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TDF5140A 数据表(PDF) 10 Page - NXP Semiconductors |
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TDF5140A 数据表(HTML) 10 Page - NXP Semiconductors |
10 / 19 page 1999 March 15 10 Philips Semiconductors Product specification Brushless DC motor drive circuit TDF5140A Introduction (see Fig.5) Full-wave driving of a three phase motor requires three push-pull output stages. In each of the six possible states two outputs are active, one sourcing (H) and one sinking (L). The third output presents a high impedance (Z) to the motor which enables measurement of the motor back-EMF in the corresponding motor coil by the EMF comparator at each output. The commutation logic is responsible for control of the output transistors and selection of the correct EMF comparator. In Table 1 the sequence of the six possible states of the outputs has been depicted. Table 1 Output states. Note 1. H = HIGH state; L = LOW state; Z = high impedance OFF-state. The zero-crossing in the motor EMF (detected by the comparator selected by the commutation logic) is used to calculate the correct moment for the next commutation, that is, the change to the next output state. The delay is calculated (depending on the motor loading) by the adaptive commutation delay block. STATE MOT1(1) MOT2(1) MOT3(1) 1Z L H 2H L Z 3H Z L 4Z H L 5L H Z 6L Z H Because of high inductive loading the output stages contain flyback diodes. The output stages are also protected by a current limiting circuit and by thermal protection of the six output transistors. The detected zero-crossings are used to provide speed information. The information has been made available on the PG/FG output pin. This is an open collector output and provides an output signal with a frequency that is half the commutation frequency. A VCR scanner also requires a PG phase sensor. This circuit has an interface for a simple pick-up coil. A multiplexer circuit is also provided to combine the FG and PG signals in time. The system will only function when the EMF voltage from the motor is present. Therefore, a start oscillator is provided that will generate commutation pulses when no zero-crossings in the motor voltage are available. A timing function is incorporated into the device for internal timing and for timing of the reverse rotation detection. The TDF5140A also contains an uncommitted transconductance amplifier (OTA) that can be used as a control amplifier. The output is capable of directly driving an external power transistor. The TDF5140A is designed for systems with low current consumption: use of I2L logic, adaptive base drive for the output transistors (patented), possibility of using a pick-up coil without bias current. |
类似零件编号 - TDF5140A |
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类似说明 - TDF5140A |
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