AD540_15 Datasheet, PDF (1/4 Pages) Analog Devices – HIGH ACCURACY LOW COST FET INPUT OPERATIONAL AMPLIFIER

ANALOG
DEVICES
HighAccuracyl,ow Cost,
FET-InputOperationaAlmplifier
FEATURES
Low Cost: $4.45 (100's, J)
Low Ib: 25pA max (K)
Low Vas: 20m V max (K)
Low Vas Drift: 25/lVtC max (K)
High Differential Input Voltage
Capability: :t20V
OBSOLETE PRODUCT DESCRIPTION
The AD540 is the lowest cost, high accuracy FET-input op
amp available which provides the user with low bias currents,
high overall performance, and accurately specified predictable
operation. The device offers maximum bias currents as low as
25pA, offset voltages below 20mV, maximum offset voltage
drift below 2511V/C and a minimum gain of 50,000.
2. The bias currents of the AD540 are specified as a maximum
for either input. Conventional IC FET op amps generally
specify bias currents as the average of the two input
currents.
3. Unlike many FET-input op amps, the AD540 allows a
maximum differential input voltage of :t20VDC. Standard
"bootstrapped" FET-input op amps permit maximum
All devices are free from latchup and are short-circuit
differential input voltages of only about :t3V.
protected. No external compensation is required as the
internal 6dB/octave roll-off provides stability in closed loop
applications,
4. Offset nulling of the AD540 is accomplished without
affecting the operating current of the FET's and results
in relatively small changes in temperature drift
The AD540 is suggested for all FET~input amplifier require-
characteristics. The additional drift induced by nulling is
ments where low cost is of prime importance. Its performance
only :t2.0/lV 1°C per millivolt of nulled offset, compared
is comparable to modular FET op amps, but its IC
to several times this for other IC FET opamps.
construction reduces the price significantly below that of
modules.
5. The gain of the AD540 is measured with the offset
voltage nulled. Nulling a FET-input op amp can cause the
All versions of the AD540 are supplied in the hermetically-
gain to decrease below its specified limit. The gain of the
sealed, 8-pin, TO-99 package. The AD540J and AD540K
are specified for 0 to +70°C applications, while the AD540S
AD540 is fully guaranteed with the offset voltage both
nulled and unnulled.
is offered for operation over the full military temperature
range of -55 to +125°C.
PRODUCT HIGHLIGHTS
1. The AD540 op amp meets specified input bias current and
6. To maximize the reliability inherent in IC construction,
every AD540 is stored for 40 hours at +150°C, temperature
cycled from -65 to +125°C and receives a high impact
shock test.
offset voltage values after full warm-up. Conventional high
speed IC testing does not allow for self-heating of the ch~p
due to internal power dissipation under operating
conditions.
Information furnished by Analog Devices is believed to be accurate
and reliable. However, no responsibility is assumed by Analog Devices
for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implica-
tion or otherwise under any patent or patent rights of Analog Devices.
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