ADT7461AR-REEL7 ON Semiconductor, ADT7461AR-REEL7 Datasheet - Page 11

• Manufacturer Part Number: ADT7461AR-REEL7
• Description: IC SENSOR TEMP 2-CH 8SOIC
• Manufacturer: ON Semiconductor

Specifications of ADT7461AR-REEL7

• Rohs Status: RoHS non-compliant
• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 127°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 120°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)

The user can switch between measurement ranges at any time.
Switching the range also switches the data format. The next
temperature result following the switching is reported back to
the register in the new format. However, the contents of the
limit registers are not changed. The user must ensure that the
limit registers are reprogrammed, as necessary, when the data
format changes. See the Limit Registers section for more
information.
ADT7461 REGISTERS
The ADT7461 contains a total of 22 8-bit registers. These regis-
ters are used to store the results of remote and local temperature
measurements and high and low temperature limits and to
configure and control the device. A description of these registers
follows. Additional details are provided in Table 7 to Table 11.
Address Pointer Register
The address pointer register does not have or require an
address, as the first byte of every write operation is automati-
cally written to this register. The data in this first byte always
contains the address of another register on the ADT7461, which
is stored in the address pointer register. This register address is
written to by the second byte of a write operation or is used for
a subsequent read operation.
The power-on default value of the address pointer register is
0x00. Therefore, if a read operation is performed immediately
after power-on, without first writing to the address pointer, the
value of the local temperature is returned, since its register
address is 0x00.
Temperature Value Registers
The ADT7461 has three registers to store the results of local and
remote temperature measurements. These registers can only be
written to by the ADC and can be read by the user over the
SMBus. The local temperature value register is at Address 0x00.
The external temperature value high byte register is at
Address 0x01, with the low byte register at Address 0x10.
The power-on default for all three registers is 0x00.
Configuration Register
The configuration register is Address 0x03 at read and
Address 0x09 at write. Its power-on default is 0x00. Only four
bits of the configuration register are used. Bits 0, 1, 3, and 4 are
reserved and should not be written to by the user.
Bit 7 of the configuration register is used to mask the ALERT
output. If Bit 7 is 0, the ALERT output is enabled. This is the
power-on default. If Bit 7 is set to 1, the ALERT output is
disabled. This only applies if Pin 6 is configured as ALERT. If
Pin 6 is configured as THERM2, the value of Bit 7 has no effect.
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If Bit 6 is set to 0 (the power-on default), the device is in
operating mode with the ADC converting. If Bit 6 is set to 1, the
device is in standby mode and the ADC does not convert. The
SMBus does, however, remain active in standby mode, so values
can be read from or written to the ADT7461 via the SMBus in
this mode. The ALERT and THERM outputs are also active in
standby mode. Changes made to the registers in standby mode
that affect the THERM or ALERT outputs cause these signals to
be updated.
Bit 5 determines the configuration of Pin 6 on the ADT7461. If
Bit 5 is 0 (default), then Pin 6 is configured as an ALERT
output. If Bit 5 is 1, then Pin 6 is configured as a THERM2
output. Bit 7, the ALERT mask bit, is only active when Pin 6 is
configured as an ALERT output. If Pin 6 is set up as a THERM2
output, then Bit 7 has no effect.
Bit 2 sets the temperature measurement range. If Bit 2 is 0
(default), the temperature measurement range is set between
0°C to +127°C. Setting Bit 2 to 1 means that the measurement
range is set to the extended temperature range.
Table 7. Configuration Register Bit Assignments
Bit
7
6
5
4, 3
2
1, 0
Conversion Rate Register
The conversion rate register is Address 0x04 at read and
Address 0x0A at write. The lowest four bits of this register are
used to program the conversion rate by dividing the internal
oscillator clock by 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024 to
give conversion times from 15.5 ms (Code 0x0A) to 16 seconds
(Code 0x00). For example, a conversion rate of 8 conversions
per second means that beginning at 125 ms intervals, the device
performs a conversion on the internal and external temperature
channels.
This register can be written to and read back over the SMBus.
The higher four bits of this register are unused and must be set
to 0. The default value of this register is 0x08, giving a rate of
16 conversions per second. Use of slower conversion times
greatly reduces the device power consumption, as shown in
Table 8.
Name
MASK1
RUN/STOP
ALERT / THERM2
Reserved
Temperature
Range Select
Reserved
Function
0 = ALERT enabled
1 = ALERT masked
0 = Run
1 = Standby
0 = ALERT
1 = THERM2
0 = 0°C to 127°C
1 = Extended range
Power-On
Default
0
0
0
0
0
0
ADT7461