STMicroelectronics VIPER26 Datasheet
Reklaam
Reklaam
VIPER26
Datasheet
Fixed frequency VIPer plus family
S O16 narrow
DC Input Voltage
Product status link
VIPER26
Product label
DIP-7
DC Output Voltage
-
Features
• 800 V avalanche rugged power MOSFET allowing wide range V
AC
input range to be covered
• Embedded HV startup and sense-FET
• Current mode PWM controller
• Minimized system input power consumption:
– Less than 30 mW @ 230 V
AC
in no-load condition
– Less than 400 mW @ 230 V
AC
with 250 mW load
• Limiting current with adjustable set point
• Jittered switching frequency to reduce the EMI filter cost:
– 60 kHz ±4 kHz (L type)
– 115 kHz ±8 kHz (H type)
• Embedded error amplifier
• Hysteretic thermal shutdown
• Built-in soft-start for improved system reliability
• Protections with automatic restart: overload/short-circuit (OLP), feedback loop disconnection
Application
• Auxiliary power supply for appliances
• Power metering
• LED drivers
• SMPS for set-top boxes, DVD players and recorders
Description
The VIPER26 device is a smart high voltage converter that integrates an 800 V avalanche-rugged power MOSFET with PWM current mode control. The power
MOSFET with 800 V breakdown voltage allows an extended input voltage range to be applied, as well as the size of the DRAIN snubber circuit to be reduced.
This IC meets the most stringent energy-saving standards with very low consumption and burst mode operation under light load.
The design of flyback, buck and buck boost converters is supported. The integrated
HV startup, sense-FET, error amplifier and oscillator with jitter allow complete application designs with a minimum number of components.
DS6901 - Rev 3 - October 2020
For further information contact your local STMicroelectronics sales office.
www.st.com
VIPER26
Pin settings
1
Note:
Pin settings
GND
GND
N.C.
N.A.
VDD
FB
COMP
SO16N
Figure 1. Connection diagram (top view)
DIP7
DRAIN
GND
DRAIN
DRAIN
VDD
DRAIN
N.C.
N.C.
N.C.
N.C.
LIM
FB
The copper area for heat dissipation has to be designed under the DRAIN pins.
DRAIN
DRAIN
COMP
Table 1. Pin descriptions
Pin number
Name Function
DIP7 SO16N
1
-
-
2
1-2
3
4
5
GND
Ground and MOSFET source.
Connection of the source of the internal MOSFET and controller ground reference.
N.C.
Not connected.
This pin can be soldered to GND.
N. A.
VDD
Not available for user.
This pin is mechanically connected to the controller die pad of the frame. In order to improve noise immunity, it is highly recommended to connect it to GND (pin 1,2).
Controller Supply . An external storage capacitor has to be connected across this pin and GND. The pin, internally connected to the high voltage current source, provides the VDD capacitor charging current at startup and during fault conditions. A small bypass capacitor (0.1 μF typ.) in parallel, placed as close as possible to the IC, is also recommended for noise filtering purposes.
3
4
5
6
7
8
LIM
FB
Drain current limitation.
This pin allows setting the drain current limitation to a lower value than the default I
Dlim
value. The limit can be reduced by connecting an external resistor between this pin and
GND. In case of high electrical noise, a capacitor may be connected between this pin and GND; the capacitor value must be lower than 470 nF in order to not impact the functionality of the pin. The pin can be left open if the default drain current limitation, I
Dlim
, is used.
Direct feedback . It is the inverting input of the internal transconductance E/A, which is internally referenced to 3.3 V with respect to GND. In a non-isolated converter, the output voltage information is directly fed into the pin through a voltage divider. In primary regulation, the FB voltage divider is connected to the VCC. The E/A is disabled by soldering FB to GND.
COMP
Compensation . It is the output of the internal E/A. A compensation network is placed between this pin and GND to achieve stability and good dynamic performance of the control loop. In case of isolated secondary side regulation, the internal E/A must be disabled and the COMP directly driven by the optocoupler to control the DRAIN peak current setpoint.
9-12 N.C.
7,8 13-16 DRAIN
Not internally connected.
These pins must be left floating in order to ensure a safe clearance distance.
