Typical Performance Characteristics–
AD7705/AD7706
32771
32770
32769
400
V
V
= 5V
T
= +25؇C
DD
A
= 2.5V
RMS NOISE = 600nV
REF
GAIN = 128
50Hz UPDATE RATE
300
200
32768
32767
32766
32765
32764
32763
100
0
0
100 200 300 400 500 600 700 800 900 1000
READING NO.
32764
32765
32766
32767
CODE
32768 32769
32770
Figure 2. Typical Noise Plot @ Gain = 128 with 50 Hz
Update Rate
Figure 5. Histogram of Data in Figure 2
1.2
1.0
0.8
0.6
0.4
0.2
0
1.2
V
T
= 5V
V
T
= 3V
DD
DD
= +25؇C
= +25؇C
A
A
BUFFERED MODE, GAIN = 128
1.0
0.8
0.6
0.4
0.2
0
BUFFERED MODE, GAIN = 128
BUFFERED MODE, GAIN = 1
BUFFERED MODE, GAIN = 1
UNBUFFERED MODE, GAIN = 128
UNBUFFERED MODE, GAIN = 128
UNBUFFERED MODE, GAIN = 1
UNBUFFERED MODE, GAIN = 1
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6
FREQUENCY – MHz
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6
FREQUENCY – MHz
Figure 3. Typical IDD vs. MCLKIN Frequency @ 3 V
Figure 6. Typical IDD vs. MCLKIN Frequency @ 5 V
1.2
1.0
BUFFERED MODE
BUFFERED MODE
f
= 5MHz,
f
= 5MHz,
CLK
CLK
0.9
0.8
CLKDIV = 1
CLKDIV = 1
1.0
0.8
0.6
0.4
BUFFERED MODE
= 2.4576MHz, CLKDIV = 0
BUFFERED MODE
= 2.4576MHz, CLKDIV = 0
UNBUFFERED MODE
UNBUFFERED MODE
f
CLK
f
f
= 1MHz,
f
= 1MHz,
CLK
CLK
CLK
0.7
0.6
0.5
CLKDIV = 0
CLKDIV = 0
UNBUFFERED MODE
= 5MHz, CLKDIV = 1
UNBUFFERED MODE
= 5MHz, CLKDIV = 1
f
CLK
f
CLK
UNBUFFERED MODE
0.4
0.3
0.2
UNBUFFERED MODE
= 2.84MHz, CLKDIV = 0
f
= 2.4576MHz, CLKDIV = 0
CLK
f
CLK
V
= 5V
V
= 3V
DD
DD
0.2
0
BUFFERED MODE
BUFFERED MODE
= 1MHz, CLKDIV = 0
EXTERNAL MCLK
CLKDIS = 1
EXTERNAL MCLK
CLKDIS = 1
f
= 1MHz, CLKDIV = 0
f
0.1
0
CLK
CLK
T
= +25؇C
T
= +25؇C
A
A
1
2
4
8
16
32
64
128
1
2
4
8
16
32
64
128
GAIN
GAIN
Figure 4. Typical IDD vs. Gain and Clock Frequency @ 3 V
Figure 7. Typical IDD vs. Gain and Clock Frequency @ 5 V
REV. A
–9–
ADI [ ADI ]
