Datasheet LTC4123 (Analog Devices) - 6

LTC4123
pin FuncTions ACIN (Pin 1):
AC Input Voltage. Connect the external LC
PROG (Pin 4):
The charge current program pin. A 1% tank, which includes the receive inductor, to this pin. Short resistor, RPROG, connected from PROG to ground programs this pin to ground when not used. the charge current. In constant-current charging mode,
V
the voltage at this pin is regulated to 0.25V. The voltage
CC (Pin 2):
The DC input voltage range is 2.2V to 5V. An internal diode is connected from the ACIN pin (anode) to on this pin sets the constant current charge current to: this pin (cathode). When an AC voltage is present at the 96 • VPROG 24V ACIN pin, the voltage on this pin is the rectified AC voltage. ICHG = = R R Connect a 4.7µF capacitor to ground on this pin. When the PROG PROG ACIN pin is not used (shorted to ground), connect this pin
BAT (Pin 5):
Battery connection pin. Connect the NiMH to a DC voltage source to provide power to the part and battery to this pin. At 25°C, the battery voltage is regulated to charge the battery. to 1.5075V. This charge voltage is temperature compen- sated with a temperature coefficient of –2.5mV/ºC.
CHRG (Pin 3):
Open-Drain charge status output. CHRG requires a pull-up resistor and/or LED to indicate the status
GND (Pin 6, Exposed Pad Pin 7):
Ground. Connect the of the battery charger. This pin has four possible states: ground pins to a suitable PCB copper ground plane for powered on/charging (blink slow), no power /not charging proper electrical operation. The exposed pad must be (high impedance), charging complete (pull-down), and soldered to PCB ground for the rated thermal performance. Zinc-Air battery/reverse polarity detection/ battery tem- perature out of range/UVCL at the beginning of the charge cycle (blink fast). To conserve power, this pin implements a 340µA pull-down current source. 4123fa 6 For more information www.linear.com/LTC4123