Troubleshooting

(1) Have you designed and are you using each device within the rated electrical specification range?

1. Check that the power supply voltage, I/O voltage, operation timing, and operating ambient temperature (heat dissipation) are all set appropriately.
   
   
2. Check that the power is being supplied correctly to all devices.
   Is the power supply current capacitance appropriate?
   Is the power supply polarity correct?
   If there are multiple power supply and ground pins, are they all connected?
   Does the power supply not oscillate? (Are the temperature characteristics of the capacitors used in the vicinity considered?)
   In case that the power supply is a battery, is a drop in the voltage or capacity at low temperatures taken into consideration?
   
   
3. Check that there is no noise on the power supply/ground lines.
   Make sure that the power supplies and grounds are wired appropriately and that bypass capacitors are connected correctly.
   
   
4. Check that there is no noise on the signal lines.
   Have you implemented appropriate measures such as attaching filters and designing the board layout and wiring to prevent noise?
   
   
5. Check that the load is not excessive.
   Are the total current and the total capacitance of the wiring and input pins connected to each output pin within the output specification range?
   
   
6. Check that you have executed the prescribed reset.
   
   
7. Check that the clock waveform is normal.
   
   
8. Is impedance matching established for RF & microwave semiconductor devices?
   

(2) Are any of the inputs of CMOS devices unconnected?

(3) Are there any collisions between outputs?
     (Except for open-drain or open-collector outputs.)

(4) Is an output connected directly to a power supply or ground?

(5) Is the digital design logic correct?

1. Check that the active level and the decoder and selector circuit logic is correct.
   

(6) Do the external circuits all have appropriate constants?

1. Constants for impedance matching, in particular, must be optimized in the case of RF & microwave semiconductor devices.
   

(7) Are the registers of programmable devices all set appropriately?

1. Check that an incorrect mode or prohibited state has not been set.
   

(8) Are devices with on-chip oscillators waiting for the oscillation stabilization time?

(9) Is the microcontroller program allocated to a memory area from which instructions can be fetched?

(10) Doesn't the stack overflow because of multiple interrupts of the microcontroller?

1. Check the setting of the stack pointer.
   

(11) Isn't a microcontroller interrupt held pending because it conflicts with other interrupts?

1. If the interrupt response is slow, the processing may not be performed in time, and the subsequent processing may not be performed. In this case, evaluate the priorities of the interrupts and multiple interrupts.
   

(12) Is the device damaged?
    (Because the specifications have been exceeded or the product has reached the end of life.)

1. Check that you have implemented measures to counter static electricity when handling MOS devices or boards on which MOS devices are mounted.
2. Check that an excessive voltage is not being applied to the pins.
3. Check that the mounting (soldering) conditions were observed.
4. Check that the product has not been stored under excessive storage temperature conditions.
5. Check that the product has not reached the end of life (is not degraded).

Remark :
If a device has been damaged due to internal short-circuiting, it may be difficult to identify the malfunctioning device since the power may not be applied properly.

As a result, it cannot be determined whether the shorting state will continue or whether the shorting will eventually cause an open state.

(2006/11)

It is possible that a non-prescribed voltage (including noise) has been input to a CMOS device causing latch-up.

If the device is undamaged, you should be able to restart the device using the correct input voltage by cutting off the power supply, reapplying power, and then executing a reset.
However, because latch-up accelerates degradation, we recommend that you don't mass produce systems that use this device.

(1) Does the transmission rate setting on the transmitting side match that on the receiving side?

(2) Is the transmission rate error on the transmitting side within the permissible range of the receiving side?

(3) Is there any noise in the receive data?
     Monitor the waveform at a sampling interval of several tens of nanoseconds.

Your program may include an infinite loop.

(1)	Has the output mode been set via a port mode register? A high level is not output simply by setting the port register to "1".
(2)	If the port in question is an open-drain port, has a pull-up resistor been connected? If a pull-up resistor is not connected, the output level is not driven to high.
(3)	If the port in question is also being used as an analog input port, has the analog power supply been connected? When a port used is an analog input alternate-function port, a power supply of the pin in some microcontrollers is internally connected to the analog power supply. Please check the I/O circuit diagram of your IC to see whether this is the case.

(2007/06)

(1)

Was overvoltage applied or overcurrent flowed? - If the design exceeds the DC characteristics or recommended operating conditions, degradation may be accelerated. - Even in the case of a design that is within the ratings, failure to implement noise countermeasures may cause degradation due to noise. Degradation may also occur in the case of an input that causes undershoot/overshoot.

(2)

Was static electricity applied? - Implement countermeasures against static electricity when mounting the semiconductor device on the substrate. In particular, when holding the device in your hands, the hands may contact with pins of a QFP, etc., so there is a high possibility that they can be destroyed if countermeasures against static electricity are insufficient. Reference material:  Guide to Prevent Damage for Semiconductor Devices by Electrostatic Discharge (ESD) - After mounting the device on a substrate, pack the set in conductive material, being careful not to touch the substrate and connector pins.

(2007/10)

The oscillator operation is delicate. Check for the following problems, including resonator matching and the noise environment.

-	The oscillator was mass-produced using an oscillation constant that happened to work during trials (variations in characteristics must be checked) Oscillators are analog circuits with variations in characteristics. The capacitance of the capacitor that is used also involves some error.
-	The wiring characteristics changed between prototyping and mass production (variance in length, position, capacity and other parameters of barrack wiring and printed wiring)
-	Long wiring (the capacitance becomes large and noise is easy to pickup)
-	Crossing other lines (noise is easy to pickup)
-	Large current line close by (fluctuation in ground potential)
-	Shared use of ground line with other circuits (fluctuation in ground potential)
-	Oscillation signal fetched (the capacitance becomes large and ground potential can be fluctuated) The same occurs when a probe is apposed for waveform monitoring. Moreover, the oscillation waveform being extremely weak voltage, clock waveform monitoring is not possible.
-	Flash microcontroller replaced with mask product (matching re-evaluation (capacitor capacitance) is required) Re-evaluation is not required if only the ROM size is changed.

(2007/11)