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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 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 October 2007 Rev 2 1/9 www.st.com Contents AN1094 Contents 1 VIPer100-E major features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 VIPer100-E pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Board features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 2.2 Feedback loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Special operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 4 5 Schematics and board layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 BOM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2/9 AN1094 VIPer100-E major features 1 VIPer100-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 Block diagram OSC Figure 2. ON/OFF OSCILLATOR SECURITY LATCH VDD PWM LATCH UVLO LOGIC R/S FF S 0.5 V ERROR _ AMPLIFIER + let so b 13 V COMP SOURCE 3/9 FC00231 P e od r + _ ct u OVERTEMP. DETECTOR )(s Q b O S R1 FF Q R2 R3 ol s eP et uc d ro DRAIN 1.7 µ s DELAY 250 ns BLANKING 0.5V _ + + _ 1 V/A CURRENT AMPLIFIER 4.5 V Boar