In tool evaluation, I could identify the normal operation of the interrupt vector but in Flash, the interrupt vector does
not operate normally. (It seems to me that after a reset is released, the interrupt vector does not operate at all.) (Target:
MB90590G)
Answer : In MB90F594A, MB90F594G, and MB90F591A, the reset vector is fixed at FFA000H. For this reason, in tool evaluation, the reset
vector specified with software is effective but in Flash, it is ineffective. You can use this hardware wired reset function
effectively as a function that considers FAIL-SAFE after power-off at flash write by specifying the interrupt vector and reset
vector in other banks.
The data sheet mentions that -40 ℃ to 105 ℃ are guaranteed for products other than MB90F543 and MB90F549. Are -40 ℃ to 125
℃ guaranteed for G/GS products? (Target: MB90540/ 545 series)
If GND opens when the microcomputer is operating, what happens?
Answer : When GND opens, the operation is not guaranteed. When "L" is input from I/O, the microcomputer operates as usual because
Vss keeps the GND voltage.
When noise voltage of about 100 to 150 V is applied to the power input pin for one to five ns, is it possible to guarantee
its ESD? (Target: MB90F549G)
Answer : We cannot discuss guarantee because Fujitsu does not guarantee the ESD. However, we think that several nanoseconds of noise
voltage does not cause any problem.
Answer : Murata Manufacturing (http://search.murata.co.jp/search/ic-j.html), Kyocera Co., Matsushita Electronic Components Co., and TDK Co. are now evaluating the matching. Inquire at each oscillator
manufacturer about matching. For the crystal oscillator, matching should be made by a board because extremely high accuracy
is often required due to oscillator characteristics. For this reason, we recommend that you ask the oscillator manufacturer
to collect matching characteristic data in a set with the board.
The data sheet mentions that the capacity of the smoothing capacitor of the Vcc pin must be greater than that of the capacitor
for stabilizing the voltage drop circuit. Can I use the same capacity as the capacitor for stabilizing the voltage drop circuit?
Answer : You can use the same capacity as the capacitor for stabilizing the voltage drop circuit but usually, the capacitor of the
Vcc pin requires a larger capacity for stabilization and a noise measure because it is used for the system power supply.
Can I insert an inductor (L) into the power pin for a noise measure?
Answer : We recommend that you insert a capacitor (C) between a microcomputer pin and L when inserting L into the power pin. When you
connect L directly to a microcomputer pin, the operation may become unstable because the voltage of the microcomputer itself
fluctuates.
When a reset occurs in the IC for monitoring the power supply, voltage returns. What is a possible cause?
Answer : In the microcomputer, current consumption for reset differs from current consumption for operation. In a reset time when an
internal bus clock is stopped, its current consumption for reset tends to be less than current consumption for operation.
It is necessary to design the power supply in consideration of this fact.
In a microcomputer with sub clocks, WTC:SCE is a bit indicating whether the displayed time is the sub clock stabilization
wait time. Is this bit initialized when the watchdog is reset?
Answer : In a microcomputer with sub clocks, WTC:SCE is a bit indicating whether the displayed time is the sub clock stabilization
wait time. This bit is not initialized even if the watchdog is reset. After the watchdog is released, the microcomputer starts
operation without waiting for the sub clock stabilization wait time.
The sub-block oscillator stabilization wait time is 2^15/SCLK. I want to know the relationship between this SCLK and external
sub clocks.
Answer : SCLK used by 2^15/SCLK of the sub clock oscillation stabilization wait time in a microcomputer with sub clocks indicates the
original oscillation (clock obtained by dividing 32 kHz by 4) of a unblock. For this reason, the sub clock oscillation stabilization
wait time becomes 2^15/SCLK= 4 s.
When I changed the oscillator to be used, the oscillation waveform was distorted. What is the cause? The Murata Manufacturing
Co. oscillator 47 pF built-in product was changed to the Murata Manufacturing oscillator 10 pF product.
Answer : When the capacitance gets smaller for the optimum load capacitance, the waveform tends to be distorted. Conversely, when the
capacitance gets bigger for the optimum load capacitance, the oscillation margin decreases. Consult the oscillator manufacturer
and determine the optimum load capacitance built-in product.
Some products are provided with the hardware standby function and some are not. What is the reason?
Answer : The hardware standby function is used when an application requires no processing at IG-OFF or sets HSTX to "L" to stop
the oscillation and the CPU at IG-OFF. This function is also used when urgent stop is required. Recently, many customers perform
constant processing and set standby mode with software at IG-OFF and many products are not provided with the hardware standby
function.
In internal ROM and external bus mode of MB90650A series (16-bit mode of external data bus), how are the output statuses of
the external bus control pins when the CPU is accessing internal ROM? (Target: MB90650A)
Answer : The output statuses of the external bus control pins are as follows:
Terminal name
State of terminal
AD00 to AD15
Hi-z status
A16 to 23
The last level of external ROM access is retained.
