IRF IRAUDPS1 12v system scalable 250w to1000w audio power supply Datasheet

-1-
IRAUDPS1
12V System Scalable 250W to1000W Audio Power Supply
For Class D Audio Power Amplifiers
Using the IR2085 self oscillating gate driver
And Direct FETS IRF6648
By
Manuel Rodríguez
CAUTION:
International Rectifier suggests the following guidelines for safe operation and handling of
IRAUDPS1 Demo Board:
• Always wear safety glasses whenever operating Demo Board
• Avoid personal contact with exposed metal surfaces when operating Demo Board
• Turn off Demo Board when placing or removing measurement probes
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IRAUDPS1
Page 1 of 35
-2-
Page
Table of Contents
Item
1
Introduction
3
2
System Specifications
4
3
Functional Block Description
5
4
IRAUDPS1 Block Diagram
6
5
Schematic IR2085 module
7
6
IRAUDPS1 mother board schematic
8
7
IR2085 module PCB layout
9
8
IRAUDPS1 mother PCB layout
10-11
9
BOM of IR2085 module
12
10
BOM of IRAUDPS1 mother board
13-14
11
BOM of Mechanical parts
14
12
Scalable IRAUDPS1 power table
14
13
Performance and test procedure
15-21
14
IRAUDPS1 Fabrication Drawings
22-24
15
Transformer winding instructions
25-27
16
Design example
28
17
Transformer design
28-30
18
MOSFET selection
30
19
Switching losses
31
20
Efficiency calculations
32
21
Frequency of oscillation
33
22
Selecting dead time
33
23
Over Temperature Protection
33
24
Short circuit protection
33
25
BJT gate driver option
33
26
Music Load
34
25
Revision Changes Descriptions
35
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IRAUDPS1
Page 2 of 35
-3-
Introduction
The IRAUDPS1 reference design is a 12 volts systems Audio Power Supply for automotive applications
designed to provide voltage rails (+B and –B) for Class D audio power amplifiers
This reference design demonstrates how to use the IR2085 as PWM and gate driver for a Push-Pull DC to
DC converter, along with IR’s Direct FETS IRF6648
The resulting design uses a compact design with the Direct FETS and provides all the required protections.
NOTE: The IRAUDPS1 is an scalable power output design, and unless otherwise noted,
this user’s manual and the reference design board is the 500W
Table 1 IRAUDPS1 scalable table
IRAUDPS1
Nominal
Voltage
output
Nominal
Output
Current
250W
500W
1000W
+B, -B
±35V
±35V
±35V
+B, -B
3.5A
7A
14A
Stereo System
8 channel System
8 channel System
100W x 2
100W x 4
100W x 8
IR Class D Model
IRAUDAMP7D
IRAUDAMP8
IRAUDAMP8 x 2
Detailed output power versions that can be configured by replacing components given in
the component selection of Table 7 on page 14
Application
.
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IRAUDPS1
Page 3 of 35
-4-
System Specification
All specs and tests are based on a 14.4V battery voltage supplying an International Rectifier Class
D reference design with all channels driven at 1 kHz and a resistive load.
Table 2
Specification
IR Class D Load
Input current with no load
ACC Remote ON Level
ACC input impedance
Turn ON delay
In-Rush Current
Output power full loaded
Input current full loaded
Output Current per supply
Output voltage
Regulation
Ripple outputs, laded at
400W audio 1khz
250W
IRAUDAMP5
0.35A +/- 10%
4.5-6V
10k+/- 10%
1-1.5 Sec
30A Max
250W
18A
3.5A
+/- 35V +/-10%
+/- 10%
1.5V P.P.
IRAUDPS1
IRAUAMP8
0.35A +/- 10%
4.5-6V
10k+/- 10%
1-1.5 Sec
30A Max
500W
35.5A
7A
+/- 35V +/-10%
+/- 10%
1.8V P.P.
1000W
IRAUAMP8 x 2
0.35A +/- 10%
4.5-6V
10k+/- 10%
1-1.5 Sec
30A Max
1000W
71A
14A
+/- 35V +/-10%
+/- 15%
2V P.P.
Efficiency at ½ and full of
rated power
Isolation between Battery
and Outputs Gnd
Battery OVP
Battery UVP
Output SCP
Outputs OVP
Over temperature
protection (OTP)
OTP hysteresis
Led Indicators
Size
90-85%
92-87%
90-80%
1k Ohm
1k Ohm
1k Ohm
18-18.5V
8.0-8.5V
10A
40-45V
90C +/- 5C
18-18.5V
8.0-8.5V
20A
40-45V
90C +/- 5C
18-18.5V
8.0-8.5V
40A
40-45V
90C +/- 5C
10C
10C
Red LED= SCP, Blue LED= OK
3” W x 5.3” L x 1.5” H
10C
Table 3
+B, -B Voltage outputs vs. Battery voltage all models
Voltage outputs at 16.0V battery input with
no signal input at class D
Voltage outputs at 12.0V
Voltage outputs at 8.0V battery input with
no signal input at class D
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IRAUDPS1
+/- 39.5V +/- 10%
+/- 28V +/- 10%
+/- 19.2V +/- 10%
Page 4 of 35
-5-
Functional Block Description
Fig 1 below shows the functional block diagram which basically is an isolated DC-DC converter
with a step-up push-pull transformer from a 12V system that converts it to +/- 35V using the
IR2085 as a PWM and gate driver along with the Direct FETS IRF6648.
The IR2085 Module contains all the housekeeping circuitry to protect the IRAUDPS1 against
streamer conditions which are:
1. Soft start circuit in order to control the inrush-current at the moment the IRAUDPS1 power
is turned ON
2. Short Circuit protection at outputs (SCP), which will shut down the IR2085 and remain in
latch mode until the Remote ON /OFF switch is released
3. 12V system Over Voltage protection (OVP1). if Battery input voltage is greater than 18V..
this could happen when the vehicle’s battery is disconnected or a vehicle’s alternator fails.
4. Over voltage Output (OVP2) is greater than +/-45V at +B terminal if battery input is greater
than 16V
5. Over Temperature Protection (OTP), resistor Thermistor senses the chassis temperatures
from Direct FETS
Fig 2 is the complete schematic for the IR2085 Module
Fig 3 is the complete schematic for the IRAUDPS1 with all scalable components required
Figs 4 to Fig 10 are the respective PCB layouts for the IR2085 Module and the IRAUDPS1
motherboard
Tables 4 to Table 6 are the respective bills of materials
Table 7 is the IRAUDPS1 detailed output power versions that can be configured by replacing
components
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IRAUDPS1
Page 5 of 35
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IRAUDPS1 Block Diagram
PUSH PULL
+B Supply
Rectifiers
& filters
FUSES
Battery
terminal
inputs
+BATT.
