U2102B Datasheet, PDF (8/16 Pages) TEMIC Semiconductors – Multifunction Timer

U2102B
RC Oscillator, Pin 5
An internal RC oscillator with following divider stage
1:2¹¹ permits a very long and reproducible tracking time.
The RC values for a certain tracking time, t_t, are calcu-
lated as follows:
W + _m R₂ (k )
t_t(s) 10³
1.4 2048 C₂ ( F)
m + _W C₂ ( F)
1.4
t_t(s) 10³
2048 R₂ (k )
In reverse phase control mode, switchover from maxi-
mum current flow angle to the value set at Pin 4 takes
place after expiry of 3/4 of the total tracking time t_t.
Current Monitoring, Pins 11 and 12
The current monitoring circuit integrated in the U2102B
represents a double electronic fuse. The circuit measures
the current flowing through the power switch by way of
the voltage drop across the shunt resistor R_sh. This voltage
is supplied to Pin 11. If this voltage exceeds a value of
500 mV because of a high load current (e.g., short-
circuit), the switch-off latch is set and the switching
output Pin 11 closes immediately. Pin 11 can be
connected to the gate via a resistor or network, depending
on load conditions, thus allowing the switch-off behavior
to be adapted to the respective requirements. The short-
circuit current is reduced to a problem-free value by this
procedure.
There is a second threshold at 100 mV. The output stage
is disabled if the voltage at Pin 11 exceeds this value and
if it reaches this value for 120 ms in every half-wave
without exceeding the switch-off threshold of 500 mV.
Since high voltage peaks would be caused by switching
off due to the line and leakage inductances, the output
stage is not switched-off immediately but is simply not
enabled in the next half-wave. The circuit is designed so
that it also switches off in the case of changing over-
currents which do not occur in every half-wave. But in
this case the switch-off time is larger.
8 (16)
TELEFUNKEN Semiconductors
Rev. A1, 30-May-96