Product Summary
The UC3844A control IC 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 of UC3844A 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 error amp 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 off-state.
Parametrics
UC3844A absolute maximum ratings: (1)Supply Voltage (low impedance source): 30 V; (2)Supply Voltage (Ii < 30mA): Self Limiting; (3)Output Current: ±1 A; (4)Output Energy (capacitive load): 5 μJ; (5)Analog Inputs (pins 2, 3): – 0.3 to 5.5 V; (6)Error Amplifier Output Sink Current: 10 mA; (7)Power Dissipation at Tamb ≤ 25 ℃ (DIP-8): 1.25 W; (8)Power Dissipation at Tamb ≤ 25 ℃ (SO-8): 800 mW; (9)Storage Temperature Range: -65 to 150 ℃; (10)Junction Operating Temperature: -40 to 150 ℃; (11)Lead Temperature (soldering 10s): 300 ℃.
Features
UC3844A features: (1)trimmed oscillator discharge current; (2)current mode operation to 500kHz automatic feed forward compensation; (3)latching PWM for cycle-by-cycle current limiting; (4)internally trimmed reference with undervoltage lockout; (5)high current totem pole output undervoltage lockout with hysteresis; (6)low start-up current (< 0.5mA) double pulse suppression.
Diagrams
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![]() UC3844AD1 |
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![]() UC3844AD8 |
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![]() UC3844AD8G4 |
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![]() UC3844AD8TR |
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![]() UC3844AD8TRG4 |
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![]() IC REG CTRLR BST FLYBK ISO 8SOIC |
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