5962-88766013A Datasheet, PDF (4/16 Pages) Analog Devices – LC2MOS 12-Bit DACPORTs

AD7245A/AD7248A
AD7245A ORDERING GUIDE
Model¹
Temperature
Range
Relative
Accuracy
Package
Option²
AD7245AAN
AD7245ABN
AD7245AAQ
AD7245ATQ³
AD7245AAP
AD7245AAR
AD7245ABR
AD7245ATE³
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–55°C to +125°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–55°C to +125°C
± 3/4 LSB
± 1/2 LSB
± 3/4 LSB
± 3/4 LSB
± 3/4 LSB
± 3/4 LSB
± 1/2 LSB
± 3/4 LSB
N-24
N-24
Q-24
Q-24
P-28A
R-24
R-24
E-28A
NOTES
1_{To order MIL-STD-883, Class B processed parts, add /883B to part number.}
Contact our local sales office for military data sheet and availability.
2_{E = Leadless Ceramic Chip Carrier; N = Plastic DIP; P = Plastic Leaded Chip}
Carrier; Q = Cerdip; R = SOIC.
3_{This grade will be available to /883B processing only.}
AD7248A ORDERING GUIDE
Model¹
Temperature
Range
Relative
Accuracy
Package
Option²
AD7248AAN
AD7248ABN
AD7248AAQ
AD7248ATQ³
AD7248AAP
AD7248AAR
AD7248ABR
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–55°C to +125°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
± 3/4 LSB
± 1/2 LSB
± 3/4 LSB
± 3/4 LSB
± 3/4 LSB
± 3/4 LSB
± 1/2 LSB
N-20
N-20
Q-20
Q-20
P-20A
R-20
R-20
NOTES
1_{To order MIL-STD-883, Class B processed parts, add /883B to part number.}
Contact our local sales office for military data sheet and availability.
2_{N = Plastic DIP; P = Plastic Leaded Chip Carrier; Q = Cerdip; R = SOIC.}
3_{This grade will be available to /883B processing only.}
TERMINOLOGY
RELATIVE ACCURACY
Relative Accuracy, or endpoint nonlinearity, is a measure of the
actual deviation from a straight line passing through the endpoints
of the DAC transfer function. It is measured after allowing for
zero and full scale and is normally expressed in LSBs or as a
percentage of full-scale reading.
DIFFERENTIAL NONLINEARITY
Differential Nonlinearity is the difference between the measured
change and the ideal 1 LSB change between any two adjacent
codes. A specified differential nonlinearity of ± 1 LSB max over
the operating temperature range ensures monotonicity.
DIGITAL FEEDTHROUGH
Digital Feedthrough is the glitch impulse injected from the digital
inputs to the analog output when the inputs change state. It is
measured with LDAC high and is specified in nV-s.
DAC GAIN ERROR
DAC Gain Error is a measure of the output error between an
ideal DAC and the actual device output with all 1s loaded after
offset error has been allowed for. It is, therefore defined as:
Measured Value—Offset—Ideal Value
where the ideal value is calculated relative to the actual refer-
ence value.
UNIPOLAR OFFSET ERROR
Unipolar Offset Error is a combination of the offset errors of the
voltage mode DAC and the output amplifier and is measured
when the part is configured for unipolar outputs. It is present
for all codes and is measured with all 0s in the DAC register.
BIPOLAR ZERO OFFSET ERROR
Bipolar Zero Offset Error is measured when the part is config-
ured for bipolar output and is a combination of errors from the
DAC and output amplifier. It is present for all codes and is
measured with a code of 2048 (decimal) in the DAC register.
SINGLE SUPPLY LINEARITY AND GAIN ERROR
The output amplifier of the AD7245A/AD7248A can have a
true negative offset even when the part is operated from a single
positive power supply. However, because the lower supply rail
to the part is 0 V, the output voltage cannot actually go nega-
tive. Instead the output voltage sits on the lower rail and this
results in the transfer function shown. This is an offset effect
and the transfer function would have followed the dotted line if
the output voltage could have gone negative. Normally, linearity
is measured after offset and full scale have been adjusted or
allowed for. On the AD7245A/AD7248A the negative offset is
allowed for by calculating the linearity from the code which the
amplifier comes off the lower rail. This code is given by the
negative offset specification. For example, the single supply
linearity specification applies between Code 3 and Code 4095
for the 25°C specification and between Code 5 and Code 4095
over the T_MIN to T_MAX temperature range. Since gain error is
also measured after offset has been allowed for, it is calculated
between the same codes as the linearity error. Bipolar linearity and
gain error are measured between Code 0 and Code 4095.
OUTPUT
VOLTAGE
0V
NEGATIVE
OFFSET
DAC CODE
–4–
REV. B