OP293FSZ Analog Devices Inc, OP293FSZ Datasheet - Page 16

• Manufacturer Part Number: OP293FSZ
• Description: IC OPAMP GP 35KHZ DUAL 8SOIC
• Manufacturer: Analog Devices Inc
• Type: General Purpose Amplifierr

Specifications of OP293FSZ

• Slew Rate: 0.015 V/µs
• Design Resources: 4 mA-to-20 mA Loop-Powered Temperature Monitor Using ADuC7060/1 (CN0145)
• Amplifier Type: General Purpose
• Number Of Circuits: 2
• Output Type: Rail-to-Rail
• Gain Bandwidth Product: 35kHz
• Current - Input Bias: 20nA
• Voltage - Input Offset: 250µV
• Current - Supply: 30µA
• Current - Output / Channel: 25mA
• Voltage - Supply, Single/dual (±): 1.7 V ~ 36 V, ±0.85 V ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Op Amp Type: Precision
• No. Of Amplifiers: 2
• Bandwidth: 35kHz
• Supply Voltage Range: 2V To ± 18V
• Amplifier Case Style: SOIC
• No. Of Pins: 8
• Rail/rail I/o Type: No
• Number Of Elements: 2
• Unity Gain Bandwidth Product: 0.035MHz
• Common Mode Rejection Ratio: 96dB
• Input Offset Voltage: 250uV
• Input Bias Current: 20nA
• Single Supply Voltage (typ): 3/5/9/12/15/18/24/28V
• Voltage Gain In Db: 106.02dB
• Power Supply Rejection Ratio: 97dB
• Power Supply Requirement: Single/Dual
• Shut Down Feature: No
• Single Supply Voltage (min): 2V
• Single Supply Voltage (max): 36V
• Dual Supply Voltage (min): ±1V
• Dual Supply Voltage (max): ±18V
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC N
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Lead Free Status / Rohs Status: Compliant

OP193/OP293
A SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER
Designing a true single-supply instrumentation amplifier with
zero-input and zero-output operation requires special care. The
traditional configuration, shown in Figure 33, depends upon
Amplifier A1’s output being at 0 V when the applied common-
mode input voltage is at 0 V. Any error at the output is multiplied
by the gain of A2. In addition, current flows through Resistor R3
as A2’s output voltage increases. A1’s output must remain at 0 V
while sinking the current through R3, or a gain error results. With
a maximum output voltage of 4 V, the current through R3 is
only 2 μA, but this still produces an appreciable error.
One solution to this problem is to use a pull-down resistor. For
example, if R3 = 20 kΩ, then the pull-down resistor must be less
than 400 Ω. However, the pull-down resistor appears as a fixed
load when a common-mode voltage is applied. With a 4 V
common-mode voltage, the additional load current is 10 mA,
which is unacceptable in a low power application.
Figure 34 shows a better solution. A1’s sink current is provided
by a pair of N-channel FET transistors, configured as a current
mirror. With the values shown, the sink current of Q2 is about
340 μA. Thus, with a common-mode voltage of 4 V, the addi-
tional load current is limited to 340 μA vs. 10 mA with a 400 Ω
resistor.
+IN
–IN
20kΩ
R1
Figure 33. A Conventional Instrumentation Amplifier
NOTES
1. ALL RESISTORS 1/4 W, 5% UNLESS OTHERWISE NOTED.
REF43GPZ
1/2 OP293
+
–
TEMP
1.98MΩ
V
GND
A1
OUT
V
R2
5V
IN
V+
V–
2
6
3
4
R1, 10kΩ
I
SINK
20kΩ
R3
1.98MΩ
1/2 OP293
–
+
R4
A2
5V
V+
V–
2
3
–
OP293
+
Figure 35. Temperature to 4 mA to 20 mA Transmitter
1/2
8
4
V
OUT
1
R3
100kΩ
V
Rev. C | Page 16 of 20
TEMP
1kΩ
R2
5kΩ
R5
ZERO
TRIM
R4
20kΩ
V
A LOW POWER, TEMPERATURE TO 4 mA TO 20 mA
TRANSMITTER
A simple temperature to 4 mA to 20 mA transmitter is shown
in Figure 35. After calibration, this transmitter is accurate to
±0.5°C over the −50°C to +150°C temperature range. The
transmitter operates from 8 V to 40 V with supply rejection
better than 3 ppm/V. One half of the OP293 is used to buffer
the TEMP pin, and the other half regulates the output current
to satisfy the current summation at its noninverting input.
The change in output current with temperature is the derivative
of the following transfer function:
Figure 34. An Improved Single-Supply, 0 V
SET
–IN
+IN
I
∆
3kΩ
R6
20kΩ
OUT
6
5
I
∆
R1
OUT
+
T
–
OP293
1/2
+
=
V
SPAN TRIM
5kΩ
1/2 OP293
TEMP
R7
–
+
∆
1.98MΩ
VN2222
V
A1
R
∆
7
R2
5V
TEMP
2
T
×
R
V+
V–
×
2
(
R9
100kΩ
R
R
Q1
×
6
(
10
5V
R
R
1%, 1/2 W
+
1kΩ
10kΩ
6
R8
10
R
+
100Ω
7
R10
R
)
7
−
2N1711
)
V
R
Q2
I
20kΩ
1N4002
OUT
IN
LOAD
SET
R3
, 0 V
8V TO 40V




OUT
R
1/2 OP293
V+
2
–
+
Instrumentation Amplifier
R
1.98MΩ
+
A2
2
R4
5V
R
×
V+
V–
6
R
+
10
R
7




V
OUT