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PFC/PWM Combination controller with 16V/10V VCC UVLO and 6.75V/3.75V PWM UVLO, 0°C to 70°C

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UCC38502DWTR General Description

The UCC2850x family provides all of the control functions necessary for an active power-factor-corrected preregulator 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 feedforward (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. This not only reduces external parts count, but also avoids the use of high-voltage components, offering a lower-cost solution. The multiplier then divides the line current by the square of VFF.

The UCC2850x PFC section incorporates a low offset-voltage amplifier with 7.5-V reference, a highly-linear multiplier capable of a wide current range, a high-bandwidth, low offset-current amplifier, with a novel noise-attenuation configuration, PWM comparator and latch, and a high-current output driver. Additional PFC features include over-voltage protection, zero-power detection to turn off the output when VAOUT is below 0.33 V and peak current and power limiting.

The dc-to-dc section relies on an error signal generated on the secondary-side and processes it by performing peak current mode control. The dc-to-dc section also features current limiting, a controlled soft-start, preset operating range with selectable options, and 50% maximum duty cycle.

The UCC28500 and UCC28502 have a wide PFC-UVLO threshold (16.5 V/10 V) for bootstrap bias supply operation. The UCC28501 and UCC28503 are designed with a narrow UVLO range (10.5 V/10 V) more suitable for fixed bias operation. The UCC28500 and UCC28501 have a narrow UVLO threshold for PWM stage (to allow operation down to 75% of nominal bulk voltage), while the UCC28502 and UCC38503 are configured for a much wider operation range for the PWM stage (down to 50% of bulk nominal voltage).

Available in 20-pin N and DW packages.

Texas Instruments, Inc Inventory

Key Features

  • Combines PFC and Downstream Converter Controls
  • Controls Boost Preregulator to Near-Unity Power Factor
  • Accurate Power Limiting
  • Improved Feedforward Line Regulation
  • Peak Current-Mode Control in Second Stage
  • Programmable Oscillator
  • Leading-Edge/Trailing-Edge Modulation for Reduced Output Ripple
  • Low Start-up Supply Current
  • Synchronized Second Stage Start-Up, with Programmable Soft-start
  • Programmable Second Stage Shutdown
Texas Instruments, Inc Original Stock
Texas Instruments, Inc Inventory


Category Integrated Circuits (ICs)Power Management (PMIC)PFC (Power Factor Correction) Mfr Texas Instruments
Series - Package Tape & Reel (TR)
Product Status Active Mode Average Current
Frequency - Switching 100kHz Current - Startup 150 µA
Voltage - Supply 9.7V ~ 18V Operating Temperature 0°C ~ 70°C
Mounting Type Surface Mount Package / Case 20-SOIC (0.295", 7.50mm Width)
Supplier Device Package 20-SOIC Base Product Number UCC38502
Topology Boost Control mode CCM
Switching frequency (max) (kHz) 200 UVLO thresholds on/off (V) 16/10
Vin (max) (V) 18 Features < 150 W applications, Average current mode, Continuous Control Mode, Enable, Overvoltage protection, Supports Flyback
Rating Catalog Operating temperature range (°C) 0 to 70
Duty cycle (max) (%) 100 feature-type Power Factor Correction and PWM Controller
feature-operation-mode CCM feature-topology Boost
feature-minimum-operating-supply-voltage-v feature-maximum-operating-supply-voltage-v 18
feature-start-up-supply-current-ma 0.15 feature-switching-frequency-khz 200
feature-maximum-duty-cycle- 100 feature-packaging Tape and Reel
feature-rad-hard feature-pin-count 20
feature-supplier-package SOIC feature-standard-package-name SO
feature-cecc-qualified No feature-esd-protection
feature-military No feature-aec-qualified No
feature-aec-qualified-number feature-eccn-code EAR99
feature-svhc No feature-svhc-exceeds-threshold No

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Availability: 7620 PCS

Qty. Unit Price(USD) Ext. Price
1+ $14.017 $14.02
200+ $5.424 $1,084.80
500+ $5.234 $2,617.00
1000+ $5.139 $5,139.00

The prices below are for reference only.