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DEMO MANUAL
DC2407A
DESCRIPTION
LT8650S
Dual Channel 42V, 4A Synchronous Step-Down
Silent Switcher with 6.2µA Quiescent Current
Demonstration circuit 2407A is a dual channel 42V, 4A
synchronous step-down Silent Switcher
®
with 6.2μA qui-
escent current featuring the LT8650S. The LT8650S is the
second-generation Silent Switcher that minimizes EMI
and reduces PCB layout sensitivity. The demonstration
circuit has two outputs: 5V and 3.3V. Each output can
source up to 4A continuous current at the same time.
Figure 1 shows the conducted EMI measurements from
150kHz to 30MHz. Figure 2 shows the radiated EMI mea-
surements from 30MHz to 1GHz. All measurements were
tested per CISPR 25 specifications. The circuit passes the
tests with wide margins.
The SYNC pin on the demo board is grounded by default
for low ripple Burst Mode
®
operation. To synchronous
to an external clock, move JP2 to FCM W/O SSM OR
L, LT, LTC, LTM, Linear Technology, the Linear logo, Silent Switcher, and Burs Mode are
registered trademarks of AnalogDevices, Inc. All other trademarks are the property of their
respective owners.
PERFORMANCE SUMMARY
SYNC position and apply the external clock to the SYNC
turret. Moving JP2 to FCM W/SSM enables spread spec-
trummode.
The demonstration circuit 2407A runs at 2MHz to mini-
mize solution size. The efficiency is 92%. The IC tempera-
ture rise is less than 50°C when both channels run at full
load, 4A each, at 2MHz.
The LT8650S data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 2407A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2407A
Specifications are at TA = 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Range 5.4 42 V
VOUT1 Output1 Voltage 4.8 5 5.2 V
IOUT1 Maximum Output1 Current 4 A
VOUT2 Output2 Voltage 3.168 3.3 3.432 V
IOUT2 Maximum Output2 Current 4 A
fSW Switching Frequency 1.85 2 2.15 MHz
EFE Efficiency at DC IOUT1 = 4A, IOUT2 = 4A, Input Voltage = 12V 92 %
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DEMO MANUAL
DC2407A
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 1. Conducted EMI Performance
Figure 2: Radiated EMI Performance (CISPR 25 Radiated Emission Test with Class 5 Peak Limits)
DC2407A DEMO BOARD
(WITH EMI FILTER INSTALLED)
12V INPUT TO 5V OUTPUT1 AT 4A AND 3.3V OUTPUT2 AT 4A, f
SW
= 2MHz
SPREAD SPECTRUM MODE
FIXED FREQUENCY MODE
FREQUENCY (MHz)
12
15
18
21
24
27
30
–40
–30
–20
–10
10
20
30
40
50
60
AMPLITUDE (dBµV/m)
DC2407 F01
DC2407A DEMO BOARD
(WITH EMI FILTER INSTALLED)
12V INPUT TO 5V OUTPUT1 AT 4A AND 3.3V OUTPUT2 AT 4A, f
SW
= 2MHz
VERTICAL POLARIZATION
PEAK DETECTOR
CLASS 5 PEAK LIMIT
SPREAD SPECTRUM MODE
FIXED FREQUENCY MODE
FREQUENCY (MHz)
100
200
300
400
500
600
700
800
900
1000
–5
10
15
20
25
30
35
40
45
50
AMPLITUDE (dBµV/m)
DC2407 F02
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DEMO MANUAL
DC2407A
Demonstration circuit 2407A is easy to set up to evaluate
the performance of the LT8650S. Refer to Figure 3 and
Figure 4 for proper measurement equipment setup and
follow the procedure below.
1. With power off, connect the input power supply to
VEMI and GND.
2. With power off, connect the loads to VOUT1 and GND
and VOUT2 and GND.
