Current-mode multiplexed-output DC-DC switch power supply of secondary current sampling

Abstract

The invention discloses a current-mode multiplexed-output DC-DC (direct current) switch power supply of secondary current sampling, belonging to the technical field of electron. The secondary side of the main transformer T1 of the switch power supply at least comprises two paths of output circuits; while the output voltage of one path of output circuit is sampled, a coupling transformer T2 is connected in series between the rectification and follow current circuit of the output circuit and the secondary winding of the main transformer T1 connected with the output circuit; on the secondary level of the coupling transformer T2, a current sampling circuit is adopted to sample coupling current. The voltage sampling circuit and the current sampling circuit of the invention sample voltage and current by aiming at same path of output circuit, and thus the obtained current sampling signal can not be affected by other paths of output current or the primary exciting current of the transformer T1, and the invention can accurately sample exciting current output by the same output circuit; meanwhile, the coupling transformer T2 also ensures that the primary level and the secondary level of the power supply are mutually isolated.

Description

technical field [0001] The invention belongs to the field of electronic technology, and relates to a current type DC / DC switching power supply, in particular to a current sampling current type multiple output DC-DC switching power supply. Background technique [0002] Switching power supplies get their name from the fact that the transistors work in alternate on and off states, acting like a switch for an instrument. The signal to control the switching of the transistor is usually a pulse width modulated signal (PWM). The DC-DC switching power supply transmits the energy of the primary input power supply to the secondary side of the transformer according to the ratio of the time when the switch tube is turned on and off, and then obtains a flat DC voltage output through the rectifier freewheeling circuit and the output filter circuit, while the PWM signal The duty cycle directly controls the time ratio of the switch tube being turned on and off. [0003] The PWM signal is ...

AI Technical Summary

Problems solved by technology

[0008] In order to overcome the problem of inaccurate primary current sampling, the present invention provides a current-type multiple-output DC-DC switching power supply for secondary current sampling, which can perform accurate current sampling and avoid the impact of transformer primary excitation current and other output currents. Influence of Main Circuit Current Sampling

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