1
dc1949af
DEMO MANUAL DC1949A
Description
LT8602
42V Quad Monolithic Synchronous
Step-Down Regulator
Demonstration circuit 1949A is a quad power supply
featuring the LT
®
8602. LT8602 is a 42V quad monolithic
synchronous step-down regulator. The demo circuit is
designed for 5.0V, 3.3V, 1.8V, and 1.2V outputs from a
nominal 12V input, with switching frequency set at 2MHz
to avoid audio band. The 1.8V and 1.2V converters are
powered from the 3.3V output. The 5V, 3.3V are powered
from a wide range of 5.5V to 42V. The current capability
is 2.5A for the 3.3V output, 1.5A for the 5V output, and
1.8A for the other outputs when running individually.
Up to 1A load current can be applied to all the channels
simultaneously without special cooling.
Individual soft-start, current limit, input voltage, power
good for each output simplify the complex design of
quad-output power converters. All regulators are syn-
chronized to a common external clock input or a resistor
programmable 250kHz to 2.2MHz internal oscillator. At
all frequencies, a 180° phase shift is maintained between
1 and 3, 2 and 4 channels, reducing the input peak cur-
rent and voltage ripple. Programmable frequency allows
optimization between efficiency and external component L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
performance summary
size. Each output can be independently disabled using its
own TRKSS or RUN pin and be placed in a low quiescent
current shutdown mode. Table 1 summarizes the perfor-
mance of the demo board at room temperature. The circuit
can be easily modified for different applications.
Figure 6 shows the typical thermal performance of the
circuit.
The demo board has an EMI filter installed on the bottom
layer. The conducted and radiated EMI performance of
the board is shown on Figure 4. The limit in Figure 4 is
CISPR Class 5, Peak. It shows the circuit passes the CISPR
Class 5, Peak test with a wide margin.
The LT8602 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 DC1949A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1949A
Specifications are at TA = 25°C
Table 1
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Voltage* 5.5 12 42 V
Standby Current When Switching IOUT1,2,3,4 = 0mA, VIN = 12V 60 µA
Output Voltage VOUT1 VIN = 12V, IOUT1 = 1A 4.80 5 5.20 V
Output Voltage VOUT2 IOUT2 = 1A 3.17 3.3 3.43 V
Output Voltage VOUT3 IOUT3 = 1A 1.73 1.8 1.87 V
Output Voltage VOUT4 IOUT4 = 1A 1.15 1.2 1.25 V
Maximum Output Current IOUT1 VIN = 12V, No Load on Other Channels 1.5 A
Maximum Output Current IOUT2 VIN = 12V, No Load on Other Channels 2.5 A
Maximum Output Current IOUT3 No Load on Other Channels 1.8 A
Maximum Output Current IOUT4 No Load on Other Channels 1.8 A
Switching Frequency VIN = 12V, IOUT1,2,3,4 = 1.0A 1.85 2 2.15 MHz
Efficiency VIN = 12V, IOUT1,2,3,4 = 1.0A 80 %
Refer to Figure 6 to determine the maximum input voltage and load. If IC temperature exceeds target, reduce input voltage, output current or switching frequency.
2
dc1949af
DEMO MANUAL DC1949A
Quick start proceDure
DC1949A is easy to set up to evaluate the performance of
the LT8602. Refer to Figure 1 for proper equipment setup
and follow the procedure below.
1. With power off, connect the input power supply to the
board through VIN and GND terminals on the top layer.
Connect the loads to the terminals VOUT1 and GND,
VOUT2 and GND, VOUT3 and GND, VOUT4 and GND on the
board. The default positions of the Headers are given
in Table 2.
Table 2. Default Positions of the Headers
NAME POSITION
EN/UVLO JP1 ON
TRKSS1 JP4 ON
TRKSS2 JP5 ON
RUN3 JP2 RUN
RUN4 JP3 RUN
2. Turn on the power at the input. Increase VIN to 12V.
Note: Make sure that the input voltage is always within
spec. Refer to data sheet on the burst mode operation
in light load and high VIN condition.
3. Check for the proper output voltages. The output should
be regulated at 5.0V (±4%), 3.3V (±4%), 1.8V (±4%),
1.2V (±4%).
Note: Do not overload unless proper thermal cooling
method such as air flow or heat sink is applied.
Note: If there is no output, temporarily disconnect the
load to make sure that the load is not set too high, and
the Headers of EN/UVLO, TRKSS1, TRKSS2, RUN3,
RUN4, are set in right positions.
