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nanoDAC - Which DACs should be used for open loop systems and which DACs should be used in closed loop systems?

Question asked by Padraic Employee on Apr 15, 2011

It must be stressed that depending on the application performance requirements, all nanoDACs can be used in both open and closed loop systems.

 

In an open loop application the DAC drives the load (a valve or an actuator, for example) directly while in a closed loop control system an ADC is in the feedback loop controlling the valve/actuator position. This type of control places different requirements on the controlling DAC.

 

 

In closed loop applications DAC resolution is more important than accuracy as the ADC provides the accuracy - therefore we pay less attention to INL.

Offset and gain errors can be calibrated out using software adjustment. Extra resolution is typically used in calibration of offset and gain errors.

 

Products include: AD566X, AD564X, AD562X offering 12/14/16 bits resolution, monotonicity and 12-bit accuracy.

 

As we said previously, in an open loop application the DAC drives the load (valve, actuator) directly.

 

Monotonicity and resolution, like in closed loop systems, are important but absolute accuracy, because of the lack of feedback, is critical in keeping the DAC output as close a fit as possible to the ideal DAC transfer function. INL(Accuracy) Offset Errors and Gain errors all contribute to the overall total unadjusted error and need to be taken into consideration.

 

Products in this category provide +/- 1 LSB INL performance at the specified resolution and include the AD5064, AD5060 and AD5541A/42A products.

 

 

Part No[i]

Resolution

No. of DACs

Max INL

Interface

Settling Time typ

Package

On-chip

Reference

Pins

SINGLE

AD5040

14

1

±1

SPI

4 μs

SOT-23

-

8

AD5060

16

1

±1

SPI

4 μs

SOT-23

-

8

AD5061

16

1

±4

SPI

4 μs

SOT-23

-

8

AD5062 (unbuffered)

16

1

±1

SPI

4 μs

SOT-23

-

8

AD5063(FB   pin)

16

1

±1

SPI

4 μs

MSOP

-

10

AD5641

14

1

±4

SPI

6 μs

SC70

-

6

AD5621

12

1

±1

SPI

6 μs

SC70

-

6

AD5611

10

1

±0.5

SPI

6 μs

SC70

-

6

AD5601

8

1

±0.5

SPI

6 μs

SC70

-

6

AD5622

12

1

±2

I2C

6 μs

SC70

-

6

AD5612

10

1

±0.5

I2C

6 μs

SC70

-

6

AD5602

8

1

±0.5

I2C

6 μs

SC70

-

6

AD5680

18

1

±64

SPI

80 μs

SOT-23

-

8

AD5660

16

1

±16

SPI

8 μs

SOT-23, MSOP

-

8

AD5662 (FB pin)

16

1

±16

SPI

8 μs

SOT-23, MSOP

-

8

AD5640

14

1

±4

SPI

8 μs

SOT-23, MSOP

-

8

AD5620

12

1

±1

SPI

8 μs

SOT-23, MSOP

-

8

DUAL

AD5667

16

2

±12

I2C

4 μs

LFCSP, MSOP

-

10

AD5627

12

2

±1

I2C

3 μs

LFCSP, MSOP

-

10

AD5667R

16

2

±12

I2C

4 μs

LFCSP, MSOP

1.25V/2.5V

10

AD5647R

14

2

±4

I2C

3.5 μs

LFCSP, MSOP

1.25V/2.5V

10

AD5627R

12

2

±1

I2C

3 μs

LFCSP, MSOP

1.25V/2.5V

10

AD5663

16

2

±12

SPI

4 μs

LFCSP, MSOP

-

10

AD5663R

16

2

±16

SPI

4 μs

LFCSP, MSOP

1.25V/2.5V

10

AD5643R

14

2

±4

SPI

3.5 μs

LFCSP, MSOP

1.25V/2.5V

10

AD5623R

12

2

±1

SPI

3 μs

LFCSP, MSOP

1.25V/2.5V

10

QUAD

AD5064

16

4

±1

SPI

5.8 μs

TSSOP

-

14,16

AD5044

14

4

±1

SPI

5.8 μs

TSSOP

-

14,16

AD5024

12

4

±1

SPI

5.8 μs

TSSOP

-

14,16

AD5066 (unbuffered)

16

4

±1

SPI

7.5 μs

TSSOP

-

16

AD5664

16

4

±12

SPI

4 μs

MSOP, LFCSP

-

10

AD5624

12

4

±1

SPI

3 μs

MSOP, LFCSP

-

10

AD5664R

16

4

±16

SPI

4 μs

MSOP, LFCSP

1.25V/2.5V

10

AD5644R

14

4

±4

SPI

3.5 μs

MSOP, LFCSP

1.25V/2.5V

10

AD5624R

12

4

±1

SPI

3 μs

MSOP, LFCSP

1.25V/2.5V

10

QUAD

AD5665

16

4

±16

I2C

4 μs

LFCSP,  TSSOP

-

10/14

AD5625

12

4

±1

I2C

3 μs

LFCSP,  TSSOP

-

10/14

AD5665R

16

4

±16

I2C

4 μs

LFCSP,  TSSOP

1.25V/2.5V

10/14

AD5645R

14

4

±4

I2C

3.5 μs

LFCSP,  TSSOP

1.25V/2.5V

10/14

AD5625R

12

4

±1

I2C

3 μs

LFCSP,  TSSOP

1.25V/2.5V

10/14

OCTAL

AD5678

12/16

8

±1/±16

SPI

6 μs

TSSOP

1.25V/2.5V

14/16

AD5668

16

8

±16

SPI

2.5 μs

TSSOP, LFCSP

1.25V/2.5V

16

AD5648

14

8

±4

SPI

2.5 μs

TSSOP, LFCSP

1.25V/2.5V

14

AD5628

12

8

±1

SPI

2.5 μs

TSSOP, LFCSP

1.25V/2.5V

12

AD5669R

16

8

±16

I2C

2.5 μs

TSSOP. LFCSP

1.25V/2.5V

16

AD5629R

12

8

±1

I2C

2.5 μs

TSSOP, LFCSP

1.25V/2.5V

16


 


[i] All of our AD56xx products have less that +/- 1 LSB DNL and are monotonic

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