Pin #

Name

I/O

Type

Description

E2

BATT_DETB

Input

Logic

This pin is used to detect the presence of a battery. When the battery

is missing, the internal 100K resistor will pull up this pin to the voltage

on CELL. When the battery is present, this pin should be pulled low.

E3

CHRG_STATE

Output

Open

Drain

This pin is used to indicate the charge status. An external 30K pull-up

resistor needs to be connected between this pin and RADIO+ if output

on this pin is desired. A low output signifies that the IC is charging the

battery cell in full-rate mode. A high output indicates that trickle/top-off

charging is in process. The output is also high when the charger is

disabled (DIS pin tied high).

E4

CHRG_DETB

Output

Open

Drain

An external 30K pull-up resistor needs to be connected between this

pin and RADIO+ if output on this pin is desired. The CHRG_DETB

indicates whether an external power supply has been detected (output

= low) or not (output = high).

E5

VDET

Input

Analog

VDET provides the internal control with a signal that is proportional to

the external voltage level and also provides power to the internal

control circuitry.

8.0 Ordering Information

Order Number

Packaging Type

NSC Package

Marking (*)

Supplied As

LM3655TL

25-bump Wafer Level

Chip Scale

(micro SMD)

XY TT S50

250 units, Tape-and-Reel

LM3655TLX

XY TT S50

3000 units, Tape-and-Reel

(*) XY - denotes the date code marking (2 digits) in production

(*) TT - refers to die/lot tracking for production

(*) S - product line designator

Package markings may change over the course of production

9.0 Operation Description

Refer to Typical Application Circuit for external and internal component reference designators such as Q1, M5, etc.

10.0 Pin Functions

10.1 V

IN

V

an external supply, cell phone operating current also passes through this pin. Total input current into the V

sensed by monitoring the voltage drop across the series sensing FET M5.

V

(VPS) potential exceeds a maximum safe limit, Q1 will be controlled to protect the cell and phone circuits from over-voltage. Q1

provides the primary over-voltage protection mechanism for the phone circuits and the cell.

10.2 CELL

CELL is connected directly to the battery/cell positive terminal. Under normal operation of the phone, it serves as the main power

supply pin for the LM3655.

When the phone is drawing current from the battery, current will flow into this pin and out through the internal FET M4 to supply

the phone’s operating rail (RADIO_B+). When connected to an external supply to charge the battery, current will flow through M5

and out of this pin into the cell. If the phone is being operated while connected to an external power supply, the phone’s operating

current (current out of the RADIO_B+ pin) will be the sum of the currents into the CELL and V

10.3 RADIO_B+

All power for the phone’s operation (other than battery charging) is derived from this pin. The phone’s operating current flows

through M4, which is controlled and monitored to prevent overload or short-circuit currents, and disabled during cell under-voltage

conditions.

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