REV. 0

ADM1032

–6–

Status Register

Bit 7 of the Status Register indicates that the ADC is busy con-

verting when it is high. Bits 6 to 3, 1, and 0 are flags that indicate

the results of the limit comparisons. Bit 2 is set when the remote

sensor is open circuit.

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

corresponding high temperature limit, or below or equal to, the

corresponding low temperature limit, one or more of these flags

will be set. These five flags (Bits 6 to 2) 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 measure-

ment, 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.

The

ALERT interrupt latch is not reset by reading the Status

Register, but will be reset when the

ALERT output has been

serviced by the master reading the device address, provided the

error condition has gone away and the Status Register flag bits

have been reset.

When Flags 1 and 0 are set, the

THERM output goes low to

indicate that the temperature measurements are outside the

programmed limits.

THERM output does not need to be reset,

unlike the

ALERT output. Once the measurements are within the

limits, the corresponding Status register bits are reset and the

THERM output goes high.

Table IV. 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

RTHRM

1 When Remote Therm Limit Tripped

0

LTHRM

1 When Local Therm Limit Tripped

*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. The SMBus does,

however, remain active in Standby Mode so values can be read

from or written to the SMBus. The

ALERT and THERM O/Ps

are also active in Standby Mode.

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 output is

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

Table II. Extended Temperature Resolution (Remote

Temperature Low Byte)

Extended

Remote Temperature

Resolution

Low Byte

0.000

°C

0 000 0000

0.125

°C

0 010 0000

0.250

°C

0 100 0000

0.375

°C

0 110 0000

0.500

°C

1 000 0000

0.625

°C

1 010 0000

0.750

°C

1 100 0000

0.875

°C

1 110 0000

ADM1032 REGISTERS

The ADM1032 contains 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 III to VII.

Address Pointer Register

The Address Pointer Register itself does not have, or 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.

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 ADM1032 has three registers to store the results of Local

and Remote temperature measurements. These registers are

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

Offset Register

Series resistance on the D+ and D– lines in processor packages

and clock noise can introduce offset errors into the remote tem-

perature measurement. To achieve the specified accuracy on

this channel these offsets must be removed.

The offset value is stored as an 11-bit, two’s complement value

in registers 11h (high byte) and 12h (low byte, left justified).

The value of the offset is negative if the MSB of register 11h is 1

and it is positive if the MSB of register 12h is 0. The value is

added to the measured value of remote temperature.

The offset register powers up with a default value of 0

°C, and

will have no effect if nothing is written to them.

Table III. Sample Offset Register Codes

Offset Value

11h

12h

–4

°C

1 111 1100

0 000 0000

–1

°C

1 111 1111

0 000 0000

–0.125

°C

1 111 1111

1 110 0000

0

°C

0 000 0000

0 000 0000

+0.125

°C

0 000 0000

0 010 0000

+1

°C

0 000 0001

0 000 0000

+4

°C

0 000 0100

0 000 0000