SCSI2SD Schematic Notes

Details for the circuit design of [SCSI2SD].

Crystal Oscillator

• LCP1751 requires a 25MHz crystal, which results in a 100MHz clock with x4 PLL
• The crystal requires 2 caps for stability. The required value is:

2 * (CL - CS)

Where CL is the crystal's load capacitance, as specified by the crystal manufacturer, and CS is the PCB's stray capacitance (around 5pF for a reasonable PCB).

3.3V Regulator

LM1117-3.3 Notes on cap values Notes on required current Notes on switching frequency

In-circuit programming

UART0 pins, + active low program enable power supply while programming ? Custom header ? Custom bootloader as well ?

Switches

TERMPWR, terminator, parity, SCSI ID