DC812A - LINEAR TECHNOLOGY

dc812af

DEMO MANUAL DC812A

Description

LTC2606

16-Bit Rail-to-Rail VOUT DAC

with I2C Interface

Demonstration circuit 812A features the LT C

2606

16-bit DAC with I2C interface. This device establishes a

new board-density benchmark for 16-bit DACs and ad-

vances performance standards for output drive and load

regulation in single-supply, voltage output DACs.

DC812A has many features for evaluating the performance

of the LTC2606. Onboard 5V, 4.096V and 2.5V precision

references are provided, and the LTC2606 may be powered

by the 5V reference for evaluating rail-to-rail operation.

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

QuikEval is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners.

performance summary

BoarD photo

Another feature of this board is the onboard LTC2421 20-bit

ADC for monitoring DAC output voltage. The 16ppm total

error of this device is adequate for taking meaningful

measurements of various LTC2606 parameters.

Design files for this circuit board are available at

http://www.linear.com/demo

SYMBOL PARAMETER CONDITIONS

Resolution 16 Bits

Monotonicity VCC = 5V, VREF = 4.096V 16 Bits

Differential Nonlinearity VCC = 5V, VREF = 4.096V ±1 LSB

Integral Nonlinearity VCC = 5V, VREF = 4.096V ±12 LSB Typical

Load Regulation VCC = VREF = 5V, Mid-Scale, IOUT = ±15mA 2 LSB/mA Max

Specifications are at TA = 25°C

Figure 1. DC812A Connection Diagram

REFERENCE MONITOR

(OR EXTERNAL

REFERENCE SOURCE;

SEE HARDWARE SET-UP)

RIBBON CABLE

DC590

dc812a F01

–

TO DAC OUTPUT

FOR LOAD

REGULATION

EXPERIMENTS

VOLTMETER

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DEMO MANUAL DC812A

Quick start proceDure

1. Connect the DC812A to a DC590 USB serial controller

using the supplied 14-conductor ribbon cable.

2. Connect the DC590 to a host PC with a standard USB

A/B cable.

3. Run the QuikEval™ evaluation software supplied with the

DC590 or download it from www.linear.com/software.

The correct control panel will be loaded automatically.

4. Click the Collect button to begin outputting codes to

the DAC and reading back the resulting output voltage.

Complete software documentation is available from the

Help menu item, as features may be added periodically.

Figure 2. QuikEval Software

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DEMO MANUAL DC812A

harDware setup

experiments

JUMPER SETTINGS

VREF: VREF Select. Select 5V, 4.096V, or 2.5V reference.

To apply an external reference through the VREF turret,

remove this jumper.

VCC: VCC Select. VCC is taken either from the onboard 5V

reference or the 5V regulated supply from the controller

board. Selecting the 5V reference for both the VCC jumper

and VREF jumper allows characterization of rail-to-rail

operation of the LTC2606.

ADC: ADC Enable/Disable. Set to ENABLE for operation

with DC590 serial controller. When using in customer’s

end application, the ADC can be completely disabled by

setting jumper to DISABLE.

For very sensitive noise measurements when using LT C

supplied software, set the output voltage and stop reading

the voltage via the collect button on the control panel. This

will stop the ADC from converting.

ANALOG CONNECTIONS

DAC VOUT: LTC2606 Output.

VREF: The VREF turret is connected directly to the reference

terminals of the LTC2606 and LTC2421 ADC. When one of

the onboard references is being used, the reference voltage

may be monitored at this point. An external reference may

also be applied to this turret after removing JP1.

GROUNDING AND POWER CONNECTIONS

Power (VCC): Normally the DC812A is powered by the

DC590 controller. VCC can be supplied to this turret, how-

ever the power supply on the DC590 must be disabled!

Refer to the DC590 Quick Start guide for more details on

this mode of operation.

Grounding: Separate power and signal grounds are pro-

vided. Any large currents drawn from the DAC outputs

should be returned to power ground. Also, if an external

power supply is connected, power ground should be

used. Signal ground is connected to the exposed ground

planes at the top and bottom edges of the board, and to

the two turrets labeled GND. Use signal ground as the

reference point for measurements and connections to

external circuits.

The following experiments are intended to demonstrate

some of the outstanding features of the LTC2606. All can

be performed using the onboard LTC2421 to monitor

the DAC output voltage. The indicated output voltage will

typically agree with an HP3458A voltmeter to five digits.

If a DAC will be sinking or sourcing a significant current,

then the output voltage should be measured as close to

the DAC as possible.

