UCC28740 Datasheet, PDF (1/32 Pages) Texas Instruments – Constant-Voltage Constant-Current Flyback Controller Using Opto-Coupled Feedback

UCC28740
www.ti.com
SLUSBF3A – JULY 2013 – REVISED JULY 2013
Constant-Voltage Constant-Current Flyback Controller Using Opto-Coupled Feedback
Check for Samples: UCC28740
FEATURES
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• 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
APPLICATIONS
• USB-Compliant Adapters and Chargers for
Consumer Electronics
– Smart Phones
– Tablet Computers
– Cameras
• Standby Supply for TV and Desktop
• White Goods
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.
SIMPLIFIED APPLICATION DIAGRAM
TYPICAL V-I DIAGRAM
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2013, Texas Instruments Incorporated