12.0 Discharge Control Functions

12.1 GENERAL DESCRIPTION

Depending on the state of charge of the cell (cell voltage), charging and discharging can occur simultaneously. There are two

scenarios: discharge while the charger power supply is connected and discharge while the charger power supply is disconnected.

This will impact the operations of the internal PMOS/NMOS devices and the pass transistor Q1. Figure 5 illustrates the relevant

components of the system.

The charge current will flow through M5 and some current will flow into the cell and some current will flow through M4 and to the

phone. When the charge power supply is not connected the pass transistor Q1 will be turned off and M5 will be off. The current

will be discharged from the cell through M4.

12.2 RADIO+ GENERATION

All current for the phone is sourced through the RADIO_B+ pin. This allows M4 to regulate or disable the battery load current in

the event of an overload condition, internal phone short circuit, or extremely low cell voltage not detected by the phone’s power

management logic.

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FIGURE 4. Peak Detector Response

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FIGURE 5. Circuit Block Diagram

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