ADT7467 データシートの表示（PDF） - ON Semiconductor
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ADT7467 Datasheet PDF : 72 Pages
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ADT7467
temperature below −63C is entered, the temperature is
clamped to −63C. In this mode, the diode fault condition
remains −128C = 1000 0000, whereas the fault condition is
represented by −64C = 0000 0000 in the extended
temperature range (−64C to +191C).
Table 9. TEMPERATURE MEASUREMENT
REGISTERS
Register
Description
Default
0x25
0x26
0x27
0x77
Remote 1 Temperature
Local Temperature
Remote 2 Temperature
Extended Resolution 2
0x01
0x01
0x01
0x00
Table 10. EXTENDED RESOLUTION TEMPERATURE
MEASUREMENT REGISTER BITS
Bit
Mnemonic
Description
<7:6>
<5:4>
<3:2>
TDM2
LTMP
TDM1
Remote 2 Temperature LSBs
Local Temperature LSBs
Remote 1 Temperature LSBs
Temperature Measurement Limit Registers
High and low limit registers are associated with each
temperature measurement channel. Exceeding the
programmed high or low limit sets the appropriate status bit
and can also generate SMBALERT interrupts.
Table 11. TEMPERATURE MEASUREMENT LIMIT
REGISTERS
Register
Description
Default
0x4E
0x4F
0x50
0x51
0x52
0x53
Remote 1 Temperature Low Limit
Remote 1 Temperature High Limit
Local Temperature Low Limit
Local Temperature High Limit
Remote 2 Temperature Low Limit
Remote 2 Temperature High Limit
0x01
0x7F
0x01
0x7F
0x01
0x7F
Reading Temperature from the ADT7467
It is important to note that temperature can be read from
the ADT7467 as an 8-bit value (with 1C resolution) or as
a 10-bit value (with 0.25C resolution). If only 1C
resolution is required, the temperature readings can be read at
any time and in no particular order.
If the 10-bit measurement is required, this involves a
2-register read for each measurement. The extended
resolution register (0x77) should be read first. Then all
temperature reading registers freeze until all temperature
reading registers are read. This prevents updating of an MSB
reading while its two LSBs are read and vice versa.
Additional ADC Functions for Temperature
Measurement
A number of other functions are available on the
ADT7467 to offer the system designer increased flexibility.
Turn-off Averaging
For each temperature measurement read from a value
register, 16 readings are made internally, the results of which
are averaged and then placed into the value register.
Sometimes it is necessary to perform a very fast
measurement. Setting Bit 4 of Configuration Register 2
(0x73) turns averaging off.
Table 12. CONVERSION TIME WITH AVERAGING
DISABLED
Channel
Measurement Time
Voltage Channels
0.7 ms
Remote Temperature 1
7 ms
Remote Temperature 2
7 ms
Local Temperature
1.3 ms
Table 13. CONVERSION TIME WITH AVERAGING
ENABLED
Channel
Measurement Time
Voltage Channels
11 ms
Remote Temperature
39 ms
Local Temperature
12 ms
Single-channel ADC Conversions
Setting Bit 6 of Configuration Register 2 (0x73) places
the ADT7467 into single-channel ADC conversion mode. In
this mode, users can read a single temperature channel only.
The appropriate ADC channel is selected by writing to
Bits <7:5> of the TACH1 minimum high byte register
(0x55).
Table 14. CHANNEL SELECTION
Bits <7:5>, Register 0x55
Channel Selected
101
Remote 1 Temperature
110
Local Temperature
111
Remote 2 Temperature
Configuration Register 2 (0x73)
<4> = 1, Averaging Off
<6> = 1, Single-channel Convert Mode
TACH1 Minimum High Byte (0x55)
<7:5> Selects ADC Channel for Single-channel Convert
Mode
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