MAX77751 datasheet(25/40 Pages) MAXIM

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MAX77751

3.15A USB-C Autonomous Charger

for 1-Cell Li+ Batteries

www.maximintegrated.com

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Fast-Charge Constant Current State

As shown in Figure 6, the fast-charge constant current (CC) state occurs when the battery voltage is greater than the

trickle threshold and less than the battery regulation threshold (VTRICKLE < VBATT < VBATTREG).

In the fast-charge CC state, the current into the battery is less than or equal to IFC. The charge current can be less than

IFC for any of the following reasons:

• The charger input current is lower than the input current limit

• The charger input voltage is low

• The charger is in thermal foldback

• The system load is consuming adapter current. Note that the system load always gets priority over the battery charge

current.

The following events cause the state machine to exit this state:

• When the battery voltage rises above VBATTREG, the charger enters the next state in the charging cycle, fast-charge

constant voltage state.

• If the battery charger remains in this state for longer than tFC, the charger state machine transitions to the timer fault

state.

The battery charger dissipates the most power in the fast-charge CC state. This power dissipation causes the internal die

temperature to rise. If the die temperature exceeds TREG, IFC is reduced. See the Thermal Foldback section for more

information.

Fast-Charge Constant Voltage State

As shown in Figure 6, the fast-charge constant voltage (CV) state occurs when the battery voltage rises to VBATTREG

from the fast-charge CC state.

In the fast-charge CV state, the battery charger maintains VBATTREG across the battery, and the charge current is less

than or equal to IFC. As shown in Figure 5, the charger current decreases exponentially in this state as the battery

becomes fully charged.

The smart power selector control circuitry might reduce the charge current lower than the battery can otherwise consume

for any of the following reasons: