UCC2809-2

经济型初级侧控制器

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.

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User Programmable Soft Start With Active Low Shutdown

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User Programmable Maximum Duty Cycle

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Accessible 5V Reference

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Undervoltage Lockout

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Operation to 1MHz

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0.4A Source/0.8A Sink FET Driver

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Low 100µA Startup Current