초록 ▼

A current regulating circuit for an inductive load (12) is proposed, in particular for an electrohydraulic pressure regulator for an automatic transmission of a motor vehicle. A push-pull end stage (16) controls the flow of current through the load (12). Connected in series with the load (12) is a m

A current regulating circuit for an inductive load (12) is proposed, in particular for an electrohydraulic pressure regulator for an automatic transmission of a motor vehicle. A push-pull end stage (16) controls the flow of current through the load (12). Connected in series with the load (12) is a measuring resistor (11), the voltage drop of which, as an actual current value, is applied along with a command current value to a comparison stage (23, 34), by the clocked output signal of which the end stage (16) can be controlled. The measuring resistor (11) is disposed between the load (12) and a first switch transistor (10) of the end stage (16). The potential at one of the pickups (19, 20) of the measuring resistor (11) is provided as a variable reference potential for an auxiliary voltage source (31) supplying the comparison stage (23, 34), which source has switch means (40) for generating an auxiliary voltage (Uh) that is constant relative to the variable reference potential. By means of this integratable and hence economical arrangement, only a few external components and no external calibration are necessary. Nevertheless, high precision is assured, over a wide temperature range that depends essentially on the precision of the measuring resistor (11) and on the precision of the analog command value present via the resistor (30).

대표청구항 ▼

A circuit for precisely regulating current through an inductive load, having means (25) for inputting a variable-duty-cycle clock signal representing a command value for said current through said load, means (11, 19, 20) for measuring an actual value of current through said load (12), a comparison s

A circuit for precisely regulating current through an inductive load, having means (25) for inputting a variable-duty-cycle clock signal representing a command value for said current through said load, means (11, 19, 20) for measuring an actual value of current through said load (12), a comparison stage (23, 34), having a pair of inputs respectively receiving said command value and said actual value, and generating an output control signal representative of deviation between said command value and said actual value, and a push-pull end stage (16) responding to said deviation signal and controlling the flow of current through the load (12) by means of first (10) and second (15) switching transistors, wherein, said means for measuring comprises a measuring resistor (11) connected in series with between said load and ground, a first voltage pickup (19) on a load-adjacent side of said resistor (11), and a second voltage pickup (20) on a ground-adjacent side of said resistor (11), said second voltage pickup furnishes a variable reference potential, said first voltage pickup (19) is connected to one of said inputs of said comparison stage (23, 34), thereby furnishing an actual current value, and said circuit further comprising an auxiliary voltage source (31), having an input connected to said second voltage pickup (20), and an output connected to said comparator stage (23, 34), thereby furnishing said stage with an auxiliary voltage (Uh) which tracks said variable reference potential.