The　current　portable　ECG　acquisition　system　needs　analog　to　digital　conversion　module,　which　has　low　power　consumption　and　high　resolution.　Although　the　analog　to　information　converter　(AIC)　based　on　pulse　width　modulation　can　effectively　reduce　the　sampling　rate　of　the　system,　the　quantization　part　of　the　conversion　clock　is　proportional　to　the　quantization　accuracy.　Therefore,　there　is　a　problem　of　high　power　consumption.　In　this　study,　a　precision　adjustable　time　to　digital　conversion　(TDC)　module　based　on　the　power　entropy　is　proposed,　which　is　based　on　the　energy　imbalance　of　ECG　signal.　The　energy　maximization　is　taken　as　the　basic　principle　of　design.　The　minimum　quantization　accuracy　of　system　observation　vector　is　determined　by　analyzing　the　power　spectrum　entropy　of　ECG　signal.　In　this　way,　the　optimal　design　of　AIC　time　coding　system　is　achieved.　Experimental　results　show　that　this　method　can　reduce　80%　TDC　clock　dynamic　reversal　while　sampling　ECG　signals　under　the　conditions　of　compression　ratio　of　4,　SNR　of　38.91　dB　and　reconstruction　accuracy　of　0.36%.　Therefore,　the　power　consumption　can　be　reduced　effectively.　©　2021,　Science　Press.　All　right　reserved.