Datasheet LTC4002 (Analog Devices) - 8

LTC4002
W U TYPICAL PERFOR A CE CHARACTERISTICS TA = 25
°
C, VCC = 10V unless otherwise noted. End-of-Charge Ratio End-of-Charge Ratio vs Temperature vs VCC
14 14 LTC4002-8.4 LTC4002-8.4 13 13 12 12 11 11 (%) (%) 10 10 EOC EOC R R 9 9 8 8 7 7 6 6 – 50 – 25 0 25 50 75 100 125 5 10 15 20 25 TEMPERATURE (°C) VCC (V) 4002 G30 4002 G31
U U U PI FU CTIO S (DFN/SO-8) COMP (Pin 1/Pin 1):
Compensation, Soft-Start and Shut- current drops below the End-of-Charge threshold for more down Control Pin. The COMP pin is the control signal of the than 120µs, the N-channel MOSFET turns off and a 25µA inner loop of the current mode PWM. Charging begins when current source is connected from the CHRG pin to GND. the COMP pin reaches 800mV. The recommended compen- When the timer runs out or the input supply is removed, sation components are a 0.47µF (or larger) capacitor and the 25µA current source is turned off and the CHRG pin a 2.2k series resistor. A 100µA current into the compen- becomes high impedance. sation capacitor also sets the soft-start slew rate. Pulling
BAT (Pin 7/Pin 6):
Battery Sense Input. A bypass capaci- the COMP pin below 360mV will shut down the charger. tor of 22µF is required to minimize ripple voltage. An
VCC (Pin 2/Pin 2):
Positive Supply Voltage Input. VCC can internal resistor divider, which is disconnected in sleep range from VBAT(FLT) + 0.5V to 22V. A 0.1µF or higher ca- mode, sets the final float voltage at this pin. If the battery pacitor is required at the VCC pin with the lead length kept connection is opened when charging, an overvoltage to a minimum. A 10µF low ESR capacitor is also required circuit will limit the charger output voltage to 10% above at the source pins of the power P-channel MOSFET. the programmed float voltage.
GATE (Pin 3/Pin 3):
Gate Drive Output. Driver Output for When VBAT is within 250mV of VCC, the LTC4002 is forced the P-Channel MOSFET. The voltage at this pin is internally into sleep mode, dropping ICC to 10µA. clamped to 8V below VCC, allowing a low voltage MOSFET
SENSE (Pin 8/Pin 7):
Current Amplifier Sense Input. A sense with gate-to-source breakdown voltage of 8V or less to be resistor, R used. SENSE, must be connected between the SENSE and BAT pins. The maximum charge current is equal to
PGND, SGND, Exposed Pad, GND (Pins 4, 5, 11/Pin 4):
100mV/RSENSE. IC Ground. The exposed pad (DFN) must be soldered to PCB
NTC (Pin 9/Pin 8):
NTC (Negative Temperature Coefficient) ground to provide both electrical contact and optimum Thermistor Input. With an external 10kΩ NTC thermistor thermal performance. to ground, this pin senses the temperature of the battery
CHRG (Pin 6/Pin 5):
Open-Drain Charge Status Output. pack and stops the charger when the temperature is out of When the battery is being charged, the CHRG pin is pulled range. When the voltage at this pin drops below 355mV at low by an internal N-channel MOSFET. When the charge 4002f 8