How to find out Iih/Iil

Discussion in 'Embedded Systems and Microcontrollers' started by nileshkhupase, Sep 7, 2011.

  1. nileshkhupase

    Thread Starter Member

    Mar 22, 2011
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    Hi ,

    I have a controller SAF-C167CR-LM-HA it has
    Output high voltage (Voh) given as 2.4V at IOH = -1.6 mA and 0.9 (VDD)=4.5V at IOH = -0.5 mA

    it is to be interfaced with EEPROM having Vih VCC x 0.7=3.5V (min.)

    so if i consider Voh as 2.4V then it is not compatible with EEPROM (AT25320B) but if i consider Voh as 4.5V then it is compatible with EEPROM level.

    so how should i determine which Voh is applicable for my EEPROM because in its datasheet they have not mentioned current levels (Iih/Iil)

     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
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    As I can see this device can operate in the voltage range 1.8 to 5.5 volt. So you can use the same power as for the controller. What you should take note of. Is that the max SCK Clock Frequency will depend on the supply voltage. This is described in table 1-3 in the data sheet. The lower VCC the slower the device become. What is your SCK frequency from your CPU?
     
    Last edited: Sep 7, 2011
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I would be gobsmacked to see a data sheet that omitted that parameter.
     
  4. nileshkhupase

    Thread Starter Member

    Mar 22, 2011
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    Hi ,

    My CPU clock freq. is 4MHz. so SCLK must be <4MHz. still i am not getting about voltage levels.....
     
  5. t06afre

    AAC Fanatic!

    May 11, 2009
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    What do you struggle with. It is all in the data sheet. And the device are able to operate from 1.8 to 5.5 volt VCC. To save you and us some time. In your next post refer to the data sheet and specific values. Data sheets can be hard for beginners to understand. And the AT25320B data sheet from Atmel. Was not so intuitive as it should have been.
     
  6. nileshkhupase

    Thread Starter Member

    Mar 22, 2011
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    Thanks....

    Please tell me one thing that in any data sheet in the Outout High and Low voltage specifications under test conditions they specify current levels like this VOH is at this IOH ... in my case it is like...

    Voh is 2.4V at IOH = -1.6 mA
    and 4.5V at IOH = -0.5 mA

    so what does this IOH signifies here..... and while designing an interface how should one use this....
     
  7. t06afre

    AAC Fanatic!

    May 11, 2009
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    Can you post the data sheet you are using. Because I can not find the numbers you are using in the data sheet I am looking at. And refer to page, table or figure
     
  8. nileshkhupase

    Thread Starter Member

    Mar 22, 2011
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    0
    HI,

    this is the link for data sheet of controller that i am prefering....on page no.63, table-10 they have specified Output high voltage (all other outputs).

    http://pdf1.alldatasheet.com/datasheet-pdf/view/241223/INFINEON/SAF-C167CR-LM.html

    I am looking this parameter because EEPROM is connected to PORT3 of controller (SPI interface) and it is not used in open drain mode and VDD=5V.

    Thank you for your kind attention...
     
  9. t06afre

    AAC Fanatic!

    May 11, 2009
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    Are you operating the controller at 2.4 volt. To me it look like the controller is designed to work in the range 4.5 to 5 volt. But then in power down mode. Which is like a sleep mode. It can have lower supply voltage down to 2.5 volt and still retain its data
     
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