Datasheet

4
UC1706
UC2706
UC3706
D1, D2: UC3611 Schottky Diodes
Transformer Coupled MOSFET Drive Circuit
CIRCUIT DESCRIPTION (cont.)
Charge Pump Circuits
D1, D2; UC3611 Schottky Diodes
APPLICATIONS
Power MOSFET Drive Circuit
D1, D2; UC3611 Schottky Diodes
Power MOSFET Drive Circuit Using Negative Bias Voltage and
Level Shifting to Ground Referenced PWMs
Analog Shutdown
This circuit is included to get a latched shutdown as close
to the outputs as possible, from a time standpoint. With
an internal 130mV threshold, this comparator has a
common-mode range from ground to (V
IN – 3V). When
not used, both inputs should be grounded. The time re
-
quired for this circuit to latch is inversely proportional to
the amount of overdrive but reaches a minimum of
180nsec. As with the flip-flop, an input off-time of at least
200nsec is required to reset the latch between pulses.
Supply Voltage
With an internal 5V regulator, this circuit is optimized for
use with a 7 to 40V supply; however, with some slight re
-
sponse time degradation, it can also be driven from 5V.
When V
IN is low, the entire circuit is disabled and no cur
-
rent is drawn from V
C. When combined with a UC1840
PWM, the Driver Bias switch can be used to supply V
IN to
the UC1706. V
IN switching should be fast as if VC is
high, undefined operation of the outputs may occur with
VI
N less than 5V.
Thermal Considerations
Should the chip temperature reach approximately 155°C,
a parallel, non--inverting input is activated driving both
outputs to the low state.