LP28400 Datasheet, PDF (16/17 Pages) Lowpower Semiconductor inc – Programmable Charge Current Up to 3000mA

Preliminary Datasheet
LP28400
plugs in and the voltage is above the battery voltage, the IC
exits SLEEP mode. The battery is disconnected from the
system and the adapter is connected to the system after exiting
SLEEP. An automatic break-before-make logic prevents
shoot-through currents when the selectors switch. The ACDRV
is used to drive a pair of back-to-back n-channel power
MOSFETs between adapter and ACP with sources connected
together to CMS. The n-channel FET with the drain connected
to the ACP (Q2, RBFET) provides reverse battery discharge
protection, and minimizes system power dissipation with its
low-RDSON. The other n-channel FET with drain connected to
adapter input (Q1, ACFET) separates battery from adapter, and
provides a limited dI/dt when connecting the adapter to the
system by controlling the FET turn-on time. The /BATDRV
controls a p-channel power MOSFET (Q3, BATFET) placed
between battery and system with drain connected to battery.
Before the adapter is detected, the ACDRV is pulled to CMS to
keep ACFET off, disconnecting the adapter from system.
/BATDRV stays at ACN-5V (clamp to ground) to connect
battery to system.
After the device comes out of SLEEP mode, the system begins
to switch from battery to adapter.
When the adapter is removed, the IC turns off ACFET and
enters SLEEP mode to turn on p-channel BATFET, connecting
the battery to the system
LP28400-00 Version 1.0 May.-2013 Email: [e-mail] www.lowpowersemi.com Page 16 of 17