XTR111_07 BURR-BROWN [Burr-Brown Corporation], XTR111_07 Datasheet - Page 12

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

XTR111
SBOS375 − NOVEMBER 2006
EXTERNAL MOSFET
The XTR 111 delivers the precise output current to the IS
pin. The voltage at this pin is normally 1.4V below V
must not fall more than 5.5V below V
This output requires an external transistor (Q
forms a cascode for the current output. The resistor must
be rated for the maximum possible voltage on V
must dissipate the power generated by the current and the
voltage across it.
The gate drive (VG) can drive from close to the positive
supply rail to 16V below the positive supply voltage (V
Most modern MOSFETs accept a maximum V
protection clamp is only required if a large drain gate ca-
pacitance can pulse the gate beyond the rating of the
MOSFET. Pulling the OD pin high disables the gate driver
and closes a switch connecting an internal 3kΩ resistor
from the VSP pin to the VG pin. This resistor discharges
the gate of the external FET and closes the channel; see
Figure 2.
Table 1 lists some example devices in SO-compatible
packages, but other devices can be used as well. Avoid ex-
ternal capacitance from IS. This capacitance could be
compensated by adding additional capacitance from VG
(1) Data from published product data sheet; not ensured.
12
International Rectifier
MANUFACTURER
ON Semiconductor
Supertex Inc.
Infineon
NEC
PART NO.
BSP170P
IRFL9014
2SJ326-Z
NTF2955
TP2510
Table 1. P-Channel MOSFET (Examples)
VSP
.
GS
EXT
of 20V. A
OUT
BREAKDOWN VGS
) that
VSP
VSP
and
. It
).
−100V
−60V
−60V
−60V
−60V
to IS; however, this compensation may slow the output
down.
The drain-to-source breakdown voltage should be se-
lected high enough for the application. Surge voltage
protection might be required for negative over-voltages.
For positive over-voltages, a clamp diode to the 24V sup-
ply is recommended, protecting the FET from reversing.
Figure 2. Equivalent Circuit for Gate Drive and
16V
PACKAGE
TO-243AA
SOT-223
SOT-223
SOT-223
Spec.
(1)
Disable Switch
OD
Switch
3kΩ
C-GATE
VSP
VG
GND
328pF
270pF
320pF
492pF
80pF
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