| Topology | Boost, Buck, Flyback, Forward |
| Duty cycle (Max) (%) | 70 |
| Vin (Max) (V) | 19 |
| UVLO thresholds on/off (V) | 15/8 |
| Features | Adjustable Switching Frequency, Multi-topology, Soft Start |
| Operating temperature range (C) | 0 to 70 |
| Switching frequency (Max) (kHz) | 1000 |
| Rating | Catalog |
| Gate drive (Typ) (A) | 0.8 |
- User Programmable Soft Start With Active Low Shutdown
- User Programmable Maximum Duty Cycle
- Accessible 5V Reference
- Undervoltage Lockout
- Operation to 1MHz
- 0.4A Source/0.8A Sink FET Driver
- Low 100μA Startup Current
The UCC3809 family of BCDMOS economy low power integrated circuits contains all the control and drive circuitry required for off-line and isolated DC-to-DC fixed frequency current mode switching power supplies with minimal external parts count. Internally implemented circuits include undervoltage lockout featuring startup current less than 100μA, a user accessible voltage reference, logic to ensure latched operation, a PWM comparator, and a totem pole output stage to sink or source peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the off state.
Oscillator frequency and maximum duty cycle are programmed with two resistors and a capacitor. The UCC3809 family also features full cycle soft start.
The family has UVLO thresholds and hysteresis levels for off-line and DC-to-DC systems as shown in the table to the left.
The UCC3809 and the UCC2809 are offered in the 8 pin SOIC (D), PDIP (N), TSSOP (PW), and MSOP (P) packages. The small TSSOP and MSOP packages make the device ideal for applications where board space and height are at a premium.
