ADA4691-2ACPZ-R2 AD [Analog Devices], ADA4691-2ACPZ-R2 Datasheet - Page 15

• Manufacturer Part Number: ADA4691-2ACPZ-R2
• Description: Dual, Low Power, Wideband, Low Noise, Rail-to-Rail Output, Operational Amplifiers
• Manufacturer: AD [Analog Devices]

SHUTDOWN OPERATION
INPUT PIN CHARACTERISTICS
The ADA4691-2 has a classic CMOS logic inverter input for
each shutdown pin, as shown in Figure 50.
With slowly changing inputs, the top transistor and bottom
transistor may be slightly on at the same time, increasing the
supply current. This can be avoided by driving the input with a
digital logic output having fast rise and fall times. Figure 51
through Figure 53 show the supply current for both sections
switching simultaneously with rise times of 1 μs, 10 μs, and
1 ms. Clearly, the rise and fall times should be faster than 10 us.
Using an RC time constant to enable/disable shutdown is not
recommended.
I
SDA, B
DUT OUTPUT
I
SDA, B
DUT OUTPUT
SY
SY
= 196mV/1k = 196µA
= 192mV/1k = 196µA
Figure 52. Shutdown Pin Rise Time = 10 μs
Figure 51. Shutdown Pin Rise Time = 1 μs
INPUT
Figure 50. CMOS Inverter
TIME (400µs/DIV)
TIME (400µs/DIV)
V
DD
P-CHANNEL
N-CHANNEL
OUTPUT
Rev. A | Page 15 of 16
INPUT THRESHOLD
The input threshold is approximately 1.2 V above the V− pin
when operating on ground and +5 V, and 0.9 V when operating
on 2.7 V (see Figure 54 and Figure 55). The threshold is rela-
tively stable over temperature. For operation on split supplies,
the logic swing may have to be level shifted.
500
450
400
350
300
250
200
150
100
300
250
200
150
100
50
50
0
0
0
0
Figure 55. Supply Current vs. Temperature, V
Figure 54. Supply Current vs. Temperature, V
ADA4691-2
T
V
ADA4691-2
V
A
SY
SY
= 25°C
0.5
= 5V
= 2.7V
0.3
Figure 53. Shutdown Pin Rise Time = 1 ms
1.0
0.6
1.5
TIME (400µs/DIV)
T
0.9
A
= –40°C
ADA4691-2/ADA4692-2
SD VOLTAGE (V)
SD VOLTAGE (V)
2.0
T
1.2
A
T
A
= +125°C
T
2.5
A
= +125°C
= –40°C
SDA, B
I
DUT OUTPUT
SY
1.5
3.0
= 724mV/1k = 724µA
1.8
3.5
T
T
A
A
T
T
= +85°C
2.1
= +85°C
A
A
4.0
SY
SY
= +25°C
= +25°C
= 2.7 V
= 5 V
2.4
4.5
5.0
2
.7