OP41BJ View Datasheet(PDF) - Analog Devices

Part Name

Description

MFG CO.

OP41BJ

Low-Bias-Current, High-Stability JFET Operational Amplifie

Analog Devices 

- ANALOGDEVICES fAX-ON-DEMAND HOTLINE

Page 12

FIGURE 13: WIDE RANGE LOW-CURRENT AMMETER

OP-41

'5V

alA

112 MAT-02EH

A12

4!<!!

A8

10nA 511\1

r INPUT

C1

lOOp

C2

2llF

R2

2.4Mil

A1

4.7kl>

AS

2kH

R3

alS

112MAT-02EH

3kU

01

IN914

&1

1ltA

02

LM1l3

Ala

51W

OBS The voltage driving the divider is obtained from a 1.22V low

voltage reference diode (LM113) through a 2N2222 transistor

O and resistor string. The voltage across the divider varies with

absolute temperature, keeping the multiplier constant.

L Calibration is simple, requiring only one adj ustment. R4 is used

E to adjust full scale deflection with a 1pA input current. This will

give maximum accuracy over the operating range of currents.

TE The low Vosand exceptionally good log conformance of the

FIGURE 14: SETTLING-TIME TEST CIRCUIT

,'5V

~O"lJt

4.99k!l 1%

MAT-O2assure high accuracy over the full 6 decade operating

range.

Figure 14 is the test circuit used to measure the settling time.

This circuit uses the "false sum-node" technique. When the

system is Initially set up. the 2000. pot is adjusted until the DC

output voltage to the scope is unchanged when the input is

changed from +10Vto -10V.The 2N4416 FET buffer isolates the

+15V

2N44l6

4.99kH'"

200n

4.99kU

-15V

1%

Vour

~O.'ltf

sum node from the scope probe load capacitance. The pulse

generator must be properly terminated and have ringing below

the expected error signal. (2.5mV in a 5V pulse for 0.1%

overshoot measurement.)

HP 5082-2836

...

-11-

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