EVAL-AD5750EBZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-AD5750EBZ' PDF : 36 Pages View PDF
Data Sheet
AD5750/AD5750-1/AD5750-2
DETAILED DESCRIPTION OF FEATURES
OUTPUT FAULT ALERT—SOFTWARE MODE
In software mode, the AD5750/AD5750-1/AD5750-2 are equipped
with one FAULT pin; this is an open-drain output allowing several
AD5750/AD5750-1/AD5750-2 devices to be connected together
to one pull-up resistor for global fault detection. In software mode,
the FAULT pin is forced active low by any one of the following
fault scenarios:
• The voltage at IOUT attempts to rise above the compliance
range due to an open-loop circuit or insufficient power supply
voltage. The internal circuitry that develops the fault output
avoids using a comparator with window limits because this
requires an actual output error before the fault output becomes
active. Instead, the signal is generated when the internal
amplifier in the output stage has less than approximately
1 V of remaining drive capability. Thus, the fault output
activates slightly before the compliance limit is reached.
Because the comparison is made within the feedback loop
of the output amplifier, the output accuracy is maintained
by its open-loop gain, and an output error does not occur
before the fault output becomes active.
• A short is detected on the voltage output pin (VOUT). The
short-circuit current is limited to 15 mA.
• An interface error is detected due to PEC failure. See the
Packet Error Checking section.
• The core temperature of the AD5750/AD5750-1/AD5750-2
exceeds approximately 150°C.
OUTPUT FAULT ALERT—HARDWARE MODE
In hardware mode, the AD5750/AD5750-1/AD5750-2 are
equipped with three fault pins: VFAULT, IFAULT, and TEMP.
These are open-drain outputs allowing several AD5750/AD5750-1/
AD5750-2 devices to be connected together to one pull-up resistor
for global fault detection. In hardware control mode, these fault
pins are forced active by any one of the following fault scenarios:
• An open circuit is detected. The voltage at IOUT attempts
to rise above the compliance range, due to an open-loop
circuit or insufficient power supply voltage. The internal
circuitry that develops the fault output avoids using a
comparator with window limits because this requires an
actual output error before the fault output becomes active.
Instead, the signal is generated when the internal amplifier
in the output stage has less than approximately 1 V of
remaining drive capability. Thus, the fault output activates
slightly before the compliance limit is reached. Because the
comparison is made within the feedback loop of the output
amplifier, the output accuracy is maintained by its open-
loop gain, and an output error does not occur before the
fault output becomes active. If this fault is detected, the
IFAULT pin is forced low.
• A short is detected on the voltage output pin (VOUT). The
short-circuit current is limited to 15 mA. If this fault is
detected, the VFAULT pin is forced low.
• The core temperature of the AD5750/AD5750-1/AD5750-2
exceeds approximately 150°C. If this fault is detected, the
TEMP pin is forced low.
VOLTAGE OUTPUT SHORT-CIRCUIT PROTECTION
Under normal operation, the voltage output sinks and sources
up to 12 mA and maintains specified operation. The maximum
current that the voltage output delivers is 15 mA; this is the
short-circuit current.
ASYNCHRONOUS CLEAR (CLEAR)
CLEAR is an active high clear that allows the voltage output to
be cleared to either zero-scale code or midscale code and is
user-selectable via the CLRSEL pin or the CLRSEL bit of the input
shift register, as described in Table 8. (The clear select feature is
a logical OR function of the CLRSEL pin and the CLRSEL bit).
The current loop output clears to the bottom of its programmed
range. When the CLEAR signal is returned low, the output returns
to its programmed value or to a new programmed value. A clear
operation can also be performed via the clear command in the
control register (see Table 11).
Table 11. CLRSEL Options
CLRSEL Unipolar Output Voltage Range
0
0V
1
Midscale
Output Clear Value
Unipolar Current Output Range Bipolar Output Range
Zero scale; for example,
4 mA on the 4 mA to 20 mA range,
0 mA on the 0 mA to 20 mA range
Negative full scale
Midscale; for example,
0V
12 mA on the 4 mA to 20 mA range,
10 mA on the 0 mA to 20 mA range
Bipolar Current Output Range
Zero scale; for example,
−24 mA on the ±24 mA range
Midscale; for example,
0 mA on the ±24 mA range
Rev. D | Page 29 of 36
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