LP28601-02

Mar.-2017

www.lowpowersemi.com

Page 9 of 12

Preliminary Datasheet

LP28601

Application Information

The LP28601 is an easy controlled power path

management device and a single cell Li-Ion battery

charger. It integrates the input reverse-blocking FET,

high-side switching FET, low-side switching FET,

and BATFET between system and battery. The

device also integrates the bootstrap diode for the

high-side gate drive.

Device Power Up from Battery without DC Source

If only battery is present and the voltage is above

depletion threshold, the BATFET turns on and

connects battery to system. The REG LDO stays off

BATFET and the low quiescent current on BAT

minimize the conduction loss and maximize the

battery run time.

Power Up from DC Source

When the DC source plugs in, the LP28601 checks

the input source voltage to turn on REG、 LDO and

all the bias circuits. It also checks the input current

limit before starts the buck converter.

Input Source Qualification

After REG LDO powers up, the LP28601 checks the

current capability of the input source. The input

source has to meet the following requirements to

start the buck converter.

1. VBUS voltage below 14V

2. VREG voltage above 2.43V

Once the input source passes all the conditions

above, the permit signal is asserted to the chip.

Input Current Limit Detection

The USB ports on personal computers are

convenient charging source for portable devices

(PDs). If the portable device is attached to a USB

host, the USB specification requires the portable

device to draw limited current. If the portable device

is attached to a charging port, it is allowed to draw up

to the maximum current form the USB host by two

parts limit：

1. VREG voltage above 2.43V

Boost Mode Operation from Battery

The LP28601 supports boost converter operation to

deliver power from the battery to other portable

devices through USB port. The boost mode output

current rating meets the 2A charging requirements

for smart phone and tablet. The boost operation can

be enabled after the OTG and BOOST is pulled low.

In battery boost mode, the LP28601 employs a

synchronous step-up switching regulator. During

boost mode, the output voltage is fixed at 5.1V and

efficiency on VDC. It is recommended to use the

minimum CIN2 cap value 20uF for boost current.

VSYS and Narrow VDC Architecture

The device deploys Narrow VDC architecture (NVDC)

with BATFET separating system from battery. The

minimum system voltage is set by battery voltage.

With a not fully depleted battery, the system is

voltage. And a selectable VSYS could be set by

SYSSEL when battery is fully depleted and adapter

is applied to VBUS.

Charge state indication