Datasheet

UC1637
UC2637
UC3637
Figure 3.
Modulation Schemes Showing (A) Zero Deadtime (B) Deadtime and (C) Deadband Configurations
Shutdown Comparator
The shutdown terminal may be used for implementing
various shutdown and protection schemes. By pulling the
terminal more than 2.5V below V
IN
, the output drivers will
be enabled. This can be realized using an open collector
gate or NPN transistor biased to either ground or the
negative supply. Since the threshold is temperature stabi-
lized, the comparator can be used as an accurate low
voltage lockout (Figure 4) and/or delayed start as in Fig-
ure 5. In the shutdown mode the outputs are held in the
low state.
Current Limit
A latched current limit amplifier with an internal 200mV
offset is provided to allow pulse-by-pulse current limiting.
Differential inputs will accept common mode signals from
-V
S
to within 3V of the +V
S
supply while providing excel-
lent
noise rejection. Figure 6 shows a typical current
sense circuit.
Figure 4.
External Under-Voltage Lockout
Figure 5.
Delayed Start-Up
Figure 6.
Current Limit Sensing
5