Download the EFM32LG942F128 datasheet PDF.
This datasheet also includes the EFM32LG942F64 variant, as both parts are published together in a single manufacturer document.
Preliminary ...the world's most energy friendly microcontrollers EFM32LG942 DATASHEET
F256/F128/F64 Preliminary • ARM Cortex-M3 CPU platform • High Performance 32-bit processor @ up to 48 MHz •.