LTC4088-1_12 LINER [Linear Technology], LTC4088-1_12 Datasheet - Page 7

• Manufacturer Part Number: LTC4088-1_12
• Description: High Efficiency Battery Charger/USB Power Manager
• Manufacturer: LINER [Linear Technology]

Typical perForMance characTerisTics
pin FuncTions
NTC (Pin 1): Input to the NTC Thermistor Monitoring
Circuits. The NTC pin connects to a negative temperature
coefficient thermistor which is typically co-packaged with
the battery pack to determine if the battery is too hot or
too cold to charge. If the battery’s temperature is out of
range, charging is paused until the battery temperature re-
enters the valid range. A low drift bias resistor is required
from V
to ground. If the NTC function is not desired, the NTC pin
should be grounded.
CLPROG (Pin 2): USB Current Limit Program and Monitor
Pin. A 1% resistor from CLPROG to ground determines
the upper limit of the current drawn from the V
A precise fraction of the input current, h
to the CLPROG pin when the high side switch is on. The
switching regulator delivers power until the CLPROG
pin reaches 1.188V. Therefore, the current drawn from
V
R
two of which correspond to the 500mA and 100mA USB
specifications. A multilayer ceramic averaging capacitor
is also required at CLPROG for filtering.
BUS
CLPROG
will be limited to an amount given by h
BUS
. There are several ratios for h
to NTC and a thermistor is required from NTC
100
80
20
60
40
0
0
CHRG Pin Current vs Voltage
(Pull-Down State)
V
V
BUS
BAT
= 3.8V
= 5V
1
CHRG PIN VOLTAGE (V)
2
3
CLPROG
4
CLPROG
408812 G19
CLPROG
5
available,
BUS
, is sent
pin.
and
V
used to sense the voltage at V
switching regulator is in operation. V
be connected directly to V
D2 (Pin 4): Mode Select Input Pin. D2, in combination with
the D0 pin and D1 pin, controls the current limit and bat-
tery charger functions of the LTC4088-1/LTC4088-2. The
LTC4088-1 and LTC4088-2 differ only in the functionality
of the D2 pin default (0, 0, 0) state (see Table 1). This pin
is pulled low by a weak current sink.
C/X (Pin 5): End of Charge Indication Program Pin. This pin
is used to program the current level at which a completed
charge cycle is indicated by the CHRG pin.
PROG (Pin 6): Charge Current Program and Charge Cur-
rent Monitor Pin. Connecting a 1% resistor from PROG
to ground programs the charge current. If sufficient input
power is available in constant-current mode, this pin servos
to 1V. The voltage on this pin always represents the actual
charge current by using the following formula:
AC-COUPLED
OUTS
500µA/DIV
I
20mV/DIV
BAT
V
0mA
I
OUT
OUT
(Pin 3): Output Voltage Sense. The V
=
R
Suspend LDO Transient Response
(500µA to 1mA)
V
PROG
PROG
T
LTC4088-1/LTC4088-2
A
= 25°C, unless otherwise noted.
• 1031
500µs/DIV
OUT
.
OUT
408812 G20
when the PowerPath
OUTS
should always
OUTS
pin is
40881fc
7