Datasheet

Setup
2-2
2.1 Setup
The BQ2420X EVM board requires a current-limited dc power source to
provide input power and a battery-pack charge current. The test setup
connections and jumper setting selections are listed in Table 2–1.
Table 2–1.I/O and Jumper Connections
Jack Connect To:
J1–DC+ Power supply positive
J1–DC– Power supply ground
J2 (Jumper) Normally connected. Option for adding current limiting resistor on board
J3 (STAT Jumper) Option for connecting STAT pin externally
J4–BAT+ Positive battery pack terminal
J4–BAT– Negative battery pack terminal
J4–TS Thermistor connection
J4–BAT– Negative battery pack terminal
J5– STAT Charge status output
J5–DC– Power supply ground
2.2 Test Procedure
Set up the evaluation board as described above, by making the necessary I/O
connections and jumper selections.
Note:
This EVM is designed specifically to work with a current-limited dc power
supply. Before test and evaluation, it is important to verify that the maximum
power dissipation on the IC is not exceeded: P
(MAX)
= 1.0 watts.
1) Select a power supply with the following specifications:
J DC output voltage at the rated current: 3–5 V
J DC no-load output voltage: 7–10 V
J Rated current: 300–500 mA
2) The bq2420x enters preconditioning mode if the battery is below the LowV
threshold. In this mode, the bq2420x precharges the battery with a low
current (typically 13 mA) for approximately 30 minutes. If the battery does
not reach the LowV threshold after this period, then the charge current is
terminated, and the bq2420x enters fault mode. Both LEDs illuminate in
fault mode. Toggling input power or battery replacement resets fault mode.
3) Once charged to the LowV-stop threshold, the battery enters fast-charge
mode. The external power supply limits the charge current during the initial
stage of charge. Note that bq2420x does not provide any current
regulation.