20-668-0011 Rabbit Semiconductor, 20-668-0011 Datasheet - Page 196

• Manufacturer Part Number: 20-668-0011
• Description: IC MPU RABIT3000A 55.5MHZ128LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0011

• Processor Type: Rabbit 3000 8-Bit
• Speed: 55.5MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 55.5 MHz
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 55 C
• Number Of Programmable I/os: 56
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 316-1061

The spreading function is implemented by dividing each 1024-clock cycle into four quad-
rants of 256 clocks each. Within each quadrant, the Pulse-Width Modulator uses the eight
MSBs of each pulse-width register to select the base width in each of the quadrants. This
is the equivalent to dividing the contents of the pulse-width register by four and using this
value in each quadrant. To get the exact high time, the Pulse-Width Modulator uses the
two LSBs of the pulse-width register to modify the high time in each quadrant according
to the table below. The “n/4” term is the base count, formed from the eight MSBs of the
pulse-width register.
The diagram below shows a PWM output for several different width values, for both
modes of operation. Operation in the spread mode reduces the filtering requirements on
the PWM output in most cases.
186
Pulse-Width LSBs
00
01
10
11
n/4 + 1
n/4 + 1
n/4 + 1
n/4 + 1
1st
n/4
n/4
n/4 + 1
n/4 + 1
2nd
Rabbit 3000 Microprocessor User’s Manual
n/4
n/4 + 1
n/4 + 1
n/4 + 1
3rd
n/4
n/4
n/4
n/4 + 1
4th