A design methodology for sequential logic circuits using controllable flip-flops is proposed. The flip-flop setup time and propagation delay is controlled with a process, voltage and temperature (PVT) detector using an additional setup time and delay control (SDC) input. With this SDC enable, it is possible to enhance the circuit timing performance when PVT variations are detected. The PVT detector is based in the propagation delay of digital buffers. When an increase in the propagation delay is detected in the digital logic, the SDC flip-flop input is enabled to reduce its setup time and Clk-Q propagation delay. When the PVT conditions are maintained under the selected threshold, the SDC control remains disabled, saving power. The proposed flip-flop and PVT detector are designed and characterized in a TSMC 28 nm bulk CMOS technology.