ST VIPER27 User Manual
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
VIPER27
Off-line high voltage converters
SO16 narrow
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
-
DIP-7
+
DC Output voltage
-
DRAIN
DRAIN
GND
VIPER27
VDD
CONT
BR
FB
Table 1. Device summary
Order codes Package Packaging
VIPER27LN / VIPER27HN DIP-7
Tu be
VIPER27HD / VIPER27LD
SO16 narrow
VIPER27HDTR / VIPER27LDTR Tape and reel
July 2010 Doc ID 15133 Rev 5 1/31
www.st.com
31
Contents VIPER27
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
2/31 Doc ID 15133 Rev 5
VIPER27 Block diagram
1 Block diagram
Figure 2. Block diagram
BR
VDD
VDD
Vcc
DRAIN
CONT
15uA
OVP
LOGIC
OVP
+
-
V
BRth
SOFT
START
.
6uA
OCP
BLOCK
Vin_OK
FB
2 Typical power
Table 2. Typical power
Internal Supply bus
&
Reference Voltages
-
OCP
+
PWM
+
-
+
-
Ref
BURST-MODE
LOGIC
2nd OCP
LOGIC
BURST
SUPPLY
& UVLO
UVLO
LEB
BURST
OSCILLATOR
TUR N -ON
LOGIC
OVP
OTPOLP
HV_ON
S
R1
I
DDch
THE RMA L
SHUTDOWN
OTP
Q
R2
Rsense
GND
230 V
Part number
Adapter
(1)
AC
Open frame
(2)
VIPER27 18 W 20 W 10 W 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 3/31
Adapter
85-265 V
(1)
AC
Open frame
(2)
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 description
Pin n.
Name Function
DIP7 SO16N
1 1...2 GND
-4N.A.
25VDD
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.
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
3 6 CONT
external resistor.
2. output voltage monitoring. A voltage exceeding V
Table 8 on page 7
) shuts the IC down reducing the device consumption.
threshold (see
OVP
This function is strobed and digitally filtered for high noise immunity.
Control input for duty cycle control. Internal current generator provides
47FB
bias current for loop regulation. A voltage below the threshold V
activates the burst-mode operation. A level close to the threshold V
FBbm
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
shuts down (not latch) the device and lowers the power
58BR
BRth
consumption. Device operation restarts as the voltage exceeds the
threshold V
BRth
+ V
. It can be connected to ground when not used.
BRhyst
High voltage drain pin. The built-in high voltage switched start-up bias
7,8 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 Electrical data
4.1 Maximum ratings
Table 4. Absolute maximum ratings
Val ue
Symbol Parameter
Min Max
Unit
V
DRAIN
E
I
DRAIN
V
CONT
V
V
V
Drain-to-source (ground) voltage 800 V
Repetitive avalanche energy
AV
(limited by T
Repetitive avalanche current
I
AR
(limited by T
Pulse drain current (limited by TJ = 150 °C) 3 A
Control input pin voltage (with I
Feed-back voltage -0.3 5.5 V
FB
Brown-out input pin voltage (with IBR = 0.5 mA) -0.3 Self limited V
BR
Supply voltage (IDD = 25 mA) -0.3 Self limited V
DD
I
Input current 25 mA
DD
Power dissipation at TA < 40 °C (DIP-7) 1
P
TOT
Power dissipation at TA < 60 °C (SO16N) 1.5
T
Operating junction temperature range -40 150 °C
J
T
Storage temperature -55 150 °C
STG
4.2 Thermal data
Table 5. Thermal data
= 150 °C)
J
= 150 °C)
J
1.5 A
= 1 mA) -0.3 Self limited V
CONT
5mJ
W
Max value
Symbol Parameter
Unit
SO16N DIP7
R
R
R
1. When mounted on a standard single side FR4 board with 100 mm2 (0.155 sq in) of Cu (35 µm thick)
Thermal resistance junction pin
thJP
(Dissipated power = 1 W)
Thermal resistance junction ambient
thJA
(Dissipated power = 1 W)
Thermal resistance junction ambient
thJA
(Dissipated power = 1 W)
25 35 °C/W
60 100 °C/W
(1)
50 80 °C/W
Doc ID 15133 Rev 5 5/31
Electrical data VIPER27
4.3 Electrical characteristics
(TJ = -25 to 125 °C, VDD = 14 V
Table 6. Power section
Symbol Parameter Test condition Min Typ Max Unit
V
BVDSS
I
OFF
R
DS(on)
Break-down voltage
OFF state drain current
Drain-source on state
resistance
(a)
; unless otherwise specified)
I
= 1 mA, VFB = GND
DRAIN
T
= 25 °C
J
V
V
I
T
I
= max rating,
DRAIN
= GND
FB
= 0.4 A, VFB = 3 V, VBR = GND,
DRAIN
= 25 °C
J
= 0.4 A, VFB = 3 V, VBR = GND,
DRAIN
TJ = 125 °C
800 V
60 μA
7 Ω
14 Ω
C
OSS
Table 7. Supply section
Effective (energy related)
output capacitance
V
DRAIN
= 0 to 640 V 40 pF
Symbol Parameter Test condition Min Typ Max Unit
Vol tag e
V
DRAIN
I
DDch
V
DD
V
DDclampVDD
V
DDon
V
DDoff
V
DD(RESTART)
Drain-source start voltage 60 80 100 V
_START
Start up charging current
V
V
V
V
= 120 V, VBR = GND, VFB = GND,
DRAIN
= 4 V
DD
= 120 V, VBR = GND, VFB = GND,
DRAIN
= 4 V after fault.
