The MP1584EN datasheet says: Absolute maximum ratings section: All other pin: -0.3V to 6V max. Figure 3 shows the 1.8V typical application. On the picture, there is a voltage divider: between GND and EN: 59k and between EN and VIN 100k.
If the input voltage is high, for example 28V, between GND and EN approximately 10V appears. It's not a problem? The 10V is higher than 6V.
Electrical – MP1584 EN pin voltage
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Related Solutions
Please look at the block diagram on page 11 of the datasheet. You'll see that there are two separate sections.
- System that takes power in from Vbus and outputs to Vout and to/from the battery.
- Buck/boost taking power from Vin1 and outputting to Vout1.
In the sample schematic you copied, notice that Vout is connected to Vin1. Therefore, Vou1 is downstream from Vout and what was said about giving priority to Vout also applies to Vou1.
Alas, no. If you give it a voltage under -0.3V it will probably be toast.
So yes, you need additional protection against reverse polarity.
Best Answer
No, it is not a problem because it is a schematic in the datasheet. If you cannot trust that then IC manufacturers would have big problems.
Also, applying a "hard" 10 V, which can deliver a large current at the EN pin might indeed damage the device (I doubt that though). But in this schematic this 10 V is "soft" it cannot deliver much current. So if something on the EN pin would start to conduct, only a small current can flow and nothing will be damaged.
You can check this, build the circuit and apply a Vin which will result in 10 V at the EN input. Now measure that voltage. If it is 10 V then the EN pin can withstand more than 6 V. If the voltage is much below 6 V then the high value of R5 saves the day.
If you're worried, you can adjust the values of R5 and R6 to get a maximum of 6 V on the EN pin. Then watch that EN will be high enough at the lowest Vin.