AN3290
Application Note
Reference design for double output SMPS for power line
modem applications using ALTAIR04-900 primary controller
Introduction
This application note introduces a new “all-primary sensing” switching regulator ALTAIR04-
900, used to build an innovative solution to supply a power line communication.
A demonstration board, implementing a wide-range double-output power supply, has been
developed and the results of its bench evaluation are reported in this document.
The board uses the new ALTAIR04-900, a quasi-resonant (QR) current-mode controller IC
specifically designed for QR ZVS (zero voltage switching at switch turn-on) flyback
converters, which combines a high-performance low-voltage PWM controller chip and a
typical 16 R
DSon
, 900 V, avalanche-rugged power MOSFET in the same package.
The device is capable of providing constant output voltage regulation using primary-sensing
constant voltage loop (CV loop). This eliminates the need for the optocoupler and the
secondary voltage reference while still maintaining quite accurate regulation.
Also, using the primary constant current loop (CC loop), it is possible to set the maximum
deliverable output current without any secondary components or current sensor.
April 2011
Doc ID 18038 Rev 1
1/34
www.st.com
Contents
AN3290
Contents
1
2
3
4
5
Test board design and evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Output voltage characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Efficiency and no load measurements . . . . . . . . . . . . . . . . . . . . . . . . . 12
Typical board waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Protection features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1
5.2
5.3
Overload and short-circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Auxiliary winding disconnection (brownout) . . . . . . . . . . . . . . . . . . . . . . . 22
Secondary winding short-circuit and transformer saturation protection . . 23
6
7
8
9
10
Conducted noise measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Modifications for ultra wide-range operations . . . . . . . . . . . . . . . . . . . 29
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Demonstration tools and documentation . . . . . . . . . . . . . . . . . . . . . . . 32
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
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Doc ID 18038 Rev 1
AN3290
List of Tables
List of Tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
ALTAIR04-900 power supply: electrical specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
ALTAIR04-900 power supply - bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
ALTAIR04-900 power supply: transformer characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 10
ALTAIR04-900 power supply: bill of material for 440 VAC input voltage option . . . . . . . . . 30
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
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List of figures
AN3290
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.
Electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
PCB: component side (not to scale) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Demonstration board image: power supply board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Demonstration board image: complete (power supply and PLM boards) . . . . . . . . . . . . . . . 8
ALTAIR04-900 power supply: transformer characteristics . . . . . . . . . . . . . . . . . . . . . . . . . 10
Output voltage characteristics with 3V3 @ 40 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Output voltage characteristics with 3V3 @ 80 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Efficiency vs. output power with 3V3 @ 40 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Efficiency vs. output power with 3V3 @ 80 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Normal operations in TX mode at 85 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Normal operations in TX mode at 115 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Normal operations in TX mode at 230 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Normal operations in TX mode at 264 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Normal operation in TX mode at 85 VAC and IOUT2=40 mA . . . . . . . . . . . . . . . . . . . . . . 15
Normal operation in TX mode at 85 VAC and IOUT2=80 mA . . . . . . . . . . . . . . . . . . . . . . 16
Normal operation in TX mode at 115 VAC and IOUT2=40 mA . . . . . . . . . . . . . . . . . . . . . 16
Normal operation in TX mode at 115 VAC and IOUT2=80 mA . . . . . . . . . . . . . . . . . . . . . 17
Normal operation in TX mode at 230 VAC and IOUT2=40 mA . . . . . . . . . . . . . . . . . . . . . 17
Normal operation in TX mode at 230 VAC and IOUT2=80 mA . . . . . . . . . . . . . . . . . . . . . 18
Normal operation in TX mode at 264 VAC and IOUT2=40 mA . . . . . . . . . . . . . . . . . . . . . 18
Normal operation in TX mode at 264 VAC and IOUT2=80 mA . . . . . . . . . . . . . . . . . . . . . 19
Short-circuit mode: 13 V shorted at 115 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Short-circuit mode: 13 V shorted at 230 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Brownout protection activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Hiccup mode OCP: protection tripping at VIN=115 VAC and full load . . . . . . . . . . . . . . . . 23
Hiccup mode OCP: protection tripping at VIN=230 VAC and full load . . . . . . . . . . . . . . . . 24
Hiccup mode OCP: operating condition at VIN=115 VAC . . . . . . . . . . . . . . . . . . . . . . . . . 24
Hiccup mode OCP: operating condition at VIN=230 VAC . . . . . . . . . . . . . . . . . . . . . . . . . 25
CE average measurement at 115 VAC and full load: line . . . . . . . . . . . . . . . . . . . . . . . . . 26
CE average measurement at 115 VAC and full load: neutral . . . . . . . . . . . . . . . . . . . . . . . 27
CE average measurement at 230 VAC and full load: line . . . . . . . . . . . . . . . . . . . . . . . . . 27
CE average measurement at 230 VAC and full load: neutral . . . . . . . . . . . . . . . . . . . . . . . 28
Electrical schematic for 440 VAC input voltage option . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
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AN3290
Test board design and evaluation
1
Test board design and evaluation
As a reference design, a 7.48 W nameplate output power SMPS has been specifically
designed and developed according to the specifications for a complete power line
communication based on ST7580 (by STMicroelectronics).
The power supply provides a 13 V output voltage to supply the power line modem (PLM)
and the analog circuitry, and a post-regulated 3.3 V to supply digital circuitry and an optional
external microcontroller.
Table 1
summarizes the electrical specifications of the power supply,
Table 2
provides the
bill of material and
Table 3
lists the transformer specifications. The electrical schematic is
shown in
Figure 2
and the PCB layout in
Figure 3
and
4.
Table 1.
ALTAIR04-900 power supply: electrical specification
Note
Min.
85
50
Analog supply voltage
Rx mode
Output current 1
Tx mode
Output voltage 2
Output current 2
External microcontroller connection
Total rated output power
Maximum output power
In TX mode
4.2
100
7.48
mA
W
W
Digital supply voltage
No external microcontroller connection
35
3.3
40
50
550
mA
V
mA
11.7
12
13
Typ. Max.
265
60
14.3
Unit
V
AC
Hz
V
mA
Parameter
AC main input voltage
Mains frequency (f
L
)
Output voltage 1
The input stage, consists of an NTC (NTC1) which limits the inrush current produced by the
capacitor charging at plug-in and a varistor (RV1) that protects the power supply against
temporary line overvoltage transients. The input EMI filter is a classic Pi-filter, 1-cell for
common and differential mode noise. The clamping network (D2-D3) limits the peak of the
leakage inductance voltage spike at turn-off, assuring reliable operation of the ALTAIR04-
900.
The sense resistor R2 and the transformer primary-to-secondary turn ratio fix the maximum
output current limitation, whereas the voltage divider made up of R6, R7, and R8 is used to
set the output voltage setpoint, in order to ensure the desired output voltage regulation. The
network connected on the COMP pin is used to compensate the loop, ensuring the right
gain and phase margin to the system, whereas the voltage across the capacitor C10 is used
to fix the voltage level for the CC loop; the value of this capacitor is not critical and e few nF
are enough to ensure correct operation. The secondary side is provided by two output
voltages; a nameplate 13 V output voltage is directly used to supply the analog circuitry of
the PLM, whereas the lower voltage is achieved by a 3V3 LDO and is intended to supply the
digital parts.
Doc ID 18038 Rev 1
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