ADM1032
Table II. Extended Temperature Resolution (Remote
Temperature Low Byte)
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.
Extended
Remote Temperature
Low Byte
Resolution
0.000°C
0.125°C
0.250°C
0.375°C
0.500°C
0.625°C
0.750°C
0.875°C
0 000 0000
0 010 0000
0 100 0000
0 110 0000
1 000 0000
1 010 0000
1 100 0000
1 110 0000
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.
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.
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.
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.
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.
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.
Table IV. Status Register Bit Assignments
Value Registers
Bit Name
Function
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.
7
6
5
4
3
2
1
0
BUSY
1 When ADC Converting
LHIGH* 1 When Local High-Temp Limit Tripped
LLOW* 1 When Local Low-Temp Limit Tripped
RHIGH* 1 When Remote High-Temp Limit Tripped
RLOW*
OPEN*
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.
1 When Remote Low-Temp Limit Tripped
1 When Remote Sensor Open-Circuit
RTHRM 1 When Remote Therm Limit Tripped
LTHRM 1 When Local Therm Limit Tripped
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.
*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.
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
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.
–4°C
–1°C
1 111 1100
1 111 1111
1 111 1111
0 000 0000
0 000 0000
0 000 0001
0 000 0100
0 000 0000
0 000 0000
1 110 0000
0 000 0000
0 010 0000
0 000 0000
0 000 0000
–0.125°C
0°C
+0.125°C
+1°C
+4°C
–6–
REV. 0