ADM1032

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9

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 8. STATUS REGISTER BIT ASSIGNMENTS

Bit

Name

Function

7

BUSY

1 When ADC Converting

6

LHIGH

(Note 1)

1 When Local High Temp Limit Tripped

5

LLOW

(Note 1)

1 When Local Low Temp Limit Tripped

4

RHIGH

(Note 1)

1 When Remote High Temp Limit

Tripped

3

RLOW

(Note 1)

1 When Remote Low Temp Limit

Tripped

2

OPEN

(Note 1)

1 When Remote Sensor Open-Circuit

1

RTHRM

1 When Remote THERM Limit Tripped

0

LTHRM1

1 When Local THERM Limit Tripped

1. 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 9. CONFIGURATION REGISTER BIT

ASSIGNMENTS

Bit

Name

Function

Power-On

Default

7

MASK1

0 = ALERT Enabled

1 = ALERT Masked

0

6

RUN/STOP

0 = Run

1 = Standby

0

5 to 0

Reserved

0

Conversion Rate Register

The lowest four bits of this register are used to program the

conversion rate by dividing the internal oscillator clock by

1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024 to give

conversion times from 15.5 ms (Code 0Ah) to 16 seconds

(Code 00h). This register can be written to and read back

over the SMBus. The higher four 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 10.

Table 10. CONVERSION RATE REGISTER CODES

Data

Conversion/Sec

Average Supply Current

00h

0.0625

0.17

01h

0.125

0.20

02h

0.25

0.21

03h

0.5

0.24

04h

1

0.29

05h

2

0.40

06h

4

0.61

07h

8

1.1

08h

16

1.9

09h

32

0.73

0Ah

64

1.23

0B to FFh

Reserved

Limit Registers

The ADM1032 has nine limit registers to store local and

remote, high, low, and THERM 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 < or = to comparison. For

example, if the high limit register is programmed with 80

°C,

measuring 81

°C results in an alarm condition. If the low

limit register is programmed with 0

°C, measuring 0°C or

lower results in an alarm condition. Exceeding either the

local or remote THERM limit asserts THERM low. A

default hysteresis value of 10

°C is provided, which applies

to both channels. This hysteresis can be reprogrammed to

any value after powerup (Reg 0x21h).

One-Shot Register

The one-shot register is used to initiate a single conversion

and comparison cycle when the ADM1032 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. The conversion time

on a single shot is 96 ms when the conversion rate is 16

conversions per second or less. At 32 conversions per

second, the conversion time is 15.3 ms. This is because

averaging is disabled at the faster conversion rates (32 and

64 conversions per second).

Consecutive ALERT Register

This value written to this register determines how many

out-of limit measurements must occur before an ALERT is

generated. The default value is that one out-of-limit

measurement generates an ALERT. The maximum value

that can be chosen is four. The purpose of this register is to

allow the user to perform some filtering of the output. This

is particularly useful at the faster two conversion rates where

no averaging takes place.