UCC28720

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Constant-voltage, constant-current controller with primary-side regulation for bipolar power devices

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Product details

Parameters

Control method Primary-side regulation Duty cycle (Max) (%) 99 Frequency (Max) (kHz) 80 UVLO thresholds on/off (V) 21/7.7 Features PSR, DCM, HV Start-up, Current Limiting, Green Mode, HV Start-up, Input Line Monitor, Leading Edge Blanking, Light Load Efficiency, Low Power, Soft Start Operating temperature range (C) -40 to 125 Rating Catalog open-in-new Find other Flyback controllers

Package | Pins | Size

SOIC (D) 7 29 mm² 4.9 x 6 open-in-new Find other Flyback controllers

Features

  • < 10-mW No-Load Power
  • Primary-Side Regulation (PSR) Eliminates Opto-
    Coupler
  • ±5% Voltage and Current Regulation Across Line
    and Load
  • 700-V Start-Up Switch
  • 80-kHz Maximum Switching Frequency Enables
    High-Power Density Charger Designs
  • Quasi-Resonant Valley-Switching Operation for
    Highest Overall Efficiency
  • Wide VDD Range Allows Small Bias Capacitor
  • Dynamic BJT Drive
  • Overvoltage, Low-Line, and Overcurrent
    Protection Functions
  • Programmable Cable Compensation
  • SOIC-7 Package
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Description

The UCC28720 flyback power supply controller provides isolated-output Constant-Voltage (CV) and Constant-Current (CC) output regulation without the use of an optical coupler. The devices process information from the primary power switch and an auxiliary flyback winding for precise control of output voltage and current.

An internal 700-V start-up switch, dynamically-controlled operating states and a tailored modulation profile support ultra-low standby power without sacrificing start-up time or output transient response.

Control algorithms in the UCC28720 allow operating efficiencies to meet or exceed applicable standards. The output drive interfaces to a bipolar transistor power switch. Discontinuous conduction mode (DCM) with valley switching reduces switching losses. Modulation of switching frequency and primary current peak amplitude (FM and AM) keeps the conversion efficiency high across the entire load and line ranges.

The controller has a maximum switching frequency of 80 kHz and always maintains control of the peak-primary current in the transformer. Protection features help keep primary and secondary component stresses in check. The UCC28720 allows compensation for voltage drop in the cable to be programmed with an external resistor.

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Technical documentation

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Type Title Date
* Datasheet UCC28720 Constant-Voltage, Constant-Current Controller With Primary-Side Regulation datasheet (Rev. B) Sep. 30, 2015
Application notes Minimize Standby Consumption for UCC287XX Family Aug. 01, 2019
Application notes Maximum Output Power and Thermal Considerations for UCC28720 and UCC28722 Dec. 06, 2017
Application notes Troubleshooting TI PSR controllers Oct. 03, 2016
Technical articles Slim down your flyback; lose that excess snubber Feb. 15, 2016
Application notes Choosing Standard Recovery Diode or Ultra-Fast Diode in Snubber Oct. 09, 2015
White papers Control Challenges for Low Power AC/DC Converters Oct. 02, 2015
White papers Control Challenges for Low Power AC/DC Converters (PPT) Oct. 02, 2015
Technical articles Designing multiple output converters with primary side sensing Aug. 04, 2015
Application notes 5-W USB Flyback Design Example Using the UCC28722 Jan. 08, 2014
Technical articles Isolated power supplies – Is analog dead? Sep. 24, 2013
User guides Using the UCC28720EVM-212 (Rev. A) Sep. 20, 2013

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Hardware development

EVALUATION BOARDS Download
document-generic User guide
$49.00
Description
The UCC28720EVM-212 is a 5W evaluation module for evaluating an off line adapter for USB applications. It is intended for evaluation purposes and is not intended to be an end product. The UCC28720EVM-212 converters 100V to 240V RMS input voltage down to 5V DC, with a 1A current limit for USB adapter (...)
Features
  • <10mW no load power
  • Primary Side Regulation (PSR) eliminates opto-coupler
  • +/- 5% Voltage & Current Regulation
  • Quasi-resonant valley switching operation for highest overall efficiency
  • Wide VDD range (35V) allows small bias capacitor
  • Drive Output for low cost Bipolar
  • Protection Functions: Over Voltage, Low (...)

