An Excellent Transient Response LDO with External Pass Device for High Current Automotive Applications

This paper presents a novel architecture of low dropout linear voltage regulators suitable for high current automotive applications. The proposed LDO can be integrated in a multi-rail power management IC (PMIC). The poor conversion efficiency of the LDO and the large current required by the load, impose an external pass device. Another important aspect for this kind of applications is the transient response during line or load variations. The proposed regulator uses an external npn bipolar device as power transistor in order to solve the on-chip power dissipation issue, and in the same time to offer a good transient performance. Therefore, only the base controller can be integrated inside the PMIC. Beside the using of the npn transistor, to further optimize the transient response, a push-pull driver is designed. The base controller is implemented in silicon (130nm BCD technology) and together with the selected external transistor represents an excellent solution for this type of applications.