ADT7461A Datasheet, PDF (12/19 Pages) Analog Devices – ±1°C Temperature Monitor with Series Resistance Cancellation

ADT7461A
Table 9. List of Registers
Read Address (Hex) Write Address (Hex)
Name
Power−On Default
Not Applicable
Not Applicable
Address Pointer
Undefined
00
Not Applicable
Local Temperature Value
0000 0000 (0x00)
01
Not Applicable
External Temperature Value High Byte
0000 0000 (0x00)
02
Not Applicable
Status
Undefined
03
09
Configuration
0000 0000 (0x00)
04
0A
Conversion Rate
0000 1000 (0x08)
05
0B
Local Temperature High Limit
0101 0101 (0x55) (85°C)
06
0C
Local Temperature Low Limit
0000 0000 (0x00) (0°C)
07
0D
External Temperature High Limit High Byte
0101 0101 (0x55) (85°C)
08
0E
External Temperature Low Limit High Byte
0000 0000 (0x00) (0°C)
Not Applicable
0F (Note 1)
One−Shot
10
Not Applicable
External Temperature Value Low Byte
0000 0000
11
11
External Temperature Offset High Byte
0000 0000
12
12
External Temperature Offset Low Byte
0000 0000
13
13
External Temperature High Limit Low Byte
0000 0000
14
14
External Temperature Low Limit Low Byte
0000 0000
19
19
External THERM Limit
0101 0101 (0x55) (85°C)
20
20
Local THERM Limit
0101 0101 (0x55) (85°C)
21
21
THERM Hysteresis
0000 1010 (0x0A) (10°C)
22
22
Consecutive ALERT
0000 0001 (0x01)
FE
Not Applicable
Manufacturer ID
0100 0001 (0x41)
FF
Not Applicable
Die Revision Code
0101 0111 (0x57)
1. Writing to Address 0x0F causes the ADT7461A to perform a single measurement. It is not a data register, and it does not matter what data
is written to it.
Serial Bus Interface
Control of the ADT7461A is carried out via the serial bus.
The ADT7461A is connected to this bus as a slave device,
under the control of a master device.
The ADT7461A has an SMBus timeout feature. When
this is enabled, the SMBus times out after typically 25 ms of
no activity. However, this feature is not enabled by default.
Bit 7 of the consecutive alert register (Address = 0x22)
should be set to enable it.
Addressing the Device
In general, every SMBus device has a 7−bit device
address, except for some devices that have extended 10−bit
addresses. When the master device sends a device address
over the bus, the slave device with that address responds.
The ADT7461Ais available with one device address, 0x4C
(1001 100b). An ADT7461A−2 is also available.
The ADT7461A−2 has an SMBus address of 0x4D (1001
101b). This is to allow two ADT7461A devices on the same
bus, or if the default address conflicts with an existing device
on the SMBus. The serial bus protocol operates as follows:
1. The master initiates a data transfer by establishing
a start condition, defined as a high−to−low
transition on SDATA, the serial data line, while
SCLK, the serial clock line, remains high. This
indicates that an address/data stream follows. All
slave peripherals connected to the serial bus
respond to the start condition and shift in the next
eight bits, consisting of a 7−bit address (MSB first)
plus an R/W bit, which determines the direction of
the data transfer, that is, whether data is written to,
or read from, the slave device. The peripheral
whose address corresponds to the transmitted
address responds by pulling the data line low
during the low period before the ninth clock pulse,
known as the acknowledge bit. All other devices
on the bus remain idle while the selected device
waits for data to be read from or written to it. If the
R/W bit is a 0, the master writes to the slave
device. If the R/W bit is a 1, the master reads from
the slave device.
2. Data is sent over the serial bus in a sequence of
nine clock pulses, eight bits of data followed by an
acknowledge bit from the slave device. Transitions
on the data line must occur during the low period
of the clock signal and remain stable during the
high period, since a low−to−high transition when
the clock is high can be interpreted as a stop
signal. The number of data bytes that can be
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