LTC1732EMS-8.4#TRPBF Linear Technology, LTC1732EMS-8.4#TRPBF Datasheet - Page 7

• Manufacturer Part Number: LTC1732EMS-8.4#TRPBF
• Description: IC CTRLR BATT CHRG LI-ION 10MSOP
• Manufacturer: Linear Technology

Specifications of LTC1732EMS-8.4#TRPBF

• Function: Charge Management
• Battery Type: Li-Ion, NiCd, NiMH
• Voltage - Supply: 4.5 V ~ 12 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

OPERATIO
The LTC1732-8.4 is a linear battery charger controller. The
charge current is programmed by the combination of a
program resistor (R
and a sense resistor (R
pins. R
trimmed 800 resistor setting up a voltage drop from V
to the input of the current amplifier (CA). The current
amplifier servos the gate of the external P-channel MOSFET
to force the same voltage drop across R
the charge current. When the voltage at the BAT pin
approaches the preset float voltage, the voltage amplifier
(VA) will start sinking current which shrinks the voltage
drop across R
A charge cycle begins when the potential at V
above the UVLO level and a program resistor is connected
from the PROG pin to ground. At the beginning of the
charge cycle, if the battery voltage is below 4.9V, the
charger goes into trickle charge mode. The trickle charge
current is 10% of the full-scale current. If the battery
voltage stays low for one quarter of the total charge time,
the charge sequence will terminate.
The charger goes into the fast charge constant-current
mode after the voltage on the BAT pin rises above 4.9V. In
constant-current mode, the charge current is set by the
combination of R
When the battery approaches the final float voltage, the
charge current will begin to decrease. When the current
drops to 10% of the full-scale charge current, an internal
comparator will turn off the pull-down N-channel MOSFET
at the CHRG pin and connect a weak current source to
ground to indicate an end-of-charge (C/10) condition.
PROG
sets a program current through an internal
SENSE
SENSE
U
, thus reducing the charge current.
PROG
SENSE
and R
) from the PROG pin to ground
) between the V
PROG
.
SENSE
CC
CC
and SENSE
which sets
pin rises
CC
An external capacitor on the TIMER pin sets the total
charge time. After a time-out occurs, the charge cycle is
terminated and the CHRG pin is forced to a high imped-
ance state. To restart the charge cycle, remove the input
voltage and reapply it, or float the PROG pin momentarily.
Replacing the battery while in the charge mode will cause
the timer to be reset if the voltage of the new battery is
below 8.05V. If the voltage is above 8.05V, the timer will
continue for the remaining charge time. In the case when
a time out has occurred, a new battery with a voltage of
less than 8.05V can be inserted and charged automatically
with the full programmed charge time.
For batteries like lithium-ion that require accurate final
float voltage, the internal 2.457V reference, voltage ampli-
fier and the resistor divider provide regulation with 1%
(max) accuracy. For NiMH and NiCd batteries, the
LTC1732-8.4 can be used as a current source by pulling
the TIMER pin to V
mode, the voltage amplifier, timer, C/10 comparator and
the trickle charge function are all disabled.
The charger can be shut down by floating the PROG
pin(I
high and clamp it at 3.5V.
When the input voltage is not present, the charger goes
into a sleep mode, dropping I
reduces the current drain on the battery and increases the
standby time.
CC
1mA). An internal current source will pull this pin
CC
. When in the constant-current only
CC
LTC1732-8.4
to 10 A. This greatly
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