DC1832A - Demo Manual

DEMO MANUAL DC1832A
LT3995
60V, 3A, 2MHz Step-Down
Switching Regulator with
2.7µA Quiescent Current
Description
Demonstration circuit 1832A is a monolithic step-down
DC/DC switching regulator featuring the LT3995. The
LT3995 is a compact, high efficiency monolithic step-down
switching regulator that consumes only 2.7μA of quiescent
current. The demo circuit is designed for 3.3V, 3A output
from a 4.3V to 60V input. The switching frequency can be
programmed either via oscillator resistor or external clock
up to 2MHz. To synchronize to an external clock, move
JP2 to SYNC and apply the external clock to the SYNC
turret. The RT resistor (R5) should be chosen to set the
LT3995 internal switching frequency at least 20% below
the lowest synchronization input frequency.
Low ripple Burst Mode® operation increases the efficiency at the light load while keeping the output ripple
below 15mV. The SYNC pin on the demo board is grounded
by default by setting JP2 at RT FREQ for low ripple
Burst Mode operation. Figure 1 shows the demo board
efficiency at 12V input voltage.
The LT3995 is in shutdown when the EN pin is low and
active when the pin is high. The threshold of the EN pin
is accurate at 1.02V with 60mV of hysteresis. Users can
populate R7 and R8 to provide a programmable under
The demo board has an EMI filter installed. The EMI
performance of the demo board at 12V input voltage is
shown on Figure 2. The limit in Figure 2 is EN55022 Class
B. The figure shows the circuit passes the test with a wide
margin. To use the EMI filter, the input should be tied to
VEMI not VIN.
The LT3995 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this demo manual
for demo circuit 1832A. The LT3995 is assembled in a 16lead plastic MSOP package with an exposed pad for low
thermal resistance. Proper board layout is essential for
both proper operation and maximum thermal performance.
See the data sheet sections for details.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
70
85
60
10dB/DIV LOG, REF 70.00dBµV
90
80
EFFICIENCY (%)
voltage lockout. A low dropout voltage of 500mV is maintained when the input voltage drops below the programmed
output voltage. During a short-circuit fault, the LT3995
has current limit foldback to limit the power dissipation.
75
70
65
60
55
50
45
40
TRACE 1 PASS
50
40
30
20
10
0
–10
–20
0
0.5
1.5
2
1
LOAD CURRENT (A)
3
2.5
dc1832a F01
–30
START 150kHz
RES BW (CISPR) 9kHz
VBW 62kHz
STOP 30.00 MHz
SWEEP 717ms (6637pts)
dc1832a F02
Figure 1. LT3995 Efficiency vs Load Current,
12VIN to 3.3VOUT Efficiency
Figure 2. LT3995 Demo Board EMI Performance
(Switching Frequency = 300kHz, VIN = 12V)
dc1832af
1
DEMO MANUAL DC1832A
Performance Summary
PARAMETER
Specifications are at TA = 25°C
CONDITIONS
Guaranteed Minimum Input Voltage
VALUE
4.3V
Maximum Input Voltage
60V
Output Voltage VOUT
VIN = 4.3V ~ 60V
3.275V ± 3%
Switching Frequency
RT = 182k
300kHz ± 20%
Guaranteed Maximum Output Current IOUT
VIN = 4.3V ~ 60V
3A
Typical Efficiency
VIN = 12V, IOUT = 3A
82.2%
Typical Output Voltage Ripple
VIN = 12V, IOUT = 3A
11mV
Quick Start Procedure
Demonstration circuit 1832A is easy to set up to evaluate the performance of the LT3995. Refer to Figure 3
for proper measurement equipment setup and use the
following procedure.
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 4 for the proper
scope technique.
1. Place JP1 on the ON position.
2. Place JP2 on the RT FREQ position.
3. With power off, connect the input power supply to VIN
and GND. Make sure that the input voltage does not
exceed 60V.
4. With power off, connect load from VOUT to GND.
5. Turn on the power at the input.
6. Check for the proper output voltage (3.3V).
NOTE. If there is no output, temporarily disconnect the
load to make sure that the load is not set too high or
is shorted.
7. Once the proper output voltage is established, adjust
the load within the operating ranges and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
8. An external clock can be added to the SYNC terminal
when SYNC function is used (JP2 on the SYNC position). Please make sure that the SYNC frequency is at
least 20% higher than the set switching frequency.
