跳至主要內容
Knowledgebase
Home
Renesas Electronics Taiwan - Knowledgebase

How should the CNVSS/VPP pin be handled in QzROM version?

Latest Updated:01/06/2006

Question:

(Pin)   How should the CNVSS/VPP pin be handled in QzROM version? [2006/01/06]

Answer:

Connect the CNVSS/VPP pin in the shortest and closest GND or VDD pattern to the GND or VDD supplying the VSS or VDD pin of the MCU.
In addition, connecting a resistor of approximately 5kΩ in series to the GND or VDD may improve noise tolerance. In this situation, connect the pin in the shortest and closest GND or VDD pattern to the GND or VDD supplying the VSS pin of the MCU, as above.
(Explanation)
The CNVSS/VPP pin of the QzROM version is the power source input pin for the built-in QzROM. When programming in the QzROM, the impedance of the VPP pin is kept low to allow the writing current to flow into the built-in QzROM. Because of this, noise can enter easily. If noise enters the CNVSS/VPP pin, instruction codes or data are not read correctly from the QzRoM, which may cause malfunction. (#105545)
Suitable Products
3803H
3803L
3850A
3858
7544
7545
7546
7547
7548
7549