MOSFET drain.
The internal high voltage current source sinks current from this pin to charge the
VCC capacitor at startup. These pins are mechanically connected to the internal metal PAD of the
MOSFET in order to facilitate heat dissipation. On the PCB, the copper area must be placed under these pins in order to decrease the total junction-to-ambient thermal resistance, thus facilitating the power dissipation.
DS6901 - Rev 3 page 2/34
2
VIPER26
Electrical and thermal ratings
Electrical and thermal ratings
Symbol
V
DRAIN
I
DRAIN
V
COMP
V
FB
V
LIM
V
DD
I
DD
P
TOT
T
J
T
STG
Table 2. Absolute maximum ratings
Parameter
Drain-to- source (ground) voltage
Pulse drain current (limited by T
J
= 150 °C)
COMP voltage
FB voltage
LIM voltage
Supply voltage
Input current
Power Dissipation @ Tamb < 40 °C (DIP7)
Power Dissipation @ Tamb < 60 °C (SO16N)
Junction Temperature operating range
Storage Temperature
Min.
-
-
-0.3
-0.3
-0.3
-0.3
-0.3
-
-
-40
-55
Max.
800
3
3.5V
4.8
2.4
Self limited
20
1
1.5
150
150
V
V
V
Unit
V
A
V mA
W
W
°C
°C
Table 3. Thermal data
Symbol Parameter
Max. value
SO16N DIP-7
R
R
R
R
TH-JC
TH-JA
TH-JC
TH-JA
Thermal resistance junction to case (1)
(Dissipated power = 1 W)
Thermal resistance junction ambient (1)
(Dissipated power = 1 W)
Thermal resistance junction to case (2)
(Dissipated power = 1 W)
Thermal resistance junction ambient (2)
(Dissipated power = 1 W)
1. When mounted on a standard, single side FR4 board with minimum copper area.
2. When mounted on a standard, single side FR4 board with 100 mm2 of Cu (35 µm thick).
10
120
5
85
10
120
5
95
Unit
°C/W
°C/W
°C/W
°C/W
DS6901 - Rev 3 page 3/34
VIPER26
Electrical characteristics
2.1
Note:
Figure 2. R th
versus area
R thJA
/(R thJA
@A=100mm 2 )
1.500
1.375
1.250
1.125
1.000
0.875
0.750
0 25 50
*Copper tickness is 35 µm
SO16N
DIP-7
75 100 125
A(mm 2 )
150 175 200 225
Symbol
E
AV
I
AR
Table 4. Avalanche characteristics
Parameter
Repetitive avalanche energy (limited by T
J
=150°C)
Repetitive avalanche current (limited by T
J
=150°C)
Electrical characteristics
T
J
= -40 to 125°C, V
DD
= 14 V (unless otherwise specified)
Adjust V
DD
above V
DD
on startup threshold before setting to 14 V
Symbol Parameter
V
BVDSS
Breakdown voltage
I
OFF
R
DS(on)
OFF state drain current
Static drain-source ON ‑ resistance
Table 5. Power section
Test condition
I
DRAIN
= 1 mA, V
COMP
= V
GND
,
T
J
= 25°C
V
DRAIN
= max. rating,
V
COMP
= V
GND
, T
J
= 25°C
I
DRAIN
= 0.2 A, T
J
= 25°C
I
DRAIN
= 0.2 A, T
J
= 125°C -
-
-
Min.
-
-
Max.
5
1.5
Unit mJ
A
Min.
Typ.
Max.
