MEC1322 Datasheet, PDF (290/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
26.0 RPM-PWM INTERFACE
26.1 Introduction
The RPM-PWM Interface is closed-loop RPM based Fan Control Algorithm that monitors the fan’s speed and automat-
ically adjusts the drive to maintain the desired fan speed.
The RPM-PWM Interface functionality consists of a closed-loop “set-and-forget” RPM based fan controller.
26.2 References
No references have been cited for this chapter
26.3 Terminology
There is no terminology defined for this chapter.
26.4 Interface
This block is designed to be accessed externally via the pin interface and internally via a registered host interface.
The registers in the block are accessed by embedded controller code at the addresses shown in Section 26.9, "Fan
Control Register Bank".
Figure 26-1 illustrates and categorizes the RPM-PWM Interface block signals. These signals are described in Table 26-
1.
FIGURE 26-1:
RPM-PWM INTERFACE I/O DIAGRAM
Host Interface
Power, Clocks and Reset
Interrupts
RPM-PWM Interface
Fan Control
26.4.1 FAN CONTROL
The Fan Control Signal Description Table lists the signals that are routed to/from the block.
TABLE 26-1: FAN CONTROL SIGNAL DESCRIPTION TABLE
Name
Direction
Description
TACH
PWM
Input
Output
Tachometer input from fan
PWM fan drive output
26.4.2 HOST INTERFACE
The registers defined for the RPM-PWM Interface are accessible by the various hosts as indicated in Section 26.9, "Fan
Control Register Bank".
DS00001719D-page 290
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