold or until the precharge timer expires. If the timer
expires, then the charge current is terminated and the bq24081 enters fault mode. Both LEDs turn off
when in fault mode. Toggling input power or battery replacement resets fault mode. Note that there are
several fault conditions. They are described in the data sheet (SLUS687).
3. Once the battery voltage is above the V_(LOWV) threshold, the battery enters fast charge mode. This
EVM is programmed for 0.7 A of fast charging current.
4. Once the battery reaches voltage regulation (4.2 V) the current tapers down as the battery reaches its
full capacity.
5. When the current reaches the termination threshold, the charge is terminated.
6. After termination, if the battery discharges down to the recharge threshold, the charger starts fast
charging.
An alternative method of testing the EVM is with a source meter, that can sink or source current. This can
be adjusted to test each mode, in place of a battery.
Another alternative to briefly view each mode, on a scope, is to connect a 1-mF or larger capacitor and a
parallel 10-kΩ resistor on the output in place of a battery to observe the charging cycling.
2.3 Alternative Test Procedure
The procedure in Section 2.3.1 describes a quick test to verify charging states without the need for a
battery or expensive test equipment.
2.3.1 Equipment
1. Power source: current limited 5-V lab supply with its current limit set to 1 A ±0.1 A.
2. Two fluke 75, equivalent or better.
3. Load test board as shown in Figure 1.
Power Supply
5.1 ±0.1 V
I_LIM 1.0 ±0.1 A
+
−
bq24081EVM
DC+
DC−
BAT+
BAT−
DMM1
BAT+
BAT−
A _{Settings for Switch S2}
1. ON (Fast Charger for USB 0.5 A)
2. OFF
3. ON (Fast Charger for Adaptive Source)
C1
+ ^{1000 mF}
R8
0.1 W
R2
120 W
0.25 W
R3
120 W
0.25 W
R4
120 W
0.25 W
R5
10 W
2W
R6
10 W
2W
R1
2 kW
0.25 W
R9
680 W
0.25 W
S3
S1
2
3
R7
2.4 W
2W
1
S2
A
DMM2
Note: R5, R6, and R7—5% or better. All other resistors—1% or better
Figure 1. bq24081EVM Testing Setup
SLUU261 – September 2006
Submit Documentation Feedback
bq24081EVM 1-A Single-Chip Li-Ion and Li-Pol Charge
3
Management IC Evaluation Module