Unit
800 V
-
-
60
7
14
µA
Ω
Ω
Symbol
I
DDch1
Parameter
V
DRAIN_START
Drain-source start voltage
Charging current during startup
Table 6. Supply section
Test condition
Voltage
I
DRAIN
T
J
= 1 mA; V
= 25°C
COMP
= GND;
V
DRAIN
= 100 to 640 V; V
DD
= 4 V
Min. Typ. Max. Unit
90 V
-0.6
-1.8
mA
DS6901 - Rev 3 page 4/34
DS6901 - Rev 3
VIPER26
Electrical characteristics
Symbol
I
DDch2
V
DD
V
DDclamp
V
DDon
V
DDCSon
V
DDoff
I
I
I
I
DD0
DD1
DDoff
DDol
Parameter
Charging current during autorestart
Operating voltage range
Test condition
V
DRAIN
= 100 to 640 V; V
DD
= 9 V falling edge
-
V
DD
clamp voltage
V
DD
startup threshold
V
DD
on internal high voltage current generator threshold
V
DD
undervoltage shutdown threshold
I
DD
= 15 mA;
-
-
-
Operating supply current, not switching
Operating supply current, switching
Operating supply current with V
DD
< V
DDoff
Open loop failure current threshold
Current
F
OSC
= 0 kHz; V
COMP
= GND
V
DRAIN
= 120 V; V
SW
= 60 kHz
V
DRAIN
= 120 V; V
SW
= 115 kHz
V
DD
< V
DDoff
V
DD
= V
DDclamp
; V
COMP
= 3.3 V
Min. Typ. Max. Unit
-7 -13 mA
11.5
23.5
V
23.5
V
12 13 14 V
9.5 10.5 11.5
V
7 8 9 V
-
-
-
-
4
-
-
0.6
2
3
-
0.35
mA
Symbol Parameter
V
REF_FB
I
FB_PULL UP
G
M
FB reference voltage
Pull-up current
Trans conductance
V
LIM_LOW
Low level clamp voltage
V
COMPH
V
COMPL
V
COMPL_HYS
Burst mode hysteresis
H
COMP
R
COMP(DYN)
Upper saturation limit
Burst mode threshold
ΔV
COMP
/ΔI
DRAIN
Dynamic resistance
Source / sink current
I
COMP
Max. source current
I
DLIM t
SS t
ON_MIN
I
Dlim_bm t
OVL
Drain current limitation
Soft-start time
Minuimum turn-on time
Burst mode current limitation
Overload time
Table 7. Controller section
Test condition
Error amplifier
Min. Typ. Max. Unit
3.2
3.3
3.4
V
-
V
COMP
= 1.5 V, V
FB
> V
FB REF
Current setting (LIM) pin
I
LIM
= -100 µA
Compensation (COMP) pin
T
J
= 25°C
T
J
= 25°C
T
J
= 25°C
-
V
COMP
= V
COMPL
Overload
-
-
-
-
1
-
-
-1
2
40
3
-
-
-
-
µA mA/V mV
V/A
V
FB
= GND
V
FB
> 100 mV
V
COMP
= GND; V
FB
= GND
Current limitation
-
-
-
-
-
-
-
15
150
220
8.5
-
-
-
-
I
LIM
= -10 µA; V
COMP
= 3.3 V; T
J
= 25 °C 0.66 0.7
0.74
kΩ
µA
A ms
480 ns
-
0.5
3
1.1
145
1.2
-
-
V
V
V mA
50 ms page 5/34
Symbol Parameter t
RESTART
Restart time after fault
F
D
T
OSC
F
F
D
M
MAX
SD
T
HYS
Thermal shutdown hysteresis
Test condition
Switching frequency
Modulation depth
Oscillator section
VIPER26L
VIPER26H
F
OSC
= 60 kHz
F
OSC
= 115 kHz
Modulation frequency
Maximum duty cycle
Thermal shutdown
Thermal shutdown temperature threshold
-
-
-
-
-
VIPER26
Electrical characteristics
Min. Typ. Max. Unit
1 s
54 60 66
103 115 127
±4 -
±8 -
230
70 -
-
80 kHz kHz
Hz
%
150 160
30 -
°C
°C
DS6901 - Rev 3 page 6/34
VIPER26
Typical electrical characteristics
3
Typical electrical characteristics
Figure 3. I
DLIM
vs. T
J
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50
IDLIM/ IDLIM@25C
0 50 100
Figure 5. V
DRAIN_START
vs. T
J
VDRAIN_START/ VDRAIN_START@25C
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50
GM / GM@25C
0
0 50
Figure 7. G
M
vs. T
J
50
100
100
150
150
150
Figure 4. F
OSC vs. T
J
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50
FOSC/ FOSC@25C
0 50 100
