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
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 Feedback loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Special operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Schematics and board layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 BOM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2/9
AN1094 VIPer100-E major features
duc
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
Figure 2. Block diagram
OSC
ON/OFF
OSCILLATOR
SECURITY
LATCH
DD
V
ERROR
AMPLIFIER
_
13 V
+
UVLO
LOGIC
0.5 V
+
_
4.5 V
FF
R/S
S
OVERTEMP.
DETECTOR
1.7
µ
DELAY
PWM
LATCH
Q
s
R1
R2 R3
S
FF
Q
250 ns
BLANKING
0.5V
+
+
_
_
CURRENT
AMPLIFIER
DRAIN
1 V/A
olete Product(s) - Obsolete Pro
COMP
SOUR CE
FC00231
3/9
Loading...