M