DD
-2 -3 -4 mA
-0.4 -0.6 -0.8 mA
Operating voltage range After turn-on 8.5 23.5 V
clamp voltage IDD = 20 mA 23.5 V
VDD start up threshold
VDD under voltage
shutdown threshold
VDD restart voltage
threshold
V
DRAIN
V
DRAIN
= 120 V, VBR = GND, VFB = GND
= 120 V, VBR = GND, VFB = GND 4 4.5 5 V
13 14 15 V
7.5 8 8.5 V
Current
I
DD0
I
DD1
I
DD_FAULT
I
DD_OFF
Operating supply current,
not switching
Operating supply current,
switching
Operating supply current,
with protection tripping
Operating supply current
with V
a. Adjust VDD above V
DD
< V
DD_OFF
DDon
VFB = GND, FSW = 0 kHz, VBR = GND,
= 10 V
V
DD
V
V
= 120 V, FSW = 60 kHz 2.5 mA
DRAIN
= 120 V, FSW = 115 kHz 3.5 mA
DRAIN
VDD = 7 V 270 μA
start-up threshold before settings to 14 V.
6/31 Doc ID 15133 Rev 5
0.9 mA
400 μA
VIPER27 Electrical data
Table 8. Controller section
Symbol Parameter Test condition Min Typ Max Unit
Feed-back pin
V
FBolp
V
FBlin
V
FBbm
V
FBbmhys
I
FB
R
FB(DYN)
H
Over load shutdown threshold 4.5 4.8 5.2 V
Linear dynamics upper limit 3.2 3.5 3.7 V
Burst mode threshold Voltage falling 0.6 V
Burst mode hysteresis Voltage rising 100 mV
= 0.3 V -150 -200 -280 μA
V
Feed-back sourced current
FB
3.3 V < VFB < 4.8 V -3 μA
Dynamic resistance V
ΔVFB / ΔI
FB
D
< 3.3 V 14 21 kΩ
FB
26V/A
CONT pin
VCONT_l Low level clamp voltage I
= -100 µA 0.5 V
CONT
Current limitation
V
= 4 V,
I
Dlim
t
SS
T
ON_MIN
Max drain current limitation
Soft-start time 8.5 ms
Minimum turn ON time 220 400 480 ns
FB
I
CONT
T
= 25 °C
J
= -10 µA
0.66 0.7 0.74 A
td Propagation delay 100 ns
t
LEB
I
D_BM
Leading edge blanking 300 ns
Peak drain current during burst mode VFB = 0.6 V 160 mA
Oscillator section
F
OSC
VIPER27H 103 115 127 kHz
FD Modulation depth
FM Modulation frequency 250 Hz
VIPER27L
D
MAX
Maximum duty cycle 70 80 %
Over current protection (2
I
DMAX
Overvoltage protection
V
OVP
T
STROBE
Second over current threshold 1 A
Overvoltage protection threshold 2.7 3 3.3 V
Overvoltage protection strobe time 2.2 us
nd
OCP)
= operating voltage range,
V
V
DD
FB
= 1 V
54 60 66 kHz
VIPER27L ±4 kHz
VIPER27H ±8 kHz
Doc ID 15133 Rev 5 7/31
Electrical data VIPER27
Table 8. Controller section (continued)
Symbol Parameter Test condition Min Typ Max Unit
Brown out protection
V
BRth
V
BRhyst
I
BRhyst
V
BRclamp
V
DIS
Brown out threshold Voltage falling 0.41 0.45 0.49 V
Voltage hysteresis above V
Current hysteresis 7 12 μA
Clamp voltage IBR = 250 µA 3 V
Brown out disable voltage 50 150 mV
Thermal shutdown
T
T
SD
HYST
Thermal shutdown temperature 150 160 °C
Thermal shutdown hysteresis 30 °C
BRth
Voltage rising 50 mV
8/31 Doc ID 15133 Rev 5
VIPER27 Electrical data
Figure 4. Minimum turn-on time test circuit
V
DRAIN
GND
14 V
3.5 V
VDD
CONT
FB
DRAIN
DRAIN
50 Ω
BR
30 V
90 %
10 %
I
DLIM
I
DRAIN
T
ONmin
Time
Time
Figure 5. Brown out threshold test circuit
V
BRth+VBRhyst
V
BRth
V
I
BRhyst
DIS
BR
I
BR
I
DRAIN
Time
Time
14 V
GND
VDD
CONT
FB
DRAIN
DRAIN
I
BRhyst
BR
V
10 kΩ
30 V
2 V
Figure 6. OVP threshold test circuit
Note: Adjust VDD above V
14 V
GND
DRAIN
VDD
DRAIN
CONT
FB
BR
10 kΩ
30 V
2 V
start-up threshold before settings to 14 V
DDon
Time
V
CONT
V
OVP
V
DRAIN
Time
Time
Doc ID 15133 Rev 5 9/31
Typical electrical characteristics VIPER27
5 Typical electrical characteristics
Figure 7. Current limit vs TJ Figure 8. Switching frequency vs T
J
Figure 9. Drain start voltage vs T
Figure 11. Brown out threshold vs T
J
J
Figure 10. HFB vs T
J
Figure 12. Brown out hysteresis vs T
J
10/31 Doc ID 15133 Rev 5
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