LTC4100 datasheet(6/24 Pages) LINER

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LTC4100

sn4100 4100is

TGATE (Pin 1): Drives the Top External P-MOSFET of the

Battery Charger Buck Converter.

PGND (Pin 2): High Current Ground Return for BGATE

Driver.

BGATE (Pin 3): Drives the Bottom External N-MOSFET of

the Battery Charger Buck Converter.

INFET (Pin 4): Drives the Gate of the External Input

P-MOSFET.

DCIN (Pin 5): External DC Power Source Input.

CHGEN (Pin 6): Digital Bidirectional Pin to Enable Charger

Function. This pin is connected as a wired AND bus.

The following events will cause the POWER_FAIL bit in

the ChargerStatus register to become set:

1. An external device pulling the CHGEN signal to within

0.9V to GND;

2. The AC adapter voltage is not above the battery

voltage.

SMBALERT (Pin 7): Active Low Interrupt Output to Host

(referred to as the SMBALERT# signal in the SMBus

Revision 1.1 specification). Signals host that there has

been a change of status in the charger registers and that

the host should read the LTC4100 status registers to

determine if any action on its part is required. This signal

can be connected to the optional SMBALERT# line of the

SMBus. Open drain with weak current source pull-up to

VDD (with Schottky to allow it to be pulled to 5V externally).

SDA (Pin 8): SMBus Data Signal from Main (host-con-

trolled) SMBus. External pull-up resistor is required.

SCL (Pin 9): SMBus Clock Signal from Main (host-con-

trolled) SMBus. External pull-up resistor is required.

ACP (Pin 10): This Output Indicates the Value of the DCDIV

Comparator. It can be used to indicate whether AC is

present or not.

DCDIV (Pin 11): Supply Divider Input. This is a high

impedance comparator input with a 1.2V threshold (rising

edge) and hysteresis.

GND (Pin 12): Ground for Digital and Analog Circuitry.

PI FU CTIO S

ILIM (Pin 13): An external resistor is connected between

this pin and GND. The value of the external resistor

programs the range and resolution of the programmed

charger current.

VLIM (Pin 14): An external resistor is connected between

this pin and GND. The value of the external resistor

programs the range and resolution of the charging volt-

age.

THB (Pin 15): SafetySignal Force/Sense Pin to Smart

Battery. See description of operation for more detail. The

maximum allowed combined capacitance on THA, THB

and SafetySignal is 1nF (see Figure 4). A series resistor

54.9k needs to be connected between this pin and the

battery’s SafetySignal for this circuit to work correctly.

THA (Pin 16): SafetySignal Force/Sense Pin to Smart

Battery. See description of operation for more detail. The

maximum allowed combined capacitance on THA, THB

and SafetySignal is 1nF (see Figure 4). A series resistor

1130

Ω needs to be connected between this pin and the

battery’s SafetySignal for this circuit to work correctly.

VDD (Pin 17): Power Supply Input for the LTC4100 Digital

Circuitry. Bypass this pin with 0.1

µF. Typically between

3.3V and 5VDC.

VSET (Pin 18): Tap Point of the Programmable Resistor

Divider, which Provides Battery Voltage Feedback to the

Charger.

ITH (Pin 19): Control Signal of the Inner Loop of the

Current Mode PWM. Higher ITH corresponds to higher

charging current in normal operation. A 0.0015

µF capaci-

tor to GND filters out PWM ripple. Typical full-scale output

current is 40

µA. Nominal voltage range for this pin is 0V

to 3V.

IDC (Pin 20): Bypass to GND with a 0.082µF Capacitor.

CSP (Pin 21): Current Amplifier CA1 Input. This pin and

the BAT pin measure the voltage across the sense resistor,

RSENSE, to provide the instantaneous current signals re-

quired for both peak and average current mode operation.

BAT (Pin 22): Battery Sense Input and the Negative

Reference for the Current Sense Resistor. A bypass ca-

pacitor of at least 10

µF is required.

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