ADT7482 View Datasheet(PDF) - Analog Devices
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ADT7482 Datasheet PDF : 24 Pages
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CONVERSION RATE REGISTER
The conversion rate register is at Address 0x04 for reads and
Address 0x0A for writes. The four LSBs of this register are used
to program the conversion times from 15.5 ms (Code 0x0A) to
16 seconds (Code 0x00). To program the ADT7482 to perform
continuous measurements, set the conversion rate register to
0x0B. For example, a conversion rate of 8 conversions/second
means that, beginning at 125 ms intervals, the device performs
a conversion on the local and the remote temperature channels.
The four MSBs of this register are reserved and should not be
written to.
This register can be written to and read back over the SMBus.
The default value of this register is 0x07, giving a rate of 8
conversions per second. Use of slower conversion times greatly
reduces the device power consumption.
LIMIT REGISTERS
The ADT7482 has three limits for each temperature channel:
high, low, and THERM temperature limits for local, Remote 1,
and Remote 2 temperature measurements. The remote
temperature high and low limits span two registers each, to
contain an upper and lower byte for each limit. There is also a
THERM hysteresis register. All limit registers can be written to
and read back over the SMBus. See Table 16 for limit register
addresses and power-on default values.
ADT7482
When Pin 8 is configured as an ALERT output, the high limit
registers perform a > comparison while the low limit registers
perform a ≤ comparison. For example, if the high limit register
is programmed with 80°C, then measuring 81°C results in an
out-of-limit condition, setting a flag in the status register. If the
low limit register is programmed with 0°C, measuring 0°C or
lower results in an out-of-limit condition.
Exceeding either the local or remote THERM limit asserts
THERM low. When Pin 8 is configured as THERM2, exceeding
either the local or remote high limit asserts THERM2 low. A
default hysteresis value of 10°C is provided that applies to both
THERM channels. This hysteresis value can be reprogrammed.
It is important to remember that the temperature limits data
format is the same as the temperature measurement data
format. If the temperature measurement uses the default binary
scale, then the temperature limits also use the binary scale. If
the temperature measurement scale is switched, however, the
temperature limits do not switch automatically.
The limit registers must be reprogrammed to the desired value
in the correct data format. For example, if the remote low limit
is set at 10°C and the default binary scale is used, the limit
register value should be 0000 1010b. If the scale is switched to
offset binary, the value in the low temperature limit register
should be reprogrammed to be 0100 1010b.
Table 11. Conversion Rate Register (Read Address = 0x04, Write Address = 0x0A)
Bit
Mnemonic
Function
7
Reserved
Reserved for future use. Do not write to this bit.
6
Reserved
Reserved for future use . Do not write to this bit.
5
Reserved
Reserved for future use . Do not write to this bit.
4
Reserved
Reserved for future use. Do not write to this bit.
<3:0> Conversion rates
These bits set how often the ADT7482 measures each temperature channel.
Conversions/sec Time (seconds)
0000 = 0.0625
16
0001 = 0.125
8
0010 = 0.25
4
0011 = 0.5
2
0100 = 1
1
0101 = 2
500 m
0110 = 4
250 m
0111 = 8 = default 125 m
1000 = 16
62.5 m
1001 = 32
31.25 m
1010 = 64
15.5 m
Rev. 0 | Page 13 of 24
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