This series devices can resist a wide range of noise interference, such as power supply noise, RF interference, power supply fluctuations, and have passed the CS (Conductive Susceptibility) 10V dynamic testing. The integrated A/D converter provides 8 input channels and the internal LED driver can drive currents up to 100mA for LED illumination. As for external communication, the devices include SPI, I2C and UART interfaces and with their integrated 128×8 EEPROM, the devices can directly store application parameters.

With Holtek's In-Application program technology, users have a convenient means with which to directly store their measured data in Flash Program Memory as well as having the ability to update their application programs. The BS66F340C is pin-compatible with the BS66F340 and supplied in a 28-pin SSOP. The BS66F350C is pin-compatible with the BS66F350 and supplied in 44-pin and 48-pin LQFP package types. As they are fully compatible with the BS66F340 and BS66F350 respectively, direct replacement is possible without the need for a new PCB.

The devices are suitable to be a master MCU, which together with a suitable power board can implement application products. Holtek provides a development system which includes a full suite of software and hardware functions. Holtek also provides a comprehensive set of touch function firmware libraries, enabling users to get started with touch functions extremely quickly. The hardware development tool is known as the e-Link which works together with an OCDS (On Chip Debug Support) architecture MCU, which provides users with a means of rapid development and simulation.