AD7794BRUZ Analog Devices Inc, AD7794BRUZ Datasheet - Page 30

• Manufacturer Part Number: AD7794BRUZ
• Description: IC ADC 24BIT SIG-DEL 6CH 24TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD7794BRUZ

• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Bits: 24
• Sampling Rate (per Second): 470
• Number Of Converters: 1
• Power Dissipation (max): 2.5mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP (0.173", 4.40mm Width)
• Resolution (bits): 24bit
• Sampling Rate: 470SPS
• Input Channel Type: Differential
• Supply Voltage Range - Analog: 2.7V To 5.25V
• Supply Voltage Range - Digital: 2.7V To 5.25V
• Number Of Elements: 1
• Resolution: 24Bit
• Architecture: Delta-Sigma
• Sample Rate: 0.47KSPS
• Input Polarity: Bipolar
• Input Type: Voltage
• Rated Input Volt: ±2.5V
• Differential Input: Yes
• Power Supply Requirement: Single
• Single Supply Voltage (typ): 3.3/5V
• Single Supply Voltage (min): 2.7V
• 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: 2.5mW
• Integral Nonlinearity Error: ±15ppm of FSR
• Operating Temp Range: -40C to 105C
• 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-AD7794EBZ - BOARD EVALUATION FOR AD7794
• Lead Free Status / Rohs Status: Compliant

AD7794/AD7795
Single Conversion Mode
In single conversion mode, the AD7794/AD7795 are placed in
shutdown mode between conversions. When a single
conversion is initiated by setting MD2 to 0, MD1 to 0, and MD0
to 1 in the mode register, the AD7794/AD7795 power up,
perform a single conversion, and then return to shutdown
mode. The on-chip oscillator requires 1 ms to power up. A
conversion requires a time period of 2 × t
low to indicate the completion of a conversion. When the data-
word has been read from the data register, DOUT/ RDY goes
high. If CS is low, DOUT/ RDY remains high until another
conversion is initiated and completed. The data register can be
read several times, if required, even when DOUT/ RDY has
gone high.
Continuous Conversion Mode
This is the default power-up mode. The AD7794/AD7795
continuously convert with the RDY pin in the status register
going low each time a conversion is complete. If CS is low, the
DOUT/ RDY line also goes low when a conversion is complete.
To read a conversion, the user writes to the communications
register, indicating that the next operation is a read of the data
register. The digital conversion is placed on the DOUT/ RDY
pin as soon as SCLK pulses are applied to the ADC. DOUT/ RDY
returns high when the conversion is read. The user can read this
register additional times, if required. However, the user must
ensure that the data register is not being accessed at the completion
of the next conversion, or else the new conversion word is lost.
ADC
. DOUT/ RDY goes
Rev. D | Page 30 of 36
Continuous Read
Rather than write to the communications register each time a
conversion is complete to access the data, the AD7794/AD7795
can be configured so that the conversions are placed on the
DOUT/ RDY line automatically. By writing 01011100 to the
communications register, the user need only apply the
appropriate number of SCLK cycles to the ADC. The 24-bit
word is automatically placed on the DOUT/ RDY line when a
conversion is complete. The ADC should be configured for
continuous conversion mode.
When DOUT/ RDY goes low to indicate the end of a conversion,
sufficient SCLK cycles must be applied to the ADC, and the
data conversion is placed on the DOUT/ RDY line. When the
conversion is read, DOUT/ RDY returns high until the next
conversion is available.
In this mode, the data can be read only once. Also, the user must
ensure that the data-word is read before the next conversion is
complete. If the user has not read the conversion before the
completion of the next conversion, or if insufficient serial clocks are
applied to the AD7794/AD7795 to read the word, the serial
output register is reset when the next conversion is complete.
The new conversion is then placed in the output serial register.
To exit the continuous read mode, the instruction 01011000
must be written to the communications register while the RDY
pin is low. While in the continuous read mode, the ADC
monitors activity on the DIN line so that it can receive the
instruction to exit the continuous read mode. Additionally, a
reset occurs if 32 consecutive 1s are seen on DIN. Therefore,
DIN should be held low in continuous read mode until an
instruction is to be written to the device.