Microchip Technology Designs (India) has designed a 28-pin, 8-bit CMOS flash µC with ADC called the PIC16F72. The device is built around Microchip's PIC architecture, and is upwards compatible with the PIC16C5X, PIC12CXXX and PIC16C7X devices. The device offers 200-ns instruction execution, and is easy to program as it has only 35 single word instructions. The chip has been implemented in 0.5 micron CMOS technology.
The PIC16F72 targets applications such as automotive body and cabin controls, battery chargers, and consumer appliances. The device features a 5-channel ADC with 2 additional timers, a capture/compare/PWM function, and a synchronous serial port that can be configured as either a 3-wire SPI or a 2-wire I2C bus. The device has 2K×14 words of program memory and 128×8 bytes of data memory on-chip, and operates in the 2- to 5.5-V range.
Special design features of the PIC16F72 include on-chip supervisory and reliability controls such as power-on-reset, a power-up timer, and an oscillator start-up timer. A brown-out reset circuit resets the device if the VDD falls below a programmable voltage for longer than a specified time.
Other key features of the PIC16F72 are selectable oscillator options, a power saving sleep mode, and in-circuit serial programming (ICSP) via two pins. Using ICSP, the µC can be serially programmed in the end-application circuit. “Inventory management becomes easier as customers can manufacture boards with unprogrammed devices, and then program the device just before shipping the product,” says Sudarshan Iyengar, director of Microchip India.
To integrate so many functions, including analog and flash, into a small die size, engineers had to protect the sensitive analog modules from the high speed signals such as the RISC CPU, which would run at up to 20 MHz. “We shielded the ADC, for example, by guard rings, so that any voltage injection by high speed circuits is not injected into the area of the A/D converter,” says Iyengar. “The next step was to shield the signals themselves, so that if there is a sensitive signal that is running a long distance on the chip, then it will be shielded on both sides by a static signal so that the influence of other metal lines is greatly reduced.”
The PIC16F72 is code and pin-out compatible with the company’s ROM-based PIC16CR72 and OTP-based PIC16C72A µCs. The flash device is available in 28-lead PDIP, SOIC, and SSOP packages, as well as the 28-lead quad flat no leads (QFN) and chip scale package (CSP). The chip is priced at US$1.97 each in 1000-unit quantities for the PDIP, SOIC, and QFN packages, and US$2.05 each for the SSOP package. The device is already shipping.
Microchip Technology Designs (India)Fax (91) 80-207-2169
www.microchip.com
