LT1239CS Linear Technology, LT1239CS Datasheet - Page 6

• Manufacturer Part Number: LT1239CS
• Description: IC BATT BACKUP MNGMNT SYS 16SOIC
• Manufacturer: Linear Technology

Specifications of LT1239CS

• Function: Back-Up Management
• Battery Type: Lithium-Ion (Li-Ion); Nickel-Metal Hydride (NiMH)
• Voltage - Supply: 7 V ~ 30 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

FUNCTIONAL DESCRIPTIO
Regulator 1: Regulator 1 is used to supply the charging
current to the backup batteries. It converts the voltage on
the main battery to a fixed output voltage to charge the
backup cells. The output voltage is set with a voltage
divider connected between the output and ground with a
tap point of the divider connected to the adjust pin. The
regulator servos its output in order to maintain the adjust
pin at 3.75V referred to ground. The resistor divider
should be chosen such that the divider current is approxi-
LT1239
ADJ (Pin 1): Adjust Pin of Regulator 1. The regulator will
servo the adjust pin to 3.75V referred to ground. Bias
current will be approximately 50nA and will flow into the
adjust pin.
GND (Pin 2): Ground Pin for Regulator 1. Note that the
three ground pins (pins 2, 4, 5) are connected together
internally and should all be grounded externally.
SHDN1 (Pin 3): Shutdown Pin for Regulator 1. Regulator
1 output will be on if the shutdown pin is either: 1) Left
floating (open circuit) or 2) pulled up to the 5V rail. If the
shutdown function is not used, the shutdown pin is nor-
mally left open circuit. Regulator 1 output will be off if the
shutdown pin is pulled to ground. The shutdown pin
current with the pin pulled to ground will be in the range of
2 A flowing out of the pin. The shutdown pin current with
the pin pulled up to 5V will be zero.
GND (Pin 4): Ground. This ground pin is tied to the
substrate of the die, between regulator 1 and the rest of the
circuit. It is used as an isolation barrier between regulator
1 and the rest of the circuitry.
GND (Pin 5): Ground Pin for Regulator 2.
SHDN2 (Pin 6): Shutdown Pin for Regulator 2. Regulator
2 output will be on if the shutdown pin is either: 1) Left
floating (open circuit) or 2) pulled up to the 5V rail. If the
shutdown function is not used, the shutdown pin is nor-
mally left open circuit. Regulator 2 output will be off if the
shutdown pin is pulled to ground. The shutdown pin
current with the pin pulled to ground will be in the range of
2 A flowing out of the pin. The shutdown pin current with
the pin pulled up to 5V will be zero.
6
PIN
U
U
FUNCTIONS
U
U
U
U
E/A (IN) (Pin 7): Noninverting Input of the Error Amplifier.
This pin should be tied to the center tap point in the output
divider for regulator 1. The bias current for this pin will be
in the range of 3nA and it will flow out of the pin.
E/A (OUT) (Pin 8): Output of the Error Amplifier. This is
normally connected to the center tap of the backup cells.
NC (Pin 9): Not Connected.
INPUT 2 (Pin 10): Input Pin (V
Amplifier, and the Low-Battery Detection Circuit.
I
current monitor function is not used, this pin should be
tied to the output pin of regulator 2.
OUT 2 (Pin 12): Output of Regulator 2. It is also the
inverting input and output of the comparator. If the main
5V system supply is up and running then the comparator
output will pull the output of regulator 2 up to 5V.
5V
the collector of the output driver. The collector of the
output driver is normally connected to the main 5V system
supply.
INPUT 1 (Pin 14): Input Pin (V
I
current flowing out of this pin will be approximately 1/200
of the output current of regulator 1. If the current monitor
function is not used, this pin should be tied to the output
pin of regulator 1.
OUT 1 (Pin 16): Output of Regulator 1.
mately 5 A. This means the impedance from the adjust pin
to ground should be approximately 750k . For safety
requirements a resistor can be placed between the output
pin and the top of the divider that sets the regulated output
voltage. The regulator will regulate the voltage at the top of
the divider. Quiescent current will be 10 A to 15 A. Output
short-circuit current will be approximately 70mA.
MON
MON
IN
2 (Pin 11): Current Monitor Pin for Regulator 2. If the
(Pin 13): Noninverting Input of the comparator and
1 (Pin 15): Current Monitor Pin for Regulator 1. The
CC
CC
) for Regulator 2, the Error
) of Regulator 1.