The U208B is an open loop phase control circuit manufactured by TELEFUNKEN Semiconductors. It has internal supply voltage monitoring, automatic retriggering, triggering pulse, and internal current and voltage synchronization. It is recommended as a low cost open-loop control.
The document describes the U208B, an integrated circuit designed as a low-cost open-loop phase control circuit in bipolar technology. Key features include internal supply voltage monitoring to prevent uncontrolled output pulses, current and voltage synchronization, and automatic retriggering capabilities.
The datasheet provides detailed information on the block diagram, operation principles for mains and DC supplies, phase control mechanisms, voltage monitoring thresholds, pulse output stage specifications, and thermal/electrical characteristics. It also includes application examples and design calculation equations.
| Current requirement | ≤ 2.5 mA |
|---|---|
| Triggering pulse typ. | 125 mA |
| Supply voltage for mains operations | 13.0 V |
| Storage temperature range | -40 to +125 °C |
| Junction temperature | 125 °C |
| Output pulse current (typ.) | 125 mA |
The typical triggering pulse current is 125 mA.
It prevents half cycles without current flow by generating another triggering pulse after a time lapse of tpp = 4.5 tp until the triac fires or the half cycle finishes.
The turn-on threshold is typically 13.0 V and the turn-off threshold is typically 10.9 V.