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CDCE937 Questions

Other Parts Discussed in Thread: CDCE937


Please answer following questions about CDCE937.

Q1: Data Retention of EEPROM

Data-sheet specify Data Retention is 10 years minimum.

Customer needs Data Retention time more than 10 years.

Please advice Data Retention Acceleration Tests conditions of CDCE937 EEPROM.

(xx-hour baking, baking temperature and Activation Energy to calculate acceleration factor)

If customer know above datas they can calculate data retention time for their use case.

MSP430 App note (SLAA392 Understanding MSP430 Flash Data Retention) page 4

has "2.3.1   Accelerated Tests " and we want same kinds of information.

Q2: EEPROM Write verification

Please advice if EEPROM write cycle include data verify after write the resistor data to EEPROM.



  • Hello,

    I have additional question form my customer.



    Customer programed SPICON bit = 1( control pins S1 (pin 19) and S2 (pin 18)) of address 02h register to use S1 and S2 as control pins.

    They connect Vddout to GND to use pin 19 and pin18 as I2C and reprogram EEPROM, but their CPU can not communicate with CDCE937.

    Their board has 4.7k ohm pull-up for SCL/SDA line.

    Please advice if additional measures are required other than connecting Vddout to GND.



  • Ushikubo-san,

    please have a look at this post:

    Note, that the I2C address change in the case VDD_OUT =GND and SPICON=1. I2C address bits: A1=A0=0

    best regards,


  • Hello Julian-san,

    Customer has additinal questions.

    Please answer following questions.



    After Vdd and Vddout voltage reached nominal voltage, how long dies it take to I2C bus is ready for accept host access.



    Customer use S1/SDA and S2/SCL as  control pins(S1 and S2), so they set the SPICON=1 and wrote to EEPRON and try to read EEPIP status bit.

    But CDCE937 returns the NACK and can not read EEPIP status.  

    (I think the reason is S1/SDA and S2/SCL pins changed to control pins(S1 and S2) when register values have written to EEPROM.)

         A) Please advice how long does it take to finish EEPROM write.

              They can not read EEPIP status so they need the time to write EEPROM.

         B) How long does it take to SDA,SCL pins change to S1,S2 function after EEPROM write is done ?



  • Hello Julian-san and forum member,

    Please respond to my above questions.


  • Hello Julian-san,

    Please send any answer to my questions.


  • Hello Ushikubo-san.


    you can program the device directly after the supplies are stable. however i would recommend to wait 0.1us before starting the programming.


    After you set SPICON=1 the I2C interface is turned of, because the SDA and SCL became the control pins S1 and S2. You can not read back afterwards.

    A: if you GND VDDOUT the I2C interface is still available through the control pins, even if SPICON=1. In this case the slave address is set to A0/A1=0. EEPROM write time is about 50us. if you wait 100us you can be sure that everything is written correctly.

    B: Directly after EEPROM write is complete.

    best regards,