Introduction and background of PWM Motherboard Closed Loop Diagram

1
Lower Cost 4 Wire PWM Voltage Controlled Fans and
Blowers

• Introduction and background of PWM Motherboard
  Closed Loop Diagram

• Thermal Management Controllers
• Analog Devices
• National, TI
• Hitachi
• Outputs
• PWM
• Inputs
• Thermistor
• Fan Tachometer

2
Lower Cost 4 Wire PWM Voltage Controlled Fans and
Blowers

• Present 4 Wire PWM Block Diagram

3
Lower Cost 4 Wire PWM Voltage Controlled Fans and
Blowers

• Present 4 Wire PWM Schematic

Open
4
Lower Cost 4 Wire PWM Voltage Controlled Fans and
Blowers

• JMC Integrator Circuit Function takes the ratio
  of time regardless of Frequency

8 micro sec
2
20 micro sec
5 micro sec
Ratio 2/5
Ratio 8/20
1/5 micro sec 20 KHz
1/20 micro sec 50 KHz
F1/T
5
Lower Cost 4 Wire PWM Voltage Controlled Fans and
Blowers

• Proposal to Remove PWM function from both the
  Motherboard and the fan and use Voltage Control