Datasheet

LT8302
7
Rev E
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PIN FUNCTIONS
EN/UVLO (Pin 1): Enable/Undervoltage Lockout. The
EN/UVLO pin is used to enable the LT8302. Pull the pin
below 0.3V to shut down the LT8302. This pin has an
accurate 1.214V threshold and can be used to program a
V
IN
undervoltage lockout (UVLO) threshold using a resis-
tor divider from V
IN
to ground. A 2.5µA current hysteresis
allows the programming of V
IN
UVLO hysteresis. If neither
function is used, tie this pin directly to V
IN
.
INTV
CC
(Pin 2): Internal 3V Linear Regulator Output. The
INTV
CC
pin is supplied from V
IN
and powers the inter-
nal control circuitry and gate driver. Do not overdrive the
INTV
CC
pin with any external supply, such as a third wind-
ing supply. Locally bypass this pin to ground with a mini-
mum 1µF ceramic capacitor.
V
IN
(Pin 3): Input Supply. The V
IN
pin supplies current to
the internal circuitry and serves as a reference voltage for
the feedback circuitry connected to the R
FB
pin. Locally
bypass this pin to ground with a capacitor.
GND (Pin 4, Exposed Pad Pin 9): Ground. The exposed
pad provides both electrical contact to ground and good
thermal contact to the printed circuit board. Solder the
exposed pad directly to the ground plane.
SW (Pin 5): Drain of the Internal DMOS Power Switch.
Minimize trace area at this pin to reduce EMI and voltage
spikes.
R
FB
(Pin 6): Input Pin for External Feedback Resistor.
Connect a resistor from this pin to the transformer pri-
mary SW pin. The ratio of the R
FB
resistor to the R
REF
resistor, times the internal voltage reference, determines
the output voltage (plus the effect of any non-unity trans
-
former turns ratio). Minimize trace area at this pin.
R
REF
(Pin 7): Input Pin for External Ground Referred
Reference Resistor. The resistor at this pin should be in
the range of 10k, but for convenience in selecting a resis
-
tor divider ratio, the value may range from 9.09k to 11.0k.
TC (Pin 8): Output Voltage Temperature Compensation.
The voltage at this pin is proportional to absolute tem-
perature (PTAT) with temperature coefficient equal to
3.35mV/°K, i.e., equal to 1V at room temperature 25°C.
The TC pin voltage can be used to estimate the LT8302
junction temperature. Connect a resistor from this pin to
the R
REF
pin to compensate the output diode temperature
coefficient.
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