Delay Circuit for Project (Help Needed)

[tewills]

I am designing a fan control circuit using a microchip TC670. This ciruict will reside in a 1U chassis for 8 fans. I have (1) ALM LED on the front panel. If a fan dies, the LED will light. The problem with the 670 is, it faults immediately until RESET. Since it takes a while to power up the motherboard, the chip senses fan failure immediately then faults. I need to delay the funciton of the chip for at few seconds to allow the computer to competely power up.

 

[bmcculla]

There are IC for just this purpose. They are called "Supervisors". They hold a device in reset until the power supply stabilizes. Digikey has a bunch of them to choose from.

Brent

 

[tewills]

Digikey Search

Thanks for the input, have you ever gone to Digikey and tried to find something using their filters? You have to be an engineer juct to nagitave their site. Might you suggest a Supervisor chip..TIA