ADM1021AARQ Datasheet PDF - Analog Devices

ADM1021AARQ View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

ADM1021AARQ

Low-Cost Microprocessor System Temperature Monitor

Analog Devices

ADM1021AARQ Datasheet PDF : 16 Pages

1 2 3 4 5 6 7 8 9 10 Next Last

ADM1021A

Table I. Temperature Data Format

Temperature

0°C

1°C

10°C

25°C

50°C

75°C

100°C

125°C

127°C

Digital Output

0 000 0000

0 000 0001

0 000 1010

0 001 1001

0 011 0010

0 100 1011

0 110 0100

0 111 1101

0 111 1111

REGISTERS

The ADM1021A contains nine registers that are used to store

the results of remote and local temperature measurements,

high and low temperature limits, and to configure and control

the device. A description of these registers follows, and further

details are given in Tables II to IV. It should be noted that the

ADM1021A’s registers are dual port, and have different addresses

for read and write operations. Attempting to write to a read address,

or to read from a write address, will produce an invalid result.

for factory test purposes and should not be written to.

Address Pointer Register

The Address Pointer Register itself does not have, nor does it

require, an address, as it is the register to which the first data

byte of every write operation is written automatically. This data

byte is an address pointer that sets up one of the other registers

for the second byte of the write operation, or for a subsequent

read operation.

Value Registers

The ADM1021A has two registers to store the results of local

and remote temperature measurements. These registers are

written to by the ADC and can only be read over the SMBus.

Status Register

Bit 7 of the Status Register indicates when it is high that the

ADC is busy converting. Bits 5 to 3 are flags that indicate the

results of the limit comparisons.

If the local and/or remote temperature measurement is above the

corresponding high temperature limit or below the corresponding

low temperature limit, then one or more of these flags will be set.

Bit 2 is a flag that is set if the remote temperature sensor is open-

circuit. These five flags are NOR’d together, so that if any of them

is high, the ALERT interrupt latch will be set and the ALERT

output will go low. Reading the Status Register will clear the five

flag bits, provided the error conditions that caused the flags to be

set have gone away. While a limit comparator is tripped due to a

value register containing an out-of-limit measurement, or the sen-

sor is open-circuit, the corresponding flag bit cannot be reset. A

flag bit can only be reset if the corresponding value register con-

tains an in-limit measurement, or the sensor is good.

Table II. Status Register Bit Assignments

Bit Name

Function

7 BUSY

1 When ADC Converting

6 LHIGH* 1 When Local High Temp Limit Tripped

5 LLOW* 1 When Local Low Temp Limit Tripped

4 RHIGH* 1 When Remote High Temp Limit Tripped

3 RLOW* 1 When Remote Low Temp Limit Tripped

2 OPEN* 1 When Remote Sensor Open-Circuit

1–0

Reserved

*These flags stay high until the status register is read or they are reset by POR.

Table III. List of ADM1021A Registers

READ Address (Hex)

WRITE Address (Hex)

Name

Power-On Default

Not Applicable

0F1

Not Applicable

Address Pointer

Local Temp. Value

Remote Temp. Value

Status

Configuration

Conversion Rate

Local Temp. High Limit

Local Temp. Low Limit

Remote Temp. High Limit

Remote Temp. Low Limit

One-Shot

Reserved

Manufacturer Device ID

Die Revision Code

Undefined

1000 0000 (80h) (–128°C)

Undefined

0000 0000 (00h)

0000 0010 (02h)

0111 1111 (7Fh) (+127°C)

1100 1001 (C9h) (–55°C)

0111 1111 (7Fh) (+127°C)

1100 1001 (C9h) (–55°C)

Undefined2

0100 0001 (41h)

0011 xxxx (3xh)

NOTES

1Writing to address 0F causes the ADM1021A to perform a single measurement. It is not a data register as such and it does not matter what data is written to it.

2These registers are reserved for future versions of the device.

REV. D

–7–

Share Link: