Test Procedures

2-3

Test Summary

Note:

For the two-cell case, at 1-A charge rate, where the battery pack is at 6 V,

the power dissipation is temporarily as high as 3.1 W until the pack charges

to 6.8 V. This condition is fine for the short time (~1 min.) before the pack

reaches 6.8 V.

Adjust the input power supply for 9.1 V. The red LED illuminates to indicate

charging, unless there is a fault or the battery is fully charged.

The bq24004/5/6 enters preconditioning mode if the battery is below the LowV

threshold. In this mode, the bq24004/5/6 trickle-charges with approximately

65 mA for approximately 23 minutes. If the battery does not reach the LowV

threshold during this period, then the charge current is terminated and the

bq24004/5/6 enters fault mode. The red LED flashes in fault mode. This

feature may be tested by removing input power, replacing the battery with a

30–40-

Ω resistor from BAT+ to DC–, and applying power (Vin) for more than

23 minutes. Fault mode is reset by toggling input power or enable pin.

Once the battery charges to the LowV-stop threshold, the battery enters fast-

charge mode and charges at the programmed 1-A level. Program charge level

may be changed by adjusting R3

R3

+ 0.10 V

I

chg

.

The battery remains at the fast-charge mode until either the selected time

expires or the battery charges to the selected regulation voltage.

The time-out feature is tested by using a 25–28-

Ω, 5-W resistor in place of the

battery. Apply the resistor after the unit is powered.

If the battery discharges down to the HighV threshold, the charger starts fast

charging. The refresh feature may be tested by charging a battery to

installing a 8–10-

Ω, 10-W resistor in parallel with the battery. The regulator

should start charging once the HIGHV threshold is reached. Note: The battery

is still charging for another 23 minutes after the LED turns off. If a load (>Iterm)

is applied before the 23 minutes has timed out then the load resets the 23

minute timer.

The circuit has an overvoltage comparator for added protection. If the battery

voltage exceeds this threshold for 330 ms, then the charger goes into fault

mode. This may be tested by connecting an external power supply in place of

the battery and adjusting the voltage above the threshold.