XTR111_07 BURR-BROWN [Burr-Brown Corporation], XTR111_07 Datasheet - Page 10

• Manufacturer Part Number: XTR111_07
• Description: Precision Voltage-to-Current Converter/Transmitter
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

XTR111
SBOS375 − NOVEMBER 2006
APPLICATION INFORMATION
The XTR111 is a voltage-controlled current source capa-
ble of delivering currents from 0mA to 36mA. The primary
intent of the device is to source the commonly-used indus-
trial current ranges of 0mA−20mA or 4mA−20mA. The per-
formance is specified for a supply voltage of up to 40V. The
maximum supply voltage is 44V. The voltage-to-current ra-
tio is defined by an external resistor, R
put voltage range can be freely set in accordance with the
application requirement. The output current is cascoded
by an external P-Channel MOSFET transistor for large
voltage compliance extending below ground, and for easy
power dissipation. This arrangement ensures excellent
suppression of typical interference signals from the indus-
trial environment because of the extremely high output im-
pedance and wide voltage compliance.
An error detection circuit activates a logic output (error
flag) in case the output current cannot correctly flow. It indi-
cates a wire break, high load resistor, or loss of headroom
for the current output to the positive supply.
10
Figure 1. Basic Connection for 0mA to 20mA Related to 0V to 5V Signal Input. The Voltage Regulator is
(Sensor or
example)
5V
DAC, for
Source
Signal
R
5.6kΩ
1
R
8.2k Ω
2
5
4
6
REGF
REGS
VIN
SET
3V
; therefore, the in-
10
GND
Set to 5V Output.
7
V
VSP
SET
C
R
1
= 24V Supply
I−Mirror
SET
The output disable (OD) provided can be used during pow-
er-on, multiplexing and other conditions where the output
should present no current. It has an internal pull-up that
causes the XTR111 to come up in output disable mode un-
less the OD pin is tied low.
The onboard voltage regulator can be adjusted between
3V to 15V and delivers up to 5mA load current. It is in-
tended to supply signal conditioning and sensor excitation
in 3-wire sensor systems. Voltages above 3V can be set
by a resistive divider.
Figure 1 shows a basic connection for the XTR111. The in-
put voltage V
of the output current. The I-Mirror has a precise current
gain of 10. This configuration leads to the transfer function:
The output of the voltage regulator can be set over the
range of 3V to 12V by selecting R
ing equation.
1
VSP
I
OUT
OD
VG
EF
= 10
VIN
IS
V
reappears across R
(
REGF
I
9
8
2
3
OUT
R
V
(± Load Ground)
VIN
SET
G
)
= 10 • (V
= 3V • (R
S
D
Load
(Pull Low for Normal Operation)
Q
P−Channel
MOSFET
0mA or 4mA to 20mA
I
OUT
EXT
VIN
V
1
OUT
1
+ R
/R
and R
SET
SET
2
)/R
)
2
and controls 1/10
2
using the follow-
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