General description
The P89LPC904 is a single-chip microcontroller in a low-cost 8-pin package based on a high performance processor architecture that executes instructions in two to four clocks, six times the rate of standard 80C51 devices. Many system-level functions have been incorporated into the P89LPC904 in order to reduce component count, board space, and system cost.

Features
Principal features
■ 1 kB byte-erasable Flash code memory organized into 256-byte sectors and 16-byte pages. Single-byte erasing allows any byte(s) to be used as non-volatile data storage.
■ 128-byte RAM data memory.
■ Two 16-bit counter/timers.
■ 23-bit system timer that can also be used as a Real-Time clock.
■ 2 -input multiplexed A/D converter/single DAC output. Two analog comparators with selectable reference.
■ Enhanced UART with fractional baud rate generator, break detect, framing error detection, automatic address detection and versatile interrupt capabilities.
■ High-accuracy internal RC oscillator option allows operation without external oscillator components. The RC oscillator option is selectable and fine tunable.
■ 2.4 V to 3.6 V VDD operating range with 5 V tolerant I/O pins (may be pulled up or driven to 5.5 V). Industry-standard pinout with VDD, VSS, and reset at locations 1, 8, and 4.
■ Up to six I/O pins when using internal oscillator and reset options.
■ 8-pin SO-8 package.

Additional features
■ A high performance 80C51 CPU provides instruction cycle times of 167 ns to 333 ns for all instructions except multiply and divide when executing at 12 MHz. This is six times the performance of the standard 80C51 running at the same clock frequency. A lower clock frequency for the same performance results in power savings and reduced EMI.
■ In-Application Programming (IAP-Lite) and byte erase allows code memory to be used for non-volatile data storage.
■ Serial Flash In-Circuit Programming (ICP) allows simple production coding with commercial EPROM programmers. Flash security bits prevent reading of sensitive application programs.
■ Watchdog timer with separate on-chip oscillator, requiring no external components. The Watchdog prescaler is selectable from 8 values.
■ Low voltage reset (Brownout detect) allows a graceful system shutdown when power fails. May optionally be configured as an interrupt.
■ Idle and two different Power-down reduced power modes. Improved wake-up from Power-down mode (a low interrupt input starts execution). Typical Power-down current is 1 µA (total Power-down with voltage comparators disabled).
■ Active-LOW reset. On-chip power-on reset allows operation without external reset components. A reset counter and reset glitch suppression circuitry prevent spurious and incomplete resets. A software reset function is also available.
■ Programmable port output configuration options: quasi-bidirectional, open drain, push-pull, input-only.
■ Port ‘input pattern match’ detect. Port 0 may generate an interrupt when the value of the pins match or do not match a programmable pattern.
■ LED drive capability (20 mA) on all port pins. A maximum limit is specified for the entire chip.
■ Controlled slew rate port outputs to reduce EMI. Outputs have approximately 10 ns minimum ramp times.
■ Only power and ground connections are required to operate the P89LPC904 when internal reset option is selected.
■ Four interrupt priority levels.
■ One keypad interrupt input.
■ Second data pointer.
■ External clock input.
■ Schmitt trigger port inputs.
■ Emulation support.