+B
SGnd
-B
+14.4V
EMI
Filter
GND
-B Supply
Rectifiers
& filters
Chassis GND
OVP1
IR2085
+Batt, OVP
Batt Gnd
SGnd
SD
Soft Start
SCP
ON
Remote
ON/OFF
Rem
Rem ON/OFF
and +12V
Regulator
+B, OVP
OTP
Thermistor
Thermally connected to heat spreader
OVP2
IR2085 Module
Fig 1 Functional Block Diagram
.
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+Current
Sense
IRAUDPS1
Page 6 of 35
-Current
Sense
-7-
1
10k
47k
Soft Start SCP SCP-
1
R23
10k
10k
1
1 2
2
2
CS
1
1
2
LO1
30K
R1
OSC
U2
HO1
7
J3
22
1
R1 @ C2_470pF:
15k=100khz
30k=50khz
VCC
1nF,15k=50kHz
GND
VS1
6
4
LO
VCC
5
Q5
14.4V
VCC
2
2
2
R25
Turn_ON
R11
VCC CP2
1
1
2
2.2R
Q1
14.4V
3
14
2
2
22
2
1
R20
Header 2
open
10uF
C8
1
12V
1
1
10k
2
0.1uF
2
2
Remote ON
22
R21
Remote ON
4.7k
TH1
2085_Control Module_R3
e-mail: [email protected]
Fig 2 schematic of IR2085 Module
IRAUDPS1
J1
1
6
5
4
3
2
1
Header 6H
2
Drawing by: M.Rodriguez
R8
R9
6
2
1
2
2
1
J5
1
DZ3
1k
R26
5
1
VS1
R30
1
4.7k
0.0
J4
4
3
2
1
14.4V
Q6
Q2
Blue
LED2
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2
1
Header 2
VS2
3
470pF
1
2
1
open
Q4 open
C2
2
R19
8
VB1
1
Header 2
R27
VCC
CS
2
0.0
J2
22
R18
0.1uF
2
3
2
1
Q3 open
R14
D4
IR2085
2
C6
1
4.7k
1
14.4V
2
C3
R13
2
CP1
100pF
2
1
DZ2
10uF
2
1
1
5.6V
4
OVP2
2
1
2
J6
R24
1k
C2:
47pF=80nS
100pF=110nS
220pF=130nS
470pF=170nS
1nF1= 200ns
2
1
2
2
D7
1
10k
1
1
1
SCP+
2
3
V1
1
2
R15
R16
1
2
R28
1
V1
8
2
10k
2
2
2
10k
D3
V1
1
10k
R3
2
1
0.01uF
2
1
C1
R2
R33
1
D2
R17
2
2
C7
U1A
12
LM393
1
DZ1
18V
2
OVP
10k
2
1
R4
0.1uF
2
1
1
14.4V
OVP2
1k
1
TH1
10k
5 1
1Meg
1
Turn_ON
D5
2
0.01uF
1
LM393
2
470
R6
C5
SCP
6
D1
6
2
1
2 7
1
1
SCP-
OTP
U1B
R31
1
2
D6
C4
2
2
5
V1
SCP+
2
4
1
LED1
3
DZ4
10k
R22 Q7
Turn_ON
470k
2
1
R10
2 1
R32
0.01uF
1
1
V1
2
R29
10V
Red
4.7k
Page 7 of 35
-8.
.
`
IRAUDPS1, 12V System SMPS, 500W Converter with Direct Fets
And IR2085 PWM Module
Optional
(open) MUR1620CTG
1
SW2
2
CR1
+V_Rectified
3
SW1
+B
J6
VS2
3
2
1
2.2K
1
2.2K
2
R14
15A
C3
2
+CS
Q1
2
VS1
1
SMAZ39-TP
Header 4
2.2nF/100V
2
1
2
VS1
R72
6.2
1uF
1uF
1
1
R43
100R
L5
1
3
2
D4
1
2
0.1uF/250V
3
S2
S2
C22
4
5
ZP42915TC
2
D2
C21
1
1
D3
C29
0.01uF
1
C26
1
C23
2
1
L2
1
2
LED2
LO2B
6
5
4
3
2
1
2
GND
1
SGnd
-B
C30
TH1, thermally connected to heat-spreader
2
1
0.01uF
C32
2
2.2k
R61
22k
R56
2.2k
2
-B
2
R52
SCP-
2
1
CP13
CP11
2700uF/35V
-CS
10k
Drawing by: M.Rodriguez [email protected]
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IRAUDPS1
Page 8 of 35
2
2
0.03R
C27
R53
2
1
10k
SGnd
.
R54
1
R48
0.01uF
Fig 3 IRAUPS1 Mother Board Schematic
-V
2
1
-B
2
1
TH1
Chassis GND
1
1
R55
+V
2
1 SGnd
3
0.03R
0.01uF
1
LED1
R45
1k
J1
2
22k
0.1uF
1
+B
1uF/100V
2
1
R16
2
2700uF/35V
7
2
4
6
2.2K
2
R60
TB4
1uF/100V
1
12
2
C24
Q2
MMBT5551
2
R32
1
1
2
0.03R
1
1
SW2
C25
1
1uF/100V
+B
D_FET16
IRF6648
3
5
1
D_FET12
1
open
3
5
2.2K
D_FET8
IRF6648 1
3
5
2
7
2
4
6
7
2
4
6
7
2
4
6
3
5
Header 2
2
off
1
S1
Remote ON/OFF
2
2
1
2
1
Manual ON/OFF
14.4V
3PSW
3
D_FET4
1
open
1
100K
TH-805
TB3
LO2A
2
R49
2
C35
J5
R47
0.03R
-V_Rectified
TB1
2
1
0.1uF/250V
3
2
2
2
C28
C31
1uF/100V
2
1
1uF
6
+B
1
+V
10k
R50
CP12
1
C9
R71
C33
1uF
6.2
2
C8
L1
3.3uH/10A
2
D1
MMBT5401
CP10
2700uF/35V
Z1
14.4V
3
C7
3
L6
7
+V_Rectified
2700uF/35V
VS2
2
2
SMAZ39-TP
4
3
2
1
2 F3
1
R44
1000pF/200V
2
1
2
J4
14.4V
R73
Z2
Fuse3
1
10k
1
1
SW1
1
S1
1
2.2nF/100V
2
1
TB2
FB2
1 R70
CP5
2 F2
15A
6.2
CP4
3300uF/25V
Fuse2
1
SCP+
1
2
CP3
3300uF/25V
15A
8
P1
10
2
C34
6.2
3300uF/25V
2 F1
2085 Module
1
14.4V
TR1
R51
2
2.2nF/100V
2
1
Header 2
FB1
1
SW1
LO1B
2
1
Fuse1
1
(open) MUR1620CTRG
3
2
CR2
-V_Rectified
1
SW2
Transformer:
Core: Magnetics P/N ZR42915TC
P1,P2=4T#18x4,60uH,DCR 3mOhms
S1,S2=10T#20x3=470uH,DCR 46mOhms
D_FET14
IRF6648
R31
J2
+Battery
7
2
4
6
7
2
4
6
D_FET10
1
open
3
5
3
5
2
D_FET6
IRF6648 1
3
5
D_FET2
1
open
1
Header 2
7
2
4
6
LO1A
2
1
3
5
Header 3
J3
7
2
4
6
SCP+
SCP-
-V
-9-
Fig 4 IR2085 Module Top silk screen layout
.
