Datasheet

LTC3375
14
3375fc
For more information www.linear.com/3375
pin FuncTions
WDO (Pin 39): Watchdog Timer Output. Open-drain
output. WDO is pulled low for 200ms during a watchdog
timer failure.
WDI (Pin 40): Watchdog Timer Input. The WDI pin must
be toggled either low to high or high to low every 1.5
seconds. Failure to toggle WDI results in the WDO pin
being pulled low for 200ms.
V
CC
(Pin 41): Always-On LDO Output Voltage/Internal
Bias Supply. When used as a regulator, V
CC
should be
connected to the emitter/source of the external LDO NPN/
NFET transistor. V
CC
serves as a low voltage rail that may
be used to provide power to external circuitry, and is
also used to power the internal top level circuitry of the
LTC3375. Alternatively the V
CC
pin may be connected to
a 2.7V to 5.5V external power supply. In this case FBV
CC
and V
SHNT
should be tied to ground.
FBV
CC
(Pin 42): Always-On LDO Feedback Pin. Receives
feedback by a resistor divider connected across V
CC
.
V
SHNT
(Pin 43): Shunt Regulator Base Control Voltage.
V
SHNT
should be connected to the base/gate of an external
high voltage NPN/NFET transistor and to its collector/drain
through a resistor.
TEMP (Pin 44): Temperature Indication Pin. TEMP out-
puts a voltage of 150mV (typical) at room temperature.
The TEMP voltage will change by 6.75mV/°C (typical)
giving an external indication of the LTC3375 internal die
temperature.
SCL (Pin 45): Serial Clock Line for I
2
C Port.
SDA (Pin 46): Serial Data Line for I
2
C Port. Open-drain
output during read back.
EN2 (Pin 47): Buck Regulator 2 Enable Input. Active high.
EN1 (Pin 48): Buck Regulator 1 Enable Input. Active high.
GND (Exposed Pad Pin 49): Ground. The exposed pad
must be connected to a continuous ground plane on the
printed circuit board directly under the LTC3375 for electri
-
cal contact and rated thermal performance.