DS87C520 datasheet(3/45 Pages) DALLAS

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DS87C520/DS83C520 EPROM/ROM High-Speed Microcontrollers

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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, cost-

sensitive 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.

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