4. Once the proper output voltage is established, adjust
the input voltage and load currents within the operat-
ing range and observe the output voltage regulation,
transient, ripple voltage, efficiency and other parameters.
Note: Refer to the thermal derating curves in LT8602
data sheet for high input voltage and/or high ambient
temperature operations.
Note: By default, SYNC is grounded, and the circuit is
set in low ripple burst mode operation. Remove R16,
and add R25 of 0Ω, the circuit is set in pulse-skipping
mode. The circuit runs in full frequency with lower load
current. Refer to the data sheet on the input voltage and
load current ranges the circuit runs in full frequency.
To synchronize to an external clock, apply the external
clock to the SYNC turret.
Note: When measuring the input or output voltage
ripples, care must be taken to avoid a long ground lead
on the oscilloscope probe. Measure the input or output
voltage ripple by touching the probe tip directly across
the VIN or VOUT capacitor terminals. See Figure 2 for
proper scope probe technique.
Note: The EMI filter is assembled on the bottom layer
of the demo circuit. For EMI test, connect the EMI test
facility to the terminals of VEMI+, and VEMI– with very
short wires.
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dc1949af
DEMO MANUAL DC1949A
Quick start proceDure
Figure 1. Proper Measurement Equipment Setup
V
OUT
OR V
OUT
GND
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
4
dc1949af
DEMO MANUAL DC1949A
Quick start proceDure
LOAD CURRENT (A)
0.6
EFFICIENCY (x100%)
0.75
0.65
0.85
0.95
0.70
0.80
0.90
1 2
DC1939A F03
2.50.50 1.5
5V, VIN = 12V
3.3V, VIN = 12V
FREQUENCY (MHz)
Vertical Polarization
–10
AMPLITUDE (dBuV/m)
5
–5
15
50
0
10
20
25
35
45
30
40
200 400
DC1939A F04a
5001000 300 700 900 1000600 800
DATA
CISPR25 CLASS 5 PK LIMIT
FREQUENCY (MHz)
–10
AMPLITUDE (dBuV/m)
5
–5
15
50
0
10
20
25
35
45
30
40
200 400
DC1939A F04b
5001000 300 700 900 1000600 800
DATA
CISPR25 CLASS 5 PK LIMIT
Horizontal Polarization
Figure 3. Typical Efficiency Curves of HV Bucks, at VIN = 12V
Figure 4. Radiated EMI (Vertical/Horizontal), VIN = 12V, IOUT1,2,3,4 = 1A
(a)
(b)
5
dc1949af
DEMO MANUAL DC1949A
Quick start proceDure
Figure 5. Thermal Image Top View, IOUT1,2,3,4 = 1A, TA = 25°C, fSW = 2MHz
VIN = 12V VIN = 24V
VIN (V)
10
TEMPERATURE RISE (°C)
40
20
60
110
30
50
70
90
80
100
16 26
DC1939A F06
41116 21 3631
1MHz, 1.5A/5V, 1.5A/3.3V,
1A AT 1.8V, 1.2V
2MHz, 1A AT 5V,
3.3V, 1.8V, 1.2V
1MHz, 1A AT 5V,
3.3V, 1.8V, 1.2V
Figure 6. LT8602 Case Temperature Rise, TA = 25°C
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dc1949af
DEMO MANUAL DC1949A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 CPVIN1 Cap., X7R 4.7µF 50V 10% 1206 Murata GRM31CR71H475KA12L
