Features
• Compatible with MCS®-51 Products
• 12K Bytes of In-System Programmable (ISP) Flash Program Memory
– SPI Serial Interface for Program Downloading
– Endurance: 10,000 Write/Erase Cycles
• 2K Bytes EEPROM Data Memory
– Endurance: 100,000 Write/Erase Cycles
• 64-byte User Signature Array
• 2.7V to 5.5V Operating Range
• Fully Static Operation: 0 Hz to 24 MHz (in x1 and x2 Modes)
• Three-level Program Memory Lock
• 256 x 8-bit Internal RAM
• 32 Programmable I/O Lines
• Three 16-bit Timer/Counters
• Nine Interrupt Sources
• Enhanced UART Serial Port with Framing Error Detection and Automatic
Address Recognition
• Enhanced SPI (Double Write/Read Buffered) Serial Interface
• Low-power Idle and Power-down Modes
• Interrupt Recovery from Power-down Mode
• Programmable Watchdog Timer
• Dual Data Pointer
• Power-off Flag
• Flexible ISP Programming (Byte and Page Modes)
– Page Mode: 64 Bytes/Page for Code Memory, 32 Bytes/Page for Data Memory
• Four-level Enhanced Interrupt Controller
• Programmable and Fuseable x2 Clock Option
• Internal Power-on Reset
• 42-pin PDIP Package Option for Reduced EMC Emission
• Green (Pb/Halide-free) Packaging Option

1. Description
The AT89S8253 is a low-power, high-performance CMOS 8-bit microcontroller with
12K bytes of In-System Programmable (ISP) Flash program memory and 2K bytes of
EEPROM data memory. The device is manufactured using Atmel’s high-density nonvolatile
memory technology and is compatible with the industry-standard MCS-51
instruction set and pinout. The on-chip downloadable Flash allows the program memory
to be reprogrammed in-system through an SPI serial interface or by a
conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU
with downloadable Flash on a monolithic chip, the Atmel AT89S8253 is a powerful
microcontroller which provides a highly-flexible and cost-effective solution to many
embedded control applications.