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
SO16 narrow
DIP-7
SO 16
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
+
DC input high voltage
wide range
■
■
■
■
■
■
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
+
DC Output voltage
-
-
DRAIN
DRAIN
BR
VIPER27
GND
VDD
CONT
FB
Table 1.
Device summary
Order codes
Package
DIP-7
Tube
SO16 narrow
Packaging
VIPER27LN / VIPER27HN
VIPER27HD / VIPER27LD
VIPER27HDTR / VIPER27LDTR
Tape and reel
July 2010
Doc ID 15133 Rev 5
1/31
www.st.com
31
Contents
VIPER27
Contents
1
2
3
4
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Typical power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1
4.2
4.3
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5
6
7
Typical electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Typical circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Operation descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
7.13
Power section and gate driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
High voltage startup generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Power-up and soft-start up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Power down operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Auto restart operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Current mode conversion with adjustable current limit set point . . . . . . . 18
Overvoltage protection (OVP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
About CONT pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Feed-back and overload protection (OLP) . . . . . . . . . . . . . . . . . . . . . . . . 20
Burst-mode operation at no load or very light load . . . . . . . . . . . . . . . . . . 23
Brown-out protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2nd level over current protection and hiccup mode . . . . . . . . . . . . . . . . . 25
8
9
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2/31
Doc ID 15133 Rev 5
VIPER27
Block diagram
1
Figure 2.
Block diagram
Block diagram
BR
VDD
VDD
Vcc
DRAIN
+
Vin_OK
-
VBRth
15uA
UVLO
-
SOFT
START
OCP
BLOCK
OCP
BURST
TURN-ON
LOGIC
S
Q
R1
OSCILLATOR
Internal Supply bus
&
Ref erence Voltages
SUPPLY
& UVLO
HV_ON
I DDch
THERMAL
SHUTDOWN
OTP
.
OVP
LOGIC
+
-
6uA
OVP
Ref
+
-
BURST-MODE
LOGIC
FB
2
Table 2.
Typical power
Typical power
230 V
AC
Part number
VIPER27
Adapter
(1)
18 W
Open frame
(2)
20 W
Adapter
(1)
10 W
85-265 V
AC
Open frame
(2)
12 W
1. Typical continuous power in non ventilated enclosed adapter measured at 50
°
C ambient.
2. Maximum practical continuous power in an open frame design at 50
°
C ambient, with adequate heat sinking.
Doc ID 15133 Rev 5
+
PWM
LEB
2nd OCP
LOGIC
BURST
CONT
R2
OLP
OVP
OTP
Rsense
GND
3/31
Pin settings
VIPER27
3
Pin settings
Figure 3.
Connection diagram (top view)
Note:
The copper area for heat dissipation has to be designed under the DRAIN pins.
Table 3.
Pin n.
Name
DIP7
1
-
2
SO16N
1...2
4
5
GND
N.A.
VDD
This pin represents the device ground and the source of the power
section.
Not available for user. It can be connected to GND (pins 1-2) or left not
connected.
Supply voltage of the control section. This pin also provides the charging
current of the external capacitor during start-up time.
Function
Pin description
3
6
Control pin. The following functions can be selected:
1. current limit set point adjustment. The internal set default value of the
cycle-by-cycle current limit can be reduced by connecting to ground an
CONT external resistor.
2. output voltage monitoring. A voltage exceeding V
OVP
threshold (see
Table 8 on page 7)
shuts the IC down reducing the device consumption.
This function is strobed and digitally filtered for high noise immunity.
Control input for duty cycle control. Internal current generator provides
bias current for loop regulation. A voltage below the threshold V
FBbm
activates the burst-mode operation. A level close to the threshold V
FBlin
means that we are approaching the cycle-by-cycle over-current set point.
Brownout protection input with hysteresis. A voltage below the threshold
V
BRth
shuts down (not latch) the device and lowers the power
consumption. Device operation restarts as the voltage exceeds the
threshold V
BRth
+ V
BRhyst
. It can be connected to ground when not used.
4
7
FB
5
8
BR
7,8
High voltage drain pin. The built-in high voltage switched start-up bias
13...16 DRAIN current is drawn from this pin too.
Pins connected to the metal frame to facilitate heat dissipation.
4/31
Doc ID 15133 Rev 5
VIPER27
Electrical data
4
4.1
Electrical data
Maximum ratings
Table 4.
Symbol
Absolute maximum ratings
Value
Parameter
Min
Max
800
5
1.5
3
-0.3
-0.3
-0.3
-0.3
Self limited
5.5
Self limited
Self limited
25
1
W
1.5
-40
-55
150
150
°C
°C
V
mJ
A
A
V
V
V
V
mA
Unit
V
DRAIN
Drain-to-source (ground) voltage
E
AV
I
AR
I
DRAIN
V
CONT
V
FB
V
BR
V
DD
I
DD
P
TOT
T
J
T
STG
Repetitive avalanche energy
(limited by T
J
= 150 °C)
Repetitive avalanche current
(limited by T
J
= 150 °C)
Pulse drain current (limited by T
J
= 150 °C)
Control input pin voltage (with I
CONT
= 1 mA)
Feed-back voltage
Brown-out input pin voltage (with I
BR
= 0.5 mA)
Supply voltage (I
DD
= 25 mA)
Input current
Power dissipation at T
A
< 40 °C (DIP-7)
Power dissipation at T
A
< 60 °C (SO16N)
Operating junction temperature range
Storage temperature
4.2
Thermal data
Table 5.
Symbol
Thermal data
Max value
Parameter
SO16N
DIP7
35
100
80
°C/W
°C/W
°C/W
Thermal resistance junction pin
(Dissipated power = 1 W)
Thermal resistance junction ambient
(Dissipated power = 1 W)
Thermal resistance junction ambient
(1)
(Dissipated power = 1 W)
Unit
R
thJP
R
thJA
R
thJA
25
60
50
1. When mounted on a standard single side FR4 board with 100 mm
2
(0.155 sq in) of Cu (35 µm thick)
Doc ID 15133 Rev 5
5/31
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