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DS87C520/DS83C520
EPROM/ROM High-Speed Microcontroller
FEATURES 
 80C52 Compatible 
8051 Pin- and Instruction-Set Compatible 
Four 8-Bit I/O Ports 
Three 16-Bit Timer/Counters 
256 Bytes Scratchpad RAM 
 Large On-Chip Memory 
16kB Program Memory 
1kB Extra On-Chip SRAM for MOVX 
 ROMSIZE Feature 
Selects Internal ROM Size from 0 to 16kB 
Allows Access to Entire External Memory Map 
Dynamically Adjustable by Software 
Useful as Boot Block for External Flash 
 High-Speed Architecture 
4 Clocks/Machine Cycle (8051 = 12) 
Runs DC to 33MHz Clock Rates 
Single-Cycle Instruction in 121ns 
Dual Data Pointer 
Optional Variable Length MOVX to Access 
Fast/Slow RAM/Peripherals 
 Power Management Mode 
Programmable Clock Source to Save Power 
CPU Runs from (crystal/64) or (crystal/1024) 
Provides Automatic Hardware and Software Exit 
 EMI Reduction Mode Disables ALE  
 Two Full-Duplex Hardware Serial Ports  
 High Integration Controller Includes: 
Power-Fail Reset 
Early-Warning Power-Fail Interrupt 
Programmable Watchdog Timer 
 13 Interrupt Sources with Six External  
 Available in 40-pin PDIP, 44-Pin PLCC, 44-Pin 
TQFP, and 40-Pin Windowed CERDIP 
 Factory Mask DS83C520 or EPROM (OTP) 
DS87C520
PIN CONFIGURATIONS 
TOP VIEW 
The High-Speed Microcontroller User’s Guide must be used in 
conjunction with this data sheet. Download it at: 
www.maxim-ic.com/microcontrollers
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device 
may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata
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