ADT7421ARMZ-2RL7 ON Semiconductor, ADT7421ARMZ-2RL7 Datasheet - Page 10

• Manufacturer Part Number: ADT7421ARMZ-2RL7
• Description: IC TEMP MONITOR 8-MSOP
• Manufacturer: ON Semiconductor
• Type: Temperature Sensorr

Specifications of ADT7421ARMZ-2RL7

• Input Type: Logic
• Output Type: Logic
• Interface: 2-Wire SMBus
• Current - Supply: 4mA
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Full Temp Accuracy: +/- 2.75 C, +/- 3.25 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Offset Register
temperature measurement by clock noise or when the
thermal transistor is located away from the hot spot. To
achieve the specified accuracy on this channel, these offsets
must be removed.
value in Register 0x11 (high byte) and Register 0x12 (low
byte, left justified). Only the upper two bits of Register 0x12
are used. The MSB of Register 0x11 is the sign bit. The
minimum, programmable offset 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 has no effect unless the user writes a different value to it.
Table 6. Sample Offset Register Codes
Offset errors can be introduced into the remote
The offset value is stored as a 10−bit, twos complement
The offset register powers up with a default value of 0°C
Offset Value
+127.75°C
−0.25°C
+0.25°C
−128°C
−4°C
−1°C
+1°C
+4°C
0°C
1000 0000
1111 1100
1111 1111
1111 1111
0000 0000
0000 0000
0000 0001
0000 0100
0111 1111
0x11
00 00 0000
00 00 0000
00 00 0000
11 00 0000
00 00 0000
01 00 0000
00 00 0000
00 00 0000
11 00 0000
0x12
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10
One−Shot Register
comparison cycle when the ADT7421 is in standby mode,
after which the device returns to standby. Writing to the
one−shot register address (0x0F) causes the ADT7421 to
perform a conversion and comparison on both the internal
and the external 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.
Consecutive ALERT Register
out−of−limit measurements must occur before an ALERT is
generated. The default value is that one out−of−limit
measurement generates an ALERT. The maximum value that
can be chosen is 4. The purpose of this register is to allow the
user to perform some filtering of the output. This is
particularly useful at the fastest three conversion rates, where
no averaging takes place. This register is at Address 0x22.
Table 7. Consecutive ALERT Register 0x22
<3−0>
†x = Don’t care bit.
The one−shot register is used to initiate a conversion and
The value written to this register determines how many
Bits
Value†
000x
001x
011x
111x
Measurements Required
Number of Out−of−Limit
1
2
3
4