Figure 6. H
COMP
vs. T
J
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50
HCOMP / HCOMP@25C
0 50 100
Figure 8. V
REF_FB
vs. T
J
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50
VREF_FB / VRE_FB@25C
0 50 100
150
150
150
DS6901 - Rev 3 page 7/34
VIPER26
Typical electrical characteristics
Figure 9. I
COMP
vs. T
J
ICOMP / ICOMP@25C
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50 0 50 100 150
Figure 11. Operating supply current (switching) vs T
J
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50
IDD1 / IDD1@25C
0 50 100 150
Figure 13. Power MOSFET on-resistance vs T
J
5.00
4.50
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
-50
RDSON/ RDSON@25C
0 50 100 150
1.00
0.80
0.60
0.40
0.20
Figure 10. Operating supply current (no switching) vs T
J
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50
IDD0 / IDD0@25C
0 50
Figure 12. I
DLIM vs. R
LIM
100
IDLIM/ IDLIM@100KOhm
1.20
150
0.00
0 20 40 60 80 100 120
Figure 14. Power MOSFET breakdown voltage vs T
J
BVDSS/ BVDSS@25C
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-50 0 50 100 150
DS6901 - Rev 3 page 8/34
VIPER26
Typical electrical characteristics
Figure 15. Power MOSFET capacitance variation vs V
DS
1000
C
OSS
[pF]
100
10
Figure 16.
1
0.1
SOA SO16N package
1
When mounted on a standard single side FR4 board with 100 mm² of
Cu (35μm thick)
I
D
[A]
1.0E+01
V
10
DS
[V]
100 1000
Figure 17. SOA DIP7 package
When mounted on a standard single side FR4 board with 100 mm² of
Cu (35μm thick)
I
D
[A]
1.0E+01
1.0E+00 1.0E+00
1.0E-01
1.0E-01
1.0E-02
1.0E-02
1.0E-03
in Rds(on)
Operation limited
by
Max
1.0E-03
in this area is
Operation limited
by Max Rds(on)
1.0E-04
1.0E-05
1us
10us
100us
1ms
Ron
1.0E-04
1.0E-05
1us
10us
100us
1ms
Ron
1.0E-06
Tj=150°C
Tc=25°C
Single pulse
1.0E-06
Tj=150°C
Tc=25°C
Single pulse
1.0E-07
1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04
V
DS
[V]
1.0E-07
1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04
V
DS
[V]
Figure 18. Thermal shutdown
V
DD
V
DDon
V
DDCSon
V
DDoff
I
DRAIN time time
T
J
T
SD
T
SD
- T
HYST
Normal operation Shut down after over temperature Normal operation time
DS6901 - Rev 3 page 9/34
4
VIPER26
Typical circuits
Typical circuits
AC IN
D1 R1
AC IN
C1
L1
Figure 19. Buck converter (V
OUT
>V
DDCSon
)
D2
C2
C3
VIPer26
FB
CONTROL
VDD
COMP LIM
DRAIN
GND
C4
R2
C5
R6
(Optional)
D3
AC IN
R1
+
BR
AC IN
C1
L1
Figure 20. Flyback converter (isolated)
C2
C3 R3
D1
D2
R2
C4
VDD
VIPer26
DRAIN
FB CONTROL
LIM COMP GND
R4
(Optional) C5
OPTO
R3
R4
C6
D4
D3
L2
C7
Vout
R5
C8
GND
Vout
C6
GND
R5
OPTO
REF
C7
R6 R7
R8
DS6901 - Rev 3 page 10/34
DS6901 - Rev 3
VIPER26
Typical circuits
AC IN
R1
AC IN
+
BR
C1
Figure 21. Flyback converter (primary regulation)
L1
C2
C3 R3
D1
R4
D2 R2
C4
VDD
VIPer26
DRAIN
FB
CONTROL
LIM COMP GND
R5
C5
R6
(Optional) C6
R7
D3 Vout
C7
GND
AC IN
R1
AC IN
+
BR
Figure 22. Flyback converter (non isolated, V
OUT
≥ V
DDCSon
)
L1
C1 C2
C3 R2
D1
D2
R3
C4
VDD
VIPer26
DRAIN
FB
CONTROL
LIM COMP GND
R4
C5
R5
(Optional) C6
R6
D3
C7
Vout
GND page 11/34
4.1
VIPER26
Block diagram
AC IN
R1
AC IN
+
BR
Figure 23. Flyback converter (non isolated, V
OUT
< V
DDCSon
)
L1
C1 C2
C3 R3