Design tools & simulation

CALCULATION TOOLS Download
SLUC528A.ZIP (2330 KB)
CALCULATION TOOLS Download
SLUC529.ZIP (44 KB)

Reference designs

REFERENCE DESIGNS Download
85 to 265VAC Input 12V/3W Low Cost Flyback with BJT Reference Design
PMP20744 — This 12V/3W reference design is optimized for very low cost and yet maintains good efficiency. Two key factors for minimizing cost are a BJT is used for the main power switch, and primary-side regulation (PSR) eliminates the need for an optocoupler. The UCC28720 quasi-resonant flyback controller is (...)
document-generic Schematic document-generic User guide
REFERENCE DESIGNS Download
High Voltage Input (184Vac…707Vac) to 12V@1A, 3.3V@100mA Non-isolated Flyback Reference Design
PMP8678 The UCC28720 is a quasi resonant controller and is specialized to drive high voltage BJTs. When the drain voltage is higher than 1KV, BJTs are the best choice for low to mid power flyback converters. In this case two voltages are supplied: 12V@1A and 3.3V@100mA.
document-generic Schematic document-generic User guide
REFERENCE DESIGNS Download
350W Constant Voltage - Constant Current (CVCC) Phase-Shifted Full Bridge reference design
PMP9622 This reference design uses the UCC3895 Phase-Shifted Full Bridge controller to implement a high efficiency, 120VAC input to 44Vdc up to 8A output.  The power supply is set up to be  constant voltage-constant current.  The voltage and current are set by fixed resistor values and could (...)
document-generic Schematic document-generic User guide
REFERENCE DESIGNS Download
Reference Design - Universal Line Input AC-DC 3W High Side Buck Converter using UCC28720
PMP9649 The PMP9649 reference design is a simple, low-cost high side Buck converter to convert universal AC input voltage (85Vac to 265Vac) to a non-isolated 20V/150mA DC output with UCC28720 controller. BJT is applied as the buck switch for cost optimization, and simplicity is achieved with bulit-in sample (...)
document-generic Schematic document-generic User guide
REFERENCE DESIGNS Download
Primary-Side Reg Flyback for Industrial AC Input Up to 583VAC w/Bipolar Transistor Reference Design
PMP9243 The PMP9243 reference design uses the UCC28720 primary-side regulated flyback controller to generate a 15V/0.25A output from an industrial AC input (up to 583VAC). A bipolar transistor is used as the switch on the primary side to minimize the circuit cost.
REFERENCE DESIGNS Download
Small Form Factor 10W Offline Flyback Power Supply Reference Design
PMP9517 The PMP9517 is a high density constant voltage / constant current power supply with an 85VAC-265VAC input range and 5V/10W outptut. The design features primary side regulation (PSR) of a low cost power transistor (BJT). With low component count and low cost, the design is suitable for USB type power (...)
document-generic Schematic document-generic User guide
Design files
REFERENCE DESIGNS Download
120VAC Input 5V/250mA Flyback Converter With BJT Switch Reference Design
PMP9235 This reference design creates a 5V at 250mA from a 120VAC Input. The UCC28720 primary side controller with a BJT power switch provides a low cost design. It is important to note the outputs are only functionally (not for safety) isolated from the input.
REFERENCE DESIGNS Download
85 to 265 VAC input 5V/10W low cost flyback with BJT reference design
PMP9135 Constant Voltage/Constant Current  power supply generates 5V at 2A output. The design features primary side regulation (PSR) of a power transistor (BJT). With a low component count and low cost, the design can be use in USB type power supplies for PDA's, tablets, cameras and cell phones.
document-generic Schematic document-generic User guide
REFERENCE DESIGNS Download
120VAC Input 5V/200mA Flyback Converter With BJT Switch Reference Design
PMP9059 — This reference design creates a 5V at 200mA from a 120VAC Input. This supply is to designed to fit into a very small volume with approximately 10mm total height. The UCC28720 primary side controller with a BJT power switch provides a low cost design. A TPS71433 is also used to provide an additional (...)
REFERENCE DESIGNS Download
Primary-Side Regulated Flyback for Universal 3-phase AC Input w/Bipolar Transistor Reference Design
PMP9044 — The PMP9044 reference design uses the UCC28720 primary-side regulated flyback controller to generate a 3.3V/0.5A output from a 3-phase univeral AC input. A bipolar transistor is used as the switch on the primary side to minimize the circuit cost.
REFERENCE DESIGNS Download
5V1A low standby power AC Charger with low cost BJT solution
PMP4373 — This reference design demostrates a low cost single PCB board solution for 5V1A adapter. By using primary side regulation (PSR) mode chip UCC28720 which drives bipolar power device, average efficiency is 76%@115V and 77%@230Vac. PMP4373 achieves high precise CC and CV regulation with 0.15V cable (...)
REFERENCE DESIGNS Download
High Efficiency 5V@1.5A Adapter (meets DOE-VI standard) using BJT Solution
PMP4372 — This reference design demostrates a low cost single PCB board solution for 5V1.5A adapter. By using primary side regulation (PSR) mode chip UCC28720 which drives bipolar power device, average efficiency >80% @230Vac is achieved. Output ripple <80mV, and Vo(min) >4.32V with 0~0.5A load transient. The (...)
REFERENCE DESIGNS Download
Universal AC Input 5V@1.2A Single Board Cube Charger
PMP4366 — This reference design demostrates a low cost single PCB board solution for 5V1.2A cube charger. By using primary side regulation (PSR) mode chip UCC28720 which drives bipolar power device, average efficiency 78% @230Vac is achieved. The overall size is limited in 22mm(L)X21mm(W)x20mm(H) and no load (...)

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SOIC (D) 7 View options

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