AD7730BRUZ Analog Devices Inc, AD7730BRUZ Datasheet - Page 33

• Manufacturer Part Number: AD7730BRUZ
• Description: IC ADC TRANSDUCER BRIDGE 24TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD7730BRUZ

• Data Interface: DSP, Serial, SPI™
• Number Of Bits: 24
• Sampling Rate (per Second): 1.2k
• Number Of Converters: 1
• Power Dissipation (max): 125mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP (0.173", 4.40mm Width)
• Resolution (bits): 24bit
• Input Channel Type: Differential, Single Ended
• Supply Voltage Range - Analog: 4.75V To 5.25V
• Supply Voltage Range - Digital: 2.7V To 5.25V
• Number Of Elements: 1
• Resolution: 24Bit
• Architecture: Delta-Sigma
• Sample Rate: 1.2KSPS
• Input Polarity: Unipolar/Bipolar
• Input Type: Voltage
• Differential Input: Yes
• Power Supply Requirement: Analog and Digital
• Single Supply Voltage (typ): 5V
• Single Supply Voltage (min): 4.75V
• Single Supply Voltage (max): 5.25V
• Dual Supply Voltage (typ): Not RequiredV
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Power Dissipation: 125mW
• Integral Nonlinearity Error: 18ppm of FSR
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 24
• Package Type: TSSOP
• Input Signal Type: Differential
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-AD7730LEBZ - BOARD EVALUATION FOR AD7730EVAL-AD7730EBZ - BOARD EVAL FOR AD7730
• Lead Free Status / Rohs Status: Compliant

The on-chip oscillator circuit also has a start-up time associated
with it before it has attained its correct frequency and correct
voltage levels. The typical start-up time for the circuit is 6 ms,
with a DV
The AD7730’s master clock appears on the MCLK OUT pin of
the device. The maximum recommended load on this pin is one
CMOS load. When using a crystal or ceramic resonator to gen-
erate the AD7730’s clock, it may be desirable to then use this
clock as the clock source for the system. In this case, it is recom-
mended that the MCLK OUT signal is buffered with a CMOS
buffer before being applied to the rest of the circuit.
System Synchronization
The SYNC input allows the user to reset the modulator and
digital filter without affecting any of the setup conditions on the
part. This allows the user to start gathering samples of the ana-
log input from a known point in time, i.e., the rising edge of
SYNC.
If multiple AD7730s are operated from a common master clock,
they can be synchronized to update their output registers simul-
taneously. A falling edge on the SYNC input resets the digital
filter and analog modulator and places the AD7730 into a con-
sistent, known state. While the SYNC input is low, the AD7730
will be maintained in this state. On the rising edge of SYNC,
the modulator and filter are taken out of this reset state and on
the next clock edge the part starts to gather input samples again.
In a system using multiple AD7730s, a common signal to their
SYNC inputs will synchronize their operation. This would nor-
mally be done after each AD7730 has performed its own cali-
bration or has had calibration coefficients loaded to it. The
output updates will then be synchronized with the maximum
possible difference between the output updates of the individual
AD7730s being one MCLK IN cycle.
Single-Shot Conversions
The SYNC input can also be used as a start convert command
allowing the AD7730 to be operated in a conventional converter
fashion. In this mode, the rising edge of SYNC starts conversion
and the falling edge of RDY indicates when conversion is com-
plete. The disadvantage of this scheme is that the settling time
of the filter has to be taken into account for every data register
update.
Writing 0, 1, 0 to the MD2, MD1, MD0 bits of the Mode regis-
ter has the same effect. This initiates a single conversion on the
AD7730 with the part returning to idle mode at the end of
conversion. Once again, the full settling-time of the filter has to
elapse before the Data Register is updated.
REV. A
Figure 17. Crystal/Resonator Connections
DD
C1
C2
of +5 V and 8 ms with a DV
CRYSTAL OR
CERAMIC
RESONATOR
MCLK OUT
MCLK IN
AD7730
DD
of +3 V.
–33–
Reset Input
The RESET input on the AD7730 resets all the logic, the digital
filter and the analog modulator while all on-chip registers are
reset to their default state. RDY is driven high and the AD7730
ignores all communications to any of its registers while the
RESET input is low. When the RESET input returns high, the
AD7730 starts to process data and RDY will return low after
the filter has settled indicating a valid new word in the data
register. However, the AD7730 operates with its default setup
conditions after a RESET and it is generally necessary to set up all
registers and carry out a calibration after a RESET command.
The AD7730’s on-chip oscillator circuit continues to function
even when the RESET input is low. The master clock signal
continues to be available on the MCLK OUT pin. Therefore, in
applications where the system clock is provided by the AD7730’s
clock, the AD7730 produces an uninterrupted master clock
during RESET commands.
Standby Mode
The STANDBY input on the AD7730 allows the user to place
the part in a power-down mode when it is not required to pro-
vide conversion results. The part can also be placed in its
standby mode by writing 0, 1, 1 to the MD2, MD1, MD0 bits
of the Mode Register. The AD7730 retains the contents of all its
on-chip registers (including the Data Register) while in standby
mode. Data can still be read from the part in Standby Mode.
The STBY bit of the Status Register indicates whether the part
is in standby or normal operating mode. When the STANDBY
pin is taken high, the part returns to operating as it had been
prior to the STANDBY pin going low.
The STANDBY input (or 0, 1, 1 in the MD2, MD1, MD0 bits)
does not affect the digital interface. It does, however, set the
RDY bit and pin high and also sets the STDY bit high. When
STANDBY goes high again, RDY and STDY remain high until
set low by a conversion or calibration.
Placing the part in standby mode, reduces the total current to
10 A typical when the part is operated from an external master
clock provided this master clock is stopped. If the external clock
continues to run in standby mode, the standby current increases
to 400 A typical. If a crystal or ceramic resonator is used as the
clock source, then the total current in standby mode is 400 A
typical. This is because the on-chip oscillator circuit continues
to run when the part is in its standby mode. This is important in
applications where the system clock is provided by the AD7730’s
clock, so that the AD7730 produces an uninterrupted master
clock even when it is in its standby mode.
Digital Outputs
The AD7730 has two digital output pins, D0 and D1. When the
DEN bit of the Mode Register is set to 1, these digital outputs
assume the logic status of bits D0 and D1 of the Mode Register.
It gives the user access to two digital port pins which can be
programmed over the normal serial interface of the AD7730.
The two outputs obtain their supply voltage from AV
thus the outputs operate to 5 V levels even in cases where
DV
DD
= +3 V.
AD7730/AD7730L
DD
,