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

Padraic

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