The UC1875 series of integrated circuits realizes phase shift relative to others, enabling constant frequency pulse width modulation with a half-bridge resonant switch, a zero-voltage switch combined with high efficiency performance of the bridge power stage control at high frequencies. This circuit can be configured to provide a separate overcurrent fault protection in the home, shutdown, fast voltage, or current mode operation control.
A programmable time delay provides the stage at which each output is turned on by inserting dead time. This delay, which provides the time to make the resonant switching action, is controlled independently for each pair of outputs (AB, CD).
Due to the excess frequency of 2MHz, it is feasible for the oscillator to operate with an overall switching frequency of 1MHz.
characteristic
- Zero to 100% duty cycle control
- Programmable output turn-on delay
- Suitable for voltage or current mode topologies
- In practice, the switching frequency is 1MHz
- Four totem poles output A
- 10MHz error amplifier
- Undervoltage lockout
- Low start-up current of 150μA
- The output is low during UVLO
- Soft-start control
- The latch overcurrent cycle is a relatively full restart
- Prune reference
parameter
| |
UC3876 |
| topology |
Full bridge |
| Control method |
Current mode, voltage mode |
| Duty cycle (max.) (%) |
100 |
| Frequency (max) (khertz) |
1000 |
| On/Off of Undervoltage Lockout Threshold (5) |
15.2/9.2 |
| Pins/Packets |
20PDIP |
| (#) Regulated output |
4 |
| Operating temperature range(°C) |
0 to 70 |