U2102B Datasheet, PDF (4/16 Pages) TEMIC Semiconductors – Multifunction Timer

U2102B
Power Supply, Synchronization Pins 15 and 16
The voltage limitation circuit contained in the U2102B
enables simple power supply via a dropping resistor R₁.
In the case of dc loads, practically all the supply current
flows into Pin 16 (the pull down resistor at Pin 16 is neces-
sary in order to guarantee reliable synchronization) and
is supplied via an internal diode to Pin 15, where the resul-
tant supply voltage is limited and smoothed by C₁. As a
result, the rectified and divided line voltage appears at
Pin 16, where the amplitude is limited. The power supply
for the circuit can be realized in all modes for dc loads as
shown in figure 3. The voltage at Pin 16 is used to
synchronize the circuit with the mains and generate the
system clock required for the buffers. The circuit detects
a “zero crossing” when the voltage at Pin 16 falls below
an internal threshold of approximately 8 V.
Sync.
R₁=R_sync
16
V_mains
+V_S
Voltage
limitation
15
Push
C₁
pull
14
R_G
Temp.
monit.
GND
13
95 9882
Load
IGBT
R_sh
Figure 3. Power supply for dc loads (R₁ is identical with R_sync)
R₁ is calculated here as follows:
+ R_1max
0.85
V_Nmin –V_S
I_tot
(1)
where:
V_Nmin =
V_mains – 15%
V_S = Supply voltage
I_tot =
I_{Smax =}
I_x =
I_Smax + I_x
Max. current consumption of the IC
Current consumption of the external
components
4 (16)
TELEFUNKEN Semiconductors
Rev. A1, 30-May-96