DC1869A - Demo Manual

DEMO MANUAL DC1869A
LT3667
40V Step-Down Regulator
with Dual LDOs
Description
Demonstration circuit 1869A is a triple power supply including one 400mA step-down regulator and two 200mA low
dropout linear regulators (LDOs) featuring the LT®3667. The
demo circuit is designed for 5.0V, 3.3V and 2.5V outputs
from a 6V to 40V input. Two LDO outputs are configured
as post-regulators of the switching regulator output. The
total current capability of three output channels is up to
400mA in this configuration, while the two LDO regulators
are capable of 200mA each.
The LT3667 internal boost diode and loop compensation
reduce the components count and solution size. The current mode control scheme creates fast transient response
and good loop stability. The switching regulator has cycleby-cycle current limit and diode current sense, providing
protection against shorted outputs.
The switching frequency of the step-down regulator can be
programmed either via a oscillator resistor over a 250kHz
to 2.2MHz range or an external clock over a 300kHz to
2.2MHz range. When the circuit is synchronized to an
external clock connected to the SYNC terminal, the RT
resistor (R8) should be chosen to set the LT3667 internal
switching frequency at least 20% below the final SYNC
frequency.
The LT3667 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 DC1869A. Proper board layout is essential for
both proper operation and maximum thermal performance.
See the PCB Layout section in the data sheet.
JP1 can be used to set the whole LT3667 in shutdown
mode. JP3 and JP4 enable and disable the 2.5V LDO output
and 3.3V LDO output respectively.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1869A
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
SYMBOL
PARAMETER
VIN1
Input Supply Range of VIN1
fSW
Switching Frequency
VOUT1
Specifications are at TA = 25°C
CONDITIONS
MIN
TYP
MAX
UNITS
6
40
V
VIN1 = 12V, VOUT1 = 5V/IOUT1 = 400mA
VOUT2 = 2.5V/IOUT2 = 0mA
VOUT3 = 3.3V/IOUT3 = 0mA
510
690
kHz
Output Voltage 1
VIN1 = 12V, VOUT1 = 5V/IOUT1 = 0mA to 400mA
VOUT2 = 2.5V/IOUT2 = 0mA
VOUT3 = 3.3V/IOUT3 = 0mA
4.9
5.1
V
VOUT2
Output Voltage 2
VIN1 = 12V, VOUT1 = 5V/IOUT1 = 0mA
VOUT2 = 2.5V/IOUT2 = 0mA to 190mA
VOUT3 = 3.3V/IOUT3 = 0mA
2.43
2.57
V
VOUT3
Output Voltage 3
VIN1 = 12V, VOUT1 = 5V/IOUT1 = 0mA
VOUT2 = 2.5V/IOUT2 = 0mA
VOUT3 = 3.3V/IOUT3 = 0mA to 190mA
3.21
3.39
V
IOUT1 + IOUT2 + IOUT3
Maximum Total Output Current
IN2 and IN3 are powered by VOUT1
400
IOUT2, IOUT3
Maximum LDO Output Current
190
mA
200
mA
dc1869af
1
DEMO MANUAL DC1869A
Quick Start Procedure
90
80
VIN1 = 24V
EFFICIENCY (%)
70
VIN1 = 12V
60
50
40
30
VOUT1 = 5V
fSW = 600kHz
IOUT2 = 0
IOUT3 = 0
20
10
0
0
0.1
0.2
0.3
LOAD CURRENT (A)
0.4
DC1869A F01
Figure 1. VOUT1 Typical Efficiency vs Load Current
+
VIN1
–
+
+
–
–
–
VOUT2
VOUT1
+
–
+
–
+
–
LOAD
+
–
+
–
LOAD
+
VOUT3
–
+
–
+
–
+
LOAD
Figure 2. Proper Measurement Equipment Setup
2
dc1869af
DEMO MANUAL DC1869A
Quick Start Procedure
Demonstration circuit 1869A is easy to set up to evaluate the performance of the LT3667. Refer to Figure 2 for
proper measurement equipment setup and follow the
procedure below:
NOTE: When measuring the input or output voltage ripple,
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 and GND terminals. See Figure 3 for the proper
scope technique.
1.Place JP1, JP3 and JP4 on the EN position. Place JP2
on the RT position.
2.With power off, connect the input power supply to VIN1
and GND.
