50 MHz 8051 with a wide supply — the PSoC 3 mixed-signal workhorse
The Cypress CY8C3246LTI-128 is an 8-bit 8051-core MCU from the PSoC 3 family, clocked at 50 MHz. What sets this part apart from a plain 8051 is the programmable analog and digital fabric around the core — 16 channels of 12-bit ADC, an 8-bit DAC, CapSense touch-sensing, LCD drive, and USB connectivity are all on-chip. The supply range from 1.71V to 5.5V means it can run directly from a 2-cell alkaline stack, a single Li-ion cell, or a legacy 5V industrial rail without a regulator in between. Program memory is 64 KB Flash, with 8K x 8 RAM and 2K x 8 EEPROM for non-volatile parameter storage.
68-QFN package and industrial temperature range
The part comes in a 68-VFQFN with exposed pad (68-QFN 8x8 mm), surface-mount only. The internal oscillator is trimmed to 1% accuracy, enough for UART and most non-critical timing — an external crystal is still advisable for USB or CAN.
CapSense and USB — the application drivers
The CapSense peripheral is Cypress's capacitive touch-sensing engine, capable of driving buttons, sliders, and proximity sensors without external capacitive-sense ICs. The LCD drive can directly segment a glass or plastic LCD panel, saving a display driver. USB connectivity (full-speed, device/host/OTG) is handled by the on-chip USB block with an integrated transceiver — no external PHY needed. These three features together make the CY8C3246LTI-128 a natural fit for human-machine interface (HMI) panels, appliance control boards, medical front-panel controllers, and portable instrumentation where a touch interface and USB data logging are required.