AD7298BCPZ Analog Devices Inc, AD7298BCPZ Datasheet - Page 22

• Manufacturer Part Number: AD7298BCPZ
• Description: IC ADC 12BIT SPI/SRL 1M 20LFCSP
• Manufacturer: Analog Devices Inc

Specifications of AD7298BCPZ

• Data Interface: Serial, SPI™
• Featured Product: AD7298 ADC with Temperature Sensor
• Number Of Bits: 12
• Sampling Rate (per Second): 1M
• Number Of Converters: 1
• Power Dissipation (max): 22.7mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 20-WFQFN, CSP Exposed Pad
• Resolution (bits): 12bit
• Sampling Rate: 1MSPS
• Input Channel Type: Single Ended
• Supply Voltage Range - Digital: 1.65V To 3.6V
• Supply Current: 5.8mA
• Digital Ic Case: RoHS Compliant
• Supply Voltage Range - Analog: 1.65V To 3.6V
• Digital Ic Case Style: LFCSP
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD7298
TEMPERATURE SENSOR READ
The temperature sensor conversion involves two phases, the
integration phase and the conversion phase as detailed in the
Temperature Sensor Operation section. The integration phase
is initiated on the falling edge of CS and once completed the
conversion is automatically initiated internally by the AD7298.
When a temperature conversion integration is initiated, the
T
conversion is in progress and remains high until the conversion
is completed.
The total time to measure and convert a temperature channel
with the AD7298 is 100 μs max. Once the T
goes low to indicate that the temperature conversion is
completed, 100 ns must elapse prior to the next falling edge
of CS . If a minimum of 100 ns is not adhered to between the
falling edge of T
CS , the next conversion will be corrupted but the temperature
result that is framed by the CS will not be affected. This
restriction is in place to ensure that sufficient acquisition time
is allowed for the next conversion.
Once the T
CS falling edge to frame the read of the previous conversion and
program the control register if required (see Figure 31).
Once the previous conversion result has been read, any
subsequent CS falling edges which occur while the T
signal is high are internally ignored by the AD7298. If addi-
tional CS falling edges are provided while T
the AD7298 provides an invalid digital output of all 1s.
SENSE
T
SENSE
_BUSY signal goes high to indicate that a temperature
_BUSY
DOUT
SENSE
SCLK
DIN
CS
_BUSY signal goes high, the user may provide a
SENSE
_BUSY and the subsequent falling edge of
REGISTER CH T SENSE SELECTED
1
DATA WRITTEN TO CONTROL
Figure 31. Serial Interface Timing Diagram for the Temperature Sensor Conversion
12
16
SENSE
SENSE
_BUSY signal
_BUSY is high,
SENSE
1
INTEGRATION BEGINS
CONFIGURE CONTROL REGISTER
THE TEMPERATURE
PREVIOUS CONVERSION
FOR NEXT CONVERSION
_BUSY
Rev. A | Page 22 of 24
RESULT
CONVERSION IS COMPLETED
THE TEMPERATURE
Alternatively, if CS remains high while T
then the DOUT bus remains in three-state.
If the user writes to the control register during the first 16 SCLK
cycles following T
the device for the next conversion, which is initiated on the
subsequent CS falling edge after T
altered. If the user configures the part for partial power-down in
a write to the control register during the first 16 SCLK cycles
following T
conversion is aborted and the part enters partial power-down
on the 16
Thus, it is recommended not to write to the control register if
the CS signal will be toggling while T
should be taken to ensure that the WRITE bit is set to zero
during the temperature conversion phase when CS is toggling.
If an SCLK frequency of more than 10 kHz is used, the
temperature conversion requires more than one standard
read cycle to complete. In this case, the user can monitor the
T
completed and the result is available for reading.
16
SENSE
_BUSY signal to determine when the conversion is
ENSURES ADEQUATE ACQUISITION
TIME FOR NEXT ADC CONVERSION
th
SCLK falling edge.
SENSE
_BUSY going high, the temperature sensor
SENSE
t
11
_BUSY going high, the configuration of
1
TEMPERATURE SENSOR RESULT
SENSE
SENSE
_BUSY goes low, is
SENSE
_BUSY is high. Care
_BUSY is high,
16