| 摘要 |
A kelvin current sensing circuit in an integrated control circuit that controls the current flowing through the driving coils of a polyphase DC motor. The invention provides for adjusting the voltage to the lower driver transistors (23,24,25) of the control circuit by having the kelvin current sensing occur internally within the chip. A ground compatible differential amplifier circuit is used in one embodiment. Each of the lower transistors is connected to the base of respective PNP transistors, the emitters of which being connected together to control one side of the differential amplifier. A control voltage (VIN) is applied to the other side of the differential amplifier. The output of a comparator, that is connected to the differential amplifier, is used to control the operation of the lower driver transistors. Therefore all of the sensing is done internally in the semiconductor chip. The voltages are taken at the source of each of the lower transistors. This eliminates the parasitic resistances associated with the connection between the transistors and the sense resistor attached externally to the device. Since the kelvin current sensing is done internally, the pin which connected the inverting input of the comparator to the sensing resistor has been eliminated. <IMAGE> |
