AD7745ARUZ-REEL Analog Devices Inc, AD7745ARUZ-REEL Datasheet - Page 15

• Manufacturer Part Number: AD7745ARUZ-REEL
• Description: IC,Converter, Other/Special/Miscellaneous,TSSOP,16PIN
• Manufacturer: Analog Devices Inc
• Type: Capacitance-to-Digital Converterr

Specifications of AD7745ARUZ-REEL

• Design Resources: Extending the Capacitive Input Range of AD7745/AD7746 (CN0129)
• Resolution (bits): 24 b
• Data Interface: Serial
• Voltage Supply Source: Single Supply
• Voltage - Supply: 2.7 V ~ 5.25 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sampling Rate (per Second): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

STATUS REGISTER
Address Pointer 0x00, Read Only, Default Value 0x07
This register indicates the status of the converter. The status
register can be read via the 2-wire serial interface to query a
finished conversion.
Table 9. Status Register Bit Map
Bit
Mnemonic
Default
Table 10.
Bit
7-4
3
2
1
0
CAP DATA REGISTER
24 Bits, Address Pointer 0x01, 0x02, 0x03, Read-Only,
Default Value 0x000000
Capacitive channel output data. The register is updated after
finished conversion on the capacitive channel, with one
exception: When the serial interface read operation from the
CAP DATA register is in progress, the data register is not
updated and the new capacitance conversion result is lost.
The stop condition on the serial interface is considered to be the
end of the read operation. Therefore, to prevent data corruption,
all three bytes of the data register should be read sequentially
using the register address pointer auto-increment feature of the
serial interface.
To prevent losing some of the results, the CAP DATA register
should be read before the next conversion on the capacitive
channel is finished.
The 0x000000 code represents negative full scale (–4.096 pF),
the 0x800000 code represents zero scale (0 pF), and the
0xFFFFFF code represents positive full scale (+4.096 pF).
Mnemonic
-
EXCERR
RDY
RDYVT
RDYCAP
Description
Not used, always read 0.
EXCERR = 1 indicates that the excitation output cannot be driven properly.
The possible reason can be a short circuit or too high capacitance between the excitation pin and ground.
RDY = 0 indicates that conversion on the enabled channel(s) has been finished and new unread data is
available.
If both capacitive and voltage/temperature channels are enabled, the RDY bit is changed to 0 after conversion
on both channels is finished. The RDY bit returns to 1 either when data is read or prior to finishing the next
conversion.
If, for example, only the capacitive channel is enabled, then the RDY bit reflects the RDYCAP bit.
RDYVT = 0 indicates that a conversion on the voltage/temperature channel has been finished and new unread
data is available.
RDYCAP = 0 indicates that a conversion on the capacitive channel has been finished and new unread data is
available.
Bit 7
-
0
Bit 6
-
0
Bit 5
-
0
Rev. 0| Page 15 of 28
Bit 4
-
0
The RDY pin reflects the status of the RDY bit. Therefore, the
RDY pin high-to-low transition can be used as an alternative
indication of the finished conversion.
VT DATA REGISTER
24 Bits, Address Pointer 0x04, 0x05, 0x06, Read-Only,
Default Value 0x000000
Voltage/temperature channel output data. The register is
updated after finished conversion on the voltage channel or
temperature channel, with one exception: When the serial
interface read operation from the VT DATA register is in
progress, the data register is not updated and the new
voltage/temperature conversion result is lost.
The stop condition on the serial interface is considered to be the
end of the read operation. Therefore, to prevent data corruption,
all three bytes of the data register should be read sequentially
using the register address pointer auto-increment feature of the
serial interface.
For voltage input, Code 0 represents negative full scale (–V
the 0x800000 code represents zero scale (0 V), and the
0xFFFFFF code represents positive full scale (+V
To prevent losing some of the results, the VT DATA register
should be read before the next conversion on the voltage/
temperature channel is finished.
For the temperature sensor, the temperature can be calculated
from code using the following equation:
Temperature (°C) = (Code/2048) − 4096
Bit 3
0
EXCERR
Bit 2
RDY
1
Bit 1
RDYVT
1
AD7745/AD7746
REF
).
Bit 0
RDYCAP
1
REF
),