July 2010 Doc ID 15133 Rev 5 1/31
31
VIPER27
Off-line high voltage converters
Features
■ 800 V avalanche rugged power section
■ PWM operation with frequency jittering for low
EMI
■ Operating frequency:
– 60 kHz for L type
– 115 kHz for H type
■ Standby power < 50 mW at 265 Vac
■ Limiting current with adjustable set point
■ Adjustable and accurate overvoltage
protection
■ On-board soft-start
■ Safe auto-restart after a fault condition
■ Hysteretic thermal shutdown
Application
■ Auxiliary power supply for consumer and home
equipments
■ ATX auxiliary power supply
■ Low / medium power AC-DC adapters
■ SMPS for set-top boxes, DVD players and
recorders, white goods
Description
The device is an off-line converter with an 800 V
rugged power section, a PWM control, two levels
of over-current protection, overvoltage and
overload protections, hysteretic thermal
protection, soft-start and safe auto-restart after
any fault condition removal. Burst mode operation
and device very low consumption help to meet the
standby energy saving regulations.
Advance frequency jittering reduces EMI filter
cost. Brown-out function protects the switch mode
power supply when the rectified input voltage
level is below the normal minimum level specified
for the system. The high voltage start-up circuit is
embedded in the device.
Figure 1. Typical topology
DIP-7
SO
16
SO16 narrow
DC input high voltage
wide range
-
+
DC Output voltage
-
+
VIPER27
DRAIN
DRAIN
BR
VDD
CONT
FB
GND
Table 1. Device summary
Order codes Package Packaging
VIPER27LN / VIPER27HN DIP-7
Tub e
VIPER27HD / VIPER27LD
SO16 narrow
VIPER27HDTR / VIPER27LDTR Tape and reel
www.st.com
Contents VIPER27
2/31 Doc ID 15133 Rev 5
Contents
1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Typical power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Typical electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Typical circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7 Operation descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1 Power section and gate driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.2 High voltage startup generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.3 Power-up and soft-start up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.4 Power down operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.5 Auto restart operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.6 Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.7 Current mode conversion with adjustable current limit set point . . . . . . . 18
7.8 Overvoltage protection (OVP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.9 About CONT pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.10 Feed-back and overload protection (OLP) . . . . . . . . . . . . . . . . . . . . . . . . 20
7.11 Burst-mode operation at no load or very light load . . . . . . . . . . . . . . . . . . 23
7.12 Brown-out protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.13 2nd level over current protection and hiccup mode . . . . . . . . . . . . . . . . . 25
8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30