ltc4001 Linear Technology Corporation, ltc4001 Datasheet - Page 6

• Manufacturer Part Number: ltc4001
• Description: 2a Synchronous Buck Li-ion Charger
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
LTC4001
FAULT (Pin 10): Battery Fault. This pin is a logic high if a
shorted battery is detected or if a temperature fault is
detected. A temperature fault occurs with the temperature
monitor circuit enabled and the thermistor temperature is
either below 0°C or above 50°C (typical).
NTC (Pin 11): Input to the NTC (Negative Temperature
Coefficient) Thermistor Temperature Monitoring Circuit.
Under normal operation, tie a thermistor from the NTC pin
to the GNDSENS pin and a resistor of equal value from NTC
to V
0°C) or below 0.29V
and the CHRG pin blinks. When the voltage on NTC comes
back between 0.74V
where it left off and charging resumes. There is approxi-
mately 3°C of temperature hysteresis associated with
each of the input comparators. If the NTC function is not
used connect the NTC pin to GNDSENS. This will disable
all of the NTC functions. NTC should never be pulled above
V
PROG (Pin 12): Charge Current Program. The R
resistor connects from this pin to GNDSENS, setting the
current:
where I
6
IN
U
R
.
IN
PROG
. When the voltage on this pin is above 0.74V
BAT
=
U
is the high rate battery charging current.
I
BAT AMPS
1 110
.
(
k
U
IN
IN
)
and 0.29V
(Hot, 50°C), charging is disabled
IN
, the timer continues
IN
(Cold,
PROG
IDET (Pin 13): Charge Rate Detection Threshold. Connect-
ing a resistor, R
rate detection threshold. If R
an I
cations Information section.
SS (Pin 14): Soft-Start/Compensation. Provides soft-start
function and compensation for the float voltage control
loop and compensation for the charge current control
loop. Tie a soft-start/compensation capacitor between this
pin and GNDSENS.
TIMER (Pin 15): Timer Capacitor. The timer period is set
by placing a capacitor, C
to:
where time is the desired charging time.
Connect this pin to IDET to disable the timer. Connect this
pin to GNDSENS to end battery charging when I
below the IDET charge rate threshold.
BATSENS (Pin 16): Battery Sense Input. An internal resis-
tor divider sets the final float voltage at this pin. The
resistor divider is disconnected in sleep mode or when
EN = H to reduce the battery drain current. Connect this pin
to the positive battery terminal.
Exposed Pad (Pin 17): Ground. This pin must be soldered
to the PCB ground (PGND) for electrical contact and rated
thermal performance.
C
BAT
TIMER
/10 indication. For other thresholds see the Appli-
= Time (Hrs) • 0.0733 (µF)
IDET
to GNDSENS programs the charge
TIMER
IDET
, to GNDSENS. Set C
= R
PROG
, CHRG provides
BAT
drops
TIMER
4001f