Manuals / Brands / Computer Equipment / Computer Hardware / SMSC / Computer Equipment / Computer Hardware

SMSC EMC2102 Note:, USER MANUAL, 5.3.5Spin-UpTime, Figure 5.14 Reduced Spin-upTime, Figure 5.13 60% Spin Level Setting

1 38

Download 38 pages, 4.31 Mb

Fan Speed Control with the EMC2102 Device

Invalid TACH Count

Figure 5.13 60% Spin Level Setting

Note: When a fan starts, the first TACH count captured by the EMC2102 may not reflect the fan’s speed correctly, since the counting clock (32.768 kHz) could only partially fill the counting window, which will cause a higher speed reading. Also for some fans, the tachometer may not work immediately after the fan starts therefore some invalid TACH signals (very short, noisy pulses) could be sent out at the beginning. In either case, the invalid TACH counts could be displayed on the ChipMan plots (Figure 5.13), but will never be used to control the fan because the EMC2102 will not look at the TACH reading until the end of spin-up routine.

5.3.5Spin-Up Time

The EMC2102 FAN Spin Up Configuration register (53h) contains 2 bits to set the overall spin-up time. This parameter allows for tailoring of rapid and slow response fans. Repeat the experiment in Section 5.3.3 with 500 ms SPINUP_TIME. This will provide a quicker response with smaller overshoot, as shown in Figure 5.14, "Reduced Spin-up Time".

In general, spin-up time should be tailored for the fan type being used or the effect may be undesirable.

Figure 5.14 Reduced Spin-up Time

Revision 0.2 (09-17-07)

USER MANUAL

SMSC EMC2102

18

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