LTC1732EMS-8.4#TR Linear Technology, LTC1732EMS-8.4#TR Datasheet - Page 9

• Manufacturer Part Number: LTC1732EMS-8.4#TR
• Description: IC BATTCHRG CNTRLR LI-ION 10MSOP
• Manufacturer: Linear Technology
• Type: Charge Controllerr

Specifications of LTC1732EMS-8.4#TR

• 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)
• Output Current: 500mA
• Output Voltage: 8.4V
• Operating Supply Voltage (min): 8.8V
• Operating Supply Voltage (max): 12V
• Operating Temp Range: -40C to 85C
• Package Type: MSOP
• Mounting: Surface Mount
• Pin Count: 10
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LTC1732EMS-8.4TR; LTC1732EMS8.4TR

APPLICATIONS
Table 1. Microprocessor Interface
IN
LOW
LOW
HIGH
When the LTC1732-8.4 is in charge mode, the CHRG pin
is pulled low by an internal N-channel MOSFET. To detect
this mode, force the digital output pin, OUT, high and
measure the voltage at the CHRG pin. The N-channel
MOSFET will pull the pin low even with a 2k pull-up
resistor. Once the charge current drops to 10% of the full-
scale current (C/10), the N-channel MOSFET is turned off
and a 35 A current source is connected to the CHRG pin.
The IN pin is then pulled high by the 2k pull-up. By forcing
the OUT pin into a high impedance state, the current
source pulls the pin low through the 400k resistor. When
the internal timer has expired, the CHRG pin changes to
high impedance and the 400k resistor pulls the pin high to
indicate that charging has stopped.
HIGH
OUT
Hi-Z
Hi-Z
LTC1732-8.4
Figure 1. Microprocessor Interface
V
V
CC
+
CHRG
8
CHARGE STATUS
Charge
C/10
Stop Charging
U
3
INFORMATION
400k
U
2k
OUT
IN
PROCESSOR
W
V
DD
1732-8.4 F01
U
ACPR Output Pin
The LTC1732-8.4 has an ACPR output pin to indicate that
the input supply (wall adapter) is higher than 8.2V and
55mV above the voltage at the BAT pin. When both
conditions are met, the ACPR pin is pulled to ground by an
N-channel MOSFET that is capable of driving an LED.
Otherwise, this pin is high impedance.
CHRG Status Output Pin (C/10)
The LTC1732-8.4 includes a comparator to monitor the
charge current to detect a near end-of-charge condition.
This comparator does not terminate the charge cycle, but
provides an output signal to indicate a near full charge
condition. The timer is used to terminate the charge cycle.
When the battery current falls below 10% of full scale, the
comparator trips and turns off the N-channel MOSFET at
the CHRG pin and switches in a 35 A current source to
ground. After an internal time delay of 15ms, this state is
latched. This delay helps prevent false triggering due to
transient currents. The end-of-charge comparator is dis-
abled in trickle charge mode.
Gate Drive
Typically the LTC1732-8.4 controls an external P-channel
MOSFET to supply current to the battery. An external PNP
transistor can also be used as the pass transistor instead
of the P-channel MOSFET. Due to the low current gain of
the current amplifier (CA), a high gain Darlington PNP
transistor is required to avoid excessive charge current
error. The gain of the current amplifier is around 0.6 A/
mV. For every 1 A of base current, a 1.6mV of gain error
shows up at the inputs of CA. With R
across R
current.
SENSE
), it represents 1.67% of error in charging
LTC1732-8.4
PROG
= 19.6k (100mV
17328f
9