UC2844BD1013TR High Performance Current Mode PWM Controller with 500 kHz Switching Frequency, 1 A Output Current, and 50% Max Duty Cycle
- TRIMMED OSCILLATOR FOR PRECISE FREQUENCY CONTROL.
- OSCILLATOR FREQUENCY GUARANTEED AT 250kHz.
- CURRENT MODE OPERATION TO 500kHz.
- AUTOMATIC FEED FORWARD COMPENSATION.
- LATCHING PWM FOR CYCLE-BY-CYCLE CURRENT LIMITING.
- INTERNALLY TRIMMED REFERENCE WITH UNDERVOLTAGE LOCKOUT.
- HIGH CURRENT TOTEM POLE OUTPUT.
- UNDERVOLTAGE LOCKOUT WITH HYSTERESIS.
- LOW START-UP AND OPERATING CURRENT
The UC384xB family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include a trimmed oscillator for precise DUTY CYCLE CONTROL under voltage lockout featuring start-up current less than 0.5mA, a precision reference trimmed for accuracy at the erroramp input, logic to insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the offstate.
Differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle ranges. The UC3842B and UC3844B have UVLO thresholds of 16V (on) and 10V (off), ideally suited off-line applications The corresponding thresholds for the UC3843B and UC3845B are 8.5 V and 7.9V. The UC3842B and UC3843B can operate to dutycycles approaching 100%. A range of the zero to <50 % is obtained by the UC3844B and UC3845B by the addition of an internal toggle flip flop which blanks the output off every other clock cycle.
| Symbol | Parameter | Value | Unit |
|---|---|---|---|
| Vi | Supply Voltage (low impedance source) | 30 | V |
| Vi | Supply Voltage (Ii < 30mA) | Self Limiting | |
| IO | Output Current | ±1 | A |
| EO | Output Energy (capacitive load) | 5 | µJ |
| Analog Inputs (pins 2, 3) | – 0.3 to 5.5 | V | |
| Error Amplifier Output Sink Current | 10 | mA | |
| Ptot | Power Dissipation at Tamb ≤ 25 °C (Minidip) | 1.25 | W |
| Ptot | Power Dissipation at Tamb ≤ 25 °C (SO8) | 800 | mW |
| Tstg | Storage Temperature Range | – 65 to 150 | °C |
| TJ | Junction Operating Temperature | – 40 to 150 | °C |
| TL | Lead Temperature (soldering 10s) | 300 | °C |
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Factory pricing with 30% deposit and 70% balance payment via T/T before shipment.
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