AN2300
Application Note
An alternative solution to Capacitive power
supply using Buck converter based on VIPer12A
Introduction
In this paper three different power supplies with two outputs are introduced: a Capacitive
passive network, and two versions of a low cost SMPS Buck converter. The last two are
based on VIPer12A, a high voltage Power MOSFET with a dedicated current mode PWM
controller , start-up circuit and protection integrated on the same silicon chip by
STMicroelectronics.
The considered converters are compared in terms of output voltage regulation, efficiency
and EMI, under the same output power conditions (about 0.6W).
Finally some modifications to the Buck converters are presented, in order to extend the
output power level to higher values, up to 1.1W.
The main specifications of the converters are listed in Table 1.
Table 1. Power supplies main specifications
AC input voltage V
Outputs
Total out put power 0.6W
IN
185÷265V
V
out1
V
out2
=12V; I
=5V; I
AC
out2
out1
=40mA
=30mA
January 2006 Rev1 1/21
www.st.com
Contents AN2300
Contents
1 Capacitive converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Modified Buck converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 EMI measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Higher output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.4 Efficiency comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.5 Different output voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2/21 Rev1
AN2300 Figures
Figures
Figure 1. Capacitive converter schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2. Buck converter modified schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 3. Buck basic operation during the switch TON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 4. Buck basic operation during the switch TOFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figu r e 5 . Modified Buc k current flow a t Io ut2 = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figu r e 6 . Modified Buc k current flow a t Io ut2¼0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figu r e 7 . Buck conver te r with VI P e r12A, s chemati c A (Vout 1 referred to GND) . . . . . . . . . . . . . . . . . 8
Figure 8. Buck with VIPer12A, schematic B (Vout1 referred to -5V) . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 9. PCB layout based on schematic B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 10. Buck waveforms (schematic A) @230VAC, full load; Ch1=VS, Ch2=Vout2, Ch3=Vout1,
Ch4=IL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 11. Buck waveforms (schematic B) @230VAC, full load; Ch1=VS, Ch2=Vout2, Ch3-Ch2=Vout1,
Ch4=IL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 12. Capacitive converter line regulation, at full load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 13. Buck converter line regulation (schematic A), at full load. . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 14. Buck converter line regulation (schematic B), at full load. . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 15. Efficiency vs Vin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 16. Capacitive converter: conducted emission @ 230VAC, full load: Phase . . . . . . . . . . . . . . 12
Figure 17. Capacitive converter: conducted emission @ 230VAC, full load: Neutral . . . . . . . . . . . . . 12
Figure 18. Buck converter: conducted emission @ 230VAC, full load: Phase . . . . . . . . . . . . . . . . . . 13
Figure 19. Buck converter: conducted emission @ 230VAC, full load: Neutral. . . . . . . . . . . . . . . . . . 13
Figure 20. Line regulation @full load (Buck converter, schematic A) . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 21. Line regulation @full load (Buck converter, schematic B) . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 22. Out1 load regulation @ Iout2 = 0 (Buck converter, schematic A) . . . . . . . . . . . . . . . . . . . . 14
Figure 23. Out2 load regulation @ Iout1 = 20mA (Buck converter, schematic A) . . . . . . . . . . . . . . . . 14
Figure 24. Out1 load regulation @ Iout2 = 0 (Buck converter, schematic B) . . . . . . . . . . . . . . . . . . . . 15
Figure 25. Out2 load regulation @ Iout1 = 20mA (Buck converter, schematic B) . . . . . . . . . . . . . . . . 15
Figure 26. Efficiency vs Vin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 27. Efficiency comparison between schematics A and B for IDz2 = 30mA . . . . . . . . . . . . . . . 16
Figure 28. Schematic A modifications for 4V < Vout1 < 11V (Vout2 @ 5V) . . . . . . . . . . . . . . . . . . . . 17
Figure 29. Schematic B modifications for 9V < Vout1 < 16V (Vout2 @ 5V) . . . . . . . . . . . . . . . . . . . . 17
Rev1 3/21
Tables AN2300
Tables
Table 1. Power supplies main specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. Capacitive converter part list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Table 3. Buck converter part list (schematic A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 4. Buck converter part list (schematic B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 5. Higher output power requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 6. Schematics A and B part list modification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 7. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4/21 Rev1
AN2300 Capacitive converter
1 Capacitive converter
The schematic of the Capacitive power supply is shown in Figure 1. The capacitor C2
accommodates the AC mains voltage to a voltage level suitable for the application, while R1
and R2 are connected in order to limit the inrush current of the capacitors. The voltage is
then rectified by the diode D1 and regulated by means of zener diodes and electrolytic
capacitors. The output capacitor values, C4 and C6, have been chosen in order to keep the
output voltages ripples below 5%, at the given output load condition. The part list of the
converter is given in Table 2.