Most of the data sheet specifications use a 4.096V refer-

ence, so this is the preferred reference to use for these

experiments. Using the 5V reference has the limitation that

VCC may be slightly lower than VREF, which may affect the

full-scale error. Selecting the 5V reference as the source

for VCC overcomes this, however the total current that the

LTC2606 can source will be limited to approximately 5mA.

Using an external power supply is highly recommended for

these experiments, especially those that draw significant

current. Refer to the DC590 Quick Start guide for details.

Resolution

The onboard LTC2421 ADC has an input resolution of

6μV. This will easily resolve a 1 LSB (76μV for VREF = 5V,

62.5μV for VREF = 4.096V) change in the LTC2606 output.

Set the DAC output to a voltage close to mid-scale. Select

the FINE slider on the control panel with the mouse and use

the right and left arrow keys to step the output by single

LSBs. The change should be clearly visible in the output

graph. Note: It may be necessary to wait for the graph to

clear if a large step has just occurred.

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DEMO MANUAL DC812A

parts List

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 1 U7 IC, 24LC025 MICROCHIP, 24LC025

2 3 C3, C7, C10 CAP, X7R, 0.1µF, 16V, 10%, 0402 TDK, C1005X7R1C104KT

3 1 C9 CAP, NPO, 100pF, 50V, 10%, 0402 AVX, 04025A101KAT

4 3 C4-C6 CAP, X5R, 1µF, 6.3V, 20%, 0603 AVX, 06036D105MAT

5 2 C1-C2 CAP, X7R, 1µF, 16V, 20%, 0603 TDK, C1608X7R1C105M

6 1 J1 HEADER, 2×7P, 2mm MOLEX, 87831-1420

7 0 JP7 DO NOT STUFF OPTION

8 1 JP1 HEADER, 2×3P, 2mm COMM CON, 2202S-06-G2

9 5 JP2-JP6 JUMPER, 3-PIN, 2mm COMM CON, 2802S-03G2

10 1 U5 IC, LT1790ACS6-2.5 LINEAR TECHNOLOGY, LT1790ACS6-2.5

11 1 U4 IC, LT1790ACS6-4.096 LINEAR TECHNOLOGY, LT1790ACS6-4.096

12 1 U3 IC, LT1790ACS6-5 LINEAR TECHNOLOGY, LT1790ACS6-5

13 1 U2 IC, LTC2421CMS LINEAR TECHNOLOGY, LTC2421CMS

14 1 U1 IC, LTC2606CDD LINEAR TECHNOLOGY, LTC2606CDD

15 1 U6 IC, NC7WB66 DUAL LOGIC SWITCH FAIRCHILD SEMI., NC7WB66K8X

16 2 R6, R9 RES, 100Ω, 5%, 1/16W, 0402 AAC, CR05-101JM

17 4 R1, R4-R5, R8 RES, 10kΩ, 5%, 1/16W, 0402 AAC, CR05-103JM

18 3 R2-R3, R10 RES, 4.99kΩ, 1%, 1/16W, 0402 AAC, CR05-4991FM

19 1 R7 RES, 7.5kΩ, 5%, 1/16W, 0402 AAC, CR05-752JM

20 6 E1-E6 TURRET MILL-MAX, 2308-2

21 7 JP1-JP7 SHUNT COMM CON, CCIJ2MM-138G

experiments

Integral Nonlinearity

A rough measurement of INL can be taken using the

onboard ADC. Measure the LTC2606 output at code 256

and 65,535 and calculate the slope and intercept using a

spreadsheet. Next, take several readings at intermediate

points. The readings should not deviate from the calcu-

lated line by more than 64 LSBs, and they will typically

be within 12 LSBs.

Load Regulation/DC Output Impedance

Select “5V REG” for the VCC source. Set one of the outputs

to mid-scale (code 32768). Source or sink 15mA from one

of the DAC outputs by pulling it to power ground or VCC

with an appropriate value resistor. The voltage change

should be less than 2.25mV, corresponding to an output

impedance of 0.15Ω. Output impedance is typically less

than 0.030Ω (measure DAC voltage at the output pin if

using a voltmeter).

Zero-Scale Error

Set the DAC output to code 0. The measured output should

be less than 9mV and will typically be less than 1mV.

Offset Error

Set the DAC output to code 256. The output voltage should

be within 9mV of the correct value, or VREF × 256/65535.

Gain Error

Set the DAC output to code 65,535. The output volt-

age should be within 0.7% of VREF, and will typically be

within 0.2%.

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DEMO MANUAL DC812A

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 3. LTC2606CDD, 16-Bit Rail-to-Rail VOUT DAC, I2C Interface

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DEMO MANUAL DC812A

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 0513 • 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

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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.).

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customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.

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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-

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Mailing Address:

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Milpitas, CA 95035