AD7675 Datasheet, PDF (7/20 Pages) Analog Devices – 16-Bit, 100 kSPS, Differential ADC

PIN CONFIGURATION
48-Lead LQFP
(ST-48)
48 47 46 45 44 43 42 41 40 39 38 37
AGND 1
AVDD 2
NC 3
BYTESWAP 4
OB/2C ⁵
NC 6
NC 7
SEP/PAR ⁸
D0 9
D1 10
D2/DIVSCLK[0] ¹¹
D3/DIVSCLK[1] 12
PIN 1
IDENTIFIER
AD7675
TOP VIEW
(Not to Scale)
36 AGND
35 _CNVST
34 PD
33 RESET
32 _CS
31 _RD
30 DGND
29 BUSY
28 D15
27 D14
26 D13
25 D12
NC = NO CONNECT ^{13 14 15 16 17 18 19 20 21 22 23 24}
AD7675
DEFINITION OF SPECIFICATIONS
INTEGRAL NONLINEARITY ERROR (INL)
Integral Nonlinearity is the maximum deviation of a straight line
drawn through the transfer function of the actual ADC. The
deviation is measured from the middle of each code.
DIFFERENTIAL NONLINEARITY ERROR (DNL)
In an ideal ADC, code transitions are 1 LSB apart. Differential
nonlinearity is the maximum deviation from this ideal value. It
is often specified in terms of resolution for which no missing
codes are guaranteed.
+FULL-SCALE ERROR
The last transition (from 011 . . . 10 to 011 . . . 11 in two’s
complement coding) should occur for an analog voltage 1 1/2 LSB
below the nominal +full scale (+2.499886 V for the ±2.5 V range).
The +full-scale error is the deviation of the actual level of the
last transition from the ideal level.
–FULL-SCALE ERROR
The first transition (from 100 . . . 00 to 100 . . . 01 in two’s
complement coding) should occur for an analog voltage 1 1/2 LSB
above the nominal –full scale (–2.499962 V for the ± 2.5 V range).
The –full-scale error is the deviation of the actual level of the
last transition from the ideal level.
BIPOLAR ZERO ERROR
The bipolar zero error is the difference between the ideal midscale
input voltage (0 V) and the actual voltage producing the midscale
output code.
SPURIOUS FREE DYNAMIC RANGE (SFDR)
The difference, in decibels (dB), between the rms amplitude of
the input signal and the peak spurious signal.
EFFECTIVE NUMBER OF BITS (ENOB)
ENOB is a measurement of the resolution with a sine wave
input. It is related to S/(N+D) by the following formula:
( ) [ ] ENOB = S / N + D – 1.76 / 6.02
dB
and is expressed in bits.
TOTAL HARMONIC DISTORTION (THD)
THD is the ratio of the rms sum of the first five harmonic
components to the rms value of a full-scale input signal and is
expressed in decibels.
SIGNAL-TO-NOISE RATIO (SNR)
SNR is the ratio of the rms value of the actual input signal to the
rms sum of all other spectral components below the Nyquist
frequency, excluding harmonics and dc. The value for SNR is
expressed in decibels.
SIGNAL-TO-(NOISE + DISTORTION) RATIO (S/[N+D])
S/(N+D) is the ratio of the rms value of the actual input signal
to the rms sum of all other spectral components below the
Nyquist frequency, including harmonics but excluding dc. The
value for S/(N+D) is expressed in decibels.
APERTURE DELAY
Aperture delay is a measure of the acquisition performance and
is measured from the falling edge of the CNVST input to when
the input signal is held for a conversion.
TRANSIENT RESPONSE
The time required for the AD7675 to achieve its rated accuracy
after a full-scale step function is applied to its input.
REV. 0
–7–