Datasheet AD8625, AD8626, AD8627 (Analog Devices) - 14

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AD8625/AD8626/AD8627 Data Sheet
The AD862x can safely withstand input voltages 15 V below
20k
Ω VSY if the total voltage between the positive supply and the input
+5V
terminal is less than 26 V. Figure 41 through Figure 43 show the
10k
Ω AD862x in different configurations accommodating signals
0V –10mV
close to the negative rail. The amplifier input stage typically maintains picoamp-level input currents across that input
–30mV
voltage range.
VSY = 5V 20k
Ω
+5V 10k
Ω
0V –2.5V VSY = 5V, 0V VOLTAGE (10mV/DIV) 5V 0V
03023-042
TIME (2
µ
s/DIV)
Figure 43. Gain-of-Two Inverter Response to 20 mV Step, Centered 20 mV below Ground
VOLTAGE (1V/DIV)
The AD862x is designed for 16 nV/√Hz wideband input voltage noise and maintains low noise performance to low frequencies,
0V
as shown in Figure 35. This noise performance, along with the AD862x’s low input current and current noise, means that the 03023-040
TIME (2
µ
s/DIV)
AD862x contributes negligible noise for applications with large Figure 41. Gain-of-Two Inverter Response to 2.5 V Step, source resistances. Centered 1.25 V below Ground The AD862x has a unique bipolar rail-to-rail output stage that
60mV
swings within 5 mV of the rail when up to 2 mA of current is
5V 20mV
drawn. At larger loads, the drop-out voltage increases, as shown
0V
in Figure 17 and Figure 18. The AD862x’s wide bandwidth and
600
Ω fast slew rate al ows it to be used with faster signals than older single-supply JFETs. Figure 44 shows the response of the AD862x, configured in unity gain, to a VIN of 20 V p-p at 50 kHz. The full-power bandwidth (FPBW) of the part is close to 100 kHz.
VSY =
±
13V RL = 600
Ω
VOLTAGE (10mV/DIV) 0V VSY = 5V RL = 600
Ω
0V VOLTAGE (5V/DIV)
03023-041
TIME (2
µ
s/DIV)
Figure 42. Unity Gain Follower Response to 40 mV Step, Centered 40 mV above Ground 03023-043
TIME (5
µ
s/DIV)
Figure 44. Unity Gain Follower Response to 20 V, 50 kHz Input Signal Rev. F | Page 14 of 20 Document Outline Features Applications Pin Configurations General Description Revision History Specifications Electrical Characteristics Absolute Maximum Ratings ESD Caution Typical Performance Characteristics Applications Information Minimizing Input Current Photodiode Preamplifier Application Output Amplifier for DACs Eight-Pole Sallen Key Low-Pass Filter Outline Dimensions Ordering Guide