ST AN1094 Application note
AN1094
Application note
Solution for off-line SMPS using VIPer100-E
Introduction
The present board prototype is a wide-range input off-line 50 W single switch Flyback, working at 100 kHz. It is based on a new off-line smart switcher: the VIPer100-E.
The VIPer100-E is a current mode PWM with a 620 V / 2.5 Ω power switch, able to withstand an avalanche current during normal operation. The start-up of the circuit is done with an internal high voltage current source, which is switched off during steady state. It also includes a regulation function designed to minimize the pin count, while maintaining design flexibility. Figure 2 presents the internal block diagram of this monolithic device. Such a device can be easily used in any off-line flyback SMPS, with a 100 W power capability for a single input voltage range, or 50 W with a wide input range. This stand-alone off-line Smart Switcher concept provides a cost effective solution for SMPS for many applications such as VCRs, TV sets, satellite receivers or decoders. The benefits for the customer are a simpler design phase and a reduced overall components count due to the optimization of the product configuration.
Figure 1. Standard evaluation board VIPerKITBD
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October 2007 |
Rev 2 |
1/9 |
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www.st.com
Contents |
AN1094 |
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Contents
1 |
VIPer100-E major features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
3 |
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1.1 |
VIPer100-E pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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2 |
Board features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
4 |
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2.1 |
Feedback loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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2.2 |
Special operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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3 |
Schematics and board layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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4 |
BOM |
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5 |
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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2/9
AN1094 |
VIPer100-E major features |
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1VIPer100-E major features
●Adjustable Switching Frequency up to 200 kHz
●Optimized for current mode control topology
●Inherent feedforward compensation
●Soft-start and enable functions
●Overcurrent protection
●Overtemperature protection
●Overvoltage protection
●Undervoltage lock-out with hysteresis
●Low standby current
●Integrated start-up supply
●Automatic burst mode operation in standby condition
●Internally trimmed BANDGAP reference
Figure 2. Block diagram
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OSC |
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d |
DRAIN |
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ON/OFF |
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Pro |
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OSCILLATOR |
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SECURITY |
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PWM |
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LATCH |
LATCH |
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UVLO |
FF |
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S |
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VDD |
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LOGIC |
R/S |
Q |
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R1 FF |
Q |
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S |
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R2 R3 |
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Obsolete |
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- |
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OVERTEMP. |
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DETECTOR |
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0.5V |
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0.5 V |
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1.7 s |
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250 ns |
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_ |
1 V/A |
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DELAY |
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_ |
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BLANKING |
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ERROR |
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CURRENT |
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AMPLIFIER |
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AMPLIFIER |
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13 V |
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Product(s) |
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+ |
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4.5 V |
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solete |
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FC00231 |
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COMP |
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SOURCE |
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