TPS65720 Datasheet, PDF (18/50 Pages) Texas Instruments – PMU for Bluetooth Headsets

TPS65720
TPS65721
SLVS979 – OCTOBER 2009
www.ti.com
POWER-ON RESET MODE
The charger enters power-on reset mode when the input voltage at AC is within the valid range: VAC > UVLO
and VAC > VBAT + VIN(DT) and VAC < VOVP, and the Bits <AC input current1, AC input current0> indicate that
the USB suspend mode is not enabled [<AC input current1, AC input current0>≠ (0,0)]. During power-on reset
mode, all internal timers and other circuit blocks are activated. The device checks for short-circuits at the ISET
pin. If no short conditions exists, the device switches on the input FET Q1 with a 100-mA current limit to check
for a short circuit at SYS. If VOUT rises above VSC, the FET Q1 switches to the current-limit threshold set by
<AC input current1, AC input current0>, and the device enters into the Idle mode.
IDLE MODE
In the Idle mode, the system is powered by the input source (Q1 is on), and the device continuously monitors the
status of the host commands. It also continuously monitors the input voltage conditions. Q2 is turned on
whenever the input source cannot deliver the required load current (supplement mode). The device also enters
Idle mode whenever <CH_EN> =0 while the input voltage is in the valid range of operation.
POWER-PATH MANAGEMENT
The current at the input pin AC of the power path manager is shared between charging the battery and powering
the system load on the SYS pin. Priority is given to the system load. The input current is monitored continuously.
If the sum of the charging and system load currents exceeds the preset maximum input current (programmed
internally by I2C), the charging current is reduced automatically. The default value for the current limit is 500mA
for the AC pin.
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