LTC4070 datasheet(6/16 Pages) LINER

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LTC4070

4070f

PIN FUNCTIONS

NTCBIAS (Pin 1): NTC Bias Pin. Connect a resistor from

NTCBIAS to NTC, and a thermistor from NTC to GND. Float

NTCBIAS when not in use. Minimize parasitic capacitance

on this pin.

NTC (Pin 2): Input to the Negative Temperature Coefficient

Thermistor Monitoring Circuit. The NTC pin connects to

a negative temperature coefficient thermistor which is

typically co-packaged with the battery to determine the

temperature of the battery. If the battery temperature is too

high, the float voltage is reduced. Connect a low drift bias

resistor from NTCBIAS to NTC and a thermistor from NTC

to GND. When not in use, connect NTC to VCC. Minimize

parasitic capacitance on this pin.

ADJ (Pin 3): Float Voltage Adjust Pin. Connect ADJ to GND

to program 4.0V float voltage. Disconnect ADJ to program

4.1V float voltage. Connect ADJ to VCC to program 4.2V

float voltage. The float voltage is also adjusted by the NTC

thermistor.

HBO (Pin 4): High Battery Monitor Output (Active High).

HBO is a CMOS output that indicates that the battery is fully

charged and current is being shunted away from BAT. This

pin is driven high when VCC rises to within VHBTH of the

effective float voltage. The absolute value of this threshold

depends on ADJ and NTC, both of which affect the float

voltage. HBO is driven low when VCC falls by more than

(VHBTH + VHBHY) below the float voltage. Refer to Table 1

for the effective float voltage.

GND (Pin 5, Exposed Pad Pin 9): Ground. The exposed

package pad must be connected to PCB ground.

LBO (Pin 6): Low Battery Monitor Output (Active High).

LBO is a CMOS output that indicates when the battery

is discharged below 3.2V or rises above 3.5V. This pin

is driven high if VCC < VLBTH, and is driven low if VCC >

(VLBTH + VLBHY).

DRV (Pin 7): External Drive Output. Connect to the gate of

an external PFET to increase shunt current for applications

which require more than 50mA charge current. Minimize

capacitance and leakage current on this pin. When not in

use, float DRV.

VCC (Pin 8): Input Supply Pin. The input supply voltage is

regulated to 4.0V, 4.1V, or 4.2V depending on the ADJ pin

state (see the ADJ pin description for more detail). This pin

can sink up to 50mA in order to keep the voltage regula-

tion within accuracy limits. When no battery is present,

decouple to GND with a capacitor, CIN, of at least 0.1μF.

LTC4070 Datasheet(PDF) 6 Page - Linear Technology

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