3. Turn on the power at the input.
4. Carefully evaluate other design parameters as needed.
QUICK START PROCEDURE
Figure 3. Proper Measurement Equipment Setup
Figure 4. Measure Output Ripple
VOUT GND
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DEMO MANUAL
DC2407A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 2 C1, C4 CAP., 10μF, X5R, 50V, 10%, 1206 MURATA, GRM31CR61H106KA12L
2 2 C9, C10 CAP., 4.7pF, C0G, 50V, ±0.25pF, 0603 MURATA, GRM1885C1H4R7CA01D
3 2 C11, C14 CAP., 4.7μF, X5R, 25V, 10%, 0603 MURATA, GRM188R61E475KE11D
4 4 C12, C13, C33, C38 CAP., 47μF, X6S, 10V, 10%, 1206 MURATA, GRM31CC81A476ME44L
5 2 C17, C18 CAP., 10nF, X7R, 25V, 10%, 0603 MURATA, GRM188R71E103KA01D
6 3 C19, C20, C32 CAP., 1μF, X5R, 50V, 10%, 0603 MURATA, GRM188R61H105KAALD
7 2 C28, C29 CAP., 1μF, X7S, 10V, 10%, 0402 MURATA, GCM155C71A105KE38D
8 2 L1, L2 INDUCTOR, 1.0μH, XFL5030 COILCRAFT, XFL5030-102ME
9 4 R1, R3, R5, R6 RES., 1M, 1/10W, 1%, 0603 VISHAY, CRCW06031M00FKEA
10 1 R7 RES., 316k, 1/10W, 1%, 0603 VISHAY, CRCW0603316KFKEA
11 1 R8 RES., 191k, 1/10W, 1%, 0603 VISHAY, CRCW0603191KFKEA
12 2 R11, R12 RES., 100k, 1/10W, 1%, 0603 VISHAY, CRCW0603100KFKEA
13 1 R13 RES., 15k, 1/10W, 1%, 0603 VISHAY, CRCW060315K0FKEA
14 2 R14, R15 RES., 0Ω, 1/10W, 0603 VISHAY, CRCW06030000Z0EA
15 1 U1 I.C. LT8650SEV, LGA LINEAR TECH., LT8650SEV#PBF
Additional Demo Board Circuit Components
1 1 C2 CAP., 22μF, ALUM, 63V SUN ELECT., 63CE22BS
2 0 C5, C6, C30, C31 (OPT) CAP., OPTION, 0402
3 0 C7, C8, C15, C16, C26, C27 (OPT) CAP., OPTION, 0603
4 2 C21, C22 CAP., 10μF, X7R, 50V, 10%, 1210 MURATA, GRM32ER71H106KA12L
5 4 C34-C37 CAP., 0.1μF, X7R, 50V, 10%, 0402 MURATA, GCM155R71H104KE02D
6 1 FB1 CHIP BEAD Wurth Elektronik, 74279226101
7 1 L3 INDUCTOR, 0.22μH Wurth Elektronik, 744373240022
8 0 R2, R4, R9, R10 (OPT) RES, OPTION 0603
Hardware for Demo Board Only
1 18 E1-E18 TESTPOINT, TURRET, 0.094" PBF MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 JP1 HEADER 3 PIN 0.079 SINGLE ROW Wurth Elektronik, 62000311121
3 1 JP2 HEADER 3 PIN 0.079 DOUBLE ROW Wurth Elektronik, 62000621121
4 2 xJP1, xJP2 SHUNT, 0.079" CENTER Wurth Elektronik, 60800213421
5 4 (STAND-OFF) STAND-OFF, NYLON 11.1mm Wurth Elektronik, 702934000
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DEMO MANUAL
DC2407A
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
SCHEMATIC DIAGRAM
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
1. ALL RESISTORS ARE 0603.
ALL CAPACITORS ARE 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
(Fsw = 2MHz)
OUT1 VBIAS
FCM W / SSM
FCM W/O SSM OR SYNC
BURST
SUNCON
63CE22BS
C32
1uF
C22
10uF
50V
1210
C19
1uF
FB1
74279226101
C10
4.7pF
E1
SYNC
C33
C35
50V
C15
OPT
C8
OPT
C20
1uF
50V
E9
GND
JP2
1 2
3
5 6
4
E14
PG2
E18
VCC
C5
OPT
0402
R14
0
C38
C7
OPT
R8
191K
C9
4.7pF
C4
10uF
50V
1206
R7
316K
E13
PG1
C18
10nF
C37
50V
JP1
1
2
3
C6
OPT
0402
E8 VOUT2
3.3V / 4A
E7
EN2
C21
10uF
50V
1210
E16
TEMP
E5 GND
C36
0.1uF
0402
E6
EN1
C13
47uF
10V
1206
C29
1uF
0402
R4
OPT
E4
VEMI
5.4V - 42V
C14
4.7uF
25V
C17
10nF
R3
1M
E15
CLKOUT
C27OPT
C30
E17 VBIAS
C34
0.1uF
0402
R13
15K
LT8650SEV
U1
VIN1
4
VIN1
5VIN2 7
VIN2 8
EN1
11 EN2 12
BST1
24 BST2 18
RT
1
GND
2GND
10
TEMP
13
PG1
14 PG2 15
SYNC
16
CLKOUT
17
SW2 19
SW2 20
SW1
22
SW1
23
VCC
25
BIAS 26
VC2 32
FB2 31
SS2 30
SS1
29
FB1
28
VC1
27
GND
33 GND
34 GND
35 GND
36 GND
37 GND
38
R1
1M
C11
4.7uF
25V
R11 100K
+
C2
22uF
63V
E11
SS1
L2
1.0uH
R12 100K
R9
OPT
E3
VOUT1
5V / 4A
C1
10uF
50V
1206
R2
OPT
E2
GND
C31
C12
47uF
10V
1206
L3
0.22uH
744373240022
R6
1M
C28
1uF
0402
E12
SS2
R15
0
R5
1M
C16
OPT
R10
OPT
C26OPT
L1
1.0uH
E10
GND
VIN1
VOUT1
VCC
VOUT1
VIN2
VOUT2
VOUT1
VCC
VOUT2
VCC VCC
VIN2
VIN1
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DEMO MANUAL
DC2407A
© LINEAR TECHNOLOGY CORPORATION 2017
LT 0917 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
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arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
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Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application
engineer.
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Copyright © 2004, Linear Technology Corporation