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MSP430F663x : 5V Tolerant IOs ?

Prodigy 120 points

Replies: 4

Views: 3992

I did not found any information about ...

Has the this uController 5V tolerant IOs?

This would simplify my design

 

Thank you in advance

 

4 Replies

  • Hi,

    After reading the absolute maximum ratings (datasheet SLAS566B):

    VCC = -0.3 to 4.1 V
    Voltage applied to any pin (excluding VCORE, VBUS, V18) = –0.3 V to VCC + 0.3 V

    No 5 V tolerant inputs :-(.

    Best regards,
    Edwin Krasser

  • Hi tech,

    if you really need 5v tolerant I/Os, take a look at the MSP430F51x2 devices, for example the MSP430F5172.

    -Leo-

    Regards,

    Leo Hendrawan

  • In reply to Edwin Krasser:

    Thank you very much both !!

  • In reply to Edwin Krasser:

    5V tolerant inputs can be achieved with a series resistor. to the input pin.

    The reason for the input voltage limit is the existence of protection (clamp) diodes from the portpin to VCC and GND. These diodes can sink/source up to 2mA rated current, whcih results in 0.3V drop (hence teh VCC+0.3V).

    If oyu just need a high-voltage-tolerant input, you can just use a series resistor where on 2mA inrush current (or less) the excess voltage drops.

    For example, if VCC is 3V, the resistor mus tbe large enough that the excess 2V are dropping on it on less than 2mA. So anything >1k would be fine. Preferrable more than that.
    Of course it increases the overall current consumption a bit, but not as much as it migh seem at first. because this current flows to VCC, effectively bypassing the VCC regulator and contributing to the MSPs own supply, so less current flows through the regulator. (you can supply the MSP through a port pin this way, as long as the outputs don't need to drive any current)

    With 4,7k series resistors you're on the safe side.

    5V compatible outputs (not just standard TTL compatible) are a different thing. Here a zener diode in series and a pullup resistor to 5V can be used - which will waste some power if you have to drive significant loads high.

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