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DS64MB201 - LVCMOS Input Specification

Kawai
Guru 19785 points
Other Parts Discussed in Thread: DS64MB201, DS100MB203

Please let me ask the LVCMOS input specification for DS64MB201.

 

[Question]

Are all the LVCMOS input pins 3.3V tolerant ?

 

I am understanding that SDA/SCL is 3.3V tolerant, but if you read the Absolute Maximum Ratings and Electrical Characteristics,

there are following description. 

- Absolute Maximum Ratings, LVCMOS Input/Output Voltage = -0.5V to +4.0V

- LVCMOS / LVTTL DC SPECIFICATIONS, VIH = 2.0V(MIN) to 3.6V(MAX)

This could be also said to DS100MB203, too.

Best Regars,

Kawai

  • 0
    Mastermind 7395 points

    Hi,

    I really dont understand the question. Do you know the difference between Abs. Max Ratings and Ellectrical Recom. Operation?

  • 0 in reply to Avi Chami1
    Guru 19785 points

    Hi, Avi-san,

    Yes, I do understand Absolute Maximum Ratings and Electrical Characteristics.

    What I wanted to confirm is, whether DS64MB201 LVCMOS inputs are all 3.3V tolerant or not, because the supply voltage is VDD=2.5V.

    I can only find 3.3V tolerant description for SDA/SCL pins.

    Best Regards,

    Kawai

  • 0 in reply to Kawai
    Guru 19785 points

    We need the answer ASAP, due to customer design schedule.

    Are DS64MB201 LVCMOS inputs all 3.3V tolerant ??

    As the current  customer design uses 3.3V CMOS signal to the LVCMOS inputs, customer may need to change schematic and PCB.

     

    Best Regards,

    Kawai

  • 0 in reply to Kawai
    TI__Genius 13475 points

    Kawai-san

    The inputs are 3.3V tolerant, the device is guaranteed with Vih up to 3.6V, which means that if the 3.3V CMOS circuit is on a power supply which is 10% high, this may result in an issue, so pay careful attention to supply regulation at 3.3V to make certain that the actual voltage does not exceed 3.6V.

    Mark Sauerwald

     

  • 0 in reply to Mark Sauerwald88474
    Guru 19785 points

    Mark-san,

    Thank you for the answer.

    We appreciate for your help.

    Best Regards,
    Kawai 

  • 0 in reply to Kawai
    Guru 19785 points

    Mark-san, Support Team,

    Additionally please let me ask the LVCMOS input VIH specification.

    Can DS64MB201interface with 2.5V LVCMOS ?

    -

    This device's VCC is 2.5, so generally the device may be used with 2.5V LVCMOS interface.

    If you see the electrical specification of LVCMOS INPUT VIH is 2.0V(MIN).

    This cannot be directly connected from the 2.5V LVCMOS , because VOH(MAX) would be around 1.7x to 1.9V.

    -

    It seems that the datasheet is written in 3.3V LVCMOS specification, VIH may be a typo.

    If the device is designed to interface 2.5V LVCMOS, VIH(MIN) should be low as about 1.7V.

    Best Regards,

    Kawai

  • 0 in reply to Kawai
    TI__Genius 13475 points

    Kawai-san

    I do not have a certain answer for you yet.   The input buffer on the DS64MB201 supports three levels, there is a low level, a float level and a high level - the float level, at about Vdd/2 is used to give additional control features with a limited number of pins.   I therefore cannot tell if the 2V Vih is real, or is a conservative number.

    Depending on what is driving the input, you may be able to assure a higher Vih with a small pull-up resistor to Vdd.

    Best Regards

    Mark