3.With power off, connect loads from VOUT1 to GND, from
VOUT2 to GND, and from VOUT3 to GND.
4.Turn on the power at the input.
NOTE: Make sure that the input voltage do not exceed
40V.
5.Check for the proper output voltages:
VOUT1 = 5V, VOUT2 = 2.5V, VOUT3 = 3.3V
NOTE. If there is no output, temporarily disconnect the
load to make sure that the loads are not set too high or
are shorted.
6.Once the proper output voltages are established, adjust
the loads within the operating ranges and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
7.An external clock can be added to the SYNC terminal
when SYNC function is used (JP2 on the SYNC position).
Please make sure that RT should be set to provide a
frequency at least 20% below the final SYNC frequency.
See the Synchronization section in the data sheet.
Figure 3. Measuring Input or Output Ripple
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3
DEMO MANUAL DC1869A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C2
CAP., X7S 2.2µF 100V 20% 1206
TDK C3216X7S2A225M
2
1
C3
CAP., X7R 0.22µF 25V 10% 0603
AVX 06033C224KAT2A
3
1
C4
CAP., NPO 22pF 25V 5% 0603
AVX 06033A220JAT2A
4
1
C5
CAP., X5R 22µF 10V 20% 0805
TAIYO YUDEN LMK212BJ226MG-T
5
2
C7, C11
CAP., X7R 4.7µF 10V 10% 0805
TAIYO YUDEN LMK212B7475KG-T
6
2
C9, C10
CAP., X5R 1µF 16V 10% 0603
TAIYO YUDEN EMK107BJ105KA-T
7
1
D1
SCHOTTKY DIODE 1A/60V POWERDITM123
DIODES INC. DFLS160-7
8
1
L1
INDUCTOR, 22µH
SUMIDA CDRH4D22HPNP-220MC
9
1
R1
RES., CHIP 1M 0.10W 5% 0603
VISHAY CRCW06031M00JNEA
10
4
R3, R5, R11, R16
RES., CHIP 150k 0.10W 5% 0603
VISHAY CRCW0603150KJNEA
11
1
R7
RES., CHIP 931k 0.10W 1% 0603
VISHAY CRCW0603931KFKEA
12
1
R8
RES., CHIP 174k 0.10W 1% 0603
VISHAY CRCW0603174KFKEA
13
1
R9
RES., CHIP 294k 0.10W 1% 0603
VISHAY CRCW0603294KFKEA
14
1
R13
RES., CHIP 340k 0.10W 1% 0603
VISHAY CRCW0603340KFKEA
15
2
R14, R17
RES., CHIP 158k 0.10W 1% 0603
VISHAY CRCW0603158KFKEA
16
1
R15
RES., CHIP 499k 0.10W 1% 0603
VISHAY CRCW0603499KFKEA
17
1
U1
I.C., VOLTAGE REG. QFN(24) (UDD) 3mm × 5mm
LINEAR TECH. CORP. LT3667EUDD#PBF
Additional Demo Board Circuit Components
1
1
C1
CAP., ALUM 10µF 63V 20% OSCON-CE-6.3
SUN ELECTRONIC INDUSTRIES 63CE10GA
2
1
C6
CAP., X7R 0.1µF 16V 10% 0603
AVX 0603YC104KAT2A
3
0
C8, C12 (OPT)
CAP., 0603
4
2
C13, C14
CAP., X7R 47nF 25V 20% 0603
5
0
C15, C16 (OPT)
CAP., 1206
6
0
C17 (OPT)
CAP., X7R 10pF 25V 10% 0603
AVX 06033C100KAT2A
7
0
FB1 (OPT)
FERRITE BEAD, 600Ω/500mA 0603
TDK MMZ1608S601AT
8
0
L2 (OPT)
INDUCTOR, 4.7µH
SUMIDA CDRH2D18/LDNP-4R7NC
9
3
R2, R6, R18
RES./JUMPER, CHIP 0Ω 0.1W 5A 0603
VISHAY CRCW06030000Z0EA
10
0
R4 (OPT)
RES., 0603
11
2
R10, R12
RES., CHIP 1.50k 0.10W 1% 0603
VISHAY CRCW06031K50FKEA
12
1
R19
RES., CHIP 200k 0.10W 1% 0603
VISHAY CRCW0603200KFKEA
13
1
R20
RES., CHIP 100k 0.10W 1% 0603
VISHAY CRCW0603100KFKEA
14
0
R21 (OPT)
RES., CHIP 10k 0.10W 5% 0603
VISHAY CRCW060310K0JNEA
AVX 06033C473MAT2A
Hardware: For Demo Board Only
4
1
17
E1-E17
TURRET, TESTPOINT
MILL-MAX 2501-2-00-80-00-00-07-0
2
4
JP1, JP2, JP3, JP4
HEADERS, 3 PINS 2mm CTRS.
SULLINS NRPN031PAEN-RC
3
4
XJP1, XJP2, XJP3, XJP4
SHUNT, 2mm CTRS.
SAMTEC 2SN-BK-G
4
4
MH1, MH2, MH3, MH4
STAND-OFF, NYLON 0.25" TALL
KEYSTONE 8831(SNAP ON)
dc1869af
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
A
B
C
EN
DIS
DIS
EN
3
2
1
3
2
1
VIN1_EMI
JP3
EN2
JP1
ENABLE
MMZ1608S601AT
0603
(OPT)
3
2
1
10pF
(OPT)
C17
174k
1%
fs=600kHz
10k
(OPT)
47nF
C14
1.50k
1%
4.7uH
C16 CDRH2D18/LDNP-4R7NC
Sumida
1206
(OPT)
(OPT)
L2
+
C1
10uF
63V

