LT1158
PIN FUNCTIONS
BOOST DR (Pin 1): Recharges and clamps the bootstrap
capacitor to 14.5V higher than pin 13 via an external
diode.
+
V (Pin10):Bottomsidedriversupply;mustbeconnected
to the same supply as pin 2.
–
SENSE (Pin 11): The floating reference for the current
+
V (Pin 2): Main supply pin; must be closely decoupled
limit comparator. Connects to the low side of a current
shunt or Kelvin lead of a current-sensing MOSFET. When
to the ground pin 7.
+
pin 11 is within 1.2V of V , current limit is inhibited.
BIAS (Pin 3): Decouple point for the internal 2.6V bias
generator. Pin 3 cannot have any external DC loading.
+
SENSE (Pin 12): Connects to the high side of the current
shuntorsenseleadofacurrent-sensingMOSFET.Abuilt-in
offsetbetweenpins11and12inconjunctionwithRSENSE
sets the top MOSFET short-circuit current.
ENABLE (Pin 4): When left open, the LT1158 operates
normally. Pulling pin 4 low holds both MOSFETs off re-
gardless of the input state.
T SOURCE (Pin 13): Top side driver return; connects to
MOSFET source and low side of the bootstrap capacitor.
FAULT (Pin 5): Open collector NPN output which turns
on when V12 – V11 exceeds the fault conduction thresh-
old.
TGATEFB(Pin14):Mustconnectdirectlytothetoppower
MOSFET gate. The bottom MOSFET turn-on is inhibited
untilV14–V13hasdischargedto1.75V.Anon-chipcharge
pump also feeds the top gate via pin 14.
INPUT (Pin 6): Taking pin 6 high turns the top MOSFET on
and bottom MOSFET off; pin 6 low reverses these states.
Aninputlatchcaptureseachlowstate,ignoringanensuing
high until pin 13 has gone below 2.6V.
T GATE DR (Pin 15): The high current drive point for the
top MOSFET. When a gate resistor is used, it is inserted
between pin 15 and the gate of the MOSFET.
B GATE FB (Pin 8): Must connect directly to the bottom
power MOSFET gate. The top MOSFET turn-on is inhibited
untilpin8hasdischargedto1.5V.Ahold-oncurrentsource
also feeds the bottom gate via pin 8.
BOOST (Pin 16): Top side driver supply; connects to the
high side of the bootstrap capacitor and to a diode either
+
+
from supply (V < 10V) or from pin 1 (V > 10V).
B GATE DR (Pin 9): The high current drive point for the
bottomMOSFET.Whenagateresistorisused,itisinserted
between pin 9 and the gate of the MOSFET.
1158fb
6
LINEAR_DIMENSIONS [ Linear Dimensions ]
