XTR111_07 BURR-BROWN [Burr-Brown Corporation], XTR111_07 Datasheet - Page 11

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

EXPLANATION OF PIN FUNCTIONS
VIN: This input is a conventional, noninverting, high-
impedance input of the internal operational amplifier
(OPA). The internal circuitry is protected by clamp diodes
to
approximately 18V protects internal circuitry. Place a small
resistor in series with the input to limit the current into the
protection if voltage can be present without the XTR111
being powered. Consider a resistor value equal to R
bias current cancellation.
SET: The total resistance connected between this pin and
VIN reference sets the transconductance. Additional
series resistance can degrade accuracy and drift. The
voltage on this pin must not exceed 14V because this pin
is not protected to voltages above this level.
IS: This output pin is connected to the transistor source of
the external FET. The accuracy of the output current to IS
is achieved by dynamic error correction in the current
mirror. This pin should never be pulled more than 6.5V
below the positive supply. An internal clamp is provided to
protect the circuit, but it must be current-limited externally
to less than 25mA.
VG: The gate drive for the external FET is protected
against shorts to the supply and GND. The circuit is
clamped so that it will not drive more than 18V below the
positive supply. The external FET should be protected if its
gate could be externally pulled beyond its ratings.
supplies.
www.ti.com
An
additional
clamp
connected
SET
for
to
REGF: The output of the regulator buffer can source up to
5mA current, but has very limited (less than 50µA) sinking
capability. The maximum short-circuit current is in the
range of 15mA to 25mA, changing over temperature.
REGS: This pin is the sense input of the voltage regulator.
It is referenced to an internal 3V reference circuit. The input
bias current can be up to 2µA. Avoid capacitive loading of
REGS that may compromise the loop stability of the
voltage regulator.
VSP: The supply voltage of up to a maximum of 44V allows
operation in harsh industrial environment and provides
headroom for easy protection against over-voltage. Use a
large enough bypass capacitor (> 100nF) and eventually
a damping inductor or a small resistor (5Ω) to decouple the
XTR111 supply from the noise typically found on the 24V
supplies.
EF: The active low error flag (logic output) is intended for
use with an external pull-up to logic-high for reliable
operation when this output is used. However, it has a weak
internal pull-up to 5V and can be left unconnected if not
used.
OD: This control input has a 4µA internal pull-up disabling
the output. A pull-down or short to GND is required to
activate the output. Controlling OD reduces output glitches
during power-on and power-off. This logic input controls
the output. If not used, connect to GND.
The regulator is not affected by OD.
SBOS375 − NOVEMBER 2006
XTR111
11