R8

R21
R12
150k
R5

100k
1%
200k
1%
JP4
EN3
3
2
1

EN
DIS
JP2
R20
FB1
E7
E5
MODE
R19
RT
SYNC
SYNC
PG
GND
5
*
4
1. ALL RESISTORS 0603.
2. ALL CAPACITORS 0603.
SEE DEMO MANUAL FOR CURRENT CAPABILITY.
NOTE: UNLESS OTHERWISE SPECIFIED.
C15
1206
(OPT)
E15
47nF
C13
1.50k
1%
R10

E8
C2
2.2µF
100V
1206
EN3/ILIM3
R17
158k
1%
R15
499k
1%
13
14
11
15
10
23
24
L1
22uH
R14
158k
1%
C9
1µF
16V
R18
340k
1%
R13
0 Ohm
R6
IN2
0 Ohm
D1
DFLS160-7
CDRH4D22HPNP-220MC
R9
294k
1%
0.22µF
CUSTOMER NOTICE
C10
1µF
16V
IN3
FB2
R2
0 Ohm
C3
3
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
C:\PADS PROJECTS\1869A(LT3776EUDD)\SCH\1869A_08_REV3.DSN
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.
C11
4.7µF
10V
0805
PG2
IN2
FB1
DA
SW
OUT2


EN2/ILIM2
SYNC
RT
PG
EN
21
22 NC
NC
17
16
2
4
18
3
(OPT)
R4
R1
1M
19
UVLO1
GND
25

20
IN1
FB3
8
E1
VIN1
6V TO 40V
TRANSIENT TO 60V
E3
GND
OUT3
7
D
9
PG1
3
1
BOOST
IN3
6
4
5
BD
PG3
12
5
C7
4.7µF
10V
0805
2
SCALE = NONE
APP ENG.
PCB DES.
E14
E13
E12
E17
E11
E10
E9
E16
E6
E4
*
GND
VOUT3
3.3V / 200mA
PG3
IN3
GND
VOUT2
2.5V / 200mA
PG2
IN2
GND
VOUT1
5V /
PG1


 www.linear.com


C12
TBD
R16
150k
C8
TBD
R11
150k
C6
0.1µF
16V
R3
150k
E2
1
MODIFY DATE:
IC NO.

17:00:05
1


SHEET
1
OF
3
1
REV.
40V STEP-DOWN REGULATOR WITH DUAL LDOS

SIZE



TECHNOLOGY
TITLE: SCHEMATIC
C5
22µF
10V
0805
APPROVALS
931k
1%
22pF
R7
C4
2
A
B
C
D
DEMO MANUAL DC1869A
Schematic Diagram
dc1869af
5
DEMO MANUAL DC1869A
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.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC 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. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC 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 LTC application engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
6
dc1869af
Linear Technology Corporation
LT 0914 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2014
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