CS51221: High Power Boost (Power Supply for Audio Class D Amplifier)

ON Semiconductor Confidential – NDA Required
Design Note – DN06056/D
Power Supply For Audio Class D Amplifier
Device
CS51221
Application
Input
Voltage
Output
Voltage
Output
Current
Topology
Audio
7.6-45 V
18V
8.3A
Boost
Table 1: CS51221 Audio Power Supply
Characteristic
Output Voltage
Output Current
Oscillator Frequency
Output Voltage Ripple
Load Regulation (Iout = 0.1-8.3A) Vin= 12V
Line Regulation to 5V
Iout = .1A)
Iout = 8.3A)
Size
Min
18.0453
1
Typ
18.0532
Max
18.06
8.3
Unit
V
A
kHz
mVpk-pk
mV/A
0.34
0.32
Height
31
%
140
150
-.693
0.28
0.25
Length
80
0.31
0.28
Width
59
Figure 1: Demonstration Board Picture
Rev 1 - January, 2009
mm
ON Semiconductor Confidential – NDA Required
Circuit Description
A boost power supply was developed for to feed 4 class D amplifiers and one auxiliary system. The design must
minimize the use of through hole components, designed as small as possible on a 4 layer PCB, and only
populated on the top side. The system level drawing is shown in Figure 2. The power supply is required to
maintain an 18V output with input voltage variation from 7.6V to 18.4V. Above 18.4V the power supply will
shutoff-minimizing losses and allow input voltage to flow to output voltage. The required voltage profile is
shown in Figure 3.
Figure 2: System Level Diagram of the Sony MCA ‘Audiofile’ radio
18.4 V
Output Voltage
pu
In
olt
tV
ag
e
18.4 V
7.6V
Time
Figure 3: CS51221 Design Boost Curve
The design has the following features:
• Adjustable cycle by cycle current limiting
• Overvoltage Shutoff
• Undervoltage shutoff
• Can be synchronized to a higher frequency
• Wide operating range 7.6-18.4V operating and 18-45V nonoperating
• Programmable soft start
• Voltage feed forward
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Performance Information
The following figures show typical performance of the evaluation board.
Efficiency (%)
CS51221 Visteon Boost Efficiency vs. Output Current
100
98
96
94
92
90
88
86
84
82
80
0
2
4
6
8
Output Current (A)
8V
9V
10V
11V
12V
13V
14V
15V
16V
17V
18V
Figure 4: CS51221 Efficiency 8V – 18V input voltage with a 18V Output Voltage
Line Regulation
18.07
Output Voltage (V)
18.065
18.06
18.055
18.05
18.045
18.04
0
2
4
6
Output Current (A)
Figure 5: CS51221 Line Regulation
Rev 1 - January, 2009
8
8V
9V
10V
11V
12V
13V
14V
15V
16V
17V
18V
HIGH
low
ON Semiconductor Confidential – NDA Required
Figure 6: Input and Output Ripple Voltage Vin = 8V Vout =18V Iout = 8.3A 231 mVpp
Figure 7: Vin = 12V Vout =18V Iout = 8.3A 166mVpp
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 8: Vin = 16V Vout =18V Iout = 8.3A
161mVpp
Figure 9: Transient Response Input Voltage = 12V output current step 1.0A to 8.0 A with 274 mV peek to peek
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 10: Soft Start Time is 5.8 ms from an Input voltage of 0V
Figure 11: Soft Start Time is 5.8 ms from an Input voltage of 12V
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 12: Soft Start and Soft Stop From 12V Volts
Figure 13: 8V Frequency Response 2.1 kHz and 2.4k Cross over at 71 and 54 Degrees of Phase Margin 2A Load
at Full Load Right
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 14: 12V Frequency Response 1.6kHz Cross over at 80 Full Load
Figure 15: 16V Frequency Response 1.5 kHz and 1.5k Cross over at 82 and 83 Degrees of Phase Margin 2A Load
at Full Load Right
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Vin vs VCC & VC
13.5
Output Voltage (V)
12.5
VC_NL
VCC_NL
VC_3A
VCC_3A
11.5
10.5
9.5
8.5
7.5
6.5
5.5
7
8
9
10 11 12 13 14 15 16 17 18 19
Input Voltage (V)
Figure 16: VCC and VC vs Input Voltage
Figure 17: Thermal Image of PCB at 8V 8.3A Load with a 25C ambient
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 18: Thermal Image of PCB at 12V 8.3A Load with a 25C ambient
Figure 19: Thermal Image of PCB at 16V 8.3A Load with a 25C ambient