D1
R4
D2 R2
C4
VDD
VIPer26
DRAIN
FB CONTROL
LIM COMP GND
R5
C5
R6
(Optional) C6
R7
D3 Vout
C7
GND
Block diagram
Figure 24. Block diagram
VDD
LIM
SOFT START
I
DLIM set-up
V
COMPL BURST-MODE
Logic
Burst
FB
V
REF_FB
-
+
E/A
-
+
OCP
Internal Supply BUS &
REFERENCE VOLTAGES
Oscillator
BURST
TURN-ON
LOGIC
SUPPLY
&
UVLO
UVLO
HV_ON
THERMAL
SHUTDOWN
I
DDch
OTP
S
Q
LEB R
-
+
PWM
OLP
LOGIC
OTP
R
SENSE
DRAIN
COMP GND
DS6901 - Rev 3 page 12/34
4.2
Typical power
Table 8. VIPer26 typical power
Adapter
18 W
230 V
AC
20 W
10 W
85-265 V
AC
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.
VIPER26
Typical power
DS6901 - Rev 3 page 13/34
5
VIPER26
Power section
Power section
The power section is implemented with an n-channel power MOSFET with a breakdown voltage of 800 V min.
and a typical R
DS(on)
of 7 Ω. It includes a SenseFET structure to allow virtually lossless current sensing and a thermal sensor.
The gate driver of the power MOSFET is designed to supply a controlled gate current during turn ON and turn
OFF in order to minimize common mode EMI. During UVLO conditions, an internal pull-down circuit holds the gate low in order to ensure that the power MOSFET cannot be turned ON accidentally.
DS6901 - Rev 3 page 14/34
6
VIPER26
High-voltage current generator
High-voltage current generator
The high voltage current generator is supplied by the DRAIN pin. On initial startup of the converter, it is enabled when the voltage across the input bulk capacitor reaches the V
DRAIN_START
threshold, sourcing the I
DDch1
current
(see
Table 6. Supply section ). As the V
DD
voltage reaches the V
DDon
start-up threshold, the power section starts switching and the high voltage current generator is turned OFF. The VIPer26 is powered by the external source.
After the start-up, the auxiliary winding or the diode connected to the output voltage must power the V
DD
capacitor with a voltage higher than the V
DDCSon
threshold (see
).
During the switching, the internal current source is disabled and the consumptions are minimized. If a fault occurs, switching is stopped and the device is self biased by the internal high voltage current source; it is activated between the levels V
DDCSon
and V
DDon
delivering the current I
DDch2
to the V
DD
capacitor during the MOSFET
.
At converter power-down, the V
DD
voltage drops and the converter activity stops as it falls below the V
DDoff
Figure 25. Power ON and power OFF
V
IN
V
DRAIN_START
V
DD
V
DDon
V
DDCSon
V
DDoff
V
DRAIN
V
IN
< V
DRAIN_START
HV startup is no more activated regulation is lost here time time
I
DD
I
DDch2
I
DDch1
Power-on Normal operation time
Power-off time
DS6901 - Rev 3 page 15/34
7
VIPER26
Oscillator
Oscillator
The switching frequency is internally fixed at 60 kHz (VIPER26LN or LD) or 115 kHz (VIPER26HN or HD).
In both cases, the switching frequency is modulated by approximately ±4 kHz (60 kHz version) or ±8 kHz (115 kHz version) at 230 Hz (typical) rate, so that the resulting spread-spectrum action distributes the energy of each harmonic of the switching frequency over a number of sideband harmonics, having the same net energy but with smaller amplitudes.
