UCC28740_15 Datasheet, PDF (1/37 Pages) Texas Instruments – UCC28740 Constant-Voltage Constant-Current Flyback Controller Using Opto-Coupled Feedback

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UCC28740
SLUSBF3B – JULY 2013 – REVISED DECEMBER 2014
UCC28740 Constant-Voltage Constant-Current Flyback Controller Using Opto-Coupled
Feedback
1 Features
•1 Less than 10-mW No-Load Power Capability
• Opto-Coupled Feedback for CV, and
Primary-Side Regulation (PSR) for CC
• Enables ±1% Voltage Regulation and ±5%
Current Regulation Across Line and Load
• 700-V Startup Switch
• 100-kHz Maximum Switching Frequency Enables
High-Power-Density Charger Designs
• Resonant-Ring Valley-Switching Operation for
Highest Overall Efficiency
• Frequency Dithering to Ease EMI Compliance
• Clamped Gate-Drive Output for MOSFET
• Overvoltage, Low-Line, and Overcurrent
Protection Functions
• SOIC-7 Package
2 Applications
• USB-Compliant Adapters and Chargers for
Consumer Electronics
– Smart Phones
– Tablet Computers
– Cameras
• Standby Supply for TV and Desktop
• White Goods
3 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.
Device Information⁽¹⁾
PART NUMBER PACKAGE
BODY SIZE (NOM)
UCC28740
SOIC (7)
4.90 mm × 3.91 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Simplified Application Diagram
Typical V-I Diagram
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.