![](http://datasheet.mmic.net.cn/30000/M38504M6A-XXXFP_datasheet_2360432/M38504M6A-XXXFP_56.png)
Rev.2.13
Apr 17, 2009
Page 56 of 56
REJ03B0125-0213
3850 Group (Spec.A QzROM version)
Handling of Source Pins
In order to avoid a latch-up occurrence, connect a capacitor
suitable for high frequencies as bypass capacitor between power
source pin (VCC pin) and GND pin (VSS pin) and between power
source pin (VCC pin) and analog power source input pin (AVSS
pin). Besides, connect the capacitor to as close as possible. For
bypass capacitor which should not be located too far from the
pins to be connected, a ceramic capacitor of 0.01
F–0.1 F is
recommended.
Power Source Voltage
When the power source voltage value of a microcomputer is less
than the value which is indicated as the recommended operating
conditions, the microcomputer does not operate normally and
may perform unstable operation.
In a system where the power source voltage drops slowly when
the power source voltage drops or the power supply is turned off,
reset a microcomputer when the power source voltage is less
than the recommended operating conditions and design a system
not to cause errors to the system by this unstable operation.
Electric Characteristic Differences Between Flash
Memory, Mask ROM and QzROM Version MCUs
There are differences in the manufacturing processes and the
mask pattern among flash memory, mask ROM, and QzROM
version MCUs due to the differences of the ROM type. Even
when the ROM type is the same, when the memory size is
different, the manufacturing processes and the mask pattern
differ. For these reasons, the oscillation circuit constants and the
characteristics such as a characteristic value, operation margin,
noise immunity, and noise radiation within the limits of electrical
characteristics may differ.
When manufacturing an application system, please perform
sufficient evaluations in each product. Especially, when
switching a product (example: change from the mask ROM
version to QzROM version), please perform sufficient
evaluations by the switching product in the stage before mass-
producing an application system.
Product Shipped in Blank
As for the product shipped in blank, Renesas does not perform
the writing test to user ROM area after the assembly process
though the QzROM writing test is performed enough before the
assembly process. Therefore, a writing error of approx.0.1 %
may occur. Moreover, please note the contact of cables and
foreign bodies on a socket, etc. because a writing environment
may cause some writing errors.
QzROM Version
Connect the CNVSS/VPP pin the shortest possible to the GND
pattern which is supplied to the VSS pin of the microcomputer.
In addition connecting an approximately 5 k
resistor in series to
the GND could improve noise immunity. In this case as well as
the above mention, connect the pin the shortest possible to the
GND pattern which is supplied to the V SS pin o f the
microcomputer.
Reason
The CNVSS/VPP pin is the power source input pin for the built-in
QzROM. When programming in the QzROM, the impedance of
the VPP pin is low to allow the electric current for writing to flow
into the built-in QzROM. Because of this, noise can enter easily.
If noise enters the VPP pin, abnormal instruction codes or data
are read from the QzROM, which may cause a program runaway.
Fig 55. Wiring for the CNVSS/VPP
Notes On QzROM Writing Orders
When ordering the QzROM product shipped after writing,
submit the mask file (extension: .mask) which is made by the
mask file converter MM.
Be sure to set the ROM option data* setup when making the
mask file by using the mask file converter MM.. The ROM
code protect is specified according to the ROM option data* in
the mask file which is submitted at ordering. Note that the
mask file which has nothing at the ROM option data* or has
the data other than “0016” and “FF16” can not be accepted.
Set “FF16” to the ROM code protect address in ROM data
regardless of the presence or absence of a protect. When data
other than “FF16” is set, we may ask that the ROM data be
submitted again.
* ROM option data: mask option noted in MM
DATA REQUIRED FOR QzROM WRITING ORDERS
The following are necessary when ordering a QzROM product
shipped after writing:
1. QzROM Writing Confirmation Form*
2. Mark Specification Form*
3. ROM data...........Mask file
* For the QzROM writing confirmation form and the mark
specification form, refer to the “Renesas Technology Corp.”
Homepage (http://www.renesas.com/homepage.jsp).
Note that we cannot deal with special font marking (customer's
trademark etc.) in QzROM microcomputer.
The shortest
CNVSS/VPP
VSS
Approx. 5k
The shortest
(Note)
Note. Shows the microcomputer’s pin.