ADT7481ARMZ ON Semiconductor, ADT7481ARMZ Datasheet - Page 10

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

Specifications of ADT7481ARMZ

• 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
• Full Temp Accuracy: +/- 2.5 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Maximum Operating Temperature: + 127 C
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Limit Registers
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 from, the SMBus.
See Table 11 for details of the limit register addresses and
power−on default values.
the status register.
measuring 0°C or lower will result in an out−of−limit
condition.
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 may be reprogrammed.
data format is the same as the temperature measurement data
format. So 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 automatically
switch.
value in the correct data format. For example, if the remote
low limit is set at 10°C and the default binary scale is being
Table 6. Conversion Rate/Channel Selector Register (Read Address 0x04, Write Address 0x0A)
<5:4>
<3:0>
The ADT7481 has three limits for each temperature
C will result in an out−of−limit condition, setting a flag in
If the low limit register is programmed with 0°C,
Exceeding either the local or remote THERM limit asserts
It is important to remember that the temperature limits
The user must reprogram the limit registers to the desired
Bit
7
6
Conversion Rates
Channel Selector
Mnemonic
Averaging
Reserved
0000 = 0.0625
0001 = 0.125
0010 = 0.25
0011 = 0.5
0100 = 1
0101 = 2
0110 = 4
0111 = 8 = default
1000 = 16
1001 = 32
1010 = 64
1011 = continuous measurements
Setting this bit to 1 disables averaging of the temperature measurements at the slower conversion
rates (averaging cannot take place at the three faster rates, so setting this bit has no effect). When
default = 0, averaging is enabled.
Reserved for future use. Do not write to this bit.
These bits are used to select the temperature measurement channels:
These bits set how often the ADT7481 measures each temperature channel.
Conversion rates are as follows:
00 = Round robin = default = all channels measured
01 = Local temperature only measured
10 = Remote 1 temperature only measured
11 = Remote 2 temperature only measured
Conversions/sec
http://onsemi.com
10
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.
Status Registers
0x02 (Status Register 1) and Address 0x23 (Status
Register 2). They contain status information for the
ADT7481.
Table 7. Status Register 1 Bit Assignments
1. These flags stay high until the status register is read, or they
Bit
The status registers are read−only registers, at Address
7
6
5
4
3
2
1
0
are reset by POR.
Function
Mnemonic
R1THRM1
D1 OPEN
R1HIGH
LTHRM1
(Note 1)
(Note 1)
(Note 1)
(Note 1)
R1LOW
LHIGH
BUSY
LLOW
16
8
4
2
1
500 m
250 m
125 m
62.5 m
31.25 m
15.5 m
73 m (averaging enabled)
1
1 when ADC converting
1 when local high
temperature limit tripped
1 when local low
temperature limit tripped
1 When Remote 1 High
Temperature Limit Tripped
1 When Remote 1 Low
Temperature Limit Tripped
1 When Remote 1 Sensor
Open Circuit
1 when Remote1 THERM
Limit Tripped
1 when local THERM Limit
Tripped
Time (seconds)
Function
ALERT
Yes
Yes
Yes
Yes
Yes
No
No
No