© 2000 Scenix Semiconductor, Inc. All rights reserved. - 16 - www.scenix.com SX48BD/SX52BD/SX52BD75/SX52BD100 4.5 FUSE WORD (READ/PROGRAM VIA PROGRAMMING COMMAND) Unused SYNC Unused  Unused  IRC  DIV1/IFBD  DIV0/FOSC2  XTLBUF_EN   CP WDTE FOSC1 FOSC0 11 10 9 8 7 6 5 4 3 2 1 0 SYNC Synchronous input enable (this bit synchronizes the signal presented at the input pins to the internal clock through two internal flip-flops). Required to be enabled unless the transition on the input pin is not close to the clock edge. If enabled, port data must be read more than 2 cycles after a change to the input level mode or Schmitt Trigger mode (see Figure 3-2). SYNC is always enabled on RTCC. 0 = enabled 1 = disabled IRC Internal RC oscillator enable 0 = enabled - OSC1 is pulled low by weak pulldown, OSC2 is pulled high by weak pullup 1 = disabled - OSC1 and OSC2 behave according to FOSC2:FOSC0 DIV1:DIV0 Internal RC oscillator divider (if IRC = 0) 00b = 4 MHz 01b = 1 MHz 10b = 128 KHz 11b = 32 KHz IFBD Internal crystal/resonator oscillator feedback resistor (10MW) 0 = Internal feedback resistor disable (external feedback required for crystal/resonator oscillator) 1 = Internal feedback resistor enabled (valid only when IRC = 1, disabled when IRC = 0) XTLBUF_EN Crystal Buffer enable (disable when not using a crystal to reduce Idd) 0 = Crystal Buffer disabled (required if not using crystal/resonator oscillator) 1 = Crystal Buffer enabled CP Code protect enable 0 = enabled (FUSE, code, and ID memories read back as scrambled data, programming dis- abled) 1 = disabled (FUSE, code, and ID memories can be read normally) WDTE Watchdog timer enable 0 = disabled 1 = enabled FOSC2:FOSC0   External oscillator configuration (valid when IRC = 1, lower settings are recommended for lower power consumption): 000b = LP1 – low power crystal (32KHz) 001b = LP2 – low power crystal/resonator (32KHz - 1MHz) 010b = XT1 – normal crystal/resonator (32KHz - 1MHz) 011b = XT2 – normal crystal/resonator (1MHz - 8MHz) 100b = HS1 – high speed crystal/resonator (1MHz - 20MHz) 101b = HS2 – high speed crystal/resonator (1MHz - 50MHz) 110b = HS3 – high speed crystal/resonator (1MHz - 100MHz) 111b = External RC network - OSC2 is pulled high by a weak pullup (no CLKOUT output)