LTC1731EMS8-4.2#TR Linear Technology, LTC1731EMS8-4.2#TR Datasheet - Page 5

• Manufacturer Part Number: LTC1731EMS8-4.2#TR
• Description: IC CTRLR BATT CHRGR LI-ION 8MSOP
• Manufacturer: Linear Technology

Specifications of LTC1731EMS8-4.2#TR

• Function: Charge Management
• Battery Type: Li-Ion, NiCd, NiMH
• Voltage - Supply: 8.8 V ~ 12 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LTC1731EMS8-4.2TR

PIN
BAT (Pin 1): Battery Sense Input. A bypass capacitor of at
least 10 F is required to keep the loop stable when the
battery is not connected. A precision internal resistor
divider sets the final float potential on this pin. The resistor
divider is disconnected in sleep mode.
CHRG (Pin 2): Open-Drain Charge Status Output. When
the battery is being charged, the CHRG pin is pulled low by
an internal N-channel MOSFET. When the charge current
drops to 10% of the full-scale current for at least 0.32
seconds, the N-channel MOSFET turns off and a 100 A
current source is connected from the CHRG pin to GND.
When the timer runs out or the input supply is removed,
the current source will be disconnected and the CHRG pin
is forced into a high impedance state.
TIMER (Pin 3): Timer Capacitor and Constant-Voltage
Mode Disable Input Pin. The timer period is set by placing
a capacitor, C
(C
connected to V
timer are disabled, the chip will operate in constant-
current mode only. Short the TIMER pin to GND to disable
the internal timer function and the C/10 function.
TIMER
U
FUNCTIONS
• 3 hours)/(0.1 F). When the TIMER pin is
U
TIMER
CC
, the constant-voltage mode and the
, to GND. The timer period is t
U
TIMER
=
GND (Pin 4): Ground Connection.
PROG (Pin 5): Charge Current Program and Shutdown
Input Pin. The charge current is programmed by connect-
ing a resistor, R
= (V
into shutdown by floating the PROG pin. An internal 2.5 A
current source will pull the pin above the shutdown
threshold voltage when the program resistor (R
disconnected.
DRV (Pin 6): Drive Output Pin for the P-Channel MOSFET
or PNP Transistor. The impedance is high at this pin,
therefore, a high beta PNP pass transistor should be used.
The DRV pin is internally clamped to 6.5V below V
V
within 54mV of V
mode, dropping I
Bypass this pin with a 1 F capacitor.
SENSE (Pin 8): Current Sense Input. A sense resistor,
R
This resistor is chosen using the following equation:
CC
SENSE
R
PROG
(Pin 7): Positive Input Supply Voltage. When V
SENSE
, must be connected from V
• 800 )/(R
LTC1731-4.1/LTC1731-4.2
= (V
PROG
PROG
CC
CC
to 7 A. V
• 800 )/(R
PROG
to ground. The charge current is I
, the LTC1731 is forced into sleep
• R
SENSE
CC
PROG
ranges from 4.5V to 12V.
). The IC can be forced
CC
• I
to the SENSE pin.
BAT
)
PROG
CC
BAT
.
5
BAT
) is
is