With a processor the best way to adjust the output voltage is via a PWM (Or a DAC if you want to get fancy).
Since a voltage into the adjustment resistor results in a linear change in current (The other side of the resistor is maintained at a constant 1.24V) in the feedback network, the output voltage changes linearly as well with a a change in duty cycle. Unlike control with a resistor which can only drive the output down to 150V, a PWM at 5V can drive the output to zero: Voltages below 1.24V result in a increase in the output where voltages above 1.24V result in a decrease. The main point to remember is that the cutoff frequency of the PWM filter must be well below the operating frequency of the switcher which can be as low as 10kHz when operating in PFM mode during light loading. This spreadsheet illustrates the circuitry and relationship between duty cycle and output voltage. http://www.tayloredge.com/storefront/SmartNixie/PSU/1363_PWMAdjust.xls jt -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/9d8738ac-b9d3-4d69-b56e-9590ec2863d8%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
