Datasheet

XTR300
SBOS336C –JUNE 2005– REVISED JUNE 2011 www.ti.com
The XTR300 can be used with asymmetric supply voltages; however, the minimum negative supply voltage
should be equal to or more negative than −3V (typically −5V). This supply value ensures proper control of 0V and
0mA with wire resistance, ground offsets, and noise added to the output. For positive output signals, the current
requirement from this negative voltage source is less than 5mA.
GND1 through GND4 must be selected to fulfill specified operating ranges. DGND must be in the range of (V−) ≤
DGND ≤ (V+) −7V.
Built on a robust high-voltage BiCMOS process, the XTR300 is designed to interface the 5V or 3V supply domain
used for processors, signal converters, and amplifiers to the high-voltage and high-current industrial signal
environment. It is specified for up to ±20V supply, but can also be powered asymmetrically (for example, +24V
and −5V). It is designed to allow insertion of external circuit protection elements and drive large capacitive loads.
FUNCTIONAL FEATURES
The XTR300 provides two basic functional blocks: an instrumentation amplifier (IA) and a driver that is a unique
operational amplifier (OPA) for current or voltage output. This combination represents an analog output stage
which can be digitally configured to provide either current or voltage output to the same terminal pin.
Alternatively, it can be configured for independent measurement channels.
Three open collector error signals are provided to indicate output related errors such as over-current or
open-load (EF
LD
) or exceeding the common-mode input range at the IA inputs (EF
CM
). An over-temperature flag
(EF
OT
) can be used to control output disable to protect the circuit. The monitor outputs (I
MON
and IA
OUT
) and the
error flags offer optimal testability during operation and configuration. The I
MON
output represents the current
flowing into the load in voltage output mode, while the IA
OUT
represents the voltage across the connectors in
current output mode. Both monitor outputs can be connected together when used in current or voltage output
mode because the monitor signals are multiplexed accordingly.
VOLTAGE OUTPUT MODE
In voltage output mode (M1 and M2 are connected low or left unconnected), the feedback loop through the IA
provides high impedance remote sensing of the voltage at the destination, compensating the resistance of a
protection circuit, switches, wiring, and connector resistance. The output of the IA is a current that is proportional
to the input voltage. This current is internally routed to the OPA summing junction through a multiplexer, as
shown in Figure 40.
A 1:10 copy of the output current of the OPA can be monitored at the I
MON
pin. This output current and the
known output voltage can be used to calculate the load resistance or load power.
During an output short-circuit or an over-current condition the XTR300 output current is limited and EF
LD
(load
error, active low) flag is activated.
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