[en] The present work introduces an improved SPICE equivalent electrical model of silicon photomultiplier (SiPM) detectors, in order to simulate and predict their transient response to avalanche triggering events. In particular, the developed circuit model provides a careful investigation of the magnitude and timing of the read-out signals and can therefore be exploited to perform reliable circuit-level simulations. The adopted modeling approach is strictly related to the physics of each basic microcell constituting the SiPM device, and allows the avalanche timing as well as the photodiode current and voltage to be accurately simulated. Predictive capabilities of the proposed model are demonstrated by means of experimental measurements on a real SiPM detector. Simulated and measured pulses are found to be in good agreement with the expected results. -- Highlights: • An improved SPICE electrical model of silicon photomultipliers is proposed. • The developed model provides a truthful representation of the physics of the device. • An accurate charge collection as a function of the overvoltage is achieved. • The adopted electrical model allows reliable circuit-level simulations to be performed. • Predictive capabilities of the adopted model are experimentally demonstrated