tb429

Using the EL7515 Demo Board
®
Technical Brief
June 7, 2004
The complete schematic of EL7515
demo board is shown in Figure 1. With
different components stuffed, this
demo board can easily be configured into the applications
shown in this technical brief. The standard demo board
being sent out is the complete 5V to 12V converter shown in
Figure 2, which occupies less than 0.4 in2 area with
components on top side only. Layout diagrams are given at
the end of this document.
TB429
3. IO - up to 600mA depending on input voltage, provided
that diode and inductor can handle the corresponding
currents (refer to data sheet for the chart)
4. Switching frequency - can be set by R3
5. R4 can be 10Ω - 51Ω if VO is less than 10V. If VO is larger
than 12V, it can be calculated by:
V O – 10
R 4 = -------------------I DD
where IDD is a function of switching frequency, as shown
in the IDD vs FS curve.
1. VIN = 2V-5.5V. Can be higher with higher voltage rated
C1
2. VO = 12V. Can be set according to the following formula:
R 

V O = V FB ×  1 + ------2-
R 1

where VFB is shown in the VFB vs VDD curve.
C21
VO4
D21
C22
C14
VO3
D12
C15
C11
VO2
D11
L1
C12
C13
D1
VO1
Q1
L2
VIN
VO11
C1
R4
R3
1 PGND
LX 10
2 SGND
VDD 9
C6
R2
3 RT
FB 8
4 EN
SS 7
5 LBI
LBO 6
C8
C4
EN
R6
C5
C3
R9
R1
C7
R7
LBO
R8
FIGURE 1. COMPLETE SCHEMATIC OF EL7515 DEMO BOARD
L1
D1
VIN
VO1
C1
R4
R6
R3
1 PGND
LX 10
2 SGND
VDD 9
C5
C6
C4
R2
3 RT
FB 8
4 EN
SS 7
5 LBI
LBO 6
C3
R1
C10
FIGURE 2. 5V TO 12V CONVERTER
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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All other trademarks mentioned are the property of their respective owners.
Technical Brief 429
EL7515 Bill of Materials for VO=12V (Figure 2)
FS = 670kHz
REFERENCE
DESIGNATOR
VALUE
MANUFACTURER
MANUFACTURER’S
PHONE NUMBER
MANUFACTURER’S
PART NUMBER
R1
10kΩ/1%, 0603
Any
R2
82.5kΩ/1%, 0603
Any
R3
100kΩ, 0603
Any
R4
1kΩ, 0603
Any
R6
0Ω
Any
C1
10µF,16V, 1206
Murata
1-770-436-1300
GRM31CR61106KC31B
C3
20nF, 0603
Any
C4
0.1µF/16V, 0805
Any
C5
22µF, 16V, 1812
TDK
C6
0.1µF/16V, 0805
Any
C10
10nF, 0603
Any
L1
10µH
Coilcraft
847-639-6400
DO1608C-103
D1
MBR0520
On Semiconductor
800-282-9855
MBR0520
MANUFACTURER’S
PHONE NUMBER
MANUFACTURER’S
PART NUMBER
1-770-436-1300
GRM31CR61106KC31B
C4532X5R1C226M
EL7515 Bill of Materials for VO=18V (Figure 2)
FS = 1.2MHz
REFERENCE
DESIGNATOR
VALUE
MANUFACTURER
R1
10kΩ/1%, 0603
Any
R2
124kΩ
Any
R3
47.5kΩ
Any
R4
2.26kΩ
Any
R6
0Ω
Any
C1
10µF, 16V, 1206
Murata
C3
20nF, 0603
Any
C4
0.1µF/16V, 0805
Any
C5
22µF, 16V, 1812
TDK
C6
0.1µF/16V, 0805
Any
C10
10nF
Any
L1
6.8µH
Coilcraft
847-639-6400
DO1608C-682
D1
MBR0520
On Semiconductor
800-282-9855
MBR0520
2
C4532X5R1C226M
Technical Brief 429
L1
VIN
(2.3V-3.7V)
D1
Q1
C1
R4
R3
1 PGND
LX 10
2 SGND
VDD 9
C6
VO11
(4V,
400mA)
C4
R2
3 RT
FB 8
4 EN
SS 7
5 LBI
LBO 6
C3
R6
C5
R5
L2
R1
C10
R7
R8
FIGURE 3. EL7515 WITH OUTPUT DISCONNECT
Disconnect voltage at:
R 