Figure 1. Capacitive converter schematic
R2
C2
D1
D2
C3
C5
C6
Dz1
Dz2
Vin
R1
Neutral
C1 C4
Line
Table 2. Capacitive converter part list
Reference Value Part type
R1 10Ω 1/4Ω Resistor
R2 150KΩ 1/4Ω Resistor
C1 47nF X2 Capacitor
C2 2.2
C3 82nF Ceramic cap acitor
C4 10002
µF X2 Capacitor
µF, 25V Elec troly tic Capa c i tor
Vout1
Vout2
C5 82nF Ceramic cap acitor
C6 4700
µF, 25V Elec troly tic Capa c i tor
D1 Diode 1N4007
D2 Diode 1N4007
Dz1 12V Zener Diode 1N5349B730
Dz2 5.1V Zener Diode BZX85C5V1
Rev1 5/21
Modified Buck converter AN2300
2 Modified Buck converter
The considered circuit is based on the modified Buck converter shown in figure 2. It
provides two outputs with reversed polarity, V
Figure 2. Buck converter modified schematic
= 12V and V
out1
out2
= -5V.
S
+
Vin
-
The second complementary output, V
1
, is generated charging the capacitor C2 during the
out2
D
Dz
L
Vout1
C1
GND
C2
Vout2
free-wheeling of the inductor current. The voltage across such a capacitor is regulated by
means of a zener diode of suitable value. The power switch, S, operates at high frequency
for power conversion. The voltage is then filtered by the LC filter made up by L and C1.
In the standard Buck topology, the voltage of the node 1 is clamped by the diode D,
allowing the free-wheeling of the inductor current. In the proposed solution, the zener diode,
D
, clamps such a voltage to (VD+VZ), where VD is the voltage drop across the diode D, and
Z
V
is the zener voltage. If a capacitor is connected across the anode of the zener and the
Z
ground, a negative voltage source is generated. Of course, due to the principle of operation,
the second output cannot supply more current than the first one.
The switching cycle can be basically divided in two periods as shown in Figure 3. and Figure
4. Considering discontinuous conduction mode (DCM), during the conduction of the switch
S the input DC bus is connected to the output and supplies the load, as shown in Figure 3.).
Once the switch is turned off, the inductor current free-wheels through the diode D
shown in F igure 4.), until it zeroes and the output capacitor C1 feeds the load.
6/21 Rev1
, as
1
AN2300 Modified Buck converter
Figure 3. Buck basic operation during the
switch TON
Vin
S
D1
Vout2
L
Rload
+
C1
The presence of the zener diode in the free-wheeling path does not affect the basic
operation of the converter, but it could impact on the efficiency. I n fact, if there is no load on
V
, the whole free-wheeling current will flow through both diodes, D1 and DZ, as shown in
out2
Figure 5.).
Figure 5. Modified Buck current flow at Iout2 = 0
Figure 4. Buck basic op eration during the
switch T
S
Vin
Figure 6. Modified Buck current flow at I
D1
Vout2
OFF
L
Rload
+
C1
out2
≠0
Vin
S
D1
DZ
L
+
C1
+
C2
As the current drawn from V
Rload1
Vout1
Vin Rload1
Iout1
Iout2 = 0
Vout2
increases, the free-wheeling current flows through a
out2
S
D1
DZ
L
+
C1
+
C2
Vout1
Iout1
Rload2
Iout2
Vout2
different path, splitting in two components as shown in Figure 6. In this way the power
dissipation in D
performs better if the complementary output is loaded, for a given output current I
In order to guarantee the proper operation of the converter when V
is reduced and the efficiency is increased accordingly. Thus, the converter
Z
is in open load
out1
out1
.
condition, a bleeder resistor has to be connected.
A practical implementation of the circuit is presented in schematic A (see figure Figure 7.),
where R1 is the bleeder resistor; D3, C3 and C4 are needed for VIPer12A biasing; L1, C1,
D1, C2 make up the input filter for EMI compliance; R0 limits the inrush current of the
capacitors.
