Datasheet

SLUU156 – April 2003
6
bq24022 (bqTINY-II) Evaluation Module
2.2 Test Procedure
Setup the evaluation board as described above, by making the necessary I/O connections and jumper
selections. Prior to test and evaluation, it is important to verify that the maximum power dissipation on the
device is not exceeded: P
MAX
= 1.5 W.
P
MAX
+
ǒ
V
(DC))
* V
(BAT))
Ǔ
I
(CHG)
1. Turn on the power supply, which is preset to 5.0 VDC, and 1.0 A for the current limit setting.
2. The bq24022 enters preconditioning mode if the battery is below the V
(LOWV)
threshold. In this
mode, the bq24022 precharges the battery with a low current, typically
I
O(CHG)
10
+
0.7 A
10
+ 70 mA
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 bq24022 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 datasheet (SLUS549).
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 taper termination threshold, the taper timer is set and allows
approximately 30 minutes of additional charging time. If the charge current increases above the
taper threshold for any reason, the taper timer is reset. If the current drops below the termination
threshold (design for detecting removal of battery) charging immediately terminates.
6. After termination, if the battery discharges down to the recharge threshold, the charger starts fast
charging.
7. The same procedure may be performed using the USB 0.5-A plug source in place of the J1 power
source. The precharge current is approximately ten percent of the programmed fast charge. The
fast charge current is either 0.1 A or 0.5 A depending on the ISET being low or high.
CAUTION:
If powered from an USB, 0.1-A port, make sure ISET2 is pulled low to program the board for
the 100mA charge.
An alternative method of testing the EVM is with a source meter, that can sink or source current. This can
easily 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-µF or larger capacitor and a
parallel 10-kΩ resistor on the output in place of a battery to observe the charging cycling.
(1)
(2)