BQ24187 Datasheet, PDF (15/44 Pages) Texas Instruments – 1A USB-OTG Support

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Device Functional Modes (continued)
bq24187
SLUSBM0 – APRIL 2014
Adapter Voltage Falls due to Adapter Current Limit
Input Current Reduced by V_INDPM function to Prevent
Adapter from Crashing
Charge Current is Reduced by V_INDPM Response
Sum of Charge Current and Load Current is limited to the
Adapter Current Limit of 750mA
Figure 7. bq24187 V_INDPM
8.4.1.1.1.3 Input Over-Voltage Protection
The bq24187 provides over-voltage protection on the input that protects downstream circuitry. The built-in input
over-voltage protection to protect the device and other components against damage from overvoltage on the
input supply (Voltage from V_IN to PGND). When V_IN > V_OVP, the bq24187 turns off the PWM converter, sends a
single 128μs pulse is sent on the STAT and INT outputs and the STATx and FAULT_x bits of the status registers
and the battery/supply status registers are updated in the I²C. Once the OVP fault is removed, the STATx and
FAULT_x bits are cleared and the device returns to normal operation.
8.4.1.1.2 Charge Mode Operation
8.4.1.1.2.1 Charge Profile
When a valid input source is connected, the CE bit in the control register determines whether a charge cycle is
initiated. By default, the bq24187 enables the charge cycle when a valid input source is connected (V_IN>V_UVLO
and V_BAT+V_SLP<V_IN<V_OVP). There are 4 loops that influence the charge current; constant current loop (CC),
constant voltage loop (CV), thermal regulation loop and input voltage dynamic power management loop (V_IN-
DPM). During the charging process, all four loops are enabled and the one that is dominant takes control. The
bq24187 supports a precision Li-Ion or Li-Polymer charging system for single-cell applications. Figure 8 shows a
typical charge.
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