LTC4066/LTC4066-1
PIN FUNCTIONS
CLPROG (Pin 22): Current Limit Program and Input Cur-
rent Monitor. Connecting a resistor, RCLPROG, to ground
programs the input to output current limit. The current
limit is programmed as follows:
ICL(A)
=
1000V
RCLPROG
In USB applications the resistor RCLPROG should be set
to no less than 2.1k.
The voltage on the CLPROG pin is always proportional to
the current flowing through the IN to OUT power path.
This current can be calculated as follows:
IIN(A)
=
VCLPROG
RCLPROG
•
1000
PROG (Pin 23): Charge Current Program. Connecting a
resistor, RPROG, to ground programs the battery charge
current. The battery charge current is programmed as
follows:
ICHG(A)
=
50,000V
RPROG
ISTAT (Pin 24): Battery Current Status Pin. One-thousandth
of the current flowing into or out of the BAT pins flows
out of this pin. The POL polarity pin indicates which
direction current is flowing. If the current flowing into
the BAT pins drops below 1mA, then the ISTAT pin will
continue to source 1μA. The ISTAT pin also programs the
charge current level at which the CHRG pin transitions to
its high impedance state. When the ISTAT voltage drops
below 0.1V while charging in constant voltage mode the
CHRG pin will transition to a high impedance state. This
corresponds to a BAT current of:
IBAT(A) =
0.1V
RISTAT
• 1000
4066fc
10