AD7414ARM-0 データシートの表示（PDF） - Analog Devices
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AD7414ARM-0 Datasheet PDF : 20 Pages
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AD7414/AD7415
In the AD7415, only three of the bits are used (D7, D6, and D2)
to set the operating modes (see Table 12). D0, D1, and D3 to D5
are used for factory settings and must have zeros written to
them during normal operation.
Table 12. AD7415 Configuration Register Settings
D7 Full power-down if = 1.
D6 Bypass SDA and SCL filtering if = 0.
D2 Initiate a one-shot temperature conversion if set to 1.
The bit status is not stored; thus this bit is 0 if read.
If the AD7414/AD7415 are in power-down mode (D7 = 1), a
temperature conversion can still be initiated by the one-shot
operation. This involves a write operation to the configuration
register and setting the one-shot bit to 1 (D2 = 1), which causes
the AD7414/AD7415 to power up, perform a single conversion,
and power down again. This is a very power efficient mode.
TEMPERATURE VALUE REGISTER (ADDRESS 0X00)
The temperature value register is a 10-bit, read-only register
that stores the temperature reading from the ADC in twos
complement format. Two reads are necessary to read data from
this register. Table 13 shows the contents of the first byte to be
read, while Table 14 and Table 15 show the contents of the
second byte to be read from the AD7414 and AD7415,
respectively. In Table 14, D3 to D5 of the second byte are used
as flag bits and are obtained from other internal registers. They
function as follows:
ALERT_Flag: The state of this bit is the same as that of the
ALERT pin.
THIGH_Flag:
This flag is set to 1 when the temperature
measured goes above the THIGH limit. It is reset
when the second temperature byte (Table 14) is
read. If the temperature is still greater than the
THIGH limit after the read operation, the flag is
again.
TLOW_Flag:
This flag is set to 1 when the temperature
measured goes below the TLOW limit. It is reset
when the second temperature byte (Table 14) is
read. If the temperature is still less than the TLOW
limit after the read operation, the flag is set again.
The full theoretical span of the ADC is 255°C, but in practice
the temperature measurement range is limited to the operating
range of the device, −40°C to +125°C for the A grade.
Table 13. Temperature Value Register (First Read)
D15 D14 D13 D12 D11 D10 D9 D8
MSB B8
B7
B6
B5
B4
B3 B2
Table 14. AD7414 Temperature Value Register (Second Read)
D7 D6 D5
D4
D3
D2 D1 D0
B1 LSB ALERT_Flag THIGH_Flag TLOW_Flag 0 0 0
Table 15. AD7415 Temperature Value Register (Second Read)
D7 D6 D5 D4 D3 D2 D1 D0
B1 LSB N/A N/A N/A N/A N/A N/A
AD7414 THIGH REGISTER (ADDRESS 0X02)
The THIGH register (see Table 16) is an 8-bit, read/write register
that stores the upper limit that activates the ALERT output.
Therefore, if the value in the temperature value register is
greater than the value in the THIGH register, the ALERT pin is
activated (that is, if ALERT is enabled in the configuration
register). Because it is an 8-bit register, the temperature
resolution is 1°C.
Table 16. THIGH Register
D7
D6 D5 D4 D3 D2 D1 D0
MSB B6 B5 B4 B3 B2 B1 B0
AD7414 TLOW REGISTER (ADDRESS 0X03)
The TLOW register (see Table 17) is an 8-bit read/write register
that stores the lower limit that deactivates the ALERT output.
Therefore, if the value in the temperature value register is less
than the value in the TLOW register, the ALERT pin is
deactivated (that is, if ALERT is enabled in the configuration
register).
Because it is an 8-bit register, the temperature resolution is 1°C.
Table 17. TLOW Register
D7
D6 D5 D4 D3 D2 D1 D0
MSB B6 B5 B4 B3 B2 B1 B0
Rev. E | Page 10 of 20
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