1. 0 DC Fan Speed Control PWM Signal Introduction Wayne_Chen ADDA RD Chief Engineer Wayne@adda.com.tw 886-8-755-0579 ext:326

2. 1 Topical: 1.Speed Control Fan Configuration (old version) 2.What is PWM Signal ? 3.PWM Control Methods Introduction 4.PWM Fan Specification 5.PWM Fan Sample 6.Q & A

3. 2 1. Speed Control Fan Structure (old version) 1-1. Use ON/OFF control by Transistor Advantage ： I. Easy design and control method II. Price cheaper. Disadvantage : I.Power Dissipation is a design issue. II.Not use friendly.

4. 3 2. What is PWM Signal ? PWM(Pulse Width Modulation): It’s a fixed frequency and pulse modulated for fan speed control. Whenever change the duty cycle, the fan speed will be changed by system requirement. Figure : PWM Control Signal  The Purpose are : 1. The power dissipation will be saving. 1. The power dissipation will be saving. 2. And the working time will be increasing if the battery could not be charged outside. (especially NB system) 2. And the working time will be increasing if the battery could not be charged outside. (especially NB system)

5. 4 3. PWM control Methods introduction 3-1Speed Control Fan Structure (old version) Disadvantage ： I.Poor Reliability ( Transistor are On/OFF continuously) II.Error judgment of tachometer signal. Advantage ： I. Easy design and control method II. Price cheaper.  Use ON/OFF control by Transistor

6. 5 Actual Tachometer Signal Waveform PWM input signal Error judgment of tachometer signal

7. 6 Advantage ： I.The better Reliability II.RPM Stable III.Power efficiency saving. Disadvantage ： I.Cost expensive. II.Control Circuit Complex 3-2. Regulator Control Fan Configuration (Current version For Notebook ) (Current version For Notebook )

8. 7 PWM input signal tachometer signal ( normality) Actual Tachometer Signal Waveform

9. 8 3-3. Control PWM Fan Configuration PWM control Configuration System Fan

10. 9 3-4. Next Generation Version PWM Control Fan: Type A Type A

11. 10 3-5. PWM Control Fan: Type B Type B

12. 11 4-1. PWM Input Signal Specification (from system) PWM Operating Frequency : 25kHz ± 5kHz Maximum Input Low Voltage (V IL-MAX ) = 0.8V Minimum Input High Voltage (V IH-MIN ) = 2.0V High Input Impedance (10K ohms at least ) (Consider Fan-In Issue ， Driver Capability)

13. 12 4-2. PWM Fan Specification Operation Voltage : 5V or 12V ± 10% Function: Locked Protection and Auto-restart Apply the Open Collector or Open Drain Tachometer Output Signal Low Speed setting with 0~17% (or 20%) on Same PRM level (Type B)

14. 13 5. PWM Fan sample 5-1. Type A( For NB fan suggestion) Fan Stop Duty Cycle Fan Start_up Duty Cycle

15. 14 5. PWM Fan sample 5-2. Type A( All kind of fan could be used.) Fan Stop Duty Cycle Fan Start_up Duty Cycle

16. 15 5. PWM Fan sample 5-3. Type B(For Desktops fan suggestion) It’s same duty cycle curve for fan start_up and stop.

17. 16 6. Question & Answer (The End)