ADM1027 datasheet(17/56 Pages) AD

17 / 56 page

REV. A

ADM1027

–17–

SMBALERT, STATUS, AND MASK REGISTERS

SMBALERT CONFIGURATION

Pin 10 of the ADM1027 can be configured as either PWM2 or

as an SMBALERT output. The SMBALERT output may be

used to signal out-of-limit conditions as explained below. The

default state of Pin 10 is PWM2. To configure Pin 10 as

SMBALERT:

Configuration Reg. 3 (Addr = 0x78), Bit 0 = 1 = SMBALERT

Configuration Reg. 3 (Addr = 0x78), Bit 0 = 0 = PWM2 =

default

LIMIT VALUES

Associated with each measurement channel on the ADM1027

are high and low limits. These can form the basis of system

status monitoring; a status bit can be set for any out-of-limit

condition and detected by polling the device. Alternatively,

SMBALERT interrupts can be generated to flag a processor or

microcontroller of out-of-limit conditions.

8-BIT LIMITS

The following is a list of 8-bit limits on the ADM1027:

Voltage Limit Registers

Reg. 0x44 2.5 V Low Limit = 0x00 default

Reg. 0x45 2.5 V High Limit = 0xFF default

Reg. 0x46 VCCP Low Limit = 0x00 default

Reg. 0x47 VCCP High Limit = 0xFF default

Reg. 0x48 VCC Low Limit = 0x00 default

Reg. 0x49 VCC High Limit = 0xFF default

Reg. 0x4A 5 V Low Limit = 0x00 default

Reg. 0x4B 5 V High Limit = 0xFF default

Reg. 0x4C 12 V Low Limit = 0x00 default

Reg. 0x4D 12 V High Limit = 0xFF default

Temperature Limit Registers

Reg. 0x4E Remote 1 Temp Low Limit = 0x81 default

Reg. 0x4F Remote 1 Temp High Limit = 0x7F default

Reg. 0x6A Remote 1 THERM Limit = 0x64 default

Reg. 0x50 Local Temp Low Limit = 0x81 default

Reg. 0x51 Local Temp High Limit = 0x7F default

Reg. 0x6B Local THERM Limit = 0x64 default

Reg. 0x52 Remote 2 Temp Low Limit = 0x81 default

Reg. 0x53 Remote 2 Temp High Limit = 0x7F default

Reg. 0x6C Remote 2 THERM Limit = 0x64 default

16-Bit Limits

The fan TACH measurements are 16-bit results. The fan TACH

limits are also 16 bits, consisting of a high byte and low byte.

Since fans running underspeed or stalled are normally the only

conditions of interest, only high limits exist for fan TACHs.

Since fan TACH period is actually being measured, exceeding

the limit indicates a slow or stalled fan.

Fan Limit Registers

Reg. 0x54 TACH1 Minimum Low Byte = 0xFF default

Reg. 0x55 TACH1 Minimum High Byte = 0xFF default

Reg. 0x56 TACH2 Minimum Low Byte = 0xFF default

Reg. 0x57 TACH2 Minimum High Byte = 0xFF default

Reg. 0x58 TACH3 Minimum Low Byte = 0xFF default

Reg. 0x59 TACH3 Minimum High Byte = 0xFF default

Reg. 0x5A TACH4 Minimum Low Byte = 0xFF default

Reg. 0x5B TACH4 Minimum High Byte = 0xFF default

OUT-OF-LIMIT COMPARISONS

The ADM1027 will measure all parameters in round-robin format

and set the appropriate status bit for out-of-limit conditions.

Comparisons are done differently depending on whether the

measured value is being compared to a high or low limit.

HIGH LIMIT: > COMPARISON PERFORMED

LOW LIMIT: < OR = COMPARISON PERFORMED

ADM1027 Datasheet(PDF) 17 Page - Analog Devices

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