Datasheet

IR2161(
S
) & (PbF)
12 www.irf.com
Figure 10, Overload Output Current.
In figures 9 and 10, trace (1) shows the half bridge
oscillations during both types of fault mode and trace (2)
shows the charging and discharging of the CSD capacitor.
The IR2161 can also be externally shut off by applying a
voltage above 9V (VCSLATCH) to the CS pin. This will
cause the system to go directly to a latched fault mode,
after a delay of approximately 1uS to avoid the possibility of
false tripping caused by transients. To restart the system, it
is necessary to cycle Vcc off and on.
In addition, any time Vcs exceeds VCSLATCH
(approximately half Vcc), this latching shutdown function
will be triggered and the system will remain in FAULT mode
until VCC is re-cycled.
The IR2161 also includes over temperature shutdown, which
latches the convertor off when the die temperature of the
IC exceeds 130-135°C. Experimental measurements reveal
that the die temperature will be no more than 20°C above
the ambient temperature at all operating frequencies inside
the convertor.
Calculating Rcs
The value of the current sense resistor Rcs is critical to
achieve correct operation in the IR2161 based Halogen
convertor.
Figure 11, Calculating RCS
Ignoring the output transformer we can assume for this
calculation that the load is connected from the half bridge to
the mid point of the two output capacitors and that the
voltage at this point will be half the DC bus voltage. The
RMS voltage of the DC bus is the same as that of the AC line
so we can see that the RMS voltage across the load shown
in Figure 8, will be half the RMS voltage of the line. The load
is the maximum rated load of the convertor. The current in
Rcs will be half the load current given by :
LOAD
RCS
VCS
DC Bus
Voltage
1/2 DC Bus
Voltage
VS
VCSpk
Figure 9, Short Circuit Output Current.