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