DEMO MANUAL DC1730A
LT3973
42V, 750mA Step-Down Regulator
with 2.5µA Quiescent Current
DESCRIPTION
Demonstration circuit 1730A features the LT3973, a mono-
lithic step-down switching regulator which consumes only
2.5μA quiescent current. The demo circuit is designed for
a 5V, 750mA output from a 5.6V to 42V input. The wide
input range of the LT3973 allows a variety of input sources
including automotive batteries and 24V industrial supplies.
In order to reduce the number of components and solution
size, the catch diode and boost diode are integrated. The
switching frequency is adjustable up to 2.2MHz. At light
loads, the regulator operates in Burst Mode
®
to maintain
high efficiency and low output ripple.
The current mode control scheme creates fast transient
response and good loop stability. During short circuit and
overvoltage conditions, the catch diode current is limited
to protect the part. Users can populate R7 and R8 on the
EN/UVLO pin to provide a programmable undervoltage
lockout. In addition, the shutdown feature can be utilized
by placing jumper JP1 in the OFF position.
The LT3973 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
working on or modifying the demo circuit 1730A.
Design files for this circuit board are available at
http://www.linear.com/demo
L,
LT, LTC, LTM, Burst Mode, 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
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
Output Voltage
Maximum Output Current
Typical Switching Frequency
Typical Efficiency
(T
A
= 25°C)
VALUE
5.6V
42V
5.04V±3%
750mA
600kHz
CONDITIONS
V
IN
= 12V, I
OUT
= 750mA
90
84%
80
EFFICIENCY (%)
70
60
50
40
0
0.1
0.2
0.3 0.4 0.5 0.6
LOAD CURRENT (A)
0.7
0.8
dc1730af F01
Figure 1. DC1730A Efficiency: V
IN
= 12V, V
OUT
= 5V, 600kHz
dc1730af
1
DEMO MANUAL DC1730A
QUICK START PROCEDURE
Demonstration circuit 1730A is easy to set up to evalu-
ate the performance of the LT3973. Refer to Figure 2 for
proper measurement equipment setup and follow the
procedure below:
1. Place Jumper JP1 in the ON position.
2. With power off, connect the input power supply to VIN
and GND.
3. With power off, connect load from VOUT to GND.
4. Turn on the power at the input.
NOTE.
Make sure that the input voltage does not exceed
42V.
5. Check for the proper output voltage.
NOTE.
If there is no output, temporarily disconnect the
load to make sure that the load is not set too high or
is shorted.
6. Once the proper output voltages are established, adjust
the loads within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
dc1730af
2
DEMO MANUAL DC1730A
QUICK START PROCEDURE
Figure 2. DC1730A Proper Measurement Equipment Setup
Figure 3. Measuring Input or Output Ripple
V
IN
GND
dc1730af
3
DEMO MANUAL DC1730A
PARTS LIST
ITEM
1
2
3
4
5
6
7
8
9
10
1
2
1
2
3
QTY
1
1
1
1
1
1
1
1
1
1
1
0
6
1
1
REFERENCE
C1
C2
C3
C5
L1
R1
R2
R5
R9
U1
C4
R7-R8
E1-E6
JP1
SHUNT
PART DESCRIPTION
CAP X5R 22μF 6.3V 20% 1206
.,
CAP X5R 0.22μF 10V 20% 0402
.,
CAP X7R 2.2μF 50V 10% 1206
.,
CAP NPO, 10pF, 25V, 10%, 0402
.,
IND, 15μH
RES., CHIP 1.00M, 1/16W, 1%, 0402
,
RES., CHIP 316k, 1/16W, 1%, 0402
,
RES., CHIP 215k, 1/16W, 1%, 0402
,
RES., CHIP 200k, 1/16W, 5%, 0402
,
I.C., Buck Reg. MSE10
CAP ALUMINUM EL. 10μF, 50V
.,
RES., 0402
TURRET, 0.094"
JMP 1X3-079
,
SHUNT, 2mm Ctrs.
MILL-MAX, 2501-2-00-80-00-00-07-0
WÜRTH, 62000311121
WÜRTH, 60800213421
MANUFACTURER/PART NUMBER
TAIYO YUDEN JMK316BJ226ML-T
AVX, 0402ZD224MAT2A
MURATA, GRM31CR71H225KA88L
AVX, 04023A100KAT2A
COOPER/COILTRONICS, MPI4040R3-150-R
NIC, NRC04F1004TRF
NIC, NRC04F3163TRF
NIC, NRC04F2153TRF
NIC, NRC04J204TRF
LINEAR TECH., LT3973EMSE
SUN ELECT, 50CE10BSS
REQUIRED CIRCUIT COMPONENTS
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS
HARDWARE FOR DEMO BOARD ONLY
dc1730af
4
5
4
3
2
1
REVISION HISTORY
ECO
_
2
PRODUCTION
JAINO P.
09-06-11
REV
DESCRIPTION
APPROVED
DATE
D
U1
LT3973EMSE
4
9
3
2
GND
5
GND
11
R5
215k
1%
(600kHz)
R2
316k
1%
RT
OUT
10
FB
EN/UVLO
1
BD
PG
8
R1
1.00M
1%
C5
10pF
BOOST
C2
0.22uF
C1
22uF
6.3V
1206
VIN
7
SW
VOUT
6
L1
15uH
E1
D
VIN E3
5.6V - 42V
C3
2.2uF
50V
1206
E2
VIN
+
C4
VOUT
5V / 750mA
SCHEMATIC DIAGRAM
GND
E4
10uF
50V
GND
SUNCON
50CE10BSS
C
C
PG
E6
R9
200K
EN/UVLO
E5
JP1
ON
OFF
R8
OPT
1
2
3
R7
OPT
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.
B
B
CUSTOMER NOTICE
NOTES: UNLESS OTHERWISE SPECIFIED
APPROVALS
KIM T.
JAINO P.
TECHNOLOGY
TITLE: SCHEMATIC
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
A
A
1. ALL RESISTORS ARE IN OHMS, 0402.
ALL CAPACITORS ARE IN MICROFARADS, 0402.
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APP ENG.
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
42V, 750mA, MICROPOWER BUCK REGULATOR
SIZE
IC NO.
N/A
SCALE = NONE
3
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
4
DEMO CIRCUIT 1730A
DATE:
09/06/2011, 10:10 AM
2
LT3973EMSE
REV.
2
SHEET 1
1
OF 1
5
DEMO MANUAL DC1730A
dc1730af
5
FPGA/CPLD
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
