This document introduces the UCC35705 and UCC35706 devices, which are 8-pin voltage mode primary side controllers with fast over-current protection. They are used as core high-speed building blocks in high performance isolated and non-isolated power converters. UCC35705/UCC35706 devices feature a high speed oscillator with integrated feed-forward compensation for improved converter performance. A typical current sense to output delay time of 25ns provides fast response to overload conditions. The IC also provides an accurate programmable maximum duty cycle clamp for increased protection which can also be disabled for the oscillator to run at maximum possible duty cycle. Two UVLO options are offered. The UCC35705 with lower turn-on voltage is intended for dc-to-dc converters while the higher turn-on voltage and the wider UVLO range of the UCC35706 is better suited for offline applications. The UCC35705/UCC35706 family is offered in 8-pin MSOP (DGK), SOIC (D) and PDIP (P) packages.
The UCC25705, UCC25706, UCC35705, and UCC35706 devices are 8-pin voltage mode primary side controllers designed for high-speed operation greater than 4 MHz. They feature an integrated oscillator with voltage feed-forward compensation to improve converter performance and maintain constant frequency over the full input voltage range. A typical current sense to output delay of 25 ns provides fast response to overload conditions.
| Operating Frequency | Greater than 4 MHz |
|---|---|
| Current Sense to Output Delay | 25 ns typical |
| Operating Current | 4.2 mA @ 1 MHz |
| Active Supply Current | 4.2 to 5.0 mA |
| Oscillator Frequency | 0.9 to 1.1 MHz |
| Current Limit Threshold | 180 to 220 mV |
The typical current sense to output delay time is 25 ns, providing fast response to overload conditions.
The UCC35705 is intended for DC-to-DC converters due to its lower turn-on voltage.
The operating frequency ranges from 0.9 MHz to 1.1 MHz depending on the VFF voltage.