  The use of silicon photomultipliers (SiPMs) to detect light signals in highly
radioactive environments presents several challenges, particularly due to their
sensitivity on radiation, temperature, and overvoltage, requiring a proper
management of their bias supply. This article presents the design and
performance of ALDO2, an application-specific integrated circuit and power
management solution tailored for SiPM-based high-energy physics detectors. The
chip's functions include adjustable and point-of-load linear regulation of the
SiPM bias voltage (10-70 V, 50 mA), monitoring of SiPM current, shutdown,
over-current and over-temperature protection. The same functions are also
available for the low-voltage regulator (1.6-3.3 V, 800 mA), used to generate
the power supply of SiPM readout chips that often demand stable and
well-filtered input voltages while consuming currents of up to several hundred
milliamperes. The chip is intended to operate in radioactive environments
typical of particle physics experiments, where it must withstand significant
levels of radiation (total ionizing dose and 1-MeV-equivalent neutron fluence
in the range of Mrad and $\mathbf{10^{14}}\ \mathrm{\mathbf{n_{eq}/cm^2}}$,
respectively). The article provides a comprehensive description of the chip
design, as well as experimental measurements, offering insights into the chip's
performance under various conditions. Finally, radiation hardening, radiation
qualification and reliability are discussed.
