[Guide]The traditional motor drive solution is a gate-level drive chip + power MOSFET architecture. For a three-phase brushless DC motor, six external MOSFETs are required to form three bridge arms to drive each phase winding separately. Under the current development trend of smaller and smaller Electronic product modules, this solution has a major disadvantage: the size of the circuit board is too large.
If six large power MOSFETs can be removed from an inch of gold circuit board, the prospect of this advantage is self-evident.
The MP6540 series products combine the gate-level drive circuit and 6 power MOSFETs into one, which perfectly solves this shortcoming of the traditional solution.
In a small 5mm x 5mm QFN-26 package, six 50V withstand voltage, 5A output current MOSFETs and corresponding drive circuits are integrated.
Not only that, MP6540 also integrates a current detection circuit, which can perform bidirectional current detection on the low-side MOSFET of each bridge arm, which saves the cost and space of an external current detection circuit.
Others such as: short-circuit protection, over-temperature protection, under-voltage protection, these standard functions of course have it. The schematic diagram of the internal function module is as follows:
Strong heat dissipation
The picture below is a double-layer circuit board used for thermal testing with MP6540 from MPS.
The actual effective size is a square of 2.5cmx2.5cm, in which the copper thickness is 1oz and the copper area is 6.25cm2. In actual applications, the board size can be adjusted according to different heat dissipation requirements.
Under the commonly used 120˚ square wave drive control condition, the left side of the figure below is 13V input, 1.4A current output, and the temperature rise is only 8˚C; the right is 24V input, 4A current output, and the temperature rise is 41˚C.
Such excellent thermal performance enables MP6540 products to meet many applications driven by three-phase brushless DC motors.
According to specific application requirements, MP6540 has subdivided the following products: MP6540, MP6540A, MP6540H, MP6540HA. The main difference between them lies in the input voltage, output current and input logic signal. For details, please refer to the table below.
The MP6540 series products all have their own current detection function, which can provide real-time and accurate current detection to control or protect the motor.
The following figure is a schematic diagram of the internal current detection circuit of MP6540H. The output of the current detection circuit can be set by the external resistor RTERM and the reference voltage VREF.
Legend: MP6540H internal current detection circuit diagram
The measured waveform shows that the output of the current detection circuit (SOB) can perfectly follow the change of the actual current (Io). This saves the cost and space of the external current detection circuit, making the entire motor drive solution cheaper, smaller and simpler.
Legend: CH1: PWM CH2: SA, CH3: SOB CH4: Io