AD693AQ Analog Devices Inc, AD693AQ Datasheet - Page 7

• Manufacturer Part Number: AD693AQ
• Description: IC TRANSMITTER 4-20MA 20-CDIP
• Manufacturer: Analog Devices Inc
• Type: Signal Conditionerr

Specifications of AD693AQ

• Rohs Status: RoHS non-compliant
• Input Type: Voltage
• Output Type: Voltage
• Interface: 3-Wire
• Current - Supply: 20mA
• Mounting Type: Through Hole
• Package / Case: 20-CDIP (0.300", 7.62mm)
• Supply Voltage Range: 12V To 36V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: DIP
• No. Of Pins: 20
• Svhc: No SVHC (18-Jun-2010)
• Operating Temperature Max: 85°C
• Operating: RoHS Compliant
• Converter Type: Voltage to Current
• Current, Output: +25 mA (Typ.)
• Current, Quiescent Supply: +500 uA (Typ.)
• Package Type: Cerdip
• Temperature, Operating, Maximum: 85 °C
• Temperature, Operating, Minimum: -40 °C
• Voltage, Operating: +12 V (Min.)
• No. Of Amplifiers: 5
• Input Offset Voltage: 200µV
• Cmrr: 90dB
• Supply Current: 500µA
• Amplifier Case Style: DIP
• Rohs Compliant: No
• Ic Function: Sensor Transmitter
• Amplifier Type: Current
• Base Number: 693

REV. A
of adjustment of the output current from nominal. Substitute
this value in the appropriate formula below for adjustment at the
4 mA tap.
Use a similar connection with the following resistances for
adjustments at the 12 mA tap.
These formulae take into account the 10% tolerance of tap
resistance and insure a minimum adjustment range of I
example, choosing I
of 1% of the 20 mA full-scale output. At the 4 mA tap the
maximum value of:
These can be rounded down to more convenient values of
7.5 k and 1.3 M , which will result in an adjustment range
comfortably greater than 200 A.
ADJUSTING INPUT SPAN
Input Span is adjusted by changing the gain of the Signal
Amplifier. This amplifier provides a 0-to-60 mV signal to the
V/I section to produce the 4-to-20 mA output span (or a
Figure 12. Optional 4 mA Zero Adjustment (12 mA Trim
Available Also)
R
R
R
R
R
R
Z1
Z2
Z1
Z2
Z2
Z1
= (1.6 V/I
= R
= (4.8 V/I
= R
= 7.6 k
= 1.6 V/200 A – 400
Z1
Z1
3.1 V/(15 mV + I
3.1 V/(45 mV + I
A
A
3.1 V/(15 mV + 200 A 3.75 ) = 1.49 M
) – 400
) – 400
A
= 200 A will give a zero adjustment range
Figure 11. Using an External Pass Transistor to Minimize Self-Heating Errors
and
and
= 7.6 k and
A
A
3.75 )
3.75 )
A
. For
–7–
0-to-75 mV signal in the 0-to-20 mA mode). The gain of this
amplifier is trimmed to 2.00 so that an input signal ranging from
0-to-30 mV will drive the V/I section to produce 4-to -20 mA.
fier gain to one, thereby requiring a 60 mV signal to drive the V/I
to a full 20 mA span.
To produce spans less than 30 mV, an external resistor, R
be connected between P1 and 6.2 V. The nominal value is given
by:
where S is the desired span. For example, to change the span to
6 mV a value of:
is required. Since the internal, 800
exhibit an absolute tolerance of 10%, R
with up to 10% range of adjustment if the span must be well
controlled.
For spans between 30 mV and 60 mV a resistor R
connected between P1 and P2. The nominal value is given by:
For example, to change the span to 40 mV, a value of:
is required. Remember that this is a nominal value and may
require adjustment up to 10%. In many applications the span
must be adjusted to accommodate individual variations in the
sensor as well as the AD693. The span changing resistor should,
therefore, include enough adjustment range to handle both the
sensor uncertainty and the absolute resistance tolerance of P1
and P2. Note that the temperature coefficient of the internal
resistors is nominally –17 ppm/ C, and that the external
resistors should be comparably stable to insure good tempera-
ture performance.
Joining P1 and P2 (Pins 15 and 16) will reduce the Signal Ampli-
R
R
R
R
S1
S1
S2
S2
400
30 mV
30 mV
400
6 mV
400
400
S
30 mV
30 mV
40 mV
S
1
1
1
1
60 mV
60 mV
40 mV
100
S
1
1
gain setting resistors
S1
800
should be provided
AD693
S2
should be
S1
, can