DS8  -  Series DataSheet
DS83C520  -  ROM High-Speed Microcontrollers  -  Maxim Integrated Products  -  8051

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

DESCRIPTION
The DS87C520/DS83C520 EPROM/ROM high-speed microcontrollers are fast 8051-compatible microcontrollers. They feature a redesigned processor core without wasted clock and memory cycles. As a result, the devices execute every 8051 instruction between 1.5 and 3 times faster than the original for the same crystal speed. Typical applications will see a speed improvement of 2.5 times using the same code and the same crystal. The DS87C520/DS83C520 offer a maximum crystal speed of 33MHz, resulting in apparent execution speeds of 82.5MHz (approximately 2.5X).
The DS87C520/DS83C520 are pin compatible with all three packages of the standard 8051, and include standard resources such as three timer/counters, serial port, and four 8-bit I/O ports. They feature 16kB of EPROM or mask ROM with an extra 1kB of data RAM. Both OTP and windowed packages are available.
Besides greater speed, the microcontroller includes a second full hardware serial port, seven additional interrupts, programmable Watchdog Timer, Brownout Monitor, and Power-Fail Reset. The device also provides dual data pointers (DPTRs) to speed block data memory moves. It also can adjust the speed of MOVX data memory access from two to nine machine cycles for flexibility in selecting external memory and peripherals.
A new Power Management Mode (PMM) is useful for portable applications. This feature allows software to select a lower speed clock as the main time base. While normal operation has a machine cycle rate of 4 clocks per cycle, the PMM runs the processor at 64 or 1024 clocks per cycle. For example, at 12MHz, standard operation has a machine cycle rate of 3MHz. In Power Management Mode, software can select either 187.5kHz or 11.7kHz machine cycle rate. There is a corresponding reduction in power consumption when the processor runs slower.
The EMI reduction feature allows software to select a reduced emission mode. This disables the ALE signal when it is unneeded.
The DS83C520 is a factory mask ROM version of the DS87C520 designed for high-volume, costsensitive applications. It is identical in all respects to the DS87C520, except that the 16kB of EPROM is replaced by a user-supplied application program. All references to features of the DS87C520 will apply to the DS83C520, with the exception of EPROM-specific features where noted. Please contact your local Dallas Semiconductor sales representative for ordering information.