DS6901 - Rev 3 page 16/34
8
VIPER26
Soft startup
Soft startup
During the converter start-up phase, the soft-start function progressively increases the cycle-by-cycle drain current limit, up to the default value I
Dlim
. This way, the drain current is further limited and the output voltage is progressively increased, therefore reducing the stress on the secondary diode. The soft-start time is internally fixed to t
SS
(see typical value on
Table 7. Controller section ) and the function is activated for any converter start-
up attempt or a fault event.
This function helps prevent transformer saturation during start-up and short-circuit.
DS6901 - Rev 3 page 17/34
9
VIPER26
Adjustable current limit set point
Adjustable current limit set point
The VIPer26 includes a current mode PWM controller: cycle by cycle the drain current is sensed through the integrated resistor R
SENSE
and the voltage is applied to the non inverting input of the PWM comparator, see
power MOSFET is switched OFF.
In parallel with the PWM operations, the comparator OCP, see
Figure 24 , checks the level of the drain current and
switch OFF the power MOSFET in case the current is higher than the threshold I
Dlim
, see
The level of the drain current limit, I
Dlim
, can be reduced depending on the sunk current from the pin LIM. The resistor R
LIM
, between LIM and GND pins, fixes the current sunk and therefore the level of the current limit, I
Dlim
,
.
When the LIM pin is left open or if the R
LIM
has a high value (i.e., > 80 kΩ), the current limit is fixed to its default value, I
Dlim
, as reported in
.
DS6901 - Rev 3 page 18/34
10
VIPER26
FB pin and COMP pin
FB pin and COMP pin
The device can be used both in non-isolated and in isolated topology. In case of non-isolated topology, the feedback signal from the output voltage is applied directly to the FB pin as inverting input of the internal error amplifier with reference voltage, V
REF_FB
, see
The output of the error amplifier sources and sinks the current, I
COMP
, to and from the compensation network connected on the COMP pin. This signal is then compared in the PWM comparator with the signal coming from the SenseFET; the power MOSFET is switched off when the two values are the same on a cycle by cycle basis.
See
When the power supply output voltage is equal to the error amplifier reference voltage, V
REF_FB
, a single resistor has to be connected from the output to the FB pin. For higher output voltages, the external resistor divider is needed. If the voltage on FB pin is accidentally left floating, an internal pull-up protects the controller.
The output of the error amplifier is externally accessible through the COMP pin and it is used for the loop compensation: usually an RC network.
, the internal error amplifier has to be disabled in isolated power supplies (FB pin shorted to
GND). In this case, an internal resistor is connected between an internal reference voltage and the COMP pin,
. The current loop has to be closed on the COMP pin through the opto-transistor in parallel with the compensation network. The V
COMP
dynamic range is between V
COMPL
and V
COMPH
.
When the voltage VCOMP drops below the voltage threshold V
COMPL
, the converter enters burst mode, see
When the voltage V
COMP
rises above the V
COMPH
threshold, the peak drain current will reach its limit, as well as the deliverable output power.
Figure 26. Feedback circuit
VREF
Rcomp VCOMPL PWM stop
RH
VOUT non iso option iso option
FB
Without isolation: switch open and E\A enabled
With isolation: switch closed and E\A disabled switch closed
(E/A disabled)
-
+
E/A
VREF_FB
SW
BUS nR
+
-
+
from RSENSE to PWM
RL
R
COMP
DS6901 - Rev 3 page 19/34
I
DRAIN
I
Dlim
Figure 27. COMP pin voltage versus I
DLIM
I
Dlim_bm
V
COMPL
V
COMPH
V
COMP
VIPER26
FB pin and COMP pin
DS6901 - Rev 3 page 20/34
11
VIPER26
Burst mode
Burst mode
When the voltage V
COMP
drops below the threshold, V
COMPL
, the power MOSFET is kept in the OFF state and the consumption is reduced to I
DD0
current, as given in
. In reaction to the energy delivery interruption, the V
COMP
voltage increases and, as soon as it exceeds the threshold V
COMPL
+ V
COMPL_HYS
, the converter starts switching again with consumption level equal to I
DD1
current. This ON-OFF operation mode,
referred to as “burst mode” (see Figure 28
), reduces the average frequency, which can fall down even to a few hundreds hertz, thus minimizing all frequency-related losses and making it easier to comply with energy saving regulations. During burst mode, the drain current limit is reduced to the value I
Dlim_bm
(given in Table 7. Controller section ) in order to avoid audible noise issues.
