Linear Technology DC1855A Quick setup guide

1
dc1855af
DEMO MANUAL DC1855A
Description
LT3030
Dual 750mA/250mA
Low Dropout, Low Noise,
Micropower Linear Regulator
Demonstration circuit 1855A is a dual, micropower, low
noise and low dropout voltage linear regulator featuring
the LT3030. The input voltages are independent for each
channel of DC1855A and can range from 2.2V to 20V.
Each channel has a jumper that sets the output voltage to
either 1.5V, 1.8V, 2.5V, 3.3V, 5V or a voltage that is user
programmed by the installation of a resistor. For channel 1
and channel 2, the maximum output currents are 750mA
and 250mA and the ceramic output capacitors are 22µF
and 10µF respectively. The internal reference of each
channel is bypassed with a 10nF capacitor for reduced
output noise. Each channel has a jumper for shutdown
and a terminal for PWRGD that is pulled up to the input
supply. A resistor divider can be easily added that allows
precise lockout at low input voltages.
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 LT3030 is well suited to applications that require
sequencing between dual regulator channels, particu-
larly microprocessor systems and instrumentation that
require low noise. Systems with batteries will benefit
from the low dropout of the LT3030 and its micropower
operation. DC1855A features the LT3030 in a 28-lead
4mm ×5mm QFN package. The LT3030 data sheet must
be read in conjunction with this demo manual to properly
use or modify demo circuit DC1855A.
Design files for this circuit board are available at
http://www.linear.com/demo
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Input Voltage, VIN VOUT = 1.8V 2.2 V
Maximum Input Voltage, VIN 20 V
Output Voltage, VOUT VOUT SELECT = 1.5V
VOUT SELECT = 1.8V
VOUT SELECT = 2.5V
VOUT SELECT = 3.3V
VOUT SELECT = 5V
1.48
1.77
2.45
3.21
4.86
1.53
1.83
2.56
3.37
5.12
V
V
V
V
V
Maximum Channel 1 Output Current, IOUT1 VIN1 = 3.3V, VOUT1 =1.8V 750 mA
Maximum Channel 2 Output Current, IOUT2 VIN2 = 3.3V, VOUT2 =1.8V 250 mA
Specifications are at TA= 25°C
Downloaded from Arrow.com.

2
dc1855af
DEMO MANUAL DC1855A
Quick start proceDure
It is easy to set up demonstration circuit DC1855A to
evaluate the performance of the LT3030. Refer to Figure 1
for the proper measurement equipment setup and follow
the procedure below:
1. With the input supplies and loads off and turned down,
make all connections according to Figure 1. Set the
output voltages for channels 1 and 2 with the VOUT
SELECT jumpers. Make sure the VOUTEN jumpers are
in the ON positions.
2. Turn on the input supplies and increase them to the
desired input voltages.
NOTE WHEN SETTING THE INPUT VOLTAGE: An input
voltage that is too close to the programmed output volt-
age (too low) may cause dropout operation and a loss
of output voltage regulation. An input voltage that is too
high above the output may increase power dissipation to
an unacceptable level. Finally, a protection feature within
the LT3030 reduces output current capability at higher
input voltages.
3. Increase the loads to the desire output current. Verify
that the output voltages are as programmed by the
VOUT SELECT jumpers.
NOTE: If an output voltage is low, temporarily disconnect
the load to make sure that it is not set too high.
4. Once the proper output voltages are established, adjust
the input voltage and load within the operating ranges
andobservetheoutputvoltageregulation,lowquiescent
current, shutdown and PWRGD operation and other
parameters.
Downloaded from Arrow.com.Downloaded from Arrow.com.

3
dc1855af
DEMO MANUAL DC1855A
Quick start proceDure
Figure 1: Proper Measurement Equipment Setup for DC1855A
+ –
+ –
LOAD
LOAD
–
+
+
–
+
–
–
+
+
–
–
+
–
+
+
–
dc1855 F01
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.