Fig 5 IR2085 Module bottom side layout
Fig 6 IR2085 Module Top side layout
.
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IRAUDPS1
Page 9 of 35
- 10 .
Fig 7 IRAUDPS1 Mother Board Top silk screen layout
.
Fig 8 IRAUDPS1 Mother Board Top copper
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IRAUDPS1
Page 10 of 35
- 11 -
.
Fig 9 IRAUDPS1 Mother Board Bottom silk screen layout
.
.
Fig 10 IRAUDPS1 Mother Board Bottom layout
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IRAUDPS1
Page 11 of 35
- 12 -
Bill of Materials
Table 4
IRS2085 Module
Quantity
Value
Description
3
0.01uF
CAP 10000PF 50V CERM X7R 0603
1
470pF
1
100pF
3
0.1uF
2
10uF
7
1N4148WT-7
1
1
Designator
Digikey P/N
Vendor
C1, C4, C5
PCC1784CT-ND
Panasonic - ECG
CAP CER 470PF 50V 5% C0G 0603
C2
490-1443-1-ND
Murata
CAP CERAMIC 100PF 50V NP0 0603
C3
311-1069-1-ND
Yageo
CAP CERM .10UF 50V 20% 0805 SMD
C6, C7, C8
478-3351-1-ND
AVX Corporation
CAP TANTALUM 10UF 16V 10% SMD
CP1, CP2
495-2236-1-ND
Kemet
DIODE SWITCH 100V 150MW SOD-523
D1, D2, D3, D4, D5, D6, D7
1N4148WTDICT-ND
Diodes Inc
18V
SOD123_Z
DZ1
MMSZ5248BS-FDICT-ND
Diodes Inc
5.6V
DIODE ZENER 5.6V 200MW SOD-323
DZ2
UDZSTE-175.6BCT-ND
Rohm
1
12V
DIODE ZENER 200MW 12V SOD323
DZ3
BZT52C12S-TPMSCT-ND
Micro Commercia
1
10V
DIODE ZENER 10V 200MW SOD-323
DZ4
MMSZ5240BSDICT-ND
Diodes Inc
1
Header
Header, 6-Pin, Right Angle
J1,J2,J3,J4,J5.J6
929500E-01-01-ND
3M
1
Red
LED RED ORAN CLEAR THIN 0805 SMD
LED1
160-1422-1-ND
Lite-On Inc
1
Blue
LED 468NM BLUE CLEAR 0805 SMD
LED2
160-1645-1-ND
Lite-On Inc
2
XN04311
TRANS ARRAY PNP/NPN W/RES MINI6P
Q1, Q7
XN0431100LCT-ND
Panasonic - SSG
1
PBSS305NX
TRANS NPN 80V 4.6A SOT-89
Q2
568-4177-1-ND
NXP
2
open
(OPEN) TRANS NPN 80V 4.6A SOT-89
Q3, Q4
568-4177-1-ND
NXP
2
open
(OPEN) TRANS PNP 80V 4A SOT-89
Q5, Q6
568-4178-1-ND
NXP
1
30K
RES 30K OHM 1/10W 5% 0603 SMD
R1
RHM30KGCT-ND
Rohm
1
1k
RES 1K OHM 1/10W 5% 0603 SMD
RHM1.0KGCT-ND
Rohm
11
10k
RES 10K OHM 1/10W 5% 0603 SMD
R2
R3,R6,R9,R14, R15, R16, R17, R23, R24,
R32,R33
RHM10KGCT-ND
Rohm
1
1Meg
RES 1.0M OHM 1/10W 5% 0603 SMD
R4
311-1.0MGRCT-ND
Yageo
4
4.7k
RES 4.7K OHM 1/10W 5% 0603 SMD
R8, R13, R22, R25
RHM4.7KGCT-ND
Rohm
1
470k
RES 470K OHM 1/10W 5% 0603 SMD
R10
RHM470KGCT-ND
Rohm
1
2.2
RES 2.2 OHM 1/4W 1% 1206 SMD
R11
P2.2RCT-ND
Panasonic - ECG
4
22
RES 22 OHM 1/8W 5% 0805 SMD
R18, R19, R20, R21
RHM22ARCT-ND
Rohm
2
1k
RES 1.0K OHM 1/10W 5% 0603 SMD
R26, R28
RHM1.0KGCT-ND
Rohm
2
0.0
RES 0.0 OHM 1/8W 5% 0805 SMD
R27, R30
RHM0.0ARCT-ND
Rohm
1
47k
RES 47K OHM 1/10W 5% 0603 SMD
R29
RHM47KGCT-ND
Rohm
1
470
RES 470 OHM 1/8W 5% 0805 SMD
R31
RHM470ARCT-ND
Rohm
1
LM393DR2G
IC COMP DUAL OFFSET LV 8SOIC
U1
LM393DR2GOSCT-ND
ON Semi
1
IR2085
Controller and Gate Driver
U2
IR2085
International Rect
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IRAUDPS1
Page 12 of 35
- 13 -
Table 5
IRAUDPS1 Mother Board Bill of Materials
Quantity
Value
Description
Designator
1
1000pF/200V
CAP CER 1000PF 10% 200V X7R 1206
C21
478-1505-1-ND
AVX Corporation
3
2.2nF/100V
CAP CER 2200PF 10% 100V X7R 1206
C22, C33, C34
478-1519-1-ND
AVX Corporation
4
1uF/100V
CAP CER 1UF 100V X7R 1206
C23, C24, C31, C35
490-3909-1-ND
Murata Electronics
4
0.01uF
CAP 10000PF 50V CERM X7R 0603
C26, C27, C30, C32
PCC1784CT-ND
Panasonic - ECG
3
0.1uF/250V
CAP CERAMIC .1UF 250V X7R 1206
C28, C29,C25
399-4674-1-ND
Kemet
3
3300uF/25V
