AD5732R Analog Devices, AD5732R Datasheet - Page 29

• Manufacturer Part Number: AD5732R
• Description: Complete, Dual, 14-Bit, Serial Input, Unipolar/Bipolar, Voltage Output DAC
• Manufacturer: Analog Devices

Specifications of AD5732R

• Resolution (bits): 14bit
• Dac Update Rate: 1.07MSPS
• Dac Settling Time: 7.5µs
• Max Pos Supply (v): +16.5V
• Single-supply: Yes
• Dac Type: Voltage Out
• Dac Input Format: Ser,SPI

DESIGN FEATURES
ANALOG OUTPUT CONTROL
In many industrial process control applications, it is vital that
the output voltage be controlled during power-up. When the
supply voltages change during power-up, the V
clamped to 0 V via a low impedance path (approximately 4 kΩ).
To prevent the output amplifiers from being shorted to 0 V
during this time, Transmission Gate G1 is also opened (see
Figure 48). These conditions are maintained until the power
supplies have stabilized and a valid word is written to a DAC
register. At this time, G2 opens and G1 closes.
POWER-DOWN MODE
Each DAC channel of the AD5722R/AD5732R/AD5752R can
be individually powered down. By default, all channels are in
power-down mode. The power status is controlled by the power
control register (see Table 27 and Table 28 for details). When a
channel is in power-down mode, its output pin is clamped to
ground through a resistance of approximately 4 kΩ, and the
output of the amplifier is disconnected from the output pin.
OVERCURRENT PROTECTION
Each DAC channel of the AD5722R/AD5732R/AD5752R
incorporates individual overcurrent protection. The user has
two options for the configuration of the overcurrent protection:
constant current clamp or automatic channel power-down. The
configuration of the overcurrent protection is selected via the
clamp enable bit in the control register.
CONTROL
VOLTAGE
MONITOR
Figure 48. Analog Output Control Circuitry
AND
G1
G2
V
OUT
OUT
A
pins are
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Constant Current Clamp (Clamp Enable = 1)
If a short circuit occurs in this configuration, the current is
clamped at 20 mA. This event is signaled to the user by the
setting of the appropriate overcurrent (OC
control register. Upon removal of the short-circuit fault, the
OC
Automatic Channel Power-Down (Clamp Enable = 0)
If a short circuit occurs in this configuration, the shorted
channel powers down, and its output is clamped to ground via a
resistance of approximately 4 kΩ. At this time, the output of the
amplifier is also disconnected from the output pin. The short-
circuit event is signaled to the user via the overcurrent (OC
bits, and the power-up (PU
powered down. After the fault is rectified, the channels can be
powered up again by setting the PU
THERMAL SHUTDOWN
The AD5722R/AD5732R/AD5752R incorporate a thermal
shutdown feature that automatically shuts down the device if
the core temperature exceeds approximately 150°C. The thermal
shutdown feature is disabled by default and can be enabled via
the TSD enable bit of the control register. In the event of a
thermal shutdown, the TSD bit of the power control register is set.
INTERNAL REFERENCE
The on-chip voltage reference is powered down by default. If an
external voltage reference source is to be used, the internal
reference must remain powered down at all times. If the
internal reference is to be used as the reference source, it must
be powered up via the PU
The internal reference voltage is accessible at the REFIN/REFOUT
pin for use as a reference source for other devices within the
system. If the internal reference is to be used external to the
AD5722R/AD5732R/AD5752R, it must first be buffered.
X
bit is cleared.
AD5722R/AD5732R/AD5752R
REF
X
) bits indicate which channels have
bit of the power control register.
X
bits.
X
) bit in the power
X
)