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DLPA200: Zener Voltage Range

user6181058
Prodigy 110 points
Part Number: DLPA200

Hello,

D1 Zener diode tries to clamp VCC2 driven by DLPA200's Voffset in appropriate voltage range
BZD27C8V2P has following tolerance between 7.7 V to 8.7 V.
If the tolerance goes min, the VCC2 becomes less than 8.25V.
So, would you tell me why this circuit work ?
Our customer would like to know this reason for their mass-production design safe.

DLP012A0001_SCH.pdf Page5

Best Regards,

Koike

  • 0
    TI__Mastermind 43060 points

    Hello Koike,

    This voltage is used by what is called the Block Step Address (BSA) which steps the CMOS memory up to the V_OFFSET voltage prior to the Reset waveform.  This Zener is to protect the CMOS memory cells which can be damaged by an overvoltage on VCC2.  

    If they are concerned they can employ a Zener with a tighter tolerance around 8.5 V.

    Fizix

  • 0 in reply to Fizix
    Prodigy 110 points

    Hello, Fizix,

    My customer have developed their board using BZD27C8V2P by reffering the EVM schematics.

    Would you please tell me whether the circuit work normally or not ?

    If no problems, my customer need not to change their circuit.

    Best Regards,

    Koike

  • 0 in reply to user6181058
    TI__Mastermind 43060 points

    Hello again Koike,

    We have not had a complaint about this creating an issue on the EVMs and numerous designs made by customers from our reference schematic.

    Fizix