CAP 3300UF 25V ELECT PW RADIAL
CP3, CP4, CP5
493-1842-ND
Nichicon
4
1200uF/63V
CAP 1200UF 63V ELECT PW RADIAL
CP10, CP11, CP12, CP13
493-1958-ND
Nichicon
1
(open)
DIODE Comm Cathode ULT FAST 16A 200V TO220
CR1
MUR1620CTGOS-ND
ON Semiconductor
1
(open)
DIODE Comm Anode ULT FAST 16A 200V TO220
CR2
MUR1620CTRGOS-ND
ON Semiconductor
4
STTH1002CB
DIODE FAST 200V 10A D-PAK
D1, D2, D3, D4
497-3536-5-ND
STMicroelectronics
4
open
Direct-FET MOSFET N-CH 60V 86A
FET2, FET4,FET10,FET12
IRF6648TR1PBFCT-ND
International Rectifier
4
IRF6648
Direct-FET MOSFET N-CH 60V 86A
FET6, FET8, FET14,FET16
IRF6648TR1PBFCT-ND
International Rectifier
3
Fuse Holder
FUSEHOLDR MINI VERT PCB MNT SNGL
F1, F2, F3
F065-ND
Littelfuse Inc
2
FERRITE QUAD LINE 10A
FERRITE 3 LINE 10A 342 OHMS
FB1, FB2
240-2494-ND
Stwart
3
15A
FUSE BLADE 15A/32V MINI FAST-ACT
Fuse1, Fuse2, Fuse3
F992-ND
Littelfuse Inc
1
Module_2085_R2
Control Module
J1,J2, J3, J4,J5,J6
Custom
IR Module_2085_R2 PCB
2
3.3uH/10A
INDUCTOR POWER 3.31UH 11.4A T/H
L1, L2
513-1522-ND
Coiltronics
1
Blue
LED 468NM BLUE CLEAR 0805 SMD
LED1
160-1645-1-ND
Lite-On Inc
1
Blue
LED 468NM BLUE CLEAR 0805 SMD
LED2
160-1645-1-ND
Lite-On Inc
1
MMBT5401
TRANSISTOR PNP 150V SOT-23
Q1
MMBT5401FSCT-ND
Fairchild Semiconductor
1
MMBT5551
TRANSISTOR NPN 160V SOT-23
Q2
MMBT5551FSCT-ND
Fairchild Semiconductor
4
2.2K
RES 2.2K OHM 1/8W 5% 0805 SMD
R14, R16, R31, R32
'RHM2.2KARCT-ND
Rohm
1
100R
RES 100 OHM 1/4W 5% 1206 SMD
R43
311-100ERCT-ND
Yageo
1
10
RES 10 OHM 1/4W 5% 1206 SMD
R44
RHM10ERCT-ND
Rohm
1
1k
RES 1.0K OHM 1/4W 5% 1206 SMD
R45
RHM1.0KERCT-ND
Rohm
4
0.03R
RES .03 OHM 1W 1% 2512 SMD
R47, R48, R49, R54
WSLG-.03CT-ND
Vishay/Dale
4
10k
RES 10K OHM 1/10W 5% 0603 SMD
R50, R51, R52, R53
RHM10KGCT-ND
Rohm
2
2.2k
RES 2.2K OHM 1W 5% 2512 SMD
R55, R56
PT2.2KXCT-ND
Panasonic - ECG
2
22k
RES 22K OHM 1/4W 5% 1206 SMD
R60, R61
RHM22KERCT-ND
Rohm
4
6.2
RES 6.2 OHM 1/4W 5% 1206 SMD
R70, R71, R72, R73
RHM6.2ERCT-ND
Rohm
IRAUDPS1
C3, C7, C8, C9
Page 13 of 35
490-3908-1-ND
Vendor
1uF/50V
www.irf.com
CAP CER 1UF 50V X7R 1206
Digikey P/N
4
Murata Electronics North
- 14 -
1
Toggle SW 3Pos
Toggle SW 3Pos
S1
EG2377-ND
E-Switch
2
Gold terminal block
1
TB 2 terminals
Gold terminal Block #8 AWG
TB1, TB2
070-850
Audio Express
CONN TERM BLOCK 2POS 5MM PCB
TB3
277-1022-ND
1
1714984
Phoenix Contact
CONN TERM BLOCK 3POS 9.52MM PCB
TB4
277-1272-ND
Phoenix Contact
1
100K
THERMISTOR 100K OHM NTC 0805 SMD
1
ZP42915TC
Power Transformer
TH1
490-2451-1-ND
Murata Electronics
TR1
Custom TR500-2085
2
SMAZ39-TP
DIODE ZENER 1W 39V SMA
Z1, Z2
Magnetics
SMAZ39-TPMSCT-ND
Micro Commercial Co
.
Table 6
Mechanical BOM
Quantity
Description
Value
Digikey P/N
Vendor
1
Aluminum Bar heat spreader R2
Aluminum Bar 2085
Custom
China
1
Aluminum Base heat sink R2
Aluminum Bar 2085
Custom 2085
China
1
Print Circuit Board IR2085_MB_R2 .PCB
PCB
IR2085_MB_R1 PCB Assy
China
1
THERMAL PAD .080" 4X4" GAPPAD
THERMAL PAD .080" 4X4" GAPPAD
Ber164-ND
Bergquist
2
(Optional) THERMAL PAD .007" W/ADH
(Optional) THERMAL PAD TO-220
173-7-240A
Wakefield
4
SPACER ROUND 1" #4 SCRW .250" BR
Stand off 0.250"
1454AK-ND
Keystone Electronics
6
NUT HEX 4-40 STAINLESS STEEL
Nut 4-40
H724-ND
Building Fasteners
6
SCREW MACHINE PHILLIPS 4-40X3/4
Screw 4-40X3/4
H350-ND
Building Fasteners
12
WASHER LOCK INTERNAL #4 SS
Washer #4 SS
H729-ND
Building Fasteners
.
