UCC3808A-2

低功耗电流模式推挽 PWM

The UCCx808A devices are a family of BiCMOS push-pull, high-speed, low-power, pulse-width modulators. The UCCx808A contains all of the control and drive circuitry required for off-line or DC-to-DC fixed frequency current-mode switching power supplies with minimal external parts count.

The UCCx808A dual output drive stages are arranged in a push-pull configuration. Both outputs switch at half the oscillator frequency using a toggle flip-flop. The dead time between the two outputs is typically 60 ns to 200 ns depending on the values of the timing capacitor and resistors, thus limiting each output stage duty cycle to less than 50%.

The UCCx808A family offers a variety of package options, temperature range options, and choice of undervoltage lockout levels. The family has UVLO thresholds and hysteresis options for off-line and battery-powered systems.

The UCCx808A is an enhanced version of the UCC3808 family. The significant difference is that the A versions feature an internal discharge transistor from the CS pin to ground, which is activated each clock cycle during the oscillator dead time. The feature discharges any filter capacitance on the CS pin during each cycle and helps minimize filter capacitor values and current sense delay.

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Dual Output Drive Stages in Push-Pull Configuration

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Current Sense Discharge Transistor to Improve Dynamic Response

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130-µA Typical Starting Current

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1-mA Typical Run Current

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Operation to 1 MHz

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Internal Soft Start

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On-Chip Error Amplifier With 2-MHz Gain Bandwidth Product

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On-Chip VDD Clamping

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Output Drive Stages Capable of 500-mA Peak-Source Current, 1-A Peak-Sink Current