Apparatus and method to provide reduced fan noise at startup

Abstract

In some embodiments, a system includes an electronic system board, a fan positioned to provide cooling for the electronic system board, wherein the fan is configured to be controlled by a pulse width modulated signal, and a fan startup circuit configured to operate the fan in accordance with a first operating condition during startup and in accordance with a second operating condition after startup. Other embodiments are disclosed and claimed.

1 . An apparatus, comprising:
 a fan configured to be controlled by a pulse width modulated signal; and   a fan startup circuit coupled to the fan and configured to operate the fan in accordance with a first operating condition during startup and in accordance with a second operating condition after startup.   
   
   
       2 . The apparatus of  claim 1 , wherein the first operating condition corresponds to a reduced fan noise during startup. 
   
   
       3 . The apparatus of  claim 2 , wherein the fan startup circuit is configured to operate the fan with a reduced fan speed during startup. 
   
   
       4 . The apparatus of  claim 3 , wherein the fan startup circuit is configured to provide a reduced operating voltage to the fan during startup. 
   
   
       5 . The apparatus of  claim 4 , wherein the fan startup circuit is configured to receive a signal indicating that the fan is ready to operate in accordance with the second operating condition. 
   
   
       6 . The apparatus of  claim 5 , wherein the second operating condition corresponds to a pulse width modulated operation by another fan control circuit. 
   
   
       7 . The apparatus of  claim 6 , wherein the fan startup circuit is configured to provide a full operating voltage to the fan in response to the signal indicating that the fan is ready to operate in accordance with the second operating condition. 
   
   
       8 . A method to reduce fan noise during startup, comprising:
 providing a fan configured to be controlled by a pulse width modulated signal;   operating the fan in accordance with a first operating condition during startup; and   operating the fan in accordance with a second operating condition after startup.   
   
   
       9 . The method of  claim 8 , wherein the first operating condition corresponds to a reduced fan noise during startup. 
   
   
       10 . The method of  claim 9 , wherein operating the fan in accordance with the first operating condition comprises:
 operating the fan with a reduced fan speed during startup.   
   
   
       11 . The method of  claim 10 , wherein operating the fan with a reduced fan speed comprises:
 providing a reduced operating voltage to the fan during startup.   
   
   
       12 . The method of  claim 11 , further comprising:
 receiving a signal indicating that the fan is ready to operate in accordance with the second operating condition.   
   
   
       13 . The method of  claim 12 , wherein operating the fan in accordance with the second operating condition comprises:
 providing pulse width modulated control signals to the fan.   
   
   
       14 . The method of  claim 13 , further comprising:
 providing a full operating voltage to the fan in response to the signal indicating that the fan is ready to operate in accordance with the second operating condition.   
   
   
       15 . A system, comprising:
 an electronic system board;   a fan positioned to provide cooling for the electronic system board, wherein the fan is configured to be controlled by pulse width modulated signal; and   a fan startup circuit configured to operate the fan in accordance with a first operating condition during startup and in accordance with a second operating condition after startup.   
   
   
       16 . The system of  claim 15 , wherein the first operating condition corresponds to a reduced fan noise during startup. 
   
   
       17 . The system of  claim 16 , wherein the fan startup circuit is configured to operate the fan with a reduced fan speed during startup. 
   
   
       18 . The system of  claim 17 , wherein the fan startup circuit is configured to provide a reduced operating voltage to the fan during startup. 
   
   
       19 . The system of  claim 18 , wherein the fan startup circuit is configured to receive a signal indicating that the fan is ready to operate in accordance with the second operating condition. 
   
   
       20 . The system of  claim 19 , wherein the second operating condition corresponds to pulse width modulated operation by another fan control circuit. 
   
   
       21 . The system of  claim 20 , wherein the fan startup circuit is configured to provide a full operating voltage to the fan in response to the signal indicating that the fan is ready to operate in accordance with the second operating condition, 
   
   
       22 . The system of  claim 21 , further comprising:
 a processor; and   a basic input/output system (BIOS), wherein the BIOS provides the signal indicating that the fan is ready to operate in accordance with the second operating condition.   
   
   
       23 . The system of  claim 21 , wherein the BIOS provides the signal indicating that the fan is ready to operate in accordance with the second operating condition after a successful completion of a power on self test (POST).