AD1555 Analog Devices, AD1555 Datasheet - Page 12

• Manufacturer Part Number: AD1555
• Description: 24-Bit, 121 dB typical SNR, Sigma-Delta A/D converter with Integrated PGA
• Manufacturer: Analog Devices

Specifications of AD1555

• Resolution (bits): 24bit
• # Chan: 2
• Sample Rate: 256kSPS
• Interface: Byte,Ser
• Analog Input Type: Diff-Bip,SE-Bip
• Ain Range: Bip 2.25V/(PGA Gain)
• Adc Architecture: Sigma-Delta Modulator
• Pkg Type: LCC

AD1555/AD1556
TERMINOLOGY
DYNAMIC RANGE
Dynamic range is the ratio of the rms value of the full scale to
the total rms noise measured with the inputs shorted together
in the bandwidth from 3 Hz to the Nyquist frequency F
value for dynamic range is expressed in decibels.
SIGNAL-TO-NOISE RATIO (SNR)
SNR is the ratio of the rms value of the full-scale signal to the
total rms noise in the bandwidth from 3 Hz to the Nyquist fre-
quency F
TOTAL HARMONIC DISTORTION (THD)
THD is the ratio of the rms sum of all the harmonic components
up to Nyquist frequency F
input signal. The value for THD is expressed in decibels.
INTERMODULATION DISTORTION (IMD)
IMD is the ratio of the rms sum of two sine wave signals of
30 Hz and 50 Hz which are each 6 dB down from full scale to
the rms sum of all intermodulation components within the
bandwidth from 1 Hz to the Nyquist frequency F
for IMD is expressed in decibels.
O
/2. The value for SNR is expressed in decibels.
O
/2 to the rms value of a full-scale
O
/2. The value
O
/2. The
–12–
OFFSET
The offset is the difference between the ideal midscale input volt-
age (0 V) and the actual voltage producing the midscale output
code (code 000000H) at the output of the AD1556. The offset
specification is referred to the output. This offset is intentionally
set at a nominal value of –60 mV (see Sigma-Delta Modulator
section). The value for offset is expressed in mV.
OFFSET ERROR DRIFT
The change of the offset over temperature. It is expressed in mV.
GAIN ERROR
The gain error is the ratio of the difference between the actual
gain and the ideal gain to the ideal gain. The actual gain is the
ratio of the output difference obtained with a full-scale analog
input (± 2.25 V) to the full-scale span (4.5 V) after correction of
the effects of the external components. It is expressed in %.
GAIN ERROR STABILITY OVER TEMPERATURE
The change of the gain error over temperature. It is expressed
in %.
REV. B