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 20: Thermal Image of PCB at 12V 4.15A Load with a 25C ambient
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Schematic
Figure 24: CS51221 Schematic
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Table 2 : CS51221 Bill of Materials
Designator
C5
C2 C8
C12
C6
C4
C20
C10
C11
C24
C16
C3
C21 C23
C22
Quantity
1
2
1
1
1
1
1
1
1
1
1
2
1
Value
330n
0.1uF
1.8nF
1nF
1uF
1uF
4.7nF
82nF
1.2n
1.2nF
1nF
1uF
4.7uF
Tolerance
20%
20%
10%
10%
10%
20%
±10%
10%
5%
10%
10%
10%
±10%
FootPrint
805
603
603
603
603
603
603
603
805
1206
1206
1206
1210
Manufacturer
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
AVX Corporation
Manufacturer Part Number
0805ZC334JAT2A
06033C104MAT2A
0603ZC272KAT2A
0603ZC102KA72A
06036D105KAT2A
06033D105MAT2A
06031C472KAT2A
0603ZC184KAT2A
08056A122JAT2A
12061A122KAT2A
12061C102KAT2A
12065C105KAT2A
12105C475KAT2A
1
Description
Ceramic Chip Capacitor 10V
Ceramic Chip Capacitor 25V
Ceramic Chip Capacitor 10V
Ceramic Chip Capacitor 50V
Ceramic Chip Capacitor 6.3V
Ceramic Chip Capacitor 25V
Ceramic Chip Capacitor 100V
Ceramic Chip Capacitor 10V
Ceramic Chip Capacitor 6.3V
Ceramic Chip Capacitor 100V
Ceramic Chip Capacitor 100V
Ceramic Chip Capacitor 50V
Ceramic Chip Capacitor 50V
Enhanced Voltage Mode PWM
Controller
U1
C7 C13-15
C9 C17-19
D1
Q5
Z1
U2-3
R5
R14
R3
R20
R9
R21
R7
R2
R1 R23
3V Ref
NA
SOIC 16
ON Semiconductor
CS51221
8
1
1
1
2
1
1
1
1
1
1
1
1
2
Electrolytic Capacitor
Schottky Power Rectifier
General Purpose NPN Transistor
Zener Diode
N MOSFET 8.1mOhm
SMT Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
680uF
30A 45V
40V 200mA
14V
60V 50A
49.9k
1.02k
1.58k
1k
20R0
27.4k
28.5k
3.09k
41.2k
20%
NA
NA
±5%
NA
1%
±1.0%
±1.0%
±1.0%
±1.0%
±1.0%
±1.0%
±1.0%
±1.0%
12.5X25
TO-220
SOT-23
SOD-123
DPAK
1206
603
603
603
603
603
603
603
603
United Chemicon
ON Semiconductor
ON Semiconductor
ON Semiconductor
Infineon
Vishay
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
EKZE500ELL681MK30S
MBR30L45CTG
MMBT3904TT1G
MMSZ5244BT1G
IPB081N06L3G
CRCW120649K9FKEA
CRCW06031K02FKEA
CRCW06031K58FKEA
CRCW060310K0FKEA
CRCW060320R0FKEA
CRCW060327K4FKEA
CRCW06033K01FKEA
CRCW06033K09FKEA
CRCW060341K2FKEA
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Table 2 : CS51221 Bill of Materials
Designator
R13
R26
R25
R8 R12
R11 R15
R10
R6
R4
Quantity
1
1
1
2
2
1
1
1
Description
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
SMD Resistor
Value
49.9k
6.04k
8.2k
0R0
10R0
4.99k
8.06K
5mOhm
Tolerance
±1.0%
±1.0%
±1.0%
±5.0%
±5.0%
±1.0%
±1.0%
±1.0%
L2
1
SMT Inductor 0.17mOhm
.1 uH
10%
L1
1
SMT Inductor
33 uH
10%
Rev 1 - January, 2009
FootPrint
603
603
603
1206
1206
1206
1206
4527
7.5mmX
7.6mm
27.94mmX
27.9mm
Manufacturer
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Vishay / Dale
Manufacturer Part Number
CRCW060349K9FKEA
CRCW06036K04FKEA
CRCW06038K20FKEA
CRCW12060000Z0EA
CRCW120610R0FKEA
CRCW12064K99FKEA
CRCW12068K06FKEA
WSR55L00F
Coilcraft
SLC7649S-101KL_
Coilcraft
SER2918H-103
ON Semiconductor Confidential – NDA Required
Figure 25: Layout Top
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 26: Layout Inner Top
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 27: Layout Inner Bottom
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Figure 28: Layout Bottom
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
High Current Reverse Polarity Protection
The boost converter input current at low line is over 21 A creating large losses when standard reverse polarity protection is used. The power loss
when using a schottkey diode capable of 30A are as follows:
PDIODE = IV ⎯Solve
⎯
⎯→ 21A * 0.7V = 14.7W
Solve
PMOSFET = I 2 R ⎯⎯
⎯→
PMOSFET
2W
=R=
= 4.5mΩ
2
21A 2
I
Since the MOSFET will be mostly on the user need only consider the RDSon as the switching losses can be negated. The final consideration is to
determine how the MOSFET might be turned on when appropriate and turned off when the voltage is reversed. Figure 29 shows one solution for
