LTC4006_15 Datasheet, PDF(6/20 Page) Linear Technology – 4A, High Efficiency, Standalone Li-Ion Battery Charger

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LTC4006_15 Datasheet, PDF (6/20 Pages) Linear Technology – 4A, High Efficiency, Standalone Li-Ion Battery Charger

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LTC4006

PI FU CTIO S

RT (Pin 4): Timer Resistor. The timer period is set by

placing a resistor, RRT, to GND.

The timer period is tTIMER = (1hour â¢ RRT/154k)

If this resistor is not present, the charger will not start.

GND (Pin 5): Ground for low power circuitry.

NTC (Pin 6): A thermistor network is connected from NTC

to GND. This pin determines if the battery temperature is

safe for charging. The charger and timer are suspended if

the thermistor indicates a temperature that is unsafe for

charging. The thermistor function may be disabled with a

300k to 500k resistor from DCIN to NTC.

ITH (Pin 7): Control Signal of the Inner Loop of the Current

Mode PWM. Higher ITH voltage corresponds to higher

charging currrent in normal operation. A 6.04k resistor, in

series with a capacitor of at least 0.1ÂµF to GND, provides

loop compensation. Typical full-scale output current is

40ÂµA. Nominal voltage range for this pin is 0V to 3V.

IMON (Pin 8): Current Monitoring Output. The voltage at

this pin provides a linear indication of charging current.

Peak current is equivalent to 1.19V. Zero current is ap-

proximately 0.309V. A capacitor from IMON to ground is

required to filter higher frequency components. If VBAT <

2.5V/cell, then V(IMON) = 1.19V when conditioning a

depleted battery. Any current sourced or sinked from this

pin directly affects the charging current accuracy. If this

pin is to be monitored, a high impedance input buffer

should be used.

CSP (Pin 9): 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 10): Battery Sense Input and the Negative

Reference for the Current Sense Resistor. A precision

internal resistor divider sets the final float potential on this

pin. The resistor divider is disconnected during shutdown.

CLP (Pin 11): Positive Input to the Supply Current Limiting

Amplifier, CL1. The threshold is set at 100mV above the

voltage at the CLN pin. When used to limit supply current,

a filter is needed to filter out the switching noise. If no

current limit function is desired, connect this pin to CLN.

CLN (Pin 12): Negative Reference for the Input Current

Limit Amplifier, CL1. This pin also serves as the power

supply for the IC. A 10ÂµF to 22ÂµF bypass capacitor should

be connected as close as possible to this pin.

TGATE (Pin 13): Drives the top external P-channel MOSFET

of the battery charger buck converter.

PGND (Pin 14): HighCurrentGroundReturnfortheBGATE

Driver.

BGATE (Pin 15): Drives the bottom external N-channel

MOSFET of the battery charger buck converter.

INFET (Pin 16): Drives the Gate of the External Input PFET.

TEST CIRCUIT

35mV

11.67ÂµA

VREF

BAT

CSP

LTC4006

ITH

LT1055

0.6V

4006 TC

4006fa

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