ADM1020 Datasheet PDF - Analog Devices

ADM1020 View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

ADM1020

8-Lead, Low-Cost, System Temperature Monitor

Analog Devices

ADM1020 Datasheet PDF : 12 Pages

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

The power-on default value of the Address Pointer Register is

00h, so if a read operation is performed immediately after power-

on, without first writing to the address pointer, the value of the

local temperature will be returned, since its register address is

00h.

Value Registers

The ADM1020 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 that the ADC is busy con-

verting when it is high. 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 corre-

sponding 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 are high, the ALERT interrupt latch will be

set and the ALERT output will go low. Reading the Status

tions 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 sensor is open-circuit, the

corresponding flag bit cannot be reset. A flag bit can only be

reset if the corresponding value register contains an in-limit

measurement, or the sensor is good.

ADM1020

The ALERT interrupt latch is not reset by reading the Status

serviced by the master reading the device address, provided the

error condition has gone away and the Status Register flag bits

have been reset.

Table II. Status Register Bit Assignments

Bit Name

Function

7 BUSY

6 LHIGH*

5 LLOW*

4 RHIGH*

3 RLOW*

2 OPEN*

1–0

1 When ADC Converting

1 When Local High-Temp Limit Tripped

1 When Local Low-Temp Limit Tripped

1 When Remote High-Temp Limit Tripped

1 When Remote Low-Temp Limit Tripped

1 When Remote Sensor Open-Circuit

Reserved

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

Configuration Register

Two bits of the Configuration Register are used. If Bit 6 is 0,

which is the power-on default, the device is in operating mode

with the ADC converting. If Bit 6 is set to 1, the device is in

standby mode and the ADC does not convert. Standby mode

can also be selected by taking the STBY pin low.

Bit 7 of the configuration register is used to mask the ALERT

output. If Bit 7 is 0, which is the power-on default, the ALERT

output is enabled. If Bit 7 is set to 1, the ALERT output is

disabled.

Table III. List of Registers

Read Address (Hex)

Write Address (Hex)

Name

Power-On Default

Not Applicable

Address Pointer

Local Temperature Value

Remote Temperature Value

Status

Configuration

Conversion Rate

Local Temperature High Limit

Local Temperature Low Limit

Remote Temperature High Limit

Remote Temperature Low Limit

One-Shot

Reserved

Manufacturer ID

Die Revision Code

Undefined

0000 0000 (00h)

Undefined

0000 0000 (00h)

0000 0010 (02h)

0111 1111

1100 1001

0111 1111

1100 1001

(7Fh) (127°C)

(C9h) (–55°C)

(7Fh) (127°C)

(C9h) (–55°C)

See Note 1

Undefined (Note 2)

1000 0000 (Note 2)

Undefined (Note 2)

0000 0000 (Note 2)

Undefined

0100 0001 (41h)

Undefined

NOTES

1Writing to address 0F causes the ADM1020 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. 0

–7–

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