UCC2870x Constant-Voltage, Constant-Current Controller With Primary-Side Regulation

1 Features

• < 30-mW No-Load Power for 5-Star Rating
• Primary-Side Regulation (PSR) Eliminates Opto-Coupler
• ±5% Voltage and Current Regulation
• 130-kHz Maximum Switching Frequency Enables High-Power Density Charger Designs
• Quasi-Resonant Valley-Switching Operation for Highest Overall Efficiency
• Patent-Pending Frequency-Jitter Scheme to Ease EMI Compliance
• Wide VDD Range Allows Small Bias Capacitor
• Clamped Gate-Drive Output for MOSFET
• Protection Functions: Overvoltage, Low-Line, and Overcurrent
• Programmable Cable Compensation (UCC28700 Only)
• NTC Resistor Interface (UCC28701, UCC28702 and UCC28703 Only) With Fixed Cable Compensation Options
• SOT-23 Package

2 Applications

• USB-Compliant Adapters and Chargers for Consumer Electronics (Cell Phones, Tablets and Cameras)
• AC and DC Power Supplies

3 Description

The UCC28700 family of flyback power supply controllers provides 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. Low start-up current, dynamically controlled operating states and a tailored modulation profile support very low standby power without sacrificing start-up time or output transient response.

Control algorithms in the UCC28700 family allow operating efficiencies to meet or exceed applicable standards. The output drive interfaces to a MOSFET 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 controllers have a maximum switching frequency of 130 kHz and always maintain control of the peak-primary current in the transformer. Protection features help keep primary and secondary component stresses in check. The UCC28700 allows the level of cable compensation to be programmed. The UCC28701, UCC28702, and UCC28703 devices allow remote temperature sensing using a Negative Temperature Coefficient (NTC) resistor while providing fixed cable-compensation levels.

1. For all available packages, see the orderable addendum at the end of the datasheet.

Typical Application Schematic

4 Revision History

Changes from * Revision (July 2012) to A Revision

• Added Handling Rating table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go

5 Device Comparison Table⁽¹⁾⁽²⁾