Table 7
Scalable IRAUDPS1 by changing the following components
Component
Notes
250W
IRAUDPS1
Power Transformer T1
See winding instructions
IR P/N TR-2085-250W
IR P/N TR-2085-500W
Direct FETs
Populate the respective Direct FET
by IR6648 as shown on respective
model
D_FET6, D_FET16
D_FET6,D_FET8,
D_FET16
1000W
IR P/N TR-2085-1000W
D_FET14,
D_FET6,D_FET8,
D_FET16
D_FET14,
D_FET2,D_FET4,
D_FET12
D_FET10,
R47, R48, R47, R54
Short circuit sensitivity
0.06R
0.03R
0.015R
Fuse F1, F2, F3
Input Current
5A
15A
25A
D1, D2, D3, D4
Output Rectifiers
4A
8A
16A
CP3, CP4, CP5
Input Filters
2200uF/25V
3300uF/25V
3900uF/25V
.
www.irf.com
IRAUDPS1
Page 14 of 35
- 15 -
IRAUPS1 Application and connections
Fig 11 test Setup
www.irf.com
IRAUDPS1
Page 15 of 35
- 16 -
Connector Description
Battery ( - )
Battery ( + )
+B output
Analog GND
-B output
TB1
TB2
TB4-1
TB4-2
TB4-3
Terminal Board for Negative supply source
Terminal Board for Positive supply source
Positive output of +B (+Bus Rail)
Output GND of +B and -B
Negative output of –B (-Bus Rail)
Switch Description
Remote-OFF-Test
Remote
OFF
Test
This position PS1 can be turned ON remotely by vehicle’s
ACC (Accessory voltage) or vehicle’s amplifier
IRAUDPS1 is always OFF regardless of ACC input
IRAUDPS1 can be turned ON manually or for test purpose
LED Indicator Description
LED1 Red
LED2 Blue
LED3 Blue
LED4 Blue
Indicate the presence of a short circuit condition on +B or -B
Indicate the presence of PWM pulses from IR2085
Indicate the presence of +B voltage
Indicate the presence of –B voltage
Power Source Requirements
The power source shall be capable of delivering 80 Amps with current limited from 1A to
80A during the test; the output voltage shall be variable from 8V to 19V during the test
Test Procedure
1.
2.
3.
4.
5.
6.
7.
Pre-adjust the main source power supply to 14.4V and set current limit to 1A
Turn on the main source power supply to standby mode
On IRAUDPS1 (Unit Under Test) Set the Remote ON switch to OFF (center)
Connect an oscilloscope probe on transformer terminals TR1 pin 1
Do NOT Connect the Class D Amp IRAUDAMP8 (IR2093) to +B and –B yet
Connect the resistive load to the class D Amp
Set the Audio OSC to 1 kHz and output level to 0.0V
Power up:
8. Turn ON the main source power supply, the input current from the source power
supply should be 0.0mA and all LEDS should be OFF
9. Look at LED2 on the IR2085_Module, it should be OFF, then turn ON the
Remote-OFF-Test to Test switch while you observe LED2; it will light slightly
after turning ON said switch, then LED2 will come fully bright one second after
the Remote switch was turned ON (Test position)
10. In the mean time, the figure on the oscilloscope will start from narrow pulses, up
to 50% duty cycle and the oscillation frequency shall be 50kHz as shown on Fig
12 and Fig 13 below; This is the soft-start test
IRAUDPS1
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Page 16 of 35
- 17 -
Fig 12, waveform from 2085 module
Fig 13, waveform from power
transformer
11. The power consumption from the source power supply shall be 0.35A maximum
typical is 0.30A and the +B and –B LEDs will turn ON as well
12. Measure the voltage on +B and –B; it will be +/-35V ±1.5V respectively; This is
the transformer’s windings turns ratio and full-wave rectifiers
UVP Test
13. Decrease the source power supply slowly until it reaches around 8 volts while
you observe LED2 or the oscilloscope. LED2 will turn OFF or oscilloscope’s
pulse will disappear at 8V ±1.5V. Typical is 8.02V
OVP1 Test
14. Increase the source power supply slowly until it reaches around 18V while you
observe LED2 or the oscilloscope. LED2 will turn OFF or the oscilloscope’s pulse
will disappear at 18V ±1.5V. Typical is 18.5V
OVP2 Test
15. Increase the source power supply slowly until it reaches around 16V while you
observe LED2 or the oscilloscope;. LED2 will begin blinking or the oscilloscope’s
pulse will decrease in duty cycle like Fig12 when +B reaches 45V ±2.5V.
Typical is 45.0V
SCP Test
16. Adjust the source power supply to 14.4V, then while IRAUPS1 is ON, apply a
short circuit between +B and AGnd with external wires, (do not make the SC on
the terminal board or it will burn said terminals) LED1 will turn ON and LED2 will
be OFF and stay OFF until the Rem-OFF-Test Switch is turned to OFF then ON
again; This is the latch of OCP
17. Repeat the last step for –B and GND
IRAUDPS1
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Page 17 of 35
- 18 -
Full Load Power Test
18. Turn OFF the IRAUDPS1 and Connect +B and –B to the Class D Amp
IRAUDAMP8 (IR2093)
19. Turn ON the IRAUDPS1, the input current from the source power supply should
be 0.85A ±0.5A; typical input current is 0.83A with the class D IRAUDAMP8
loaded with no signal input
20. Increase the current limit from the source power supply to 35A
21. Increase slowly the output level from the Audio Oscillator until the Class D amp
gets 100W RMS per channel; if resistive loads are 4 Ohms the outputs amplitude
from amplifier will be 20V RMS
22. Under these conditions the consumption current from the source power supply
shall be 36.6A maximum; this correlates to a 10% loss for each channel and a
20% loss of the IRAUDPS1; this is the power output and efficiency test
23. The output voltages from +B and –B should be +/- 30V ±2.5V
24. Monitor the transformer waveform; it should be like Fig 14 below
25. The ripple current for +B or –B should be 3V P.P. maximum as shown on Fig 15
below
Fig 15 +B and –B Ripple voltage
Fig 14 TR1 waveform loaded
OTP Test
26. Leave the class D amp running with 100W x 4 continuous power until IRAUDPS1
gets hot and trips the shut down level while the temperature on the heat sink is
monitored next to the Thermistor sensor. The temperature for shutdown will be
90C +/-5C and the time required to make OTP will be around 30 minutes when
tested at ambient temperature
27. The thermal hysteresis shall be 10C and the time to recover it shall be one
minute, the time to make shutdown again will be 10 minutes
28. Load Regulation and Efficiency are shown in Fig 16-20 below
IRAUDPS1
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Page 18 of 35
- 19 -
Typical Performance
Regulation
Voltage output
40
35
30
25
20
15
10
5
0
1
2
3
4
5
6
7
8
IRAUDPS1-500W Load (Amps)
Fig 16
.
Effiency of IRAUDPS1-250W
100
90
80
Efficiency %
70
60
50
40
30
20
10
0
0
7
14
21
28
35
42
49
56
63
70
138
204
268
Watts
Fig 17
.
IRAUDPS1
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Page 19 of 35
- 20 -
Efficiency of IRAUPS1-500W
100
90
80
Efficiency %
70
60
50
40
30
20
10
0
0
7
14
21
28
35
42
49
56
63
69 137 204 267 333 393 457 512
Watts
Fig 18
.
