The C8051T62x, C8051T32x, and C8051F34A have a power-saving mode called Suspend Mode, which is a function of the internal 48 MHz oscillator and is entered by setting the SUSPEND bit in the OSCICN register to “1”. When placed into suspend mode, the 48 MHz oscillator reverts to a very low-power state where it is no longer oscillating but can wake quickly and begin clocking the device again on certain events. The C8051T62x and C8051T32x devices are able to wake-up from multiple sources, while the C8051F34A will only wake on a non-idle USB event or VBUS interrupt. On the ‘T62x and ‘T32x devices, one of the new wake-up events is the port match feature, which allows the device to wake on specified logic states of Port 0 and Port 1 pins. If Timer 3 is running from an external oscillator source or the internal low-frequency oscillator, a Timer 3 overflow can wake the device from suspend mode.

