ADT7481ARMZ-1 ON Semiconductor, ADT7481ARMZ-1 Datasheet - Page 11

• Manufacturer Part Number: ADT7481ARMZ-1
• Description: IC SENSOR TEMP 2CH ALARM 10MSOP
• Manufacturer: ON Semiconductor

Specifications of ADT7481ARMZ-1

• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 120°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 120°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

together. When any flag is high, the ALERT interrupt latch
is set and the ALERT output goes low (provided that the
flag(s) is/are not masked out).
through Bit 2) in Status Register 1, provided the error
conditions that caused the flags to be set have gone away.
Reading the Status 2 register will clear the three flags (Bit 4
through Bit 2) in Status Register 2, provided the error
conditions that caused the flags to be set have gone away. A
flag bit can only be reset if the corresponding value register
contains an in−limit measurement, or if the sensor is good.
status register. It will be reset when the ALERT output has
been serviced by the master reading the device address,
provided the error condition has gone away and the status
register flag bits have been reset.
of Status Register 2 are set, the THERM output goes low to
indicate that the temperature measurements are outside the
programmed limits. The THERM output does not need to be
reset, unlike the ALERT output. Once the measurements are
within the limits, the corresponding status register bits are
reset automatically, and the THERM output goes high. The
user may add hysteresis by programming Register 0x21. The
THERM output will be reset only when the temperature falls
below the THERM limit minus hysteresis.
temperature limits are relevant. If Flag 6 and Flag 4 of Status
Register 1, or Flag 4 of Status Register 2 are set, the
THERM2 output goes low to indicate that the temperature
measurements are outside the programmed limits. Flag 5
and Flag 3 of Status Register 1, and Flag 3 of Status
Register 2 have no effect on THERM2. The behavior of
THERM2 is otherwise the same as THERM.
output is asserted low. Thus, the user need only read Status
Register 2 to determine if the ADT7481 is responsible for
Table 8. Status Register 2 Bit Assignments
1. These flags stay high until the status register is read, or they
Bit
The eight flags that can generate an ALERT are NOR’d
Reading the Status 1 register will clear the five flags (Bit 6
The ALERT interrupt latch is not reset by reading the
When Flag 1 and/or Flag 0 of Status Register 1, or Flag 1
When Pin 8 is configured as THERM2, only the high
Bit 0 of Status Register 2 gets set whenever the ALERT
7
6
5
4
3
2
1
0
are reset by POR.
Mnemonic
R2THRM1
D2 OPEN
R2HIGH
(Note 1)
R2LOW
(Note 1)
(Note 1)
ALERT
Res
Res
Res
Reserved for Future Use
Reserved for Future Use
Reserved for Future Use
1 When Remote 2 High
Temperature Limit Tripped
1 When Remote 2 Low
Temperature Limit Tripped
1 When Remote 2 Sensor
Open Circuit
1 When Remote 2
THERM Limit Tripped
1 When ALERT Condition
Exists
Function
ALERT
Yes
Yes
Yes
No
No
No
No
No
http://onsemi.com
11
the ALERT. This bit gets reset when the ALERT output gets
reset. If the ALERT output is masked, then this bit is not set.
Offset Register
temperature measurement by clock noise or by the thermal
diode being located away from the hot spot. To achieve the
specified accuracy on this channel, these offsets must be
removed.
values.
•
•
MSB of the MSB offset register is the sign bit. The minimum
offset that can be programmed is −128°C, and the maximum
is +127.75°C. The value in the offset register is added to, or
subtracted from, the measured value of the remote
temperature.
and will have no effect unless the user writes a different
value to it.
One−Shot Register
comparison cycle when the ADT7481 is in standby mode,
after which the device returns to standby. Writing to the
one−shot register address (0x0F) causes the ADT7481 to
perform a conversion and comparison on both the local and
the remote temperature channels. This is not a data register
as such, and it is the write operation to Address 0x0F that
causes the one−shot conversion. The data written to this
address is irrelevant and is not stored. However the ALERT
and THERM outputs are not operational in one−shot mode
and should not be used.
Table 9. Sample Offset Register Codes
Offset errors may be introduced into the remote
The offset values are stored as 10−bit, twos complement
Only the upper two bits of the LSB registers are used. The
The offset register powers up with a default value of 0°C
The one−shot register is used to initiate a conversion and
The Remote 1 offset MSBs are stored in Register 0x11
and the LSBs are stored in Register 0x12 (low byte, left
justified).
The Remote 2 offset MSBs are stored in Register 0x34
and the LSBs are stored in Register 0x35 (low byte, left
justified). The Remote 2 offset can be written to, or
read from, the Remote 1 offset registers if Bit 3 of the
Configuration 1 register is set to 1. This bit should be
set to 0 (default) to read the Remote 1 offset values.
Offset Value
+127.75°C
−0.25°C
+0.25°C
−128°C
−4°C
−1°C
+1°C
+4°C
0°C
0x11/0x34
1000 0000
0000 0000
0000 0000
0000 0001
0000 0100
1111 1100
0111 1111
1111 1111
1111 1111
00 00 0000
00 00 0000
10 00 0000
00 00 0000
01 00 0000
00 00 0000
00 00 0000
11 00 0000
0x12/0x35
00 000000