Rev1 7/21
Modified Buck converter AN2300
Figure 7. Buck converter with VIPer12A, schematic A (V
DZ1
AC IN
16V
R0
L1
D1
VDD
DRAIN SOURCE
FB
+
C3
referred to GND)
out1
D3
C4
L
VIPer12A
D2
DZ2
5.1V
+
C6
C7
R1
+
GND
Vout1
Vout2
AC IN
+
C2C1
Due to the connection of the bleeder resistor, a constant power loss appears in the circuit of
Figure 7., given by (1):
V
----------------==
out1
R1
2
(1)
2
VR1
-------------
P
L
R1
Referring V
such a case the voltage drop across the bleeder is only (V
Figure 8. Buck with VIPer12A, schematic B (V
AC IN
to -5V output, the circuit schematic B shown in Figure 8. can be used: in
out1
referred to -5V)
out1
D4
R2
DZ1 C5
11V
R0
L1
D1
VDD
DRAIN SOURCE
FB
+
C4
C3
out1
- V
D3
L
) instead of V
out2
out1
.
VIPer12 A
AC IN
+
C1
C2 Vout1
D2
DZ2
5.1V
C6 GND
C7
R1
+
Vout2
+
The part lists of the proposed circuits are given in Tab le 3. and Table 4. A lab prototype
based on schematic B (see Figure 8.) has been built using the layout shown in Figure 9.
8/21 Rev1
AN2300 Modified Buck converter
Figure 9. PCB layout based on schematic B
Table 3. Buck converter part list (schematic A)
Reference Value Part type
R0 22Ω 1/2W Resistor
R1 330Ω 1/2W Resistor (bleeder)
C1 47nF X2 capacitor
C2 2.2µF, 400V Electrolytic capacitor
C3 22nF Ceramic capacitor
C4 4.7µF, 63V Electrolytic capacitor
C6 33µF, 25V Electrolytic capacitor
C7 33µF, 25V Electrolytic capacitor
D1 Diode 1N4004
D2 Diode STTA106
D3 Diode BA157
Dz1 16V Zener Diode
Dz2 5.1V, 1/2W Zener Diode
L1 1mH Axial inductor
L 1.5mH Axial ind uc t or
IC VIPer12A - DIP8
Table 4. Buck converter part list (schematic B)
Reference Value Part type
R0 22Ω 1/2W Resistor
R1 120Ω 1/2W Resi stor (bleeder)
R2 1kΩ 1/4W Resistor
Rev1 9/21
Modified Buck converter AN2300
Table 4. Buck converter part list (schematic B)
Reference Value Part type
C1 47nF X2 capacitor
C2 2.2µF, 400V Electrolytic capacitor
C3 22nF Ceramic cap acitor
C4 4.7µF, 63V Electrolytic capacitor
C5 470nF Ceramic cap acitor
C6 33µF, 25V Electrolytic capacitor
C7 33µF, 25V Electrolytic capacitor
D1 Diode 1N4004
D2 Diode STTA106
D3 Diode BA157
D4 Diode 1N4148
Dz1 11V Zener Diode
Dz2 5.1V, 1/2W Zener Diode
L1 1mH A xial inductor
L 1.5mH Axial inductor
IC VIPer12A - DIP8
2.1 Experimental results
In Figure 10. and Figure 11. the typical waveforms of the Buck converters are shown, at Vin
= 230V
Figure 10. Buck waveforms (schematic A)
@230V
Ch2=V
and full load (i.e. I
AC
, full load; Ch1 =V
AC
, Ch3= V
out2
out1
out1
S,
, Ch4=I
L
= 30mA and I
Figure 11. Buck waveforms (schematic B)
= 40mA) .
out2
@230V
Ch2=V
, full load; Ch1=V
AC
, Ch3-Ch2=V
out2
out1
S,
, Ch4= I
L
10/21 Rev1
AN2300 Modified Buck converter
Line regulation diagrams are shown in Figure 12., Figure 13. and Figure 14. for the
Capacitive and the Buck converters respectively.
Figure 12. Capacitive converter line regulation, at full load
Figure 13. Buck converter line regulation
(schematic A), at full load
The efficiency (η = P
/ PIN) of the power supplies has been evaluated at the same output
OUT
power value (about 0.6W), in the whole input voltage range. The results are shown in F igure
15.
