S128 Datasheet, PDF (3/107 Pages) Renesas Technology Corp – Microcontroller

General Precautions
1. Precaution against Electrostatic Discharge (ESD)
A strong electrical field, when exposed to a CMOS device, can cause destruction of the gate oxide and ultimately
degrade the device operation. Steps must be taken to stop the generation of static electricity as much as possible, and
quickly dissipate it when it occurs. Environmental control must be adequate. When it is dry, a humidifier should be
used. This is recommended to avoid using insulators that can easily build up static electricity. Semiconductor devices
must be stored and transported in an anti-static container, static shielding bag or conductive material. All test and
measurement tools including work benches and floors must be grounded. The operator must also be grounded using a
wrist strap. Semiconductor devices must not be touched with bare hands. Similar precautions must be taken for
printed circuit boards with mounted semiconductor devices.
2. Processing at power-on
The state of the product is undefined at the time when power is supplied. The states of internal circuits in the LSI are
indeterminate and the states of register settings and pins are undefined at the time when power is supplied. In a
finished product where the reset signal is applied to the external reset pin, the states of pins are not guaranteed from
the time when power is supplied until the reset process is completed. In a similar way, the states of pins in a product
that is reset by an on-chip power-on reset function are not guaranteed from the time when power is supplied until the
power reaches the level at which resetting is specified.
3. Input of signal during power-off state
Do not input signals or an I/O pull-up power supply while the device is powered off. The current injection that results
from input of such a signal or I/O pull-up power supply may cause malfunction and the abnormal current that passes
in the device at this time may cause degradation of internal elements. Follow the guideline for input signal during
power-off state as described in your product documentation.
4. Handling of unused pins
Handle unused pins in accordance with the directions given under handling of unused pins in the manual. The input
pins of CMOS products are generally in the high-impedance state. In operation with an unused pin in the open-circuit
state, extra electromagnetic noise is induced in the vicinity of the LSI, an associated shoot-through current flows
internally, and malfunctions occur due to the false recognition of the pin state as an input signal become possible.
5. Clock signals
After applying a reset, only release the reset line after the operating clock signal becomes stable. When switching the
clock signal during program execution, wait until the target clock signal is stabilized. When the clock signal is
generated with an external resonator or from an external oscillator during a reset, ensure that the reset line is only
released after full stabilization of the clock signal. Additionally, when switching to a clock signal produced with an
external resonator or by an external oscillator while program execution is in progress, wait until the target clock
signal is stable.
6. Voltage application waveform at input pin
Waveform distortion due to input noise or a reflected wave may cause malfunction. If the input of the CMOS device
stays in the area between V_IL (Max.) and V_IH (Min.) due to noise, for example, the device may malfunction. Take
care to prevent chattering noise from entering the device when the input level is fixed, and also in the transition
period when the input level passes through the area between V_IL (Max.) and V_IH (Min.).
7. Prohibition of access to reserved addresses
Access to reserved addresses is prohibited. The reserved addresses are provided for possible future expansion of
functions. Do not access these addresses as the correct operation of the LSI is not guaranteed.
8. Differences between products
Before changing from one product to another, for example to a product with a different part number, confirm that the
change will not lead to problems. The characteristics of a microprocessing unit or microcontroller unit products in the
same group but having a different part number might differ in terms of internal memory capacity, layout pattern, and
other factors, which can affect the ranges of electrical characteristics, such as characteristic values, operating
margins, immunity to noise, and amount of radiated noise. When changing to a product with a different part number,
implement a system-evaluation test for the given product.