LTC4001-1 Linear Technology, LTC4001-1 Datasheet - Page 6

• Manufacturer Part Number: LTC4001-1
• Description: 2A Synchronous Buck Li-Ion Charger
• Manufacturer: Linear Technology

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PIN FUNCTIONS
LTC4001-1
NTC (Pin 11): Input to the NTC (Negative Temperature
Coeffi cient) 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
(Cold, 0°C) or below 0.29V
disabled and the CHRG pin blinks. When the voltage on
NTC comes back between 0.74V
continues where it left off and charging resumes. There is
approximately 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
IDET (Pin 13): Charge Rate Detection Threshold. Connect-
ing a resistor, R
detection threshold. If R
I
tions Information section.
6
BAT
R
/10 indication. For other thresholds see the Applica-
PROG
BAT
IN
=
. When the voltage on this pin is above 0.74V
is the high rate battery charging current.
I
BAT(AMPS)
1.110k
IN
IDET
.
to GNDSENS programs the charge rate
IDET
= R
IN
(Hot, 50°C), charging is
PROG
IN
and 0.29V
, CHRG provides an
IN
, the timer
PROG
IN
SS (Pin 14): Soft-Start/Compensation. Provides soft-start
function and compensation for the fl oat 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 resistor
divider sets the fi nal fl oat 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
TIMER
= Time (Hrs) • 0.0733 (μF)
TIMER
, to GNDSENS. Set C
BAT
drops
TIMER
40011fa