V IN = 0.22 ×  1 + ------7-
R 8

EL7515 Bill of Materials for VO=4V (Figure 3)
FS = 670kHz
REFERENCE
DESIGNATOR
VALUE
MANUFACTURER
R1, R5, R8
10kΩ/1%, 0603
Any
R2
20kΩ/1%, 0603
Any
R3
100kΩ, 0603
Any
R4
51Ω, 0603
Any
R6
0Ω
Any
R7
56.2kΩ
Any
C1
10µF, 16V, 1206
Murata
C3
20nF, 0603
Any
C4
0.1µF/16V, 0805
Any
C5
330µF
100µF
C6
0.1µF/16V, 0805
Any
C10
10nF, 0603
Any
L1
10µH
Coilcraft
L2
0Ω
Any
D1
MBR0520
On Semiconductor
Q1
IRLML6402
IR
3
MANUFACTURER’S
PHONE NUMBER
MANUFACTURER’S
PART NUMBER
1-770-436-1300
GRM31CR61106KC31B
Vishay/Sprague
207-324-4140
293D476X-020D20
Murata
1-770-436-1300
GRM43SR60J107M***B
847-639-6400
DO1608C-103
800-282-9855
MBR0520
IRLML6402
Technical Brief 429
D11
D12
VO3
(14.5V)
L1
VIN
(2.7V4.2V)
C14
C11 D
1
C13
C1
R4
R3
1 PGND
LX 10
2 SGND
VDD 9
C5
C6
C4
R2
3 RT
FB 8
4 EN
SS 7
5 LBI
LBO 6
C3
R6
C15
VO1
(5.1V)
R1
C10
FIGURE 4. EL7515 WITH DUAL OUTPUTS
EL7515 Bill of Materials (Figure 4)
VO1 = 5.1V, VO3 = 14.5V, FS = 670kHz
REFERENCE
DESIGNATOR
VALUE
MANUFACTURER
MANUFACTURER’S
PHONE NUMBER
MANUFACTURER’S
PART NUMBER
R1
133kΩ/1%
Any
R2
402kΩ/1%
Any
R3
100kΩ
Any
R4
51Ω
Any
R6
0Ω
Any
C1
10µF, 16V, 1206
Murata
1-770-436-1300
GRM31CR61106KC31B
C3
20nF
Any
C4, C6, C11, C14
0.1µF/16V
Any
C5
22µF, 10V, 1210
Murata
1-770-436-1300
GRM32ER61A226KA65B
C10
10nF, 0603
Any
C13
1µF
Any
C15
4.7µF
Panasonic
408-945-5660
ECJ-3YF1C4752
L1
10µH
Coilcraft
847-639-6400
DO1608C-103
D1
MBR0520
On Semiconductor
800-282-9855
MBR0520
D2, D3
BAT54S
Vishay/Telefunken
402-563-6866
BAT54S
4
Technical Brief 429
C21
VO4
(~9.5V)
D21
C22
C11
VO2
(19.5V)
D11
L1
C12
D1
VIN
C1
VO1
(10V)
R4
R3
1 PGND
LX 10
2 SGND
VDD 9
C5
C4
R2
3 RT
FB 8
4 EN
SS 7
5 LBI
LBO 6
C3
R6
C6
R1
C10
FIGURE 5. EL7515 FOR TRIPLE OUTPUT
EL7515 Triple Output Bill of Materials (Figure 5)
VO1 = 10V, VO2 = 19.5V, VO4 = -9.5V
REFERENCE
DESIGNATOR
VALUE
MANUFACTURER
R1
10kΩ/1%, 0603
Any
R2
66.5kΩ/1%, 0603
Any
R3
100kΩ, 0603
Any
R4
51Ω, 0603
Any
R6
0Ω
Any
C1
10µF, 16V, 1206
Murata
C3
20nF, 0603
Any
C4, C6, C11, C21
0.1µF/16V, 0805
Any
C5
22µF, 16V, 1812
TDK
C10
10nF, 0603
Any
C12, C22
4.7µF, 25V
Panasonic
408-945-5660
ECJ-3YF1C4752
L1
10µH
Coilcraft
847-639-6400
DO1608C-153
D1
MBR0520
On Semiconductor
800-282-9855
MBR0520
D11, D21
BAT54S
Vishay/Telefunken
402-563-6866
BAT54S
5
MANUFACTURER’S
PHONE NUMBER
MANUFACTURER’S
PART NUMBER
1-770-436-1300
GRM31CR61106KC31B
C4532X5R1C226M
Technical Brief 429
Typical Performance Curves
1.355
3.6
1.35
3.4
3.2
IDD (mA)
1.345
VFB
VDD=10V
VO=12V-18V
1.34
1.335
1.33
3
2.8
2.6
2.4
1.325
2.2
1.32
5
6
7
8
9
10
VDD
FIGURE 6. VFB vs VDD
6
11
12
2
650
750
850
950
1050
FS (kHz)
FIGURE 7. IDD vs FS
1150
1250
Technical Brief 429
Demo Board Layout
2000 mil
2000 mil
FIGURE 8. TOP LAYER
2 in
2 in
FIGURE 9. TOP SILKSCREEN
2000 mil
2000 mil
FIGURE 10. BOTTOM LAYER
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verify that the Application Note or Technical Brief is current before proceeding.
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