I am once again foraying into microcontroller design and I want to integrate an MX1508 for medium-power motor control. I have found two schematics and they are identical aside from one thing. Schematic 1: [image] Schematic 2: [image] This schematics are basically identical except that the firs…

[image] anon77129126: The second one does not. It has the same nets though. In the first they call it 5V which suggests they assume that Vcc is fed with 5V and not the more generic 2~10V indicated elsewhere. In that sense it's overspecified, the second isn't. [image] anon77129126: What i…

[image] anon35827816: It has the same nets though. In the first they call it 5V which suggests they assume that Vcc is fed with 5V and not the more generic 2~10V indicated elsewhere. In that sense it's overspecified, the second isn't. So if I were to make this circuit on a board with a microc…

[image] anon77129126: So if I were to make this circuit on a board with a microcontroller would I supply 5V or leave it be? You should not connect that part to the 5V microcontroller supply. [image] anon77129126: A stupid way to do it though. If you say so... [image] anon77129126: …

[image] anon35827816: [image] anon77129126: What is the purpose of the diode? Protect the device from (momentary) polarity inversion of the power supply. Not at all. It's a Zener used as a shunt regulator - which is why the resistor is there! :roll_eyes:

The 5volt supply is there if you use a 3.3volt processor, and don't have a 5volt supply available. You can omit that resistor and zener if you have/connect 5volt from the Arduino. Leo..

Sorry, you're right, it's a zener. I somehow missed that.

MX1508 schematic

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Paul_B April 4, 2022, 10:56pm 5

Not at all. It's a Zener used as a shunt regulator - which is why the resistor is there!

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MX1508 schematic

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