Figure 14. Buck converter line regulation
(schematic B), at full load
Rev1 11/21
Modified Buck converter AN2300
Figure 15. Efficiency vs V
P o u t /P in [%]
100
80
60
40
20
0
180 200 220 240 260 280
2.2 EMI measurements
Conducted EMI measurements have been performed according to EN55022 Class B
standard, using a 50Ω LI SN and a spectrum analyz er.
In Figure 16., Figure 17., Figure 18. and Figure 19., Phase and Neutral measurement
results are shown under full load conditions at nominal 230V
in
ca p ac itiv e
sche m. A b uc k
sche m. B b uc k
Vin [V]
input voltage.
ac
Figure 16. Capacitive converter: conducted
emission @ 230V
, full loa d: Ph ase
AC
Figure 17. Capacitive converter: conducted
emission @ 230VAC, full load:
Neutral
12/21 Rev1
AN2300 Modified Buck converter
Figure 18. Buck converter: conducted
emission @ 230V
, full loa d: Ph ase
AC
2.3 Higher output power
Higher output power levels could be required in some applications. Typical values are 50mA
on the 12V output and 100mA on the -5V output, as listed in Table 5.
Figure 19. Buck converter: conducted
emission @ 230VAC, full load:
Neutral
Table 5. Higher output power requirements
AC input voltage V
Outputs
Total output power 1.1W
IN
185÷265V
=12V; I
V
out1
V
=-5V ; I
out2
AC
out1
out2
=50mA
=100mA
The proposed Buck converters can provide such current values adjusting the value of the
bleeder resistor, R1. In fact, in order to maintain the regulation when out1 is in open load
condition, (2) has to be verified:
V
R1
---------- I
R1
Since I
V
R1
V
R1
= 100mA, we can set VR1/R1 = 120mA, resulting in:
out2
/R1≈12/R1=120mA, therefore R1=100Ω for schematic A (see Figure 7.);
/R1≈7/R1=120mA, therefore R1 = 56Ω for schematic B (see Figure 8. ).
+>
out2IDz2
(2)
Thus, the R1 value is lower than in the previous case. Of course, this results in higher power
dissipation across the bleeder.
In Table 6. the part list of the modified components is given.
Rev1 13/21
Modified Buck converter AN2300
Table 6. S chema tics A and B part list modification
Reference Value Part type
R1
C6 47µF, 25V Electrolytic capacitor
C7 47µF, 25V Electrolytic capacitor
Dz1 12V (schematic B) Zener diode
R2 0Ω (schematic B)
L820 µH Radial inductor
100Ω 2W (schematic A)
56Ω 2W (schematic B)
The line regulation of the two Buck converters is shown in Figure 20., Figure 21., the load
regulation in Figure 22., Figure 23., Figure 24. and Figure 25. the efficiency in Figure 26.
Figure 20. Line regulation @full load (Buck
converter, schematic A)
Resistor (bleeder)
Figure 21. Line regulation @full load (Buck
converter, schematic B)
Figure 22. Out1 loa d re gu lation @ Iout2 = 0
Figure 23. Out2 load regulation @ Iout1 =
(Buck converter, schematic A)
14/21 Rev1
20mA (Buck converter, schematic A)
AN2300 Modified Buck converter
Figure 24. Out1 loa d re gu lation @ Iout2 = 0
(Buck converter, schematic B)
Figure 26. Efficiency vs Vin
Figure 25. Out2 load regulation @ Iout1 =
20mA (Buck converter, schematic B)
If a Capacitive network were used to supply such output power, it would require quite big
and expensive capacitors.
In fact, referring to figure 1, the value of the output capacit ors, C4 and C6, can be calculated
using equation (3):
I
+()T•
where I
C
out
is the current flowing through Dz1 or Dz2 in the circuit of Figure 1., and T is the
Dz
outIDz
----------------------------------- -=
V
∆
OUTmax
(3)
discharging time of the capacitor.
Fixing f = 60Hz for the input voltage frequency and 5% for the maximum output voltage
ripple, (3) becomes:
I
+
outIDz
---------------------------------
C
out
fV
ƥ
OUTmax
Rev1 15/21
+
I
outIDz
--------------------- -=≅
f5•
%V
OUT
(4)
Modified Buck converter AN2300
Assuming IDz = 5mA, (4) gives C4 = C
C
> 7000µF for I
out2
= 100mA, V
out2
2.4 Efficiency comparison
The power loss on the bleeder has the main impact on the efficiency η of the modified Buck
converters. In fact, the output power and the power loss on the zener diode, D
same for both converters.
