The UC3854A/B product is a compatibleenhanced version of Pin UC3854. Like the UC3854, these products provide all the features required for active power factor correction preregulators. The controller achieves a unit power factor close to the unit power factor by shaping the AC input current waveform corresponding to the AC input line voltage. To do this, the UC3854A/B uses average current mode control. Average current-mode control remains stable, and low-distortion sinusoids do not require slope compensation currents unlike peak current-mode control.
A 1%, 7.5 V reference, fixed frequency oscillator, pulse width modulation, voltage amplifier with soft start, line voltage feed-forward（VRMS squared), input supply voltage clamp, more than lilst feataures is currently relatively round.
characteristic
- PWM control boosts to near power factor
- Limit line current distortion
- Global action, no switches
- Precise power limiting
- Fixed frequency average current mode control
- High bandwidth (5 MHz), low bias current amplifier
- Integrated current and voltage amplifier output clips
- Multiplier improvements: linear, 500 mValternating currentOffset (no external resistors required), 0 V to 5 V Multout common-mode range
- VGood comparison of REF
- Faster, improved accuracy allows comparison
- UVLO options (V/10, 16th, V/10 V or 10.5 V).
- 300μA start-up supply current
parameter
| |
|
UC3854A |
| On/Off of Undervoltage Lockout Threshold (5) |
|
16/10 |
| Operating power supply (max) (5) |
|
20 |
| Starting current (mA) |
|
0.25 |
| Operating Supply Current (mA) |
|
12 |
| Vref's (V) |
|
7.5 |
| Thor of Vref (%) |
|
1.3 |
| Duty cycle (max.) (%) |
|
95 |
| Actual operating frequency (max) (MHz) |
|
0.2 |
| Pins/Packets |
|
16PDIP，16SOIC |