Efficiency of IRAUDPS1-1000W
100
90
80
Effiency %
70
60
50
40
30
20
10
0
0
7
14
21
28
35
42
49
56
63
69 137 267 393 512 626 732 833
Watts
Fig 19
.
IRAUDPS1
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Page 20 of 35
- 21 -
+B, -B vs. Battery voltage outputs
50
+B and -B Voltage outputs
45
40
35
30
25
20
15
10
5
0
8
9
10
11
12
13
14
15
16
17
18
Battery voltage
Fig 20
.
.
IRAUDPS1
www.irf.com
Page 21 of 35
- 22 -
IRAUDPS1 Fabrication Drawings
Mechanical assembly
.
HEX NUT 4-40
P/N H216-ND
HEX NUT 4-40
P/N H216-ND x 6
Lock washer
Lock washer
PCB
Stand off
0.250"
P/N 1454AK-ND x 4
Lock washer
Stand off
0.250"
P/N 1454AK-ND
Thermal Pad
Aluminum
Bracket
Lock washer
Lock washer
H729-ND x 12
Screw
H350-ND x 6
Lock washer
Lock washer
Screw
H350-ND
Aluminum Base
Lock washer
Screw
H350-ND
Fig 22 Mechanical assembly
.
0.032"
0.062"
DirectFETS Gap
0.030"
Lock washer
PCB
Lock washer
Heat Spreader (Bar)
Alumimum plate (Base)
Lock washer
Lock washer
Fig 23 Direct FET thermal dissipation
.
IRAUDPS1
www.irf.com
Page 22 of 35
- 23 -
.
Fig 24 Aluminum base
Fig 25 Heat Spreader for DirectFETs
.
IRAUDPS1
www.irf.com
Page 23 of 35
- 24 -
Fig 26 Thermal Pad
.
.
Fig 27 Input Battery Terminals
IRAUDPS1
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Page 24 of 35
- 25 -
IRAUDPS1 transformer winding instructions
IR Assy P/N IR-TR500-2085-500W
Schematic
Start
Start
P1
S1
Finish
Finish
Start
Start
P2
Materials required
Core: Magnetics material “P” ZP42915TC
S2
Finish
Finish
Fig 29
Fig 28
.
Step No. 1
Winding P1:
1. Cut 30cm length of 1.0mm gage x
4 wires of magnet wire (AWG 18)
2. Start winding P1 at 0 degrees
forward or Clock wise, as shown
on Fig 30, start is the top side,
and finish is the bottom side
3. Wind 4 turns in parallel at the
same time, evenly spaced around
the core as shown on Fig 30
4. Leave 4 cm of wire at both ends,
spaced ½ inch between ends, as
shown on Fig 30
Fig No. 30
.
Step No. 2
Winding P2:
5. Cut 30cm of 1.0mm gage x 4
wires of magnet wire (AWG 18)
6. Start winding P2 starting on the
end of P1, as shown in Fig 31,
start is the top side, and finish is
the bottom side
7. Wind the 4 at the same time
between the spaces of P1 evenly
spaced around the core, in the
same direction as shown on Fig
31
8. Leave 4 cm of wire at both ends,
spaced ½ inch between ends, as
shown on Fig 31
Fig No. 31
.
IRAUDPS1
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Page 25 of 35
- 26 Step No. 3
Winding S1:
9. Cut 60cm of 20 AWG (0.86mm) x
3 magnet wires
10. Start winding of S1 at 90 degrees
forward respect to the start point
of P1, as shown on Fig 32, start is
the top side, and finish is the
bottom side
11. Wind 10 turns whit the three
parallel wires at the same time,
evenly spaced around the core on
same direction as shown on Fig
32
12. Leave 4 cm of wire at both ends.
Fig No. 32
.
Winding S2:
13. Cut 60cm of 20 AWG (0.86mm) x
3 magnet wires
14. Start winding of S1 at 90 the end
pf S1 forward respect to the start
point of S1, as shown on Fig 33
15. Wind 10 turns whit the three
parallel wires at the same time,
evenly spaced around the core on
same direction as shown on Fig
33
16. Leave 4 cm of wire at both ends.
Fig No. 33
.
Step No. 5
Performing “Start and Finish wires”
Mounting holes; using an IR2085_MB_R2 PCB, perform the next instruction:
4
1
5
2
3
6
Fig No. 34
17. Perform “P1 Start” to fit into Pad 1 as
shown Fig 6.
18. Perform “P1 finish” and “P2 Sstart” to
be fitted into pad 2 as shown on Fig
No. 34, this is the center tap of the
Primary side
19. Perform “P2 finish”, to be fitted into
mounting hole 3 as shown in fig No. 6.
20. Perform “S1 start” (top winding) to be
connected on Pad 4 as shown on Fig
34
21. Perform “S1 finish” wire (bottom
winding) to be connected at Pad 5,
this is the center tap of the secondary
side
22. Perform “S2 start (top winding) to the
IRAUDPS1
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Page 26 of 35
- 27 center tap on Pad 5
23. Perform “S2 finish” of (bottom
winding) to be connected to hole 6 as
shown on fig 35
24. Cut and strip magnet wires for ½
inches long to be performed as
surface mounting as shown on Fig 35
25. Thin the transformer terminals as
shown on Fig 36
26. Before mounting on PCB measure
inductance according to next Table 8
Fig 35
Fig 36
Fig. 37
.
Table 8
Transformer’s Electrical Characteristics
Inductance at P1 and P2 on terminals 1,2 and 2,4
65uH-75uH
Inductance difference between windings P1 and P2 1uH maximum
Inductance at S1 and S2 on terminals 5,7 and 7,8
470uH minimum
Inductance difference between windings S1 and S2 2uH maximum
DCR at P1 winding 1,2 and P2 winding 2,4
3.0mOhms max
DCR at S1 terminals 5,6 and S2 terminals 7,8
46mOhms max
Number of turns for P1 and P2
4 Turns 18 AWG x 4
Number of turns for S2 and S2
10 Turns 20 AWG x 3
Leakage Inductance, with S1 and S2 shorted
1uH max
Resistance between Primary and Secondary (P and
Infinite
S windings)
Resistance between any winding and core
Infinite
High-Pot between primary and secondary windings
500VAC
High-Pot between any winding and core
500VAC
Dimensions
1.4” OD x 0.80” Height
Mounting
See Fig 37
.
