LTC4065 LINER [Linear Technology], LTC4065 Datasheet - Page 7

• Manufacturer Part Number: LTC4065
• Description: High Efficiency Battery Charger/USB Power Manager
• Manufacturer: LINER [Linear Technology]

pin FuncTions
Typical perForMance characTerisTics
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
100
80
40
20
60
0
will be limited to an amount given by h
0
CHRG Pin Current vs Voltage
(Pull-Down State)
BUS
V
V
BUS
BAT
. There are several ratios for h
= 3.8V
= 5V
to NTC and a thermistor is required from NTC
1
CHRG PIN VOLTAGE (V)
2
3
4
4088 G19
5
AC COUPLED
20mV/DIV
CLPROG
5mA/DIV
V
I
LDO3V3
LDO3V3
CLPROG
0mA
CLPROG
3.3V LDO Transient Response
(5mA to 15mA)
V
BAT
available,
, is sent
BUS
= 3.8V
pin.
and
20µs/DIV
LDO3V3 (Pin 3): LDO Output. The LDO3V3 pin provides
a regulated, always-on 3.3V supply voltage. This pin gets
its power from V
as a real-time clock or housekeeping microprocessor. A
1µF capacitor is required from LDO3V3 to ground if it will
be called upon to deliver current. If the LDO3V3 output is
not used it should be disabled by connecting it to V
D2 (Pin 4): Mode Select Input Pin. D2, in combination
with the D0 pin and D1 pin, controls the current limit and
battery charger functions of the LTC4088 (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:
I
BAT
=
R
V
T
PROG
PROG
4088 G20
A
= 25°C, unless otherwise noted.
AC-COUPLED
OUT
• 1031
500µA/DIV
20mV/DIV
. It may be used for light loads such
V
0mA
I
OUT
OUT
Suspend LDO Transient Response
(500µA to 1mA)
500µs/DIV
LTC4088
OUT
4088 G21
4088fb
7
.