The comparison between the circuits of Figure 7. and Figure 8. has shown that:
η
B>ηA
where:
=efficiency of the schematic A (B) Buck converter;
η
B>ηA
(V
V
R1A
= current across Dz2.
I
Dz2
Assuming I
where I
) = voltage across the bleeder resistor R1 in the schematic A (B);
R1B
= 30mA, V
Dz2
η
B>ηA if
and I
out1
The efficiency comparison between the two converters, based on (6), is shown in Figure 27.
if
= 12V, V
R1A
are expressed in mA.
out2
I
out2
> 1500µF for I
out1
= -5V.
out2
1
--------------------- - I
VR1B
1
------------ -–
VR1A
= 7V, equa tion (5) becomes:
R1B
I
2.4I
out2
out1
out1
–•>
out1IDz2
30–> (6)
= 50mA, V
= 12V, and C6 =
out1
, are the
z2
(5)
In conclusion, the schematic B (in figure 8) can be used in both cases, although in the lower
power case it features a slightly lower efficiency (3÷4%).
Figure 27. Efficiency comparison between schematics A and B for I
2.5 Different output voltages
If a lower value of the output V
changed. Since V
out1+VDz2
is desired, the value of the zener diode Dz1 has to be
out1
is lower than 16V, the biasing network of the VIPer12A in the
= 30mA
Dz2
16/21 Rev1
AN2300 Modified Buck converter
2
1
schematic A will also be modified, in order to ensure the start-up of the device. In this way
the only difference between the two schematics will be in the reference of the output
voltages and in the values of the zener diodes, as can be seen fromFigure 28. and Figure
29..
Figure 28. Schematic A modifications for 4V < V
R2
AC IN
DZ1
(Vout1+VDz2)-1
R0
L1
D1
VDD
DRAIN SOURCE
C4
C3
FB
VIPer12A
+
C2
AC IN
Figure 29. Schematic B modifications for 9V < V
R2
out1
D4
out1
D4
< 1 1V (V
+
C5
D2
DZ2
5.1V
< 16V (V
≅ 5V)
out2
D3
L
R1
+
C6C1
+
C7
≅ 5V)
out2
D3
GND
Vout
Vout
+
C5
L
AC IN
DZ1
Vout1-1
R0
L1
D1
VDD
DRAIN SOURCE
C4
C3
FB
VIPer12A
AC IN
C1
+
C2 Vout1
D2
DZ2
5.1V
C6
C7
R1
+
+
GND
Vout2
In order to make the VIPer12A properly supplied by the biasing network of the Figure 28.
and Figure 29., the formulas (7) and (8) have to be satisfied:
Schematic A 9 V V
(Figure 28.)
Rev1 17/21
out1VDZ2
16V<+<
(7)
Modified Buck converter AN2300
This means that, if V
is fixed at 5V, the allowed range of V
out2
in the schematic A will be
out1
about 4V ÷ 11V; if not, these limits will be moved together upwards or downwards depending
on the value of V
Schematic B
Thus, for the schematic B the minimum allowable value of V
value of V
out2
Dz2
(≅ V
).
out2
(Figure 29.)
9V V
out1
16V<<
(8)
is 9V, quite apart from the
out1
.
The resistor R2 is optional and can be experimentally fixed between 0 and 1kΩ if a tune of
the output voltage is needed.
18/21 Rev1
AN2300 Conclusions
3 Conclusions
Two versions of a very low cost Buck converter based on VIPer12A have been proposed
and compared with a Capacitive converter in terms of output voltage regulation, input power
consumption, EMI and efficiency, in the same output power conditions.
As a result of the analysis, it can be pointed out that:
– the efficiency of both the Buck converters is higher than the efficiency of the
Capacitive network;
– the output capacitors needed in the Capacitive power supply are much bigger and
expensive than those required in the Buck converters (1mF and 4.7mF vs 33µF);
– due to the switching operation of the Buck converter, an EMI input filter has to be
inserted, as shown in figures 5 and 6;
– the Buck solution is less expensive than the Capacitive one, with a cost sav ing of
about 10 ÷ 15%.
Rev1 19/21
Revision history AN2300
4 Revision history
Table 7. Document revision history
Date Revision
26-Jan-2006
Changes
1
First issue
20/21 Rev1
AN2300
I
s
o
d
b
t
t
t
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