80C51 3Header

TK87C751 Microcontroller, 64K ROM, TWI

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  • 8 Bit Microcontroller with 8051 architecture
  • 64Kx8 internal Flash based ROM, 128x8 RAM
  • Reprogrammable
  • Low standby current at full supply voltage
  • 0-20 MHz operation
  • Classic architecture instruction timing
  • 3 Bidirectional ports (19 bits)
  • 28 pin PLCC package
  • Built in power management
  • Two Wire Interface (TWI) (I2C™compatible)
  • 16 bit Timer/Counter with auto-reload.
  • Fixed rate Timer
  • LED compatible outputs
  • Direct replacement for Philips 87C751 / 87C751 microcontrollers
  • Implemented with the Tekmos Customer Configured Microprocessor (CCM) technology


General Description

The TK87C751 is a derivative of the 8051 microcontroller architecture. With 64Kx8 of Flash ROM, and 128x8 of scratchpad RAM, this part is a pin-for-pin replacement of the NXP 87C751 microcontroller.

The TK87C751 is intended to provide the 80C51 architecture in a small package and with a hardware Two Wire Interface (TWI). The integrated TWI interface allows the TK87C751 to operate as either a master or a slave on the TWI bus.

To achieve this, port P2, and 5 bits of port P0 were removed, along with the external bus control pins.  This allows the TK83C751 to fit within either a 24 pin, 300 mil PDIP package, or a 28 pin PLCC package.

The 8051 architecture has been modified to provide a Two-Wire Interface (TWI). Starting with the basic 80C51 design, the serial port and the two timers in the 80C51 were removed and replaced with the TWI interface and its associated timers. The external interrupt pins and the timer gate and count pins were relocated from port P3 to port P1. The interrupt controller was simplified to provide only a single set of priorities.

The ability of the design to access external program and data memory was also removed, along with the PSEN, ALE, and EA pins.

Because the TK87C751 utilizes a Flash ROM, it may be re-programmed if required. The original part was a One-Time-Programmable (OTP) part.

The TK87C751 is built utilizing the Tekmos Customer Configured Microprocessor (CCM) technology.  Refer to the CCM data sheet for details on creating other microprocessors.

I2C is a registered trademark of Philips Corporation.



The data sheet is available here: pdf TK87C751 (369 KB)


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