4
dc1855af
DEMO MANUAL DC1855A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 2 C1, C2 CAP, X7R, 1µF, 25V, 20%, 0805 TDK C2012X7R1E105M
2 1 C3 CAP, X5R, 22µF, 6.3V, 20%, 0805 TAIYO YUDEN, JMK212ABJ226M
3 1 C4 CAP, X5R, 10µF, 6.3V, 20%, 0805 AVX, 08056D106MAT
4 2 R5, R6 RES., CHIP., 237K, 1%, 1/16W, 0603 VISHAY, CRCW0603237KFKEA
5 1 R8 RES., CHIP., 54.9K, 1%, 1/16W, 0603 VISHAY, CRCW060354K9FKEA
6 1 R9 RES., CHIP., 113K, 1%, 1/16W, 0603 VISHAY, CRCW0603113KFKEA
7 1 U1 IC., LT3030EUFD, QFN28EUFD-4 ×5 LINEAR, LT3030EUFD
Optional Demo Board Circuit Components
1 0 C5, C6 CAP, X7R, 0.01µF, 25V, 10%, 0603 AVX, 06033C103KAT2A
2 0 C7, C8 CAP, OPT, TANT, 4.7µF, 50V, 10%, 7343
3 0 C9, C10 CAP., OPT, 7343
4 0 R1, R2, R3, R4 RES., 1M, 5%, 1/16W, 0603 VISHAY, CRCW06031M00JNEA
5 0 R7 RES., CHIP., 54.9k, 1%, 1/16W, 0603 VISHAY, CRCW060354K9FKEA
6 0 R10 RES., CHIP., 113k, 1%, 1/16W, 0603 VISHAY, CRCW0603113KFKEA
7 0 R11, R12 RES., CHIP., 249k, 1%, 1/16W, 0603 VISHAY, CRCW0603249KFKEA
8 0 R13, R14 RES., CHIP., 402k, 1%, 1/16W, 0603 VISHAY, CRCW0603402KFKEA
9 0 R15, R16 RES., CHIP., 732k, 1%, 1/16W, 0603 VISHAY, CRCW0603732KFKEA
10 0 R17, R18, R19, R20 RES., OPT, 0603
Hardware: For Demo Board Only
1 10 E1-E10 TESTPOINT, TURRET, .095" MILL-MAX, 2501-2-00-80-00-00-07-0
2 2 JP1, JP2 3 PIN, 0.079 SINGLE ROW HEADER SAMTEC, TMM103-02-L-S
3 2 JP3, JP4 2 ×6, 0.079 DOUBLE ROW HEADER SAMTEC, TMM106-02-L-D
4 4 XJP1-XJP4 SHUNT, .079" CENTER SAMTEC, 2SN-BK-G
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.

5
dc1855af
DEMO MANUAL DC1855A
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
U1
LT 3030EUFD
BYP1
28
IN1 20
BYP2
9
ADJ2
10
GND
29
ADJ1
27
SHDN1
23
OUT 1
2
SHDN2
14
OUT 2
8
IN2 17
OUT 1
1
OUT 2
7
IN1 21
IN2 16
PWRGD1
22
GND
19
GND
24
GND
25
GND
3
GND
4
GND
18
GND
13
GND
12
GND
11
GND
6
GND
5
GND
26
PWRGD2
15
R4 1M 5%
R3 1M 5%
E9
PWRGD1
2. ALL CAPACIT ORS ARE IN MICROFARADS 0603. 1. ALL RESISTORS ARE IN OHMS 1% 0603.
R19 OPT
R20
OPT
+
C10 OPT
+
C9
OPT JP3
1
3
56
4
2
7
9
8
10
1112
+
C7 4.7uF
2.2V - 20V
R5
237k
22uF
C3
E8
* VIN2
E7
GND
R13
402k
R15
732k
E5
VOUT2
250mA
E6
GND
VOUT 1 S ELECT VOUT 2 S ELECT
1.8V
1.5V
5V
OPT
25V
VOUT 1EN
25V
50V
3.3V
2.5V
R6 237k
6.3V
10uF
C4
6.3V
50V
OFF
ON
JP1
1
3
2
ON
JP2
1
3
2
OFF
VOUT 2EN
0805
0805
OPT
OPT
R14
402k
R8
54.9k
R18 OPT
OPT
NOTE: UNLESS OTHERWISE SPECIFIED
R12
249k
2.5V
3.3V
R10
113k
1.8V
R16
732k
1.5V
JP4
1
3
5 6
4
2
7
9
8
10
11 12
C6
0.01uF
E1
* VIN1
E2
GND
750mA
2.2V - 20V
E3
VOUT 1
E4
GND
R11
249k
R7
54.9k
R9
113k
R17 OPT
+
C8
4.7uF
1uF C2
1uF
C1
R2
1M 5%
0805
0805
7343
7343
7343
7343
R1
1M
5%
C5
0.01uF
5V
* SEE PERFORMANCE SUMMARY
FOR MINIMUM INPUT VOLTAGE CONDITIONS.
E10
PWRGD2
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.

6
dc1855af
DEMO MANUAL DC1855A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2013
LT 0213 • 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
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.