PC8374L datasheet(127/239 Pages) NSC

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8.0

Health Management (HM)

8.1 OVERVIEW

The PC8374L Health Management module (“HM”) is the digital component of the System Health Monitor and Control func-

tion. The analog component of this function is implemented by external LMxx Sensor devices. Communication between the

HM and an external LMxx Sensor is automatic (i.e., there is no need for user intervention/configuration) via the SensorPath

bus, working in asynchronous mode.

The HM monitors three temperature channels, five voltage channels, and four tachometer channels.

In addition, it generates three FANPWM fan drive control signals.

The temperature data, together with the tachometer data, can be used to control the FANPWM signals.

The HM automatically reads temperature and voltage data from an LMxx Sensor device. It then compares the data to the

limit data set in the Limit registers and sets the corresponding status bits.

Access to the HM is possible through a dedicated SMBus interface (HMSMBus with HMSCL and HMSDA pins) or through

the LPC interface.

The HM can automatically use one of the following four LMxx device options to supply temperature and voltage inputs:

• LM96011 provides two temperature channels (one remote diode, one ambient) and ﬁve voltage channels

• LM96011+LM95010 provides three temperature channels (one remote diode, two ambient) and ﬁve voltage channels

• LM96010 provides three temperature channels (two remote diode, one ambient) and ﬁve voltage channels

• LM96012 provides three temperature channels (two remote diode, one ambient) and no voltage channels

Note: When the LM96011, LM96010 or LM96012 is used, it should be strapped as device number 1.

When the LM95010 is used, it should be strapped as device number 2.

Figure 30 on page 128 shows the HM Block Diagram.

8.2 FUNCTIONAL DESCRIPTION

The HM functions are:

• Sensor Monitoring (voltage channels and temperature channels monitoring)

• Fan monitoring (fan speed measurements)

• Fan control (driving fans)

8.2.1

Health Management Module Access

The HM can be accessed either through the LPC Bus or through a dedicated SMBus (HMSMBus).

For access through the HMSMBus, the HM responds to SMBus transactions addressed according to the SMBus slave ad-

dress set by the HM SMBus Configuration register (see Section 3.7.12 on page 59). For the SMBus transaction protocols,

see Section 8.3 on page 140.

Access through the LPC Bus is done through the HM LPC Access registers. For more details see Section 8.4 on page 141.

Simultaneous write accesses through the LPC Bus and SMBus may cause unpredictable results. However, for simultaneous

read accesses, consistency is retained (except for the 16-bit measurement data registers, such as Fan Tachometer Reading

1-3 MSB/LSB).

8.2.2

SensorPath Bus

The HM communicates with the LMxx Sensor devices via the SensorPath bus. The HM is the bus master on the SensorPath

bus and supports asynchronous mode.

The SensorPath bus uses timing encoding based on a 360 KHz internal clock to provide the following types of bit signals

over the bus (the HM supports all five types):

• Data Bit 0

• Data Bit 1

• Start Bit

• Attention Request

• Reset

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