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SMSC EMC2102 Figure 5.16 Default Step Size with Different UPDATE Settings, Figure 5.17 Default UPDATE with Different Step Size Settings

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Fan Speed Control with the EMC2102 Device

UPDATE = 100 ms

UPDATE = 400 ms

Figure 5.16 Default Step Size with Different UPDATE Settings

In the next experiment (Figure 5.17, "Default UPDATE with Different Step Size Settings"), two different maximum step sizes, 16 and 63, were used. with the 63 STEP SIZE setting, the output takes less steps (updates) from 4000 rpm to 7500 rpm because it gives the fan more power to follow the desired rpm settings.

STEp SIZE

= 63

STEp SIZE

= 16

Figure 5.17 Default UPDATE with Different Step Size Settings

In the last experiment, an extremely slow ramp rate is demonstrated. The UPDATE was set to maximum (1600 ms), and the STEP SIZE was changed to 01h (Figure 5.18, "Exceptionally Slow Rate"). Note the large scale of the “Time per division” in the figure.

SMSC EMC2102

USER MANUAL

Revision 0.2 (09-17-07)

Contents

USER MANUAL Page Page Page Page Page Figure 4.1 EMC2102 Fan Control Evaluation System Figure 4.2 EVB-EMC2102Board 5.1.1ChipMan Installation 5.1.2Setting Up the ChipMan Figure 5.1 ChipMan Message for First Operation Note: Figure 5.2 ChipMan Device Selection Window Figure 5.3 Selecting the Device and Master Controller Type Figure 5.4 ChipMan Operation Window Notes: Figure 5.5 Changing Fan Speed 5.1.3Plotting From ChipMan Figure 5.6 Plotting from the ChipMan Figure 5.7 Plot Windows Figure 5.8 Plot Examples 5.2.1Getting Started 5.2.2Basic RPM Based Fan Control Figure 5.9 Plots for Proper Control Settings 5.2.3Effects of Loading Figure 5.10 Effects of Loading 5.2.4Register Change Summary Table 5.1 Register Change Summary for Experiment REGISTER DEFAULT 5.3.1Fan Control Parameters Figure 5.11 Fan Control Parameters 5.3.2Getting Started 5.3.3Forced Kick Function Figure 5.12 Forced Kick Function 5.3.4Spin-UpLevel Figure 5.13 60% Spin Level Setting 5.3.5Spin-UpTime Figure 5.14 Reduced Spin-upTime 5.3.6Register Change Summary Table 5.2 Register Change Summary for Experiment 5.4.1General Setup 5.4.2Controlling the Ramp Rate Figure 5.15 Default Ramp Rate Figure 5.16 Default Step Size with Different UPDATE Settings Figure 5.17 Default UPDATE with Different Step Size Settings Figure 5.18 Exceptionally Slow Rate 5.4.3Register Change Summary Table 5.3 Register Change Summary for Experiment 5.5.1General Setup 5.5.2Fan Configuration Register (52h) Figure 5.19 Update Time Modifications 5.5.3FAN Minimum Drive Register (55h) and Valid TACH Count (56h) Figure 5.20 Minimum Drive Setting Figure 5.21 Valid Tach Count Setting 5.5.4Register Change Summary Table 5.4 Register Change Summary for Experiment 5.6.1General Setup 5.6.2Fan Spin and Stall Interrupts Figure 5.22 Fan Spin and Stall 5.6.3Register Change Summary 5.7.1.1Case 1 - Spin-upLvel RPM < Valid RPM < Target RPM Figure 5.24 Theoretical Plot of Case Figure 5.25 Spin-upCase 1 Fix 5.7.1.2Case 2 - Valid RPM << Target RPM < Spin-upLevel RPM 5.7.1.3Case 3 - Valid RPM =< Target RPM << Spin-upLevel RPM Figure 5.30 Spin-upCase Figure 5.31 Spin-upRoutine Restarted During Normal Operation 5.7.1.4Case 4 - 4.Valid RPM < Spin-upLevel RPM (rpm60 or rpm75) < Target RPM 5.7.1.5Case 5 - Correct RPM Relationships with a Slow Response DC Fan Figure 6.1 A Typical 2-poleDC Fan Figure 6.2 Output Signal of a 2-poleFan Figure 6.3 Fan TACH Measurement With EMC2102 [1] 6.2.1General Setup 6.2.2Set the Correct LIMIT2K Value 6.2.3Determine the Number of Poles and the Maximum Fan Speed 6.2.4Determine the Minimum Startup Speed 6.2.5Determine the Stall Speed 6.2.6Determine the Minimum Valid TACH Speed 6.2.8.1Spin-upLEVEL (Register 53h[2]) 6.2.8.2Minimum Fan Speed 6.2.8.3Valid TACH Count Speed (Function of Register 56h) 6.2.8.4Maximum Fan Speed