Figure 28. Load-dependent operating modes: timing diagrams
V
COMP
V
COMPL
+V
COMPL_HYS
V
COMPL
I
DD
I
DD1
I
DD0
I
DRAIN
I
Dlim_bm time time time
Burst Mode
DS6901 - Rev 3 page 21/34
12
VIPER26
Automatic restart after overload or short-circuit
Automatic restart after overload or short-circuit
The overload protection is implemented automatically through the integrated up-down counter. Every cycle, it is incremented or decremented depending on whether the current logic detects the limit condition or not. The limit condition is the peak drain current, I
Dlim
R
LIM
resistor, as shown in Figure 12. I
given in Table 7. Controller section
, or the one set by the user through the
.
After the reset of the counter, if the peak drain current is continuously equal to the level I
Dlim
, the counter will be incremented until the fixed time, t
OVL
, after which the power MOSFET switch ON is disabled. It is activated again, through the soft start, after the t
RESTART
time, see
Figure 29. Timing diagram: OLP sequence and the relevant
In case of an overload or short-circuit event, the power MOSFET switching is stopped after a time that depends on the counter and whose maximum can equal t
OVL
. The protection occurs in the same way until the overload condition is removed, see
This protection ensures restart attempts of the converter with low repetition rate, so that it works safely with extremely low power throughput and avoids IC overheating in case of repeated overload events.
If the overload is removed before the protection tripping, the counter will be decremented cycle by cycle down to zero and the IC will not be stopped.
V
DD
Short-circuit occurs
Figure 29. Timing diagram: OLP sequence
Short-circuit removed
V
DDon
V
DDCSon
I
DRAIN
I
DLIM time t
OVL t
RESTART t
SS t
OVL t
RESTART t
SS time
DS6901 - Rev 3 page 22/34
13
VIPER26
Open loop failure protection
Open loop failure protection
If the power supply is built in fly-back topology and the VIPer26 is supplied by an auxiliary winding, as shown in
Figure 30. FB pin connection for non-isolated flyback and
Figure 31. FB pin connection for isolated fly-back , the
converter is protected against feedback loop failure or accidental disconnections of the winding.
schematics for non-isolated flyback and isolated flyback, if R
H
is opened or R
L
is shorted, the VIPer26 works at its drain current limitation. The output voltage, V
OUT
, will increase and so will the auxiliary voltage, V
AUX
, which is coupled with the output according to the secondary-to-auxiliary turns ratio.
As the auxiliary voltage increases up to the internal V
DD
active clamp, V
DDclamp
(value given in Table 7. Controller section ) and the clamp current injected on V
DD
pin exceeds the open loop failure current threshold, I
DDol
(value
given in Table 7 ), a fault signal is internally generated.
In order to distinguish an actual malfunction from a bad auxiliary winding design, both the above conditions (drain current equal to the drain current limitation and V
DD
current higher than I
DDol
through V
DD
clamp) have to be verified to reveal the fault.
If R
L
is opened or R
H
is shorted, the output voltage, V
OUT
, will be clamped to the reference voltage V
REF_FB
in case of non isolated flyback or to the external T
L
voltage reference in case of isolated flyback).
Figure 30. FB pin connection for non-isolated flyback
RAUX DAUX
CVDD
VAUX
VDD
VOUT
VCOMPL PWM stop
-
+
RH BUS
FB
-
+
E/A from RSENSE
RL VREF_FB nR
-
+ to PWM
R
Cp
COMP
Rs
Cs
DS6901 - Rev 3 page 23/34
DS6901 - Rev 3
VIPER26
Open loop failure protection
Figure 31. FB pin connection for isolated fly-back
RAUX DAUX
CVDD
FB
Disabled
-
+
E/A
VREF_FB
VREF_FB
Rcomp
SW
BUS
VCOMPL
+
nR from RSENSE
+
-
R
PWM st op to PWM
COMP
Ccomp
VAUX
VOUT
Ropto
R3
U5
Rc Cc
TL
R
H
R
L page 24/34
VIPER26
Package information
14
14.1
Package information
In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions and product status are available at: www.st.com
. ECOPACK is an ST trademark.
