Analog Devices Linear Technology DC2432B Quick setup guide

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dc2432bfb
DEMO MANUAL DC2432B
DESCRIPTION
LT6658
Precision Dual Output, High Current,
Low Noise, Voltage Reference
Demonstrationcircuit2432BfeaturestheLT
®
6658,apreci-
sion dual output reference that combines the performance
of a low drift low noise reference and a linear regulator.
Demonstrationcircuitsareavailablewith1.25V,2.5V,3.0V,
3.3V, 4.096V and 5V output option parts. Both outputs
are ideal for driving the precision reference inputs of high
resolution ADCs and DACs, even with heavy loading while
simultaneouslyactingasoutputsuppliesforpoweringmi-
crocontrollersand other supporting devices. Both outputs
have the same precision specifications and track each L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Refulator is a trademark of Analog Devices, Inc. All other trademarks are the property of their
respective owners.
PERFORMANCE SUMMARY
LT6658 BLOCK DIAGRAM
other over temperature. Each output can be configured
with external resistors to give an output voltage up to 6V.
Using Kelvin connections, the LT6658 typically has
0.1ppm/mA load regulation with up to 150mA load
current. A noise reduction pin is available to band-limit
and lower the total integrated noise.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2432B
Specifications are at TA= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Range 5V 36 V
VOUT Output Voltage Accuracy –0.05 +0.05 %
Temperature Drift 10 ppm
IQSupply Current 2 mA
Load Regulation OUT1 0mA to 150mA 2 µV/mA
Load Regulation OUT2 0mA to 50mA 3.75 µV/mA
14
4
16
15
1
2
6
3
5
9
17
10
8
7
12
13
11
R3
R4
R1
R2
V
IN
THERMAL
SHUTDOWN
DNC
DNC
NC
GND
GND
GND
GND
OD
V
IN2
V
IN1
V
OUT2_F
V
OUT1_F
V
OUT2_S
V
OUT1_S
NR
BYPASS
DC2432 BD
BANDGAP
BUFFER 2
BUFFER 1
Voltage Option
(V)
R1
(Ω)
R2
(Ω)
R3, R4
(Ω)
1.2 400 9600 768
1.8 400 2903 705
2.5 400 OPEN 800
3 400 OPEN 800
3.3 400 OPEN 800
5 400 OPEN 800

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DEMO MANUAL DC2432B
QUICK START PROCEDURE
With the demonstration circuit, it is easy to set up and
evaluate the performance of the LT6658. Refer to Figure1
for proper measurement equipment setup and follow the
procedure below.
1. With the power off, connect the power supply positive
to VIN and the common to GND. With default settings,
the supply can range from VOUT + 2.5V to 36V.
2. Connect a DVM to the VOUT turret OUT1 with the com-
mon connection attached to ground.
3. Turn on power supply and confirm reference operation
on OUT1, and also OUT2.
JUMPER SUMMARY
JP1: VIN Input Selection. This jumper has 3 positions:
1. SEP:Separates the VIN from the VIN1 and VIN2 output
buffer supplies
2. COM/V2 : Shorts the VIN2 output buffer supply pin to VIN
3. COM/V1:Shorts the VIN1 output buffer supply pin to VIN
JP2: VIN1/VIN2 Output Buffer Supply Connection:
1. SEP:Separates the VIN1 and VIN2 output buffer supply
2. COM: Shorts the VIN1 and VIN2 output buffer supplies
Figure 1. Test Setup
DMM
A V COM
2.500V
POWER
SUPPLY
COM +
5.00V
DC2432B F01
2.5
C

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DEMO MANUAL DC2432B
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.
JP3: OD Output Disable:
1. ENA: Enables the outputs
2. DIS/EXT:Disables the outputs or allows the OD pin to
be driven externally.
JP4: Noise Reduction Select:
1. LF: 10μF
2. NF: Optional cap
3. HF: 0.1μF
JP5: OUT1 Select:
1. Fixed:OUT1 sense line is shorted to OUT1 Force and
the output is fixed.
2. ADJ:OUT1 sense line is separated from OUT1 Force
allowing for resistors R1 and R2 to be installed and
programming the OUT1 voltage to a different value.
JP6: OUT2 Select:
1. Fixed:OUT2 sense line is shorted to OUT2 Force and
the output is fixed.
2. ADJ:OUT2 sense line is separated from OUT2 Force
allowing for resistors R4 and R5 to be installed and
programming the OUT2 voltage to a different value.
OPTIONAL SETTINGS
1. Programming the Output Voltage
By separatingthe VOUT_S line fromthe VOUT_F and using
2resistors to create a divider in the feedback of the out-
put amplifier, the reference output can be programmed
from the nominal output voltage, up to 2.5V below the
supply voltage. The output voltage range is limited on
the high side due to internal ESD clamps that protect
the pins when the voltage goes above 6V. The output
voltage can be set using the equation:
VOUT = VREF • (R1 + R2)/R2 with VREF set by nominal
output voltage
QUICK START PROCEDURE
The resistors will affect the temperature drift and
accuracy of the LT6658 output, so care should be
given when choosing resistors. It is crucial that the
resistor ratio stay consistent over temperature to
guarantee the best reference performance.
2. Setting the Noise Reduction
Thenoise reductionpincanbe usedtofilterthe reference
output. The demo board comes with two pre-installed
capacitors that can be selected with the NR jumper.
The effects of the different capacitors are shown in
Figure2, and the 3dB frequencies produced by vari-
ous NR capacitors for each output voltage variant are
provided in Table 1.
Table 1. NR Capacitor Values and the Corresponding 3dB Frequency
NR
Capacitor
(µF)
1.2V NR 3dB
Frequency
(Hz)
1.8V NR 3dB
Frequency
(Hz)
2.5V, 3V, 3.3V, 5V
NR 3dB Frequency
(Hz)
0.1 4145 4522 3979
0.22 1884 2055 1809
0.47 882 962 847
1 414 452 398
2.2 188 206 181
4.7 88 96 85
10 41 45 40
22 19 21 18
Figure 2. LT6658 Bandgap Output Voltage
Noise with Various NR Capacitor Values
C
NR
= 0µF
C
NR
= 1µF
C
NR
= 10µF
FREQUENCY (kHz)
0.01
0.1
1
10
100
1000
0
50
100
150
200
250
NOISE (nV/√
Hz
)
DC2432B F02

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DEMO MANUAL DC2432B
 LINEAR TECHNOLOGY CORPORATION 2017
LT 0917 REV B • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
Thisdemonstrationboard(DEMOBOARD)kitbeingsoldorprovidedbyLinearTechnologyisintendedfor 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

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