2 1 CPVIN2 Cap., X7R 10µF 50V 10% 1210 Murata ERIE GRM32ER71H106KA12L
3 3 C1, CPVIN3, CPVIN4 Cap., X7R 4.7µF 10V 10% 0805 Murata GRM21BR71A475KA73L
4 1 CVIN Cap., X7R 1µF 50V 10% 0805 TDK C2012X7R1H105KT
5 5 C2, C11, C36, C37, C39 Cap., X7R 0.1µF 50V 10% 0402 TDK CGA2B3X7R1H104K050BB
6 1 C3 Cap., NPO 4.7pF 25V 5% 0603 AVX 06033A4R7JAT2A
7 3 C14, C17, C20 Cap., NPO 27pF 25V 5% 0603 AVX 06033A270JAT2A
8 3 C4, C18, C21 Cap., X5R 47µF 10V 20% 1206 Murata GRM31CR61A476ME15L
9 4 C5, C16, C19, C22 Cap., X7R 0.1µF 50V 10% 0603 Murata GRM188R71H104KA93D
10 1 C6 Cap., Alum 22µF 50V 10% Sun Elect. 50CE22BSS
11 1 C15 Cap., X5R 220µF 4V 20% 1206 Murata GRM31CR60G227ME11L
12 1 C27 Cap., X7R 220pF 25V 10% 0603 AVX 06033C221MAT2A
13 2 C29, C30 Cap., X5R 10µF 50V 10% 1206 Murata CGA5L3X5R1H106K160AB
14 2 C32, C33 Cap., X7R 47nF 25V 20% 0603 AVX 06033C473MAT2A
15 1 FB1 Ferrite Bead, 330Ω TDK Corp. MPZ2012S331AT000
16 1 L1 Inductor, 4.7µH Coilcraft XAL5030-472MEB
17 1 L2 Inductor, 2.2µH Coilcraft XAL5030-222MEB
18 2 L3, L4 Inductor, 1.0µH ±30% NIC Comp. Corp. NPIS42LS1R0YTRF
19 1 L5 Inductor, 0.22µH Vishay, IHLP1212BZERR22M11
20 1 R1 Res., Chip 806k 0.06W 1% 0603 Vishay CRCW0603806KFKEA
21 2 R2, R5 Res., Chip 200k 0.06W 1% 0603 Vishay CRCW0603200KFKEA
22 1 R3 Res., Chip 464k 0.06W 1% 0603 Vishay CRCW0603464KFKEA
23 1 R4 Res., Chip 340k 0.06W 1% 0603 Vishay CRCW0603340KFKEA
24 4 R6, R7, R8, R9 Res., Chip 19.1k 0.06W 1% 0603 Vishay CRCW060319K1FKEA
25 4 R10, R19, R21, R22 Res., Chip 100k 0.06W 1% 0603 Vishay CRCW0603100KFKEA
26 1 R11 Res., Chip 187k 0.06W 1% 0603 Vishay CRCW0603187KFKEA
27 2 R12, R14 Res., Chip 150k 0.06W 1% 0603 Vishay CRCW0603150KFKEA
28 1 R13 Res., Chip 75.0k 0.06W 1% 0603 Vishay CRCW060375K0FKEA
29 1 R16 Res., Chip 10.0k 0.06W 1% 0603 Vishay CRCW060310K0FKEA
30 1 R18 Res., Chip 28.7k 0.06W 1% 0603 Vishay CRCW060328K7FKEA
31 2 R23, R24 Res, Chip 0Ω 0.25W 5A 0603 Vishay CRCW06030000Z0EA
32 1 U1 Buck Regulator QFN(40)(UJ) 6mm × 6mm Linear Tech. Corp. LT8602EUJ#PBF
Additional Demo Board Circuit Components
1 0 R25 (Opt) Res, Chip 0Ω 0.25W 5A 0603 Vishay CRCW06030000Z0EA
2 0 C31, C34 (Opt) Cap., 0603
3 0 C35 (Opt) Cap., 1206
Hardware: For Demo Board Only
15 XJP1, XJP2, XJP3, XJP4, XJP5 Shunt, 2mm Ctrs. Samtec 2SN-BK-G
2 4 MH1-MH4 Stand-Off, Nylon 0.25" Tall Keystone, 8831 (Snap On)
3 21 E1, E2, E3, E4, E5, E6, E7, E8, E9, E10, E11, E12,
E13, E14, E15, E16, E17, E18, E19, E20, E21
Turret, Testpoint Mill Max 2501-2-00-80-00-00-07-0
4 5 JP1, JP2, JP3, JP4, JP5 Headers, 3 Pins 2mm Ctrs. Samtec TMM-103-02-L-S
7
dc1949af
DEMO MANUAL DC1949A
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
(2MHz)
*
NOTE: UNLESS OTHERWISE SPECIFIED.
1. All Resistors 0603.
See Demo Manual for details on VOUT current capability.
2. All Capacitors 0603.
*
See Demo Manual for operation details.
