ADM1021AARQ-REEL ON Semiconductor, ADM1021AARQ-REEL Datasheet - Page 10

• Manufacturer Part Number: ADM1021AARQ-REEL
• Description: IC SENSOR TEMP DUAL3/5.5V 16QSOP
• Manufacturer: ON Semiconductor

Specifications of ADM1021AARQ-REEL

• Rohs Status: RoHS non-compliant
• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 100°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: No
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP

Conversion Rate Register
the conversion rate by dividing the ADC clock by 1, 2, 4, 8,
16, 32, 64, or 128 to give conversion times from 125 ms
(Code 0x07) to 16 seconds (Code 0x00). This register can be
written to and read back over the SMBus. The higher five
bits of this register are unused and must be set to 0. Use of
slower conversion times greatly reduces the device power
consumption, as shown in Table 5.
Limit Registers
remote and high and low temperature limits. These registers
can be written to and read back over the SMBus. The high
limit registers perform a > comparison, while the low limit
registers perform a < comparison. For example, if the high
limit register is programmed as a limit of 80°C, measuring
81°C results in an alarm condition. Even though the
temperature measurement range is from 0° to 127°C, it is
possible to program the limit register with negative values.
This is for backwards compatibility with the ADM1021.
Offset Register
the user to remove errors from the measured remote
temperature. These errors can be introduced by clock noise
and PCB track resistance. See Table 6 for an example of
offset values.
value. The value of the offset is negative if the MSB of
Register 0x11 is 1, and is positive if the MSB of Register
0x11 is 0. This value is added to the remote temperature. The
offset register defaults to 0 at powerup. The offset register
range is −128°C to +127°C.
Table 4. Configuration Register Bit Assignments
Table 5. Conversion Rate Register Code
5 to 0
0x08 to 0xFF
The lowest three bits of this register are used to program
The ADM1021A has four limit registers to store local and
An offset register is provided at Address 0x11. This allows
The offset value is stored as an 8−bit, twos complement
Bit
7
6
Data
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
RUN/STOP
MASK1
Name
Conversion/
Reserved
0.0625
0.125
0.25
Sec
0.5
1
2
4
8
0 = ALERT Enabled
1 = ALERT Masked
0 = Run
1 = Standby
Reserved
Function
Average Supply Current
mA Typ at V
150
150
150
150
150
150
160
180
CC
Power−On
Default
= 3.3 V
0
0
0
http://onsemi.com
ADM1021A
10
One−Shot Register
conversion and comparison cycle when the ADM1021A is
in standby mode, after which the device returns to standby.
This is not a data register as such, and it is the write operation
that causes the one−shot conversion. The data written to this
address is irrelevant and is not stored.
Serial Bus Interface
The ADM1021A is connected to this bus as a slave device,
under the control of a master device. Note that the SMBus
and SCL pins are three−stated when the ADM1021A is
powered down and will not pull down the SMBus.
Address Pins
(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.
to allow selection of the device address so that several
ADM1021A’s can be used on the same bus, and/or to avoid
conflict with other devices. Although only two address pins
are provided, these are three−state and can be grounded, left
unconnected, or tied to V
addresses are possible, as shown in Table 7.
sampled at powerup, so changing them after powerup has no
effect.
Table 6. Offset Values
Table 7. Device Addresses
1. ADD0 and ADD1 are sampled at powerup only.
0000 0000
0000 0001
0000 0100
The one−shot register is used to initiate a single
Control of the ADM1021A is carried out via the serial bus.
In general, every SMBus device has a 7−bit device address
The ADM1021A has two address pins, ADD0 and ADD1,
It should be noted that the state of the address pins is only
1111 1100
1111 1111
(0x11)
ADD0
NC
NC
NC
Offset Register
0
0
0
1
1
1
Offset
Value
−4°C
−1°C
+1°C
+4°C
0°C
ADD1
NC
NC
NC
0
1
0
1
0
1
DD
so that a total of nine different
(With Offset)
(Note 1)
14°C
17°C
18°C
19°C
22°C
Remote Temperature
Device Address
0011 000
0011 001
0011 010
0101 001
0101 010
0101 011
1001 100
1001 101
1001 110
(Without
Offset)
18°C
18°C
18°C
18°C
18°C