DIP-7 package information
Figure 32. DIP-7 package outline
DS6901 - Rev 3 page 25/34
DS6901 - Rev 3
Dim.
D
E
E1 e eA eB
L
M
N
N1
O
A
A1
A2 b b2 c
6.10
-
-
-
2.92
-
0.40
-
-
0.36
1.14
0.20
9.02
7.62
Min.
-
0.38
2.92
Table 9. DIP-7 package mechanical data
9.27
7.87
6.35
2.54
7.62
-
3.30
2.508
0.50
-
0.548
3.30
0.46
1.52
0.25
mm
Typ.
-
-
0.60
0.60
-
Max.
5.33
-
4.95
0.56
1.78
0.36
10.16
8.26
7.11
-
-
10.92
3.81
VIPER26
DIP-7 package information
Notes
-
-
-
-
-
-
-
6 - 8
-
-
7 - 8
-
-
-
-
-
page 26/34
14.2
SO16 narrow package information
Figure 33. SO16 narrow package outline
VIPER26
SO16 narrow package information
DS6901 - Rev 3 page 27/34
Dim.
e h
L
E
E1 k ccc
A
A1
A2 b c
D
Table 10. SO16 narrow mechanical data
Min.
mm
Typ.
0.1
1.25
0.31
0.17
9.8
5.8
3.8
0.25
0.4
0
9.9
6
3.9
1.27
VIPER26
SO16 narrow package information
Max.
1.75
0.25
0.51
0.25
10
6.2
4
0.5
1.27
8
0.1
DS6901 - Rev 3 page 28/34
15
Order code
Order code
VIPER26LN
VIPER26HN
VIPER26HD
VIPER26HDTR
VIPER26LD
VIPER26LDTR
Table 11. Order code
Package
DIP-7
SO16N
Packing
Tube
Tube
Tape and reel
Tube
Tape and reel
VIPER26
Order code
DS6901 - Rev 3 page 29/34
Revision history
Date
26-Aug-2010
01-Sep-2010
11-Oct-2020
Version
1
2
3
Table 12. Document revision history
Changes
Initial release.
Updated Figure 30 on page 23.
Throughout document:
- updated document template
- general reorganisation of sections
- minor text edits
On cover page:
- updated Features and Description
- added Product status link and Product label
:
- updated Table 1. Pin descriptions
In Section 2 Electrical and thermal ratings
:
- updated Table 3. Thermal data
versus area and Table 4. Avalanche characteristics
- updated V
DRAIN_START
and I
DD1
Max. values
In Section 3 Typical electrical characteristics :
- added Figure 16. SOA SO16N package
and
:
- updated all figures
VIPER26
DS6901 - Rev 3 page 30/34
VIPER26
Contents
Contents
DS6901 - Rev 3 page 31/34
VIPER26
List of tables
List of tables
DS6901 - Rev 3 page 32/34
VIPER26
List of figures
List of figures
Figure 10. Operating supply current (no switching) vs T
Figure 11. Operating supply current (switching) vs T
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 13. Power MOSFET on-resistance vs T
Figure 14. Power MOSFET breakdown voltage vs T
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 15. Power MOSFET capacitance variation vs V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 22. Flyback converter (non isolated, V
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 23. Flyback converter (non isolated, V
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 27. COMP pin voltage versus I
DS6901 - Rev 3 page 33/34
VIPER26
IMPORTANT NOTICE – PLEASE READ CAREFULLY
STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on ST products before placing orders. ST products are sold pursuant to ST’s terms and conditions of sale in place at the time of order acknowledgement.
Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of
Purchasers’ products.
No license, express or implied, to any intellectual property right is granted by ST herein.
Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product.
ST and the ST logo are trademarks of ST. For additional information about ST trademarks, please refer to www.st.com/trademarks . All other product or service names are the property of their respective owners.
Information in this document supersedes and replaces information previously supplied in any prior versions of this document.
© 2020 STMicroelectronics – All rights reserved
DS6901 - Rev 3 page 34/34
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