LM3655 Datasheet, PDF (1/21 Pages) National Semiconductor (TI) – Charge Control and Protection IC for embedded single

November 2004
LM3655
Charge Control and Protection IC for embedded single
cell Li-Ion/Polymer batteries
1.0 General Description
The LM3655 provides complete charge control, discharge
control and battery safety of a single Lithium-Ion cell. It
supports battery charging by using a variety of power supply
types including unregulated current-limited wall adapters,
regulated wall adapters and vehicle power adapters. Charge
current control is achieved using an external bipolar PNP
power transistor.
Furthermore, the LM3655 provides effective and compre-
hensive discharge control functionality. All operating load
current is supplied by the Li-Ion battery and passes through
this IC. This allows the battery power to disconnect due to
overload, short-circuit or low battery conditions. The IC also
offers extensive battery safety protection against over-
voltage and over-current. The internal safety circuit is
backed up by an identical circuit to provide safety redun-
dancy. The LM3655 requires minimal external components
and is packaged in a micro surface mount device for inte-
gration in a single cell battery pack.
2.0 Key Specifications
n 1% precision pin-selectable nominal 4.10V and 4.16V
termination voltages
n Up to 1.2A full-rate charge current
n Safety Shunt voltage 4.35V
n 800 mW power regulation of external PNP at 25˚C
allows operation up to 30V (peak-to-peak) and 18V DC
3.0 Features
n Input over-voltage protection for load and battery pack
n Input over-current protection for load and battery pack
n Reverse current protection
n Reverse charger protection
n Input short circuit protection that protects the cell from a
short on the charger-connector
n Output overload current and short circuit protection
n Complete charge control with pre-charging for depleted
batteries, full-rate and trickle charging.
n Support for charging with regulated and non-regulated
wall adapters and vehicle power adapters.
n Power regulation of the external Power PNP
n Chemistry selection for Li-ion and Li-polymer
n Complete linear Peak detector function for filtering ripple
on input power supply
n Digital filtering of the cell voltage transients during
transmit pulses when LM3655 is used in a battery pack
for cell phones.
n 25-pin, 2.5 mm x 2.5 mm microSMD package for
mounting on four layered PCB inside the battery pack.
4.0 Applications
n Cell phones and other portable applications which use
embedded Li-ion batteries
5.0 Typical Application Circuit
20111501
Because the LM3655 and associated external components provide safety protection for both the Li-Ion cell and the phone circuitry, appropriate precautions
must be taken in system design and layout to ensure proper operation.
© 2004 National Semiconductor Corporation DS201115
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