**
**
*
*
*
VOUT1
VOUT2
VOUT3
VOUT4
INTVcc
PG4
PG3
PG2
PG1
VEMI
VIN
INTVcc
VIN
VOUT1 VOUT2 VOUT3 VOUT4
PG2
VOUT2
VOUT2
PG2
VOUT2
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
www.linear.com
4
DEMO CIRCUIT 1949A
Jun 16, 2015 11
42V Quad Monolithic Step-Down
N/A
LT8602EUJ
Regulator with Power-On Reset
DC1949A_02_REV4
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
www.linear.com
4
DEMO CIRCUIT 1949A
Jun 16, 2015 11
42V Quad Monolithic Step-Down
N/A
LT8602EUJ
Regulator with Power-On Reset
DC1949A_02_REV4
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
TECHNOLOGY
Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
www.linear.com
4
DEMO CIRCUIT 1949A
Jun 16, 2015 11
42V Quad Monolithic Step-Down
N/A
LT8602EUJ
Regulator with Power-On Reset
DC1949A_02_REV4
E5 VOUT2
3.3V /
U1
LT8602EUJ#PBF
PVIN2
14
SW3 36
BST1 4
FB1 26
PVIN1
37
SW1 3
GND
8
SW2 6
BST2 5
FB2 25
SYNC 33
FB3 27
SW4 15
FB4 24
RT
29
INTVCC
28
VIN
23
EN/UVLO
22
PG1
1
TRKSS1
21
TRKSS2
20
RUN3
30
RUN4
18
GND
9
GND
2
BIAS
10
PVIN3
34
PVIN4
17
PG2
11
PG3
40
PG4
12
RST
32
N/C
19
GND
13
GND
16
GND
35
GND
38
GND
41
SW2 7
CPOR 31
POREN 39
R13
75.0k
1%
C27
220pF
C32
47nF
X7R
CVIN
1µF
50V
X7R
0805
E18
POREN
L5
0.22µH
IHLP1212BZERR22M11
VISHAY
R22
100k
1%
C1
4.7µF
10V
X7R
0805
JP4
OFF
ON
TRKSS1
1
3
2
R23
0 Ohm
C16
0.IµF
0603
50V
E15
RST
L2
2.2µH
XAL5030-222MEB
Coilcraft
R21
100k
1%
C35
(Opt)
1206
E8
GND
R25
0 Ohm
(Opt)
E1 VOUT1
5V / 1A
JP2
RUN
EXT
RUN3
1
3
2
+
C6
22µF
50V
JP1
ON
OFF
EN/UVLO
1
3
2
C18
47µF
10V
1206
X5R
CPVIN1
4.7µF
50V
X7R
1206
E10 VOUT4
1.2V / 1A
TP1
VIN
E17
RUN3
R19
100k
1%
E20
TRKSS1
C14
27pF
CPVIN3
4.7µF
10V
X7R
0805
C37
0.1µF
50V
0402
JP3
RUN
EXT
RUN4
1
3
2
E19
RUN4
E4
VEMI-
C39
0.1µF
50V
0402
C3
4.7pF
C5
0.IµF
0603
50V
C21
47µF
10V
1206
X5R
R4
340k
1% R3
464k
1%
L3
1.0µH
NIC Comp. Corp.
NPIS42LS1R0YTRF
R24
0 Ohm
C20
27pF
E6
GND
C22
0.IµF
0603
50V
R5
200k
1%
R14
150k
1%
CPVIN2
10µF
50V
X7R
1210
L4
1.0µH
NIC Comp. Corp.
NPIS42LS1R0YTRF
C31
(Opt)
E7 VOUT3
1.8V / 1A
C4
47µF
10V
1206
X5R
CPVIN4
4.7µF
10V
X7R
0805
C33
47nF
X7R
C29
10µF
50V
1206
X5R
R18
28.7k
1%
E13
PG4
TP2
GND
C34
(Opt)
R10
100k
1%
E3
GND
R1
806k
1%
L1
4.7µH
XAL5030-472MEB
Coilcraft
E11
PG2
E12
PG3
FB1
MPZ2012S331AT000
330 Ohm
E21
TRKSS2
E16
SYNC
R9
19.1k
1%
C15
220µF
4V
1206
R11
187k
1%
C17
27pF
R16
10.0k
1%
E14
GND
R8
19.1k
1%
E9
PG1
JP5
OFF
ON
TRKSS2
1
3
2
E2
VEMI+
5.5V - 42V C30
10µF
50V
1206
X5R
R7
19.1k
1%
R2
200k
1%
C11
0.1µF
50V
0402
C2
0.1µF
50V
0402
C36
0.1µF
50V
0402
R6
19.1k
1%
C19
0.IµF
0603
50V
R12
150k
1%
8
dc1949af
DEMO MANUAL DC1949A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2015
LT 0715 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C ) 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 LT C 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.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LT C from all claims
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
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LT C assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LT C currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
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 LT C applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
