An electronic device has a power control module for causing selected functional blocks to run in a low power mode of operation, while leaving other functional blocks supplied continuously with power. A power mode control distribution network includes serially connected chains of buffers in a distribution tree for distributing power mode control signals received at a common input end to respective output ends which are connected to respective functional blocks. In the low power mode of operation the power control module causes power to be supplied continuously to output buffers at the output ends of the chains while causing power supplied to other buffers to be reduced or cut-off. The output buffers include feedback paths for causing the states of the output buffers prior to the low power mode of operation to latch during the low power mode of operation.