See the data sheet Synchronization section.
dc1832af
2
DEMO MANUAL DC1832A
Quick Start Procedure
Figure 3. Proper Measurement Equipment Setup
Figure 4. Measuring Input or Output Ripple
dc1832af
3
DEMO MANUAL DC1832A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
CAP., X5R, 47µF, 10V, 20%, 1210
TDK, C3225X5R1A476M
Required Circuit Components
1
2
C1, C8
2
1
C2
CAP., X5R, 0.47µF, 25V, 10%, 0603
TDK, C1608X5R1E474M
3
2
C3, C7
CAP., X7R, 2.2µF, 100V, 10%,1210
TDK, C3225X7R2A225M
4
1
C5
CAP., C0G, 10pF, 50V, 10%, 0402
TDK, C1005C0G1H100D
5
1
C6
CAP., X7R, 10nF, 25V, 10%, 0402
TDK, C1005X7R1E103K
6
1
C11
CAP., X5R, 1µF, 10V, 10%, 0603
TDK, C1608X5R1A105K
7
1
C12
CAP., X7R, 0.1µF, 100V, 10%, 0603
MURATA, GRM188R72A104KA35D
8
1
D1
DIODE, PDS360 PowerDi5
DIODE INC., PDS360
9
1
L1
IND, 8.2µH
COILCRAFT, XAL6060-822ME
10
1
R1
RES., CHIP, 1.00M, 1/16W, 1%, 0402
NIC, NRC04F1004TRF
11
1
R2
RES., CHIP, 576k, 1/16W, 1%, 0402
NIC, NRC04F5763TRF
12
1
R5
RES., CHIP, 182k, 1/16W, 1%, 0402
NIC, NRC04F1823TRF
13
1
R6
RES., CHIP, 200k, 1/16W, 1%, 0402
NIC, NRC04F2003TRF
14
1
U1
I.C., LT3995EMSE, MSE16
LINEAR TECHNOLOGY, LT3995EMSE
Additional Demo Board Circuit Components
1
1
C4
CAP., ALUM., 100µF, 100V, 10%
SUN ELECT, 100CE100KXT
2
2
C9, C10
CAP., X7R, 2.2µF, 100V, 10%, 1210
TDK, C3225X7R2A225M
3
1
C13
CAP., HVP SERIES, 33µF, 63V, 20%
SUNCON, 63HVP33M
4
1
L2
IND, 1.0µH
VISHAY, IHLP-1616BZER1R0M01
5
1
L3
IND, 3.3µH
VISHAY, IHLP-2020BZER3R3M01
6
0
R7,R8
RES., 0603
OPT
Hardware: For Demo Board Only
1
7
E1, E2, E3, E4, E5, E6, E7 TURRET, 0.094"
MILL-MAX, 2501-2-00-80-00-00-07-0
2
2
E8, E9
TESTPOINT, TURRET, 0.061" PBF
MILL-MAX, 2308-2-00-80-00-00-07-0
3
2
JP1, JP2
JMP, 1X3-079
SAMTEC, TMM-103-02-L-S
4
2
XJP1, XJP2
SHUNT, 2mm CTRS.
SAMTEC, 2SN-BK-G
dc1832af
4
EN/UVLO
PG
GND
VIN
4.3V - 60V
E5
E6
E4
E3
SUNCON
100CE100KXT
100uF
100V
+ C4
VIN
OFF
ON
JP1
C3
2.2uF
100V
1210
1
2
3
C7
2.2uF
100V
1210
R8
OPT
0603
R7
OPT
0603
C12
0.1uF
100V
0603
R6
200K
C6
10nF
2
13
15
GND
VEMI
SS
EN
PG
10
11 VIN
12 VIN
VIN
E9
E8
8
NC
17
GND
SW
SW
SW
RT
SYNC
FB
OUT
BOOST
C9
2.2uF
100V
1210
9
NC
U1
LT3995EMSE
R5
182k
1%
(300kHz)
C2
0.47uF
0603
33uF
63V
63HVP33
+ C13
R2
576k
1%
R1
1.00M
1%
VIN
3
2
1
JP2
E7
E2
C11 E1
1uF
10V
0603
RT FREQ
SYNC
C8
47uF
10V
1210
SYNC
GND
VOUT
3.3V / 3A
1. ALL RESISTORS ARE IN OHMS, 0402.
ALL CAPACITORS ARE IN MICROFARADS, 0402.
C5
10pF
C1
47uF
10V
1210
VOUT
NOTE: UNLESS OTHERWISE SPECIFIED
L3
3.3uH
IND-IHLP2020BZ-01
D1
PDS360
1
2
3
L2
1.0uH
IND-IHLP1616BZ-01
C10
2.2uF
100V
1210
14
16
1
3
4
5
6
7
L1
8.2uH
DEMO MANUAL DC1832A
Schematic Diagram
dc1832af
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.
5
DEMO MANUAL DC1832A
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
dc1832af
6
Linear Technology Corporation
LT 0513 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2013
Similar pages