IRAUDPS1
www.irf.com
Page 27 of 35
- 28 -
Design Example
Assume the following customer specifications are required:
A 12V system automotive power supply to drive a stereo class D amplifier 300 Watts per
channel into 4 ohms, and the maximum standby power consumption of the power supply
should be 5 watts at 14V battery voltage with no load; also efficiency should be greater
than 80%, compact design size 3 inches wide, 5 ½ long and 1 ½ high
Voltages outputs required
The first step is to calculate the output voltages and the input and output currents; the
control circuits in the IRAUDPS1 are a good reference design to design the whole
control system
+B and –B are calculated as following:
AUDIO signal VRMS = Sqrt (300W X 4 Ohms) = 34.6VRMS
Thus, +B = 34.6 x 1.4142 = +50VDC and –B = -50VDC
Input Current required from Battery
Input Current Loaded = 300W x 2 = 600W
If efficiency of the Class D amp is 90% then 600 x 1.1 = 660W
If the efficiency of the power supply is 80% then 660W x 1.2 = 792W = 800W
Thus, I loaded = 800W / 14V = 57A
Output Current provided
Total output current = 660W / 50V = 13.2A
Thus +B = 13.2 / 2 = 6.6A and –B = -6.6A
Transformer Design Example
The transformer design is a trade-off between size, operating frequency, physical
windings to achieve low leakage inductance, form factor, primary turns ratio to meet
standby input current, and type of core material
Core Selection
Core must be selected as power material composite and it can be chosen from any
major manufacturers which are Magnetics Inc, TDK, Ferroxcube, Siemens or Thomson.
Each manufacturer has a number of different powder core mixes of various materials to
achieve different advantages, so in this case Magnetics Inc core ZP42915TC is selected
according the estimated size required to fit the power required
Notice on IRADUPS1 Fig 30 and Fig 31 the primary windings are 4 turns and they are
distributed equally and spaced around the core in order to provide uniform magnetic flux
density therefore low leakage inductance, so 4 turns on primary side is a good practice
for now because it fits most of the requirements mentioned above, of which the most
important factor here is size and physical windings to achieve low leakage inductance
and core material
IRAUDPS1
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Page 28 of 35
- 29 -
Primary inductance
Primary Inductance called here as Lp is 65uH that belongs to 4 turns according to
Magnetics ZP42915TC permeability data sheet
Magnetizing current
The standby current with no load depends on the magnetizing idle of the power
transformer called here as IM and it depends on the operating switching frequency
called here as Fs
Magnetizing current = IM = 5W of standby current / 14V = 0.35A
Therefore this is the transformer’s primary windings impedance current
Thus, Transformer magnetizing impedance = ZM = 14V / 0.35A = 40 ohms
Then we assume that ZM is the same impedance of XL where XL = 6.28 x Lp x Fs
Therefore switching frequency = Fs = XL / (Lp x 6.28)
Operating switching frequency calculation
Because this is a push-pull DC-DC converter, switching frequency is calculated as
follows:
Operating switching frequency = Fs = ½ (XL / (Lp x 6.28) = 1 / 2 (6.28 x 65uH) / 40 ohms
= 48.9 kHz
Therefore we will use 50 kHz
Verification of the computations:
Transformer primary windings Impedance = XL = 6.28 x 65uH x 50 kHz = 20.41 ohms
IM = ½ (V / XL) = ½ (14V / 20.41) = 0.34A
Thus, the standby current will be 0.34A at 14V = 4.9W which will meet the customer’s
specifications
Turns ratio calculations
If the primary windings are 4 turns and they are distributed equally spaced around the
core as shown on Fig 30 and Fig 31
Thus, Volts per turn ratio = 14V / 4 turns = 3.5V per turn
Turns required on secondary = 50V / 3.5V = 14 turns
Number of wires and gauge required
Primary Windings
Because the input current will be 57A, the wire’s gauge will be the biggest possible to fit
into the core with the lowest DCR possible for a maximum efficiency and lower
temperature dissipation
Assuming 5 watts DC power dissipation on the primary side, then Primary DCR
maximum required = 5W / (57)2 = 5 / 3249 = 0.0015 ohms
IRAUDPS1
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Page 29 of 35
- 30 Wire length required is 6 inches for 4 turns in this case in particular for Magnetics Core
ZP42915TC, Then considering copper DC resistance according to gauge table 9 below
Thus, a single # 14 AWG magnet wire is required considering only the DC resistance
(DCR), but considering the skin effect of the high frequency of operation which in this
case will be 50 kHz, therefore 5 wires in parallel # 18 are required in order to minimize
the skin effect and therefore minimize the AC resistance at 50 kHz
.
Table 9
Round copper magnet wire DCR and AC/DC Resistance ratio due to skin effect
versus frequency
25kHz
50 kHz
100kHz
AWG
#
Diameter
mils
DCR per 1ft
mΩ
Skin
depth
ratio
Rac /
Rdc
Skin
depth
ratio
Rac /
Rdc
Skin
depth
ratio
Rac
/
Rdc
12
81.6
1.59
4.56
1.45
6.43
1.85
9.10
2.55
14
64.7
2.52
3.61
1.30
5.09
1.54
7.21
2.00
16
51.3
4.02
2.87
1.10
4.04
1.25
4.54
1.40
18
40.7
6.39
2.27
1.05
3.20
1.15
4.54
1.40
20
32.3
10.1
1.80
1.00
2.54
1.05
3.6
1.25
22
25.6
16.2
1.48
1.00
2.02
1.00
2.85
1.10
24
20.3
25.7
1.13
1.00
1.60
1.00
2.26
1.04
26
16.1
41.0
0.90
1.00
1.27
1.00
1.79
1.00
.
Secondary Windings
Because the secondary current is only 6.6A, lets assume a power dissipation of 2W on
the secondary windings
Secondary DCR maximum rewired = 2 / (6.6) 2 = 0.045 ohms
Thus, 3 wires # 20 required from table 9
MOSFTS Selection
Because part of the customer specification has to be a compact design, the Direct FET
IRF6648 is selected due to small package, high current capability, 60VDS, low RDSON
and low Qg feature
Quantity of MOSFETS required
Since the input current at full load will be 57 amperes, and operating frequency is 50 kHz
with 50% duty cycle (10us turn ON) and according to IRF6648 data sheet the safe
operating area (Fig 12 from data sheet)
Therefore, 15A will be the adequate current to be into the SOA
Number of devices = 57A / 15A = 3.8 devices
Thus, 4 devices required per each side of the Push-Pull transformer
IRAUDPS1
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Page 30 of 35
- 31 Gate Drive Current required
The Peak Gate drive current from IRS2085 = (VCC / RGATE ) x 2 outputs = (10V/ 22 ohms)
x 2 = 0.9A
The average current required to drive each gate depends on the switching frequency
and Qg of the selected MOSFET, which in this case Qg is 50nC (nano-coulombs) from
data sheet, there are two FETS in parallel per gate drive.
