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ADT7318
(Rev.:RevPrN)

SPI/I2C® Compatible, 10-Bit Digital Temperature Sensor and Quad Voltage Output 12/10/8-Bit DAC

Analog Devices 

PRELIMINARY TECHNICAL DATA

ADT7316/7317/7318

TERMINOLOGY

RELATIVE ACCURACY

Relative accuracy or integral nonlinearity (INL) is a mea-

sure of the maximum deviation, in LSBs, from a straight

line passing through the endpoints of the DAC transfer

function. Typical INL versus Code plots can be seen in

TPCs 1, 2, and 3.

DIFFERENTIAL NONLINEARITY

Differential Nonlinearity (DNL) is the difference be-

tween the measured change and the ideal 1 LSB change

between any two adjacent codes. A specified differential

nonlinearity of ±1 LSB maximum ensures monotonicity.

This DAC and Temperature Sensor ADC is guaranteed

monotonic by design. Typical DAC DNL versus Code

plots can be seen in TPCs 4, 5, and 6.

OFFSET ERROR

This is a measure of the offset error of the DAC and the

output amplifier. (See Figures 5 and 6.) It can be negative

or positive. It is expressed in mV.

OFFSET ERROR MATCH

This is the difference in Offset Error between any two

channels.

GAIN ERROR

This is a measure of the span error of the DAC. It is the

deviation in slope of the actual DAC transfer characteristic

from the ideal expressed as a percentage of the full-scale

range.

GAIN ERROR MATCH

This is the difference in Gain Error between any two

channels.

OFFSET ERROR DRIFT

This is a measure of the change in offset error with

changes in temperature. It is expressed in (ppm of full-

scale range)/°C.

GAIN ERROR DRIFT

This is a measure of the change in gain error with

changes in temperature. It is expressed in (ppm of full-

scale range)/°C.

DC POWER-SUPPLY REJECTION RATIO (PSRR)

This indicates how the output of the DAC is affected by

changes in the supply voltage. PSRR is the ratio of the

change in VOUT to a change in VDD for full-scale output of

the DAC. It is measured in dBs. VREF is held at 2 V and

VDD is varied ±10%.

DC CROSSTALK

This is the dc change in the output level of one DAC in

response to a change in the output of another DAC. It is

measured with a full-scale output change on one DAC

while monitoring another DAC. It is expressed in µV.

REFERENCE FEEDTHROUGH

This is the ratio of the amplitude of the signal at the

DAC output to the reference input when the DAC output

is not being updated (i.e., LDAC is high). It is expressed

in dBs.

CHANNEL-TO-CHANNEL ISOLATION

This is the ratio of the amplitude of the signal at the out-

put of one DAC to a sine wave on the reference input of

another DAC. It is measured in dBs.

MAJOR-CODE TRANSITION GLITCH ENERGY

Major-code transition glitch energy is the energy of the

impulse injected into the analog output when the code in

the DAC register changes state. It is normally specified as

the area of the glitch in nV secs and is measured when the

digital code is changed by 1 LSB at the major carry transi-

tion (011 . . . 11 to 100 . . . 00 or 100 . . . 00 to

011 . . . 11).

DIGITAL FEEDTHROUGH

Digital feedthrough is a measure of the impulse injected

into the analog output of a DAC from the digital input

pins of the device but is measured when the DAC is not

being written to the. It is specified in nV secs and is mea-

sured with a full-scale change on the digital input pins,

i.e., from all 0s to all 1s or vice versa.

DIGITAL CROSSTALK

This is the glitch impulse transferred to the output of one

DAC at midscale in response to a full-scale code change

(all 0s to all 1s and vice versa) in the input register of

another DAC. It is measured in stand-alone mode and is

expressed in nV secs.

ANALOG CROSSTALK

This is the glitch impulse transferred to the output of one

DAC due to a change in the output of another DAC. It is

measured by loading one of the input registers with a full-

scale code change (all 0s to all 1s and vice versa) while

keeping LDAC high. Then pulse LDAC low and monitor

the output of the DAC whose digital code was not

changed. The area of the glitch is expressed in nV secs.

DAC-TO-DAC CROSSTALK

This is the glitch impulse transferred to the output of one

DAC due to a digital code change and subsequent out-

put change of another DAC. This includes both digital

and analog crosstalk. It is measured by loading one of the

DACs with a full-scale code change (all 0s to all 1s and

vice versa) with LDAC low and monitoring the output of

another DAC. The energy of the glitch is expressed in nV

secs.

MULTIPLYING BANDWIDTH

The amplifiers within the DAC have a finite bandwidth.

The multiplying bandwidth is a measure of this. A sine

wave on the reference (with full-scale code loaded to the

DAC) appears on the output. The multiplying band-

width is the frequency at which the output amplitude falls

to 3 dB below the input.

–8–

REV. PrN

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