UCC38500DW
TEXAS INSTRUMENTS UCC38500DW.. 芯片, PFC/PWM控制器, 20-SOIC
The is a BiCMOS PFC/PWM Combination Controller provides all of the control functions necessary for an active power-factor-corrected pre-regulator and a second-stage DC to DC converter. The controller achieves near-unity power factor by shaping the ac input line current waveform to correspond to the ac input-line voltage using average current-mode control. The DC to DC converter uses peak current-mode control to perform the step-down power conversion. The PFC stage is leading-edge modulated while the second stage is trailing-edge synchronized to allow for minimum overlap between the boost and PWM switches. This reduces ripple current in the bulk-output capacitor. In order to operate with over three-to-one range of input-line voltages, a line feed-forward VFF is used to keep input power constant with varying input voltage. Generation of VFF is accomplished using IAC in conjunction with an external single-pole filter.
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- Combines PFC and downstream converter controls
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- Controls boost preregulator to near-unity power factor
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- Accurate power limiting
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- Improved feedforward line regulation
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- Peak current-mode control in second stage
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- Programmable oscillator
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- Leading-edge/trailing-edge modulation for reduced output ripple
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- Low start-up supply current
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- Synchronized second stage start-up, with programmable soft-start
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- Programmable second stage shutdown
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- Green product and no Sb/Br