Average Gate Current = IGATE = 2Qg x Fs = 2 x 50E-9 x 50kHz = 5mA
Total Average Gate Current required = 0.005A x 4 devices = 0.02A
MOFETS Power Dissipation losses
The power dissipation at DC can be calculated as following:
57A / 4 devices = 14.25A
DC Power dissipation per device = I2 x RDSON / 2
Note RDSON at 100C from Data sheet Fig 5, is divided by 2 because it is 50% duty cycle
Power dissipation per device = (14.25)2 x 7.5mOhms / 2 = 0.76W
Total power dissipation = (57)2 x ¼ 7.5 mOhms = 3249 x 1.875 = 6.091 watts
MOSFET Switching loses
The MOSFETS switching losses can be calculated as following:
Switching losses = Turn ONLOSSES + Turn OFFLOSSES + Gate Drive LOSSES
From IRF6648 data sheet T(RISE TIME) = 29nS and T(FALL TIME) = 13nS and QGD = 14nC
Losses contributed by the size of the gate series resistor
Gate drive series resistors actually slowdown the turn ON and turn OFF timing
(See Fig 2, R18-R21)
Delay losses contributed by the gate series resistor = GRES Delay = QGD / ((VCC – VML )/
RGATE )). VML is the miller effect plateau voltage of gate charge curve. It is 5.5V for
IRF6648.
GRES Delay = 14E-9 / ((10V-5.5V) / 22 ohms ) = 14E-9 / 0.2A = 70nS
The delay time that caused by large gate resistor is much longer than the rise time that
defined in IRF6648 datasheet. Thus gate resistor delay time will be used to calculate
MOSFET switching losses.
Turn ONLOSSES = FOSC x ½ x (G RES Delay) x I x 2VDS = 50kHz x 0.5 x 70nS x 14.25A x 28V
= 0.7 watts per device
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- 32 Total Turn ON losses = 0.7 x 8 = 5.6W
Note: VDS is multiplied by 2 because VDS occurs twice in Push-Pull converters
Turn OFFLOSSES = FOSC x ½ (G RES Delay) x I x 2VDS = 50kHz x 0.5 x 70nS x 14.25A x 28V =
0.70 watts per device
Total Turn ON losses = 0.70 x 8 = 5.6W
Gate losses = Qg x VGATE x FOSC
Qg from IRF6648 data sheet is 36nC typical
Gate losses = 36E-9 x 10 x 50khz = 0.018W per FET
Total Gate losses = 0.018W x 8 = 0.144W
Total switching losses = 5.6 + 5.6 + 0.144 = 11.34W
Output Rectifiers Losses
+DC rectifier losses = V(DIODE) x I(OUT) = 0.7V x 6.6A = 4.62W per diode
Total Diode rectifiers for +B and –B = 4.62 x 4 = 18.48 watts
Efficiency
Total losses then will be; Transformer losses + MOSFETS losses + switching losses +
output rectifiers losses + core losses
Core losses according to material P from Magnetics-Inc data sheet is 2 watts at 50 kHz
Total transformer losses = Primary winding loses + Secondary winding losses + Core
Losses 5W +2W + 2W +2 W = 11 watts
Total MOSFET losses = RDSON losses + Switching losses = 6.09W + 11.34W = 17.43W
Overall Losses = 11W + 17.43W + 18.48W = 46.91W
Efficiency = 600 / 600+ 46.91 = 92.74% Therefore meet the efficiency specification
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- 33 -
Frequency of oscillation
From Fig 2, the frequency of oscillation is managed by R1 and C2 values and it shall be
calculated by the equation below
FOSC = 1 / R1 x C2 = 50 kHz
Thus, at 50Khz if R1 is 30k, then C2 will be 470pF, said values as shown on schematic
Fig 2 (See IR2085 data sheet for more details)
Selecting Dead-time
Dead time selection depends on the turn ON and OFF delay of the power MOSFETS
selected, in this case IRF6648 data sheet shows 16nS for turn ON delay and 28nS for
turn OFF delay, rise time 29nS and fall time 13nS,
Therefore dead time required = 16nS + 28nS + 29nS + 13nS = 86nS per phase
Because this is a push-pull then 86nS are multiplied by two giving 172nS
Thus, dead time can be programmed according to the 2085 datasheet where dead time
values are the relationship weight of C versus R.
Therefore, Fig 2 30K ohms and 470pF gives 170nS of dead time
Over-Temperature Protection (OTP)
Thermistor is selected to get 8.2 k ohms at 90OC, it can be readjusted changing R16 or
R15 and R17 for any other temperature
Over Current Protection (OCP)
From Fig3; R47, R48, R49 and R54 can be calculated at any current protection desired
by the following equation:
OCP resistor = 0.6V / OCP current
Example: If OCP desired is 20A
Then ROCP = 0.6V / 20A = 0.03 ohms
Thus, R47, R48, R49 and R54 will be 0.06 ohms each one because two of them are in
parallel
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- 34 -
BJT gate driver option
Notice on schematic Fig 2 and their PCB layout that it is prepared for extra BJT drivers
Q3-Q6 that in this case they are not populated, this is in case that the customer wants
more than 4 MOSFETS in parallel for large power outputs applications
Music Load
NOTE, All previous calculations were made for continuous sine wave load for the safe
and reliable design; the average currents and power dissipations actually will be 1/8 of
power for soft music, ¼ of power for heavy rock music and 3/8 of power with dead metal
music, and ½ of rated power for subwoofer amplifiers
Music load Input current calculations
RMS Input current with constant sine wave outputs at 1 kHz all channels driven:
•
•
•
•
•
•
IRMS SINE WAVE = 14V/800W = 57A
I PEAK MUSIC = 57 x 1.4142 = 80A
ISOFT MUSIC = 57A x 1/8 = 7.1A
I ROCK MUSIC = 57 x ¼ = 14.2A
I HEAVY METAL MUSIC = 57A x 5/8 = 21.3A
I Subwoofer = 57A x ½ =28A
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- 35 -
Revision changes descriptions
Revision
IRAUDPS1_R3
IRAUDPS1_R3.1
IRAUDPS1_R3.2
IRAUDPS1_R3.3
Changes description
Released
Reviewed
Tables 1, 2, 5, 7 Revised for 500W
Page 30, 50 khz with 50% duty cycle (10us
turn ON)
Page 30, number of devices 57A/15A
Page 31-32, corrected gate drive current
calculation. Corrected power dissipation
loss calculation numbers. Corrected
MOSFET switching loss calculation.
Corrected efficiency number according to
new power losses data.
Page 33, corrected typo of dead-time, ns
Date
January 23, 2009
March 24, 2009
April 22, 2009
Feb 21, 2013
WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105
Data and specifications are subject to change without notice.
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