Product details

Topology Boost Control mode CCM Practical operating frequency (Max) (MHz) 0.2 UVLO thresholds on/off (V) 10.5/10 Device type Controllers Operating supply current (mA) 12 Features > 750W Applications, Average Current Mode, Continuous Control Mode , Enable Rating Catalog Operating temperature range (C) 0 to 70
Topology Boost Control mode CCM Practical operating frequency (Max) (MHz) 0.2 UVLO thresholds on/off (V) 10.5/10 Device type Controllers Operating supply current (mA) 12 Features > 750W Applications, Average Current Mode, Continuous Control Mode , Enable Rating Catalog Operating temperature range (C) 0 to 70
PDIP (N) 16 181 mm² 19.3 x 9.4 SOIC (DW) 16 77 mm² 10.3 x 7.5
  • Controls Boost PWM to Near-Unity Power Factor
  • Limits Line Current Distortion To <3%
  • World-Wide Operation Without Switches
  • Accurate Power Limiting
  • Fixed-Frequency Average Current-Mode Control
  • High Bandwidth (5 MHz), Low-Offset Current Amplifier
  • Integrated Current- and Voltage-Amplifier Output Clamps
  • Multiplier Improvements: Linearity, 500 mV VAC Offset (Eliminates External Resistor), 0 V to 5 V Multout Common-Mode Range
  • VREF GOOD Comparator
  • Faster and Improved Accuracy ENABLE Comparator
  • UVLO Options (16 V/10 V or 10.5 V/10 V)
  • 300-µA Start-Up Supply Current

  • Controls Boost PWM to Near-Unity Power Factor
  • Limits Line Current Distortion To <3%
  • World-Wide Operation Without Switches
  • Accurate Power Limiting
  • Fixed-Frequency Average Current-Mode Control
  • High Bandwidth (5 MHz), Low-Offset Current Amplifier
  • Integrated Current- and Voltage-Amplifier Output Clamps
  • Multiplier Improvements: Linearity, 500 mV VAC Offset (Eliminates External Resistor), 0 V to 5 V Multout Common-Mode Range
  • VREF GOOD Comparator
  • Faster and Improved Accuracy ENABLE Comparator
  • UVLO Options (16 V/10 V or 10.5 V/10 V)
  • 300-µA Start-Up Supply Current

The UC3854A/B products are pin compatible enhanced versions of the UC3854. Like the UC3854, these products provide all of the functions necessary for active power factor corrected preregulators. The controller achieves near unity power factor by shaping the ac input line current waveform to correspond to the ac input line voltage. To do this the UC3854A/B uses average current mode control. Average current mode control maintains stable, low distortion sinusoidal line current without the need for slope compensation, unlike peak current mode control.

A 1%, 7.5-V reference, fixed frequency oscillator, PWM, voltage amplifierwith soft-start, line voltage feedforward (VRMS squarer), input supply voltage clamp, and over current comparator round out the lilst of feataures.

Available in the 16-pin N (PDIP), DW (SOIC Wide), and J (CDIP) and 20-pin Q (PLCC) package. See Ordering Information table for availability by temperature range.

The UC3854A/B products improve upon the UC3854 by offering a wide bandwidth, low offset current amplifier, a faster responding and improved accuracy enable comparator, a VREF GOOD comparator, UVLO threshold options (16 V/10 V for offline, 10.5 V/10 V for startup from an auxiliary 12-V regulator), lower startup supply current, and an enhanced multiply/divide circuit. New features like the amplifier output clamps, improved amplifier current sinking capability, and low offset VAC pin reduce the external component count while improving performance. Improved common mode input range of the multiplier output/current amplifier input allow the designer greater flexibility in choosing amethod for current sensing. Unlike its predecessor, RSET controls only oscillator charging current and has no effect on clamping the maximum multiplier output current. This current is now clamped to a maximum of 2 × IAC at all times which simplifies the design process and provides foldback power limiting during brownout and extreme low line conditions.

The UC3854A/B products are pin compatible enhanced versions of the UC3854. Like the UC3854, these products provide all of the functions necessary for active power factor corrected preregulators. The controller achieves near unity power factor by shaping the ac input line current waveform to correspond to the ac input line voltage. To do this the UC3854A/B uses average current mode control. Average current mode control maintains stable, low distortion sinusoidal line current without the need for slope compensation, unlike peak current mode control.

A 1%, 7.5-V reference, fixed frequency oscillator, PWM, voltage amplifierwith soft-start, line voltage feedforward (VRMS squarer), input supply voltage clamp, and over current comparator round out the lilst of feataures.

Available in the 16-pin N (PDIP), DW (SOIC Wide), and J (CDIP) and 20-pin Q (PLCC) package. See Ordering Information table for availability by temperature range.

The UC3854A/B products improve upon the UC3854 by offering a wide bandwidth, low offset current amplifier, a faster responding and improved accuracy enable comparator, a VREF GOOD comparator, UVLO threshold options (16 V/10 V for offline, 10.5 V/10 V for startup from an auxiliary 12-V regulator), lower startup supply current, and an enhanced multiply/divide circuit. New features like the amplifier output clamps, improved amplifier current sinking capability, and low offset VAC pin reduce the external component count while improving performance. Improved common mode input range of the multiplier output/current amplifier input allow the designer greater flexibility in choosing amethod for current sensing. Unlike its predecessor, RSET controls only oscillator charging current and has no effect on clamping the maximum multiplier output current. This current is now clamped to a maximum of 2 × IAC at all times which simplifies the design process and provides foldback power limiting during brownout and extreme low line conditions.

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Technical documentation

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Type Title Date
* Data sheet Advanced High Power Factor Preregulator datasheet (Rev. E) 25 Aug 2006
Application note DN-44 UC3854A and UC3854B Advanced Power Factor Correction Control ICs (Rev. A) 15 Nov 2005
Application note AC Requirements for Power Factor Correction Circuits 28 Mar 2002
Application note Accurate PWM Duty Cycle Clamp 25 Jan 2002
Application note DN-66 UC3854A/B and UC3855A/B Provide Power Limiting with Sinusoidal Input (Rev. A) 06 Nov 2001

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PDIP (N) 16 View options
SOIC (DW) 16 View options

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