UCC28740 Series

Constant-Voltage, Constant-Current (CVCC) Flyback controller with Secondary Side Regulation (SSR)

Catalog

Constant-Voltage, Constant-Current (CVCC) Flyback controller with Secondary Side Regulation (SSR)

Part	Main Purpose	Voltage - Output	Regulator Topology	Voltage - Input [Min]	Voltage - Input [Max]	Current - Output	Supplied Contents	Board Type	Power - Output	Outputs and Type	Outputs and Type	Fault Protection	Operating Temperature [Min]	Operating Temperature [Max]	Voltage - Supply (Vcc/Vdd) [Max]	Voltage - Supply (Vcc/Vdd) [Min]	Internal Switch(s)	Output Isolation	Topology	Voltage - Start Up	Package / Case [custom]	Package / Case	Package / Case [custom]	Package / Case	Frequency - Switching [Max]	Frequency - Switching [Min]	Mounting Type	Supplier Device Package
Texas Instruments UCC28740EVM-525	AC/DC Primary Side	5 V	Flyback	85 VAC	265 VAC	2.1 A	Board(s)	Fully Populated	10 W	Isolated	1
Texas Instruments UCC28740DR												Current Limiting Over Voltage	-40 °C	125 ¯C	35 V	9 V		Isolated	Flyback	21 V	7	8-SOIC	3.9 mm	0.154 in	100 kHz	170 Hz	Surface Mount	7-SOIC

Catalog

Constant-Voltage, Constant-Current (CVCC) Flyback controller with Secondary Side Regulation (SSR)

Key Features

• Less than 10-mW No-Load Power CapabilityOptocoupled Feedback for CV, andPrimary-Side Regulation (PSR) for CCEnables ±1% Voltage Regulation and ±5% Current Regulation Across Line and Load700-V Startup Switch100-kHz Maximum Switching Frequency Enables High-Power-Density Charger DesignsResonant-Ring Valley-Switching Operation for Highest Overall EfficiencyFrequency Dithering to Ease EMI ComplianceClamped Gate-Drive Output for MOSFETOvervoltage, Low-Line, and Overcurrent Protection FunctionsSOIC-7 PackageCreate a Custom Design Using the UCC28740 With theWEBENCH®Power DesignerLess than 10-mW No-Load Power CapabilityOptocoupled Feedback for CV, andPrimary-Side Regulation (PSR) for CCEnables ±1% Voltage Regulation and ±5% Current Regulation Across Line and Load700-V Startup Switch100-kHz Maximum Switching Frequency Enables High-Power-Density Charger DesignsResonant-Ring Valley-Switching Operation for Highest Overall EfficiencyFrequency Dithering to Ease EMI ComplianceClamped Gate-Drive Output for MOSFETOvervoltage, Low-Line, and Overcurrent Protection FunctionsSOIC-7 PackageCreate a Custom Design Using the UCC28740 With theWEBENCH®Power Designer

Description

The UCC28740 isolated-flyback power-supply controller provides Constant-Voltage (CV) using an optical coupler to improve transient response to large-load steps. Constant-Current (CC) regulation is accomplished through Primary-Side Regulation (PSR) techniques. This device processes information from opto-coupled feedback and an auxiliary flyback winding for precise high-performance control of output voltage and current. An internal 700-V startup switch, dynamically controlled operating states, and a tailored modulation profile support ultra-low standby power without sacrificing startup time or output transient response. Control algorithms in the UCC28740 allow operating efficiencies to meet or exceed applicable standards. The drive output 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 controller has a maximum switching frequency of 100 kHz and always maintains control of the peak-primary current in the transformer. Protection features keep primary and secondary component stresses in check. A minimum switching frequency of 170 Hz facilitates the achievement of less than 10-mW no-load power. The UCC28740 isolated-flyback power-supply controller provides Constant-Voltage (CV) using an optical coupler to improve transient response to large-load steps. Constant-Current (CC) regulation is accomplished through Primary-Side Regulation (PSR) techniques. This device processes information from opto-coupled feedback and an auxiliary flyback winding for precise high-performance control of output voltage and current. An internal 700-V startup switch, dynamically controlled operating states, and a tailored modulation profile support ultra-low standby power without sacrificing startup time or output transient response. Control algorithms in the UCC28740 allow operating efficiencies to meet or exceed applicable standards. The drive output 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 controller has a maximum switching frequency of 100 kHz and always maintains control of the peak-primary current in the transformer. Protection features keep primary and secondary component stresses in check. A minimum switching frequency of 170 Hz facilitates the achievement of less than 10-mW no-load power.