29 April 2009
Microprocessor support
The latest addition to Lattice Semiconductor's Power Manager II range, is the ProcessorPM device
It is a programmable, single chip solution for the reset generation, watchdog timer and voltage supervision functions found in many microprocessor or dsp designs. The ProcessorPM device integrates the functions of reset generator ICs with variable pulse stretch timing, watchdog timer ICs running up to two minutes, and six supply supervisor ICs.
The device provides six programmable threshold comparators (accuracy -0.7 %) with individual glitch filters to monitor up to six supply rails without using external resistors and capacitors. The comparator outputs are connected to a 16 macrocell, ruggedised on chip programmable logic device that generates the reset and brownout signals by using simple logic equations. Four timers can be individually programmed from 32microseconds to 2seconds and used for implementing watchdog timers or for reset pulse stretching. Two digital inputs can be used for manual reset inputs or for monitoring other digital inputs such as Power Down or Disable Processor signals.
All device settings are stored using on chip nonvolatile EEPROM that is programmed via a JTAG interface. Design modifications after the board is assembled, such as changing thresholds or altering timer values, can be achieved by modifying the design in PAC Designer software and then downloading it into the design through JTAG.
Author
Chris Shaw