The DS1842A integrates the discrete high-voltage components necessary for avalanche photodiode (APD) bias and monitor applications. A switch FET and precision voltage-divider network are used in conjunction with an external DC-DC controller to create a boost DC-DC converter. A current clamp limits current through the APD and also features an external shutdown. The precision voltage-divider network is provided for precise control of the APD bias voltage. The device also includes a dual current mirror to monitor the APD current.