XTR111_07 BURR-BROWN [Burr-Brown Corporation], XTR111_07 Datasheet - Page 15

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

LEVEL SHIFT OF 0V INPUT AND
TRANSCONDUCTANCE TRIM
The XTR111 offers low offset voltage error at the input,
which normally does not require cancellation. If the signal
source cannot deliver 0V in a single-supply circuit, an
additional resistor from the SET pin to a positive reference
voltage or the regulator output (Figure 8) can shift the zero
level for the input (V
signal source can drive this value within a positive voltage
range. The example shows a +100mV (102.04mV) offset
generated to the signal input. The larger this offset,
however, the more influence of its drift and inaccuracy is
seen in the output signal. The voltage at SET should not
be larger than 12V for linear operation
Transconductance (the input voltage to output current
ratio) is set by R
found by choosing a combination of two resistors.
VOLTAGE REGULATOR
The externally adjustable voltage regulator provides up to
5mA of current. It offers drive (REGF) and sense (REGS)
to allow external setting of the output voltage as shown in
Figure 9. The sense input (REGS) is referenced to 3.0V
representing the lowest adjustable voltage level. An
external resistor divider sets V
V
REGF
www.ti.com
= V
V
3V
REG
REGS
470nF
• (R
470nF
SET
1
IN
. The desired resistor value may be
+ R
) to a positive voltage. Therefore, the
REGF
REGS
V
SP
(a)
1kΩ
(c)
220Ω
R
5.6kΩ
R
8.2kΩ
2
)/R
1
2
3V
2
Figure 9. Basic Connections of the Voltage Regulator
1kΩ
REGF
.
REGF
REGS
3V
Table 2 provides example values for the regulator
adjustment resistors.
(1) Values have been rounded.
Table 2. Examples for the Resistor Values Setting
V
Source
REG
Figure 8. Input Voltage Level Shift for 0mA
5V
V
12.4V
VIN
REGF (1)
3.3V
3V
5V
470nF
47kΩ
R
3
Reference
XTR111
the Regulator Voltage
R
5.6kΩ
R
8.2kΩ
5V
Output Current
1
2
I−V Amp
REGF
REGS
(b)
(d)
3.3kΩ
5.6kΩ
27kΩ
120k Ω
R
3V
0
1
REGF
REGS
SBOS375 − NOVEMBER 2006
3V
SET
R
2kΩ
SET
+100mV
Offset
REG
8.2kΩ
8.6kΩ
33kΩ
R

XTR111
2
15