ad1879 Analog Devices, Inc., ad1879 Datasheet - Page 5

• Manufacturer Part Number: ad1879
• Description: High Performance 16-/18-bit Stereo Adcs
• Manufacturer: Analog Devices, Inc.

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DEFINITIONS
Dynamic Range
The ratio of a full-scale output signal to the integrated output
noise in the passband (0 kHz to 20 kHz), expressed in decibels
(dB). Dynamic range is measured with a –60 dB input signal
and is equal to (S/[THD+N]) + 60 dB.
Signal to (Noise + Distortion)
The ratio of the root-mean-square (rms) value of the fundamen-
tal input signal to the rms sum of all spectral components in the
passband, expressed in decibels (dB).
Signal to Total Harmonic Distortion (THD)
The ratio of the rms sum of all harmonically related spectral
components in the passband to the fundamental input signal,
expressed either as a percentage (%) or in decibels (dB).
Passband
The region of the frequency spectrum unaffected by the attenu-
ation of the digital decimator’s filter.
Passband Ripple
The peak-to-peak variation in amplitude response from equal
amplitude input signal frequencies within the passband, ex-
pressed in decibels.
Stopband
The region of the frequency spectrum attenuated by the digi-
tal decimator’s filter to the degree specified by “stopband
attenuation.”
Gain Error
With a near full-scale input, the ratio of actual output to ex-
pected output, expressed as a percentage.
Interchannel Gain Mismatch
With near full-scale inputs, the ratio of outputs of the two stereo
channels, expressed in decibels.
Gain Drift
Change in response to a near full-scale input with a change in
temperature, expressed as parts-per-million (ppm) per C.
Midscale Offset Error
Output response to a midscale input (i.e., zero volts dc), ex-
pressed in least-significant bits (LSBs).
Midscale Drift
Change in midscale offset error with a change in temperature,
expressed as parts-per-million (ppm) of full scale per C.
Crosstalk
Ratio of response on one channel with a grounded input to a
full-scale 1 kHz sine-wave input on the other channel, expressed
in decibels.
Interchannel Phase Deviation
Difference in input sampling times between stereo channels, ex-
pressed as a phase difference in degrees between 1 kHz inputs.
Power Supply Rejection
With analog inputs grounded, energy at the output when a
300 mV p-p signal is applied to power supply pins, expressed in
decibels of full scale.
Group Delay
Intuitively, the time interval required for an input pulse to ap-
pear at the converter’s output, expressed in milliseconds (ms).
More precisely, the derivative of radian phase with respect to
radian frequency at a given frequency.
–5–
Group Delay Variation
The difference in group delays at different input frequencies.
Specified as the difference between largest and the smallest
group delays in the passband, expressed in microseconds ( s).
Pin Input/Output Pin Name Description
11
12
13
14
15
16
17
18
19
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
THEORY OF OPERATION
The stereo, differential analog modulators of the AD1878/
AD1879 employ a proprietary feedforward and feedback archi-
tecture that passes input signals in the audio band with a unity
transfer function yet simultaneously shape the quantization
noise generated by the one-bit comparator out of the audio
band. See Figure 1. Without the
tion noise would be spread uniformly from dc to one-half the
oversampling frequency, 64
64 times oversampling by itself significantly reduces the quanti-
zation noise in the audio band if the input is properly dithered.
However, the noise reduction is only [log
Figure 1. AD1878/AD1879 Modulator Noise-Shaper (One
Channel)
0.200 (5.05)
0.125 (3.18)
Modulator Noise-Shaping
(6.35)
0.250
MAX
I/O
I/O
I
I
I
I
I
I
I
I
I
I
I/O
I/O
I
I
I
I
I
I
I
I
I
I
I
O
I/O
PIN 1
0.022 (0.558)
0.014 (0.356)
2
8
1
AD1878/AD1879 PIN LIST
LRCK
BCK
S0
64/32
DV
DGND
N/C
AV
AV
AGND
APD
VINR–
VINR+
REFR
REFL
VINL+
VINL–
AGND
AV
AV
AV
DV
DGND
RESET
S1
CLOCK
DATA
WCK
SS
SS
DD
DD
SS
DD
DD
1
2
1
0.625 (15.87)
0.600 (15.24)
1
2
0.015 (0.381)
0.008 (0.204)
(2.54)
0.100
BSC
1.565 (39.70)
1.380 (35.10)
F
S
Left/Right Clock
Bit Clock
Mode Select 0
Bit Rate Select
+5 V Digital Supply
Digital Ground
No Connection; Do Not Connect
–5 V Analog Supply
–5 V Analog Logic Supply
Analog Ground
Analog Power Down
Right Inverting Input
Right Noninverting Input
Right Reference Capacitor
Left Reference Capacitor
Left Noninverting Input
Left Inverting Input
Analog Ground
+5 V Analog Supply
+5 V Analog Logic Supply
–5 V Analog Supply
+5 V Digital Supply
Digital Ground
Reset
Mode Select 1
Master Clock Input
Serial Data Output
Word Clock
. (Regardless of architecture,
AD1878/AD1879
architecture, this quantiza-
0.195 (4.95)
0.125 (3.18)
2
64]
0.070 (1.77)
MAX
3 dB = 18 dB.)
15
14
0.580 (14.73)
0.485 (12.32)
0.060 (1.52)
0.015 (0.38)
SEATING
PLANE
0.150
(3.81)
MIN