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3.3 V vs. PCF8814-based "Nokia 1100" LCD?

Discussion in 'Electronic Design' started by Ivan Shmakov, Jun 13, 2013.

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  1. Ivan Shmakov

    Ivan Shmakov Guest

    I've got a "Nokia 1100" LCD, which (unless I be mistaken) is
    based on PCF8814, whose digital I/O range is (1.7 .. 3.3) V.

    The question is: is there an easy and safe way to connect it to
    an otherwise 3.3 V (+/- some) circuit (as in: one interfacing an
    SD card, or having an Arduino as its core, etc.)?

    (Will a few diodes suffice, for instance?)

    Also, the pinout for the LCD (e. g., [1]) has two pins for the
    "+" rail (and one more for the backlight):

    6 VddI
    7 Vdd

    The datasheet for PCF8814, however, mentions [2, p. 44] /three/
    Vdd pads, with allowed Vdd1 voltage range being (1.7 .. 3.3) V
    (presumably meaning 3.0 V + 10% allowance), and Vdd2, Vdd3
    ranges being both (2.4 .. 4.5) V.

    Looking at the ESD structures [2, p. 66], my guess is that the
    I/O voltage is Vdd1, thus 3.0 V + 10% being the upper bound.
    But is it connected to the LCD's Vdd or VddI?

    TIA.

    [1] http://www.circuitvalley.com/2011/09/nokia-1100-lcd-interfacing-with.html
    [2] http://mylcd.sourceforge.net/files/pcf8814.pdf
     
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