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Note To Be Added to Technical Datasheets about the PMD Circuit

Product name
TOSHIBA Microcontrollers 870 Family

  •  
    • MP88CH47
    • TMP88PH47
    • TMP88CK48
    • TMP88CM48
    • TMP88CS48A
    • TMP88CK49
    • TMP88CM49
    • TMP88PS49


Dear Customer

Thank you for your continued patronage of Toshiba semiconductor products.
With regard to the TLCS-870/X Series microcontrollers listed above, Toshiba would like to inform you of the note to be added to the technical datasheets about the overload protection function of the programmable motor drive (PMD) circuit. Please carefully read the following and check to see if your use of the PMD overload protection function is affected by this issue.


Note to be added to the technical datasheets

When using the overload protection function of the PMD circuit, make sure that no low-level input shorter than 6 clocks is made on the overload protection input pin. If a low-level input shorter than 6 clocks is made, the sampling counter of the overload protection circuit may count up erroneously, causing an abnormal current limiting state which cannot be released normally.


Explanation
The overload protection function activates a current limiting state when a low-level input longer than the specified sampling count is made on the overload protection input pin. When the input pin becomes high again, the sampling counter will be cleared and the current limiting state can then be released.

However, if a low-level input shorter than 6 clocks is made and the sampling counter counts up erroneously, the sampling counter may not be cleared even if the pin input level becomes high again. If this count-up operation occurs successively the number of specified times, an abnormal current limiting state will be entered.

This abnormal current limiting state cannot be released by normal processing even if the overload protection input becomes high again. An exception is when a low-level input lasting 6 clocks or longer is made on the overload protection input pin after an abnormal current limiting state has been entered. This will cause the abnormal current limiting state to change to a normal current limiting state which can be released by normal processing.


How to release an abnormal current limiting state

An abnormal current limiting state can be released by turning off the power and then turning on the power again or by a reset.
It is also possible to release an abnormal current limiting state by the following procedure.

  1. If an abnormal current limiting state occurs, set the multiple-function ports which are also used for overload protection input (P07, P37) as port outputs, set each output latch to 0 and then set each output latch to 1.
  2. Set ports P07 and P37 as inputs
  3. The abnormal current limiting state can now be released by normal release processing.

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·Before creating and producing designs and using, customers must also refer to and comply with the latest versions of all relevant TOSHIBA information and the instructions for the application that Product will be used with or for.