AD561

–4–

REV. A

THE AD561 OFFERS TRUE 10-BIT RESOLUTION OVER

FULL TEMPERATURE RANGE

Accuracy: Analog Devices defines accuracy as the maximum

deviation of the actual, adjusted DAC output (see page 5) from

the ideal analog output (a straight line drawn from 0 to FS – l

LSB) for any bit combination. The AD561 is laser trimmed to

1/4 LSB (0.025% of FS) maximum error at +25

°C for the K

and T versions – 1/2 LSB for the J and S.

Monotonicity: A DAC is said to be monotonic if the output

either increases or remains constant for increasing digital inputs

such that the output will always be a single-valued function of the

input. All versions of the AD561 are monotonic over their full

operating temperature range.

Differential Nonlinearity: Monotonic behavior requires that

the differential nonlinearity error be less than

1 LSB both at +25

°C and over the temperature range of

interest. Differential nonlinearity is the measure of the variation

in analog value, normalized to full scale, associated with a

1 LSB change in digital input code. For example, for a 10 volt

full scale output, a change of 1 LSB in digital input code should

result in a 9.8 mV change in the analog output (1 LSB = 10 V

× 1/1024 = 9.8 mV). If in actual use, however, a 1 LSB change

in the input code results in a change of only 2.45 mV (1/4 LSB)

in analog output, the differential nonlinearity error would be

7.35 mV, or 3/4 LSB The AD561K and T have a max differen-

tial linearity error of 1/2 LSB.

The differential nonlinearity temperature coefficient must also

be considered if the device is to remain monotonic over its full

operating temperature range. A differential nonlinearity tempera-

ture coefficient of 2.5 ppm/

°C could, under worst case condi-

tions for a temperature change of +25

°C to +125°C, add 0.025%

(100

2.5 ppm/

°C of error). The resulting error could then be

as much as 0.025% + 0.025% = 0.05% of FS (1/2 LSB represents

0.05% of FS). To be sure of accurate performance all versions of

the AD561 are therefore 100% tested to be monotonic over the

full operating temperature range.

Figure 1. Chip Bonding Diagram

CONNECTING THE AD561 FOR BUFFERED VOLTAGE

OUTPUT

The standard current-to-voltage conversion connections using

an operational amplifier are shown here with the preferred

trimming techniques. If a low offset operational amplifier

(AD510, AD741L, AD301AL) is used, excellent performance

can be obtained in many situations without trimming. (A 5 mV

op amp offset is equivalent to 1/2 LSB on a 10 volt scale.) If a

25

Ω fixed resistor is substituted for the 50 Ω trimmer, unipolar

zero will typically be within

±1/10 LSB (plus op amp offset),

and full scale accuracy will be within

±1 LSB. Substituting a

25

Ω resistor for the 50 Ω bipolar offset trimmer will give a

bipolar zero error typically within

±1 LSB.

The AD509 is recommended for buffered voltage-output

applications that require a settling time to

±1/2 LSB of one

microsecond. The feedback capacitor is shown with the

optimum value for each application; this capacitor is required to

compensate for the 25 picofarad DAC output capacitance.

ORDERING GUIDE

ACCURACY

GAIN T C

PACKAGE

TEMP RANGE

@ +25 C

(of FS/ C)

AD561JD

0

°C to +70°C

±1/2 LSB max

80 ppm max

D-16

AD561JN

0

°C to +70°C

±1/2 LSB max

80 ppm max

N-16

AD561KD

0

°C to +70°C

±1/4 LSB max

30 ppm max

D-16

AD561KN

0

°C to +70°C

±1/4 LSB max

30 ppm max

N-16

AD561SD

–55

°C to +125°C ±1/2 LSB max

60 ppm max

D-16

AD561TD

–55

°C to +125°C ±1/4 LSB max

30 ppm max

D-16

AD561/883B

–55

°C to +125°C*

*

*

NOTES

Analog Devices Military Products Databook or current AD561/883B data sheet.

*Refer to AD561/883B military data sheet.

PIN CONFIGURATION

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