Linear Technology DC1883A Quick setup guide
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dc1883Af
DEMO MANUAL DC1883A
Description
LTC3103EDD
1.8µA Quiescent Current, 15V,
300mA Synchronous Step-Down
DC/DC Converter
DemonstrationCircuit1883AfeaturestheLTC
®
3103, a high
efficiency, monolithic synchronous step-down converter
using a current mode architecture capable of supplying
300mA of output current. The IC operates with a fixed
frequency oscillator at 1.2MHz.
The LTC3103 has two user selectable (JP2) operating
modes: Burst Mode
®
operation and forced continuous
operation (fixed frequency PWM). The IC has internal
compensation and an accurate programmable RUN pin.
The LTC3103 operates with a 2.5V to 15V input voltage
range. The demo board has been designed with a main
output set to 1.8V. Since the LTC3103 is a buck converter,
as VIN approaches VOUT, the output will start dropping out
of regulation. Consult the data sheet for information on
the minimum VIN to VOUT differential for regulation. The
regulation range is also a function of the load current.
Typical demo board efficiency is shown in Figures 1 and 2.
The LTC3103 data sheet has detailed information about
the operation, specification and applications of the part.
The data sheet should be read in conjunction with this
Quick Start Guide.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
performance summary
(TA= 25°C)
PARAMETER CONDITIONS TYPICAL VALUE
Input Voltage Range (See Note 1) 2.5V to 15V
VOUT (See Note 1) 1.8V
IOUT 300mA
Note 1. The demo board can operate with VIN less than VOUT, however VOUT will drop out of regulation. The regulation range is a function of IOUT. Please
refer to the data sheet for more information.
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DEMO MANUAL DC1883A
Quick start proceDure
Using short twisted-pair leads for any power connections
and with all loads and power supplies off, refer to Figure3
for the proper measurement and equipment setup. The
battery/power supply (PS1) should not be connected to
the circuit until it is stated in the following procedure.
When measuring the input or output voltage ripple, care
must be taken to avoid a long ground lead on the oscil-
loscope 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), or by using an oscil-
loscope probe tip jack.
1. Jumper, PS1 and LOAD settings to start:
PS1 = OFF
JP1 (RUN) = OFF
JP2 (MODE) = FIXED FREQUENCY
2. With power off, connect the power supply (PS1) as
shown in Figure 3. If accurate current measurements
are desired (for efficiency calculation for example),
then connect an ammeter in series with the supply as
shown. The ammeter is not required, however.
3. Connect a load to VOUT, as shown in Figure 3. The load
can be up to 300mA or 6Ω for VOUT = 1.8V. Connect an
ammeter if accuratecurrentmeasurementormonitoring
is desired.
4. Turn on PS1 and slowly increase voltage until the volt-
age at VIN is 5V. Move Jumper JP1 to ON.
5. Verify VOUT is ~1.8V.
6. VIN can now be varied between 3V and 15V. VOUT should
remain in regulation.
7. VIN can also be varied down to 2.5V. For VIN ≤ 3V,
VOUT may drop out of regulation, as previously de-
scribed.
8. IOUT can also be varied from 0mA to 300mA.
9. For Burst Mode operation, move jumper JP2 to BURST.
See the data sheet for more information.
NOTES:
(1) If VOUT drops out of regulation, check to be sure
themaximumloadhasnotbeenexceeded,orthatVIN is
not below the minimum value for regulation (see
the data sheet).
(2) To measure no-load input current, remove R4.
VIN (V)
3
50
EFFICIENCY (%)
55
65
70
75
100
85
711 13
60
90
95
80
5915
dc1883a F01
300mA LOAD
100mA LOAD
VIN (V)
3
50
EFFICIENCY (%)
55
65
70
75
100
85
711 13
60
90
95
80
5915
dc1883a F02
5mA LOAD
1mA LOAD
10mA LOAD
Figure 1. DC1883A Efficiency in PWM Mode Figure 2. DC1883A Efficiency in Burst Mode Operation
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DEMO MANUAL DC1883A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C1 CAP CER, 10µF, 25V, X5R, 1210 TDK, C3225X5R1E106M
2 3 C2, C4, C6 CAP CER, 1µF, 25V, X5R, 0603 TDK, C1608X5R1E105M
3 1 C3 CAP CER, 22µF, 10V, X5R, 20%, 1206 TDK, C3216X5R1A226M
4 1 C7 CAP CER, 12pF, 50V, C0G 5%, 0603 TDK, C1608C0G1H120J
5 1 C8 CAP CER, 0.1µF, 50V, X7R, 0603 TDK, C1608X7R1H104M
6 1 L1 Inductor, 15µH Coilcraft, LPS4018-153MLB
7 1 R1 RES, 2MΩ, 1/10W, 1%, 0402, SMD Panasonic, ERJ-2GEJ205X
8 1 R2 RES, 2.21kΩ, 1/10W, 1%, 0402, SMD Panasonic, ERJ-2RKF2211X
9 4 R3, R4, R5, R6 RES, 1MΩ, 1/10W, 1%, 0402, SMD Panasonic, ERJ2RKF1004X
10 1 U1 LTC3103EDD Linear Technology Corporation, LTC3103EDD
Additional Demo Board Circuit Components
1 0 C5 (OPT) CAP CER, 1000pF, 50V, X7R, 20%, 0603 OPT
2 0 C9 (OPT) OPT CAP TANT, 68µF, 20V, 10%, SMD, 7343 OPT
3 0 R9 OPT RES, 1/10W, 1%, 0402, SMD OPT
Hardware—for Demo Board Only
1 5 E1, E2, E3, E4, E5 Testpoint, Turret 0.094" Mill-Max, 2501-2-00-80-00-00-07-0
2 2 JP1, JP2 JMP, 0.079” Single Row Header, 30-Pin Samtec, TMM-103-02-L-S
3 2 XJP1, XJP2 Shunt, 0.079" Center Samtec, 2SN-BK-G
4 4 (Stand-Offs) Stand-Off, Nylon, 0.375" Tall Keystone, 8832 (Snap on)
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dc1883Af
DEMO MANUAL DC1883A
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
Figure 5. Circuit Schematic
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dc1883Af
DEMO MANUAL DC1883A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ●FAX: (408) 434-0507 ●www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2011
LT 1211 • 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.
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 applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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