AN4164
Application note
STEVAL-ISA113V1: 12 V/4 W, 115 kHz non-isolated flyback
By Mirko Sciortino
Introduction
This document describes a 12 V-350 mA power supply set in non-isolated flyback topology
with the new VIPer06 offline high voltage converter by STMicroelectronics.
The features of the device are:
■
■
■
■
■
■
800 V avalanche rugged power section
PWM operation at 115 kHz with frequency jittering for lower EMI
Limiting current with adjustable set point
Onboard soft-start
Safe auto-restart after a fault condition (overload, short-circuit)
SSO-10 package
Moreover, the VIPER06 does not require a biasing circuit to operate because the IC can be
supplied by an internal current generator, therefore saving the cost of the transformers
auxiliary winding (self-biasing). If the device is biased through an auxiliary winding or
through a diode connected to the output (external biasing), it can reach very low standby
consumption (< 50 mW at 265 V
AC
).
Both cases are treated in the present document.
The available protection features are: thermal shutdown with hysteresis, delayed overload
protection, and open loop failure protection (the last is available only if the IC is externally
biased).
Figure 1.
Demonstration board image
February 2013
Doc ID 023660 Rev 1
1/38
www.st.com
Contents
AN4164
Contents
1
2
3
4
5
Adapter features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Schematic and bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Testing the board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1
5.2
5.3
5.4
5.5
Typical waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Line/load regulation and output voltage ripple . . . . . . . . . . . . . . . . . . . . . 13
Burst mode and output voltage ripple . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Light load performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6
Functional check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.1
6.2
6.3
Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Overload protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Feedback loop failure protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7
Feedback loop calculation guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.1
7.2
Transfer function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Compensation procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8
9
10
11
Thermal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
EMI measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Board layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2/38
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List of tables
AN4164
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Electrical specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Transformer characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Output voltage line-load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Output voltage ripple at no/light load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
No load input power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Energy consumption criteria for no load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Light load performance P
OUT
=25 mW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Light load performance P
OUT
=50 mW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
P
OUT
@ P
IN
=1 W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
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Doc ID 023660 Rev 1
AN4164
List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
Figure 35.
Figure 36.
Figure 37.
Figure 38.
Figure 39.
Figure 40.
Figure 41.
Figure 42.
Figure 43.
Figure 44.
Figure 45.
Figure 46.
Figure 47.
Demonstration board image. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
V
DD
waveforms IC externally biased (J1 selected) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
V
DD
waveforms IC self-biased (J1 not selected) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Transformer, pin distances. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Transformer, electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Transformer side view 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Transformer side view 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Drain current/voltage at 115 V
ac
, max. load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Drain current/voltage at 230 V
ac
, max. load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Drain current/voltage at 90 V
ac
, max. load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Drain current/voltage at 265 V
ac
, max. load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Line regulation, IC externally biased (J1 selected) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Line regulation, IC self-biased (J1 not selected) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Load regulation, IC externally biased (J1 selected) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Load regulation, IC self-biased (J1 not selected). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Output voltage ripple at 115 V
AC
no load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Output voltage ripple at 230 V
AC
no load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Output voltage ripple at 115 V
AC
25 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Output voltage ripple at 230 V
AC
25 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Active mode efficiency of the demonstration board and comparison
with energy efficiency standards (IC externally biased) . . . . . . . . . . . . . . . . . . . . . . . . . . 15
P
IN
vs. V
IN
at no load and light load; IC externally biased (J1 selected) . . . . . . . . . . . . . . 17
P
IN
vs. V
IN
at no load and light load, IC self-biased (J1 not selected) . . . . . . . . . . . . . . . . 17
Efficiency at P
IN
= 1 W; IC externally biased (J1 selected) . . . . . . . . . . . . . . . . . . . . . . . . 18
Efficiency at P
IN
= 1 W; IC self biased (J1 not selected) . . . . . . . . . . . . . . . . . . . . . . . . . . 18
P
IN
at P
OUT
= 250 mW; IC externally biased (J1 selected) . . . . . . . . . . . . . . . . . . . . . . . . 19
P
IN
at P
OUT
= 250 mW; IC self biased (J1 not selected) . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Soft-start @ startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Soft-start @ startup (zoom) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
OLP short-circuit applied: OLP tripping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Output short-circuit maintained: OLP steady-state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Output short-circuit maintained: OLP steady-state (zoom) . . . . . . . . . . . . . . . . . . . . . . . . 21
Output short-circuit removal and converter restart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Feedback loop failure protection: tripping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Feedback loop failure protection: steady-state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Feedback loop failure protection: steady-state, zoom . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Feedback loop failure protection: converter restart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Control loop block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Thermal measurement at V
IN
= 90 V
AC
, full load, IC externally biased . . . . . . . . . . . . . . . 26
Thermal measurement at V
IN
= 115 V
AC
, full load, IC externally biased . . . . . . . . . . . . . . 26
Thermal measurement at V
IN
= 230 V
AC
, full load, IC externally biased . . . . . . . . . . . . . . 27
Thermal measurement at V
IN
= 265 V
AC
, full load, IC externally biased . . . . . . . . . . . . . . 27
Thermal measurement at V
IN
= 90 V
AC
, Iout = 310 mA, IC self biased . . . . . . . . . . . . . . . 27
Thermal measurement at V
IN
= 115 V
AC
, Iout = 310 mA, IC self biased . . . . . . . . . . . . . . 28
Thermal measurement at V
IN
= 230 V
AC
, full load, IC self biased . . . . . . . . . . . . . . . . . . . 28
Thermal measurement at V
IN
= 265 V
AC
, full load, IC self biased . . . . . . . . . . . . . . . . . . . 28
Average measurements at full load, T
AMB
=25 ×C, 115 V
AC
, IC externally biased . . . . . . 29
Doc ID 023660 Rev 1
5/38
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