the low side reverse polarity protection
Figure 29: Low Side Reverse Polarity Protection and Simulated Results
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Current Sharing of Parallel MOSFETS
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
Efficiency Calculator
An efficiency calculator was constructed for boost converter applications to predict the effect of component changes on system efficiency and to
aid the designer in making critical design tradeoffs. The user should enter all of the information they know about the design then change
parameters like RDSon and frequency to gauge the system sensitivity to the parameter. Figure 30 Shows the predicted efficiency of the design at
140kHz. The efficiency can also be predicted for the 375 kHz, 417kHz, and 500kHz .
95%
95%
94%
94%
93%
93%
92%
92%
91%
91%
90%
90%
89%
89%
88%
88%
87%
87%
86%
86%
85%
85%
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Figure 30: Predicted Efficiency of Design at 140 kHz Left 375 kHz Blue = 8V, Green = 12V, Red = 18V
95%
95%
94%
94%
93%
93%
92%
92%
91%
91%
90%
90%
89%
89%
88%
88%
87%
87%
86%
86%
85%
85%
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
Figure 30: Predicted Efficiency of Design at 417 kHz Left 500 kHz Blue = 8V, Green = 12V, Red = 18V
Rev 1 - January, 2009
9
ON Semiconductor Confidential – NDA Required
The on resistance of the MOSFET makes a large impact at low line on the system level efficiency. The charts below compare the Fairchild
FDD13AN06A0CT with the On Semiconductor NTB45N06LT4G which has similar gate charge characteristics, and the NTB75N06G which has
similar RDSon. The Infineon IPB081N06L3G can also be used for higher efficiency.
95%
95%
94%
94%
93%
93%
92%
92%
91%
91%
90%
90%
89%
89%
88%
88%
87%
87%
86%
86%
85%
85%
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Figure 30: Predicted Efficiency of Design at 140 kHz FDD13AN06A0CT Left and NTB45N06LT4G right Blue = 8V, Green = 12V, Red = 18V
95%
95%
94%
94%
93%
93%
92%
92%
91%
91%
90%
90%
89%
89%
88%
88%
87%
87%
86%
86%
85%
85%
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Figure 31: Predicted Efficiency of Design at 140 kHz FDD13AN06A0CT Left and NTB75N06G right Blue = 8V, Green = 12V, Red = 18V
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
When calculating the component values for the worst case it is important to find to local ambient temperature. One way to predict the local
temperature of components is to use linear super position as discussed in [1]. Using linear super position one can take a series of measurements of
a PCB temperature shown in Figure 32 when major power component are made to dissipate a know power. The temperatures are then recorded
and coefficients are calculated to determine the influence of all components running simultaneously at a given area of interest shown in Figure 33 .
Once the data is collected the only remaining information needed is the power dissipation of each component.
Figure 32: Steady State Thermal Image Captures on Individual Component Heating
Rev 1 - January, 2009
ON Semiconductor Confidential – NDA Required
A
Temperature vs Load
B
C
200
D
E
Area Temperature (C)
180
160
F
G
140
H
I
120
J
K
100
L
M
80
60
N
O
40
P
Q
20
0
0
1
2
3
4
5
6
Output Current (A)
7
8
9
R
S
T
U
Figure 33: Area of Interest Selected for Temperature Evaluation and Calculated Thermal Data
1
© 2009 ON Semiconductor.
Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor does ON Semiconductor convey any license
to its or any third party’s intellectual property rights. This document is provided only to assist customers in evaluation of the referenced circuit implementation and the
recipient assumes all liability and risk associated with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of
its products at any time, without notice.
Design note created by Tim Kaske and Bryan McCoy, e-mail: [email protected] ; [email protected]
Rev 1 - January, 2009
Similar pages