In internal ROM and external bus mode of MB90650A series (8-bit mode of external data bus), how are the output statuses of
the external bus control pins when the CPU is accessing internal ROM? (Target: MB90650A)
Answer : The output statuses of the external bus control pins are as follows:
Terminal name
State of terminal
AD00 to AD07
Hi-z status
A08 to A23
The last level of external ROM access is retained.
When the power supply (Vcc) of the microcomputer is off, can I apply voltage to N-ch open drain pins? (Target: MB90370)
Answer : Voltage (up to Vss + 5.5 V) can be applied to N-ch open drain pins (P80, P81, and P90 to P95) even if voltage is not supplied
to the Vcc of the microcomputer. For details, see the H Level Input Voltage Standard of the data sheet.
I want to know the fetch specification of mode pins (MD0, MD1, MD2). (Target: MB90650A)
Answer : Type latched at reset. Note that the mode pin fetch specification differs per type. Example: MB905xx series fetches mode
pins even if the MCU is operating. For this reason, if a mode pin input level changes due to the influence of an external
noise, the MCU may malfunction.
What is the difference between QFP and LQFP in Fujitsu specifications?
Answer : QFP and LQFP differ in height. The height of LQFP is less than or equal to 1.5 mm and the height of QFP is greater than 1.5
mm (not including errors).
How much does the oscillation start time of the crystal oscillator depend on its frequency?
Answer : The higher the frequency, the faster the oscillation start time. This is because as the frequency increases, the crystal
becomes thin and the crystal impedance decreases. As the frequency decreases, the crystal becomes thick and the crystal impedance
increases. Example: Characteristic result with large vacuum oscillator by DAISHONKU CORP. by MB90594G Condition Vcc = 5.0 V, Ta = 25 ℃ typical sample 4 MHz: 5 ms, 8 MHz: 3 ms, 16 MHz: 0.6 ms
Does the value maintained in RAM when external reset is generated in the state to which 5V power supply is steady change?
Answer : When external reset is generated in the state to which the power supply is steady, a miss-writing is not generated by the
synchronous reset making circuit. Therefore, the value of RAM is never rewritten by mistake.
I should install a 0.1µF ceramic capacitor on a FLASH product because it is the C pin. Is it not a problem if I install this
capacitor on a mask product for sharing?
Answer : For the mask product, internal logic operates on the power supply voltage, so a 0.1 µF ceramic capacitor should be installed
on the N.C pin, not the C pin for the internal power supply. It is not a problem to install the 0.1 µF capacitor on this pin.
Answer : We evaluate ESD under the following conditions: (1)Human Body model (HBM, 100 pF, 1.5 kΩ): ±2000 V JEDEC class 2 (2) Machine
Model: ±300 V JEDEC class B
Can I input an external clock to X0A and X1A sub clock pins?
Answer : You can input an external clock to the X0A and X1A sub clock pins. Input an external clock to the X0A pin and use the X1A
pin in the open status.
When I increased the power supply voltage conforming to power-on reset standards, "L" was input to the HST pin but oscillation
did not stop. Why? (Target: MB90540/ 545G)
Answer : When a power-on reset occurs, voltage step down circuit stabilization time occurs. Even if "L" is input from the HST pin
within this time, oscillation does not stop because the signal is not internally propagated.
The manual mentions that I should perform pull-down treatment for the X0A pin and use the X1A pin in open when using a microcontroller
with one system. Is it not a problem if I perform pull-up treatment for the X0A pin?
Answer : he X0A pin is an input pin. (See the circuit type in the manual and data sheet.) Be sure to use the X1A pin in the open status
because it is fixed at a high level in stop mode.
The manual mentions that the CPUF (CPU operation detection flag) and LVRF (low voltage detection flag) of the low voltage/CPU
operation detection reset control register (LVRC) are not initialized by internal reset but initialized by external reset
input. Are these flag initialized by WDT reset? (Target: MB90420/
Answer : Internal resets (such as WDT reset, software reset, power-on reset) are those other than external resets, so these flags are
not initialized by WDT reset.
A noise canceller exists in the low voltage / CPU operation detection reset block diagram written in the manual. How much
noise width can the noise canceller eliminate? (Target: MB90420/ 425G)
Answer : The YD010L1 cell (unreleased) is used as the noise canceller. YD010L1 eliminates 25-ns pulses with TYP. It can detect a noise
when the reference voltage decreases by this width or more.
Answer : In an integrated circuit (IC), many elements are integrated on a small die and they are connected by wiring. The number of
interconnects increases and high current flows to cross sections of small interconnects. Electric conduction occurs in a metal
when an electron move in substance. An moving electron collides with atoms of interconnect metal repeatedly. This collision
is repeated many times and usually biased in one direction, so atoms move a little by a little. This movement is uneven, so
a part of interconnects bores. When a part of interconnects bores, the current density of the continuous part increases to
accelerate atom movement. Finally, a disconnection occurs. This is called electronic migration. The life till a disconnection
occurs depends on the type of metal, interconnect formation method, and interconnect surface status. For aluminum interconnect,
design it so that current of 10^5 (A/cm2) or higher does not flow. The current value of the microcomputer is defined in absolute maximum rating. (From Basic Theory
of Semiconductor)
