AD7294BSUZRL Analog Devices Inc, AD7294BSUZRL Datasheet - Page 26

• Manufacturer Part Number: AD7294BSUZRL
• Description: IC,Data Acquisition System,4-CHANNEL,12-BIT,TQFP,64PIN,PLASTIC
• Manufacturer: Analog Devices Inc
• Type: ADC, DACr

Specifications of AD7294BSUZRL

• Resolution (bits): 12 b
• Sampling Rate (per Second): 22.22k
• Data Interface: Serial
• Voltage Supply Source: Analog and Digital
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -55°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 64-TQFP, 64-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD7294
This generates the 5 V output span from a 2.5 V reference.
Digitally inverting the DAC allows the circuit to operate as a
generic DAC when no offset is applied. If the offset pin is not
being driven, it is best practice to place a 100 nF capacitor
between the pin and ground to improve both the settling time
and the noise performance of the DAC.
Note that a significant amount of power can be dissipated in the
DAC outputs. A thermal shutdown circuit sets the DAC outputs
to high impedance if a die temperature of >150°C is measured
by the internal temperature sensor. This also sets the overtem-
perature alert bit in Alert Register C, see the Alerts and Limits
Theory section. Note that this feature is disabled when the
temperature sensor powers down.
High Impedance Input Pin
When the high impedance pin (DAC HIGH-Z pin) is taken
high by the user (see Figure 47), the voltage on the offset pin
appears on the DAC output voltage pin. Essentially, the Internal
Amplifier A2 acts as a voltage follower. This feature allows a fast
change in the output when a fault occurs.
ADC AND DAC REFERENCE
The AD7294 has two independent internal high performance
2.5 V references, one for the ADCs and the other for the four
on-chip DACs. If the application requires an external reference,
it can be applied to the REF
REF
before being used by external circuitry. Decouple both the REF
REF
220 nF capacitor. On power-up, the AD7294 is configured for
use with an external reference. To enable the internal references,
write a zero to both the D4 and D5 bits in the power-down
OUT
IN
DAC pin and the REF
/REF
IN
ADC pin. The internal reference should be buffered
OUT
OUT
/REF
/REF
IN
IN
ADC pin to AGND using a
DAC pin and/or to the
OUT
Rev. F | Page 26 of 48
/
register (see the Register Setting section for more details). Both
the ADC and DAC references require a minimum of 60 μs to
power up and settle to a 12-bit performance when a 220 nF
decoupling capacitor is used.
The AD7294 can also operate with an external reference.
Suitable reference sources for the AD7294 include AD780,
AD1582, ADR431, REF193, and ADR391. In addition, choosing
a reference with an output trim adjustment, such as the ADR441,
allows a system designer to trim system errors by setting a
reference voltage to a voltage other than the nominal.
Long-term drift is a measure of how much the reference drifts
over time. A reference with a low long-term drift specification
ensures that the overall solution remains stable during its entire
lifetime. If an external reference is used, select a low temperature
coefficient specification to reduce the temperature dependence
of the system output voltage on ambient conditions.
V
The AD7294 also has a V
which the I
the supply to which the I
and output threshold levels for the digital logic pins and the
I
to easily interface to both 3 V and 5 V processors. For example,
if the AD7294 is operated with a V
be powered from a 3 V supply, allowing a large dynamic range
with low voltage digital processors. Thus, the AD7294 can be
used with the 2 × V
capable of interfacing to 3 V digital parts. Decouple this pin to
DGND with a 100 nF and a 1 μF capacitor.
SENSE
DRIVE
OVERRANGE pins. The V
FEATURE
2
C interface operates. The V
REF
input range with a V
2
DRIVE
C bus is pulled. This pin sets the input
feature to control the voltage at
DRIVE
DD
of 5 V, the V
feature allows the AD7294
DRIVE
DD
pin is connected to
of 5 V, yet remains
DRIVE
pin can