Safe start-up sequence of integrated charge pumps using dedicated control circuit

Abstract

The circuit presented eliminates forward biasing of p–n junctions during the start-up phase of an IC containing charge pumps. The result is achieved by a precharge mechanism that freezes the voltage level of the wells in the IC during the start-up phase. The design has been implemented in a TFT display driver from Philips Semiconductors; measurements show no spurious currents in the start-up phase.