AD7607 Analog Devices, AD7607 Datasheet - Page 20

• Manufacturer Part Number: AD7607
• Description: 8-Channel DAS with 14-Bit, Bipolar, Simultaneous Sampling ADC
• Manufacturer: Analog Devices

Specifications of AD7607

• Resolution (bits): 14bit
• # Chan: 8
• Sample Rate: 200kSPS
• Interface: Par,Ser,SPI
• Analog Input Type: SE-Bip
• Ain Range: Bip 10V,Bip 5.0V
• Adc Architecture: SAR
• Pkg Type: QFP

AD7607
Analog Input Antialiasing Filter
An analog antialiasing filter (a second-order Butterworth) is
also provided on the AD7607. Figure 33 and Figure 34 show
the frequency and phase response, respectively, of the analog
antialiasing filter. In the ±5 V range, the −3 dB frequency is
typically 15 kHz. In the ±10 V range, the −3 dB frequency is
typically 23 kHz.
Track-and-Hold Amplifiers
The track-and-hold amplifiers on the AD7607 let the ADC
accurately acquire an input sine wave of full-scale amplitude to
14-bit resolution. The track-and-hold amplifiers sample their
respective inputs simultaneously on the rising edge of CONVST x.
The aperture time for the track-and-hold (that is, the delay time
between the external CONVST x signal and the track-and-hold
actually going into hold) is well matched, by design, across all eight
track-and-holds on one device and from device to device. This
matching allows more than one AD7607 device to be sampled
simultaneously in a system.
–10
–15
–20
–25
–30
–35
–40
–5
18
16
14
12
10
–2
–4
–6
–8
5
0
100
Figure 33. Analog Antialiasing Filter Frequency Response
8
6
4
2
0
10
Figure 34. Analog Antialiasing Filter Phase Response
AV
f
T
AV
f
T
±10V RANGE
±5V RANGE
SAMPLE
A
SAMPLE
A
±10V RANGE
CC
= 25°C
±5V RANGE
CC
= 25°C
, V
, V
DRIVE
DRIVE
= 200kSPS
= 200kSPS
–40
+25
+85
–40
+25
+85
= 5V
= 5V
0.1dB
10,303
9619
9326
0.1dB
5225
5225
4932
INPUT FREQUENCY (Hz)
1k
INPUT FREQUENCY (Hz)
1k
3dB
24,365Hz
23,389Hz
22,607Hz
3dB
16,162Hz
15,478Hz
14,990Hz
±5V RANGE
10k
10k
±10V RANGE
100k
100k
Rev. B | Page 20 of 32
The end of the conversion process across all eight channels is
indicated by the falling edge of BUSY, and it is at this point that the
track-and-holds return to track mode and the acquisition time
for the next set of conversions begins.
The conversion clock for the part is internally generated, and
the conversion time for all channels is 4 µs. On the AD7607, the
BUSY signal returns low after all eight conversions to indicate the
end of the conversion process. On the falling edge of BUSY, the
track-and-hold amplifiers return to track mode. New data can
be read from the output register via the parallel, parallel byte, or
serial interface after BUSY goes low; or, alternatively, data from
the previous conversion can be read while BUSY is high. Reading
data from the AD7607 while a conversion is in progress has little
effect on performance and allows a faster throughput to be
achieved. In parallel mode at V
by ~1.5 dB when reading during a conversion.
ADC TRANSFER FUNCTION
The output coding of the AD7607 is twos complement. The
designed code transitions occur midway between successive
integer LSB values, that is, 1/2 LSB, 3/2 LSB. The LSB size is
FSR/16,384. The ideal transfer characteristic is shown in Figure 35.
The LSB size is dependent on the analog input range selected.
±10V RANGE +10V
±5V RANGE
011...111
011...110
000...001
000...000
111...111
100...010
100...001
100...000
–FS + 1/2LSB
Figure 35. Transfer Characteristics
+FS
+5V
±10V CODE =
±5V CODE =
MIDSCALE
0V
0V
0V – 1LSB +FS – 3/2LSB
ANALOG INPUT
10V
DRIVE
VIN
VIN
5V
× 8182 ×
× 8192 ×
–FS
–10V
–5V
> 3.3 V, the SNR is reduced
LSB =
REF
2.5V
REF
2.5V
LSB
1.22mV
610µV
+FS – (–FS)
Data Sheet
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