LM3622

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SNVS043B – FEBRUARY 2000 – REVISED APRIL 2013

APPLICATION INFORMATION

CEL PIN CURRENT DRAIN

The LM3622 has an internal power down switch in series with the on-chip resistor divider that is used for sensing

resistor divider from the CS pin, preventing the battery from discharging through the CEL pin.

EXT PIN

base-emitter resistor when driving a PNP transistor, or the gate-source resistor when driving a P-MOSFET.

LV PIN CURRENT RATING

The LV pin is a low power, NPN open collector output that is rated to sink 10mA maximum. Therefore, the value

of the pull up resistor should be chosen high enough to limit the current to be less than 10mA.

CS PIN

In normal operation, the current limit threshold voltage for the CS pin is 100mV typical. In case of a fault

condition, the voltage to this pin should be limited to below 5V.

TYPICAL APPLICATION

Figure 9. Low Dropout, Constant Current/Constant Voltage Li-ion Battery Charger

The low dropout linear charger shown in Figure 9 provides constant current and constant voltage charging of 1-

cell lithium-ion battery packs. J1 and J2 are used for selecting the operation of the low-voltage detection. The

LM3622 initializes the charge cycle based on the battery voltage and the enable status of the low-voltage

detection.

When the low-voltage detection is disabled, the LM3622 starts the charge cycle constant current mode if the

battery voltage is below the controller's regulation level. In constant current mode, the LM3622 modulates the

base drive of Q2 to regulate a constant 100mV across the current sense resistor R1, thus generating charge

current of

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