1
dc1729af
DEMO MANUAL DC1729A
DESCRIPTION
LT3086
40V, 2.1A Low Dropout Adjustable
Linear Regulator with Monitoring
and Cable Drop Compensation
Demonstration circuit 1729A is a 2.1A low dropout adjust-
able linear regulator featuring the LT
®
3086. The device is
designed with multiple features and operates over a wide
1.4V to 40V input supply range. The LT3086 requires only
one resistor to set the output voltage from 0.4V to 32V
and it is stable with ceramic output capacitors requiring
a minimum of 10μF.
The key features of the LT3086 include programmable
cable drop compensation, master/slave configuration for
paralleling of multiple devices for higher load current and
heat spreading, output current and temperature monitor-
ing, and programmable power good flag.
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
The LT3086 is offered in the packages of 16-lead DFN,
16-lead TSSOP, 7-lead DD-PAK, and a 7-lead TO-220.
The LT3086 data sheet gives a complete description of
the device, operation and application information. The data
sheet should be read in conjunction with this quick start
guide for working on or modifying the demo circuit 1729A.
Design files for this circuit board are available at
http://www.linear.com/demo
Specifications are at TA = 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Range VOUT = 1V, IOUT1 = 1mA 1.55 40 V
VOUT Output Voltage Shunt at 1, 2 for JP1 0.97 1 1.03 V
Shunt at 3, 4 for JP1 1.164 1.2 1.236 V
Shunt at 5, 6 for JP1 1.455 1.5 1.545 V
Shunt at 7, 8 for JP1 3.201 3.3 3.399 V
Shunt at 9, 10 for JP1 4.85 5 5.15 V
Shunt at 11, 12 for JP1 and R10 Stuffed as 232k 11.64 12 12.36 V
IOUT Maximum Output Current (Note 1) 2.1 A
Note 1: The maximum output current 2.1A is when the internal current
limit is active and when VIN-VOUT is smaller than 9V. For the maximum
output current under other conditions, please refer to the data sheet.
2
dc1729af
DEMO MANUAL DC1729A
QUICK START PROCEDURE
Figure 2. Measuring Input or Output Ripple
Figure 1. DC1729A Proper Equipment Setup
Demonstration circuit 1729A is easy to set up to evalu-
ate the performance of the LT3086. Refer to Figure 1 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 ter-
minals of the input or output capacitors. See Figure 2 for
proper scope probe technique.
1. Use JP1 to set the desired output voltage.
2. With power off, connect the input power supply to VIN
and GND.
3. Turn on the power at the VIN.
Note: Make sure that the VIN voltage does not exceed 40V.
4. Check for the proper output voltages:
Note: If there is no output, temporarily disconnect the
load to make sure that the load is not set too high or
is shorted.
5. Once the proper output voltages are established, adjust
the loads within the operating range and observe
the output voltage regulation, efficiency and other
parameters.
Note: Make sure that the power dissipation is limited
below the thermal limit.
GNDVIN OR VOUT
3
dc1729af
DEMO MANUAL DC1729A
THERMAL IMAGE
An example thermal image shows the temperature distri-
bution on the board. The test is done in still air at room
temperature with 2.2W power dissipation in the LT3086.
This gives the IC case-to-ambient thermal resistance
θJA = 23°C/W on the demo board.
Figure 3. Temperature Rise at 2.2W Dissipation
The cable drop compensation on the DC1729A can be
turned on by placing R4 (RCDC) with a value which is gov-
erned by the following equation provided in the data sheet:
RCDC =
R
MON
•R
SET
3000 •R
WIRE
Please note that when cable drop compensation is activated,
it also changes the power good threshold. R23 needs to
be the same value as R4 in order to keep the same output
voltage power good threshold at the load.
CABLE DROP COMPENSATION
POWER GOOD SETTING
The power good setting jumper JP2 on the DC1729A is
used for setting the power good threshold for the cor-
responding output voltages. JP2 needs to be configured
at the same position as JP1 for any specific output volt-
ages. For example, when JP1 is configured on 7 and 8 for
3.3VOUT, JP2 also needs to be configured on 7 and 8 for
the correct power good setting for 3.3VOUT.
4
dc1729af
DEMO MANUAL DC1729A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C1 CAP., X7R, 10µF 50V, 10%, 1210 MURATA, GRM32ER71H106KA12L
2 1 C2 CAP., X5R, 22µF 16V, 10%, 1206 AVX, 1206YD226KAT2A
3 1 C3 CAP., X7R, 10nF 25V, 10%, 0603 AVX, 06033C103KAT2A
4 2 R1, R12 RES., CHIP, 100k, 1/16W, 1% 0603 VISHAY, CRCW0603100KFKEA
5 1 R3 RES., CHIP, 357Ω, 1/16W, 1% 0603 VISHAY, CRCW0603357RFKEA
6 1 R5 RES., CHIP, 12.1k, 1/16W, 1% 0603 VISHAY, CRCW060312K1FKEA
7 1 R6 RES., CHIP, 16.2k, 1/16W, 1% 0603 VISHAY, CRCW060316K2FKEA
8 1 R7 RES., CHIP, 22.1k, 1/16W, 1% 0603 VISHAY, CRCW060322K1FKEA
9 1 R8 RES., CHIP, 57.6k, 1/16W, 1% 0603 VISHAY, CRCW060357K6FKEA
10 1 R9 RES., CHIP, 90.9k, 1/16W, 1% 0603 VISHAY, CRCW060390K9FKEA
11 1 R14 RES., CHIP, 82.5k, 1/16W, 1% 0603 VISHAY, CRCW060382K5FKEA
12 1 R15 RES., CHIP, 51.1k, 1/16W, 1% 0603 VISHAY, CRCW060351K1FKEA
13 1 R16 RES., CHIP, 19.1k, 1/16W, 1% 0603 VISHAY, CRCW060319K1FKEA
14 1 R17 RES., CHIP, 13.7k, 1/16W, 1% 0603 VISHAY, CRCW060313K7FKEA
15 1 R18 RES., CHIP, 10k, 1/16W, 1% 0603 NIC, NRC06F1002TRF
16 1 R20 RES., CHIP, 1.1k, 1/16W, 1% 0603 VISHAY, CRCW06031K10FKEA
17 1 U1 I.C., LT3086EFE, TSSOP16EFE-BB LINEAR TECH., LT3086EFE
Additional Demo Board Circuit Components
1 0 C4 CAP., OPT 0603
2 1 C5 CAP., SMT, 10µF 50V, 50CE10BSS SANYO, 50CE10BSS
3 0 R2, R4, R10, R11, R13, R19, R21, R23 RES., CHIP, OPT 0603 OPT
4 0 R22 RES., CHIP, OPT 0805 OPT
Hardware-For Demo Board Only
1 9 E1, E2, E3, E4, E5, E6, E7, E8, E9 TP, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0
2 2 JP1, JP2 JMP, 2X6, 0.079" SULLINS, NRPN062PAEN-RC
3 1 JP3 JMP, 1X2, 0.079" SULLINS, NRPN021PAEN-RC
4 2 XJP1, XJP2 SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G
5
dc1729af
DEMO MANUAL DC1729A
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
TECHNOLOGY
TECHNOLOGY
TECHNOLOGY
+
+
6
dc1729af
DEMO MANUAL DC1729A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2013
LT 1113 • 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
