TTL Clock Source 16MHz, 8MHz, 4MHz, 1kHz, 1Hz

TTL Clock Source 16MHz, 8MHz, 4MHz, 1kHz, 1Hz

Sometimes it can be useful to use an external clock for a number of reasons

• You need a clock source for your circuit
• You need to sychronize clocks across multiple devices
• The device you are using has an inaccurate internal clock but can accept an external TTL clock source.

When designing one of our boards we were in the last position and needed an external TTL clock source. There are dedicated chips that will do this but they were expensive (why?). We checked on the internet for suitable circuits, but they would end up taking too much space and again become expensive. That's when we decided we could try one of Microchips latest PIC microcontrollers to generate the clock outputs we required.

The PIC12F1501 has an internal factory calibrated 16MHz clock that has an error rate of less than 1%. Not as accurate as a crystal, but accurate enough for our needs. It also has two Configurable Logic Cells (CLC's) which allow you to build some basic logic circuits without any programming code. These allowed us to generate the 16MHz and 8MHz clock outputs which would not be possible using program code. 

Features

• TTL Clock source with error rate of < 1%
• Clock Outputs of
  
  • 16MHz
  • 8MHz
  • 4MHz
  • 1kHz
  • 1Hz
• Runs at both 5V and 3.3V

Pinout