ADuC81

The ADuC816 is a complete smart transducer front-end, integrating two high-resolution sigma-delta ADCs, an 8-bit MCU, and program/data Flash/EE Memory on a single chip. This low power device accepts low-level signals directly from a transducer.

The two independent ADCs (Primary and Auxiliary) include a temperature sensor and a PGA (allowing direct measurement of
low-level signals). The ADCs with on-chip digital filtering are intended for the measurement of wide dynamic range, low frequency signals, such as those in weigh scale, strain gauge, pressure transducer, or temperature measurement applications. The ADC output data rates are programmable and the ADC output resolution will vary with the programmed gain and output rate.

The device operates from a 32 kHz crystal with an on-chip PLL generating a high-frequency clock of 12.58 MHz. This clock is, in turn, routed through a programmable clock divider from which the MCU core clock operating frequency is generated. The microcontroller core is an 8052 and therefore 8051-instructionset- compatible. The microcontroller core machine cycle consists of 12 core clock periods of the selected core operating frequency. 8 Kbytes of nonvolatile Flash/EE program memory are provided on-chip. 640 bytes of nonvolatile Flash/EE data memory and 256 bytes RAM are also integrated on-chip.

The ADuC816 also incorporates additional analog functionality with a 12-bit DAC, current sources, power supply monitor, and a bandgap reference. On-chip digital peripherals include a watchdog timer, time interval counter, three timers/counters, and three serial I/O ports (SPI, UART, and I²C-compatible).

On-chip factory firmware supports in-circuit serial download and debug modes (via UART), as well as single-pin emulation mode via the EA pin. A functional block diagram of the ADuC816 is shown above with a more detailed block diagram shown in Figure 12.

The part operates from a single 3 V or 5 V supply. When operating from 3 V supplies, the power dissipation for the part is below 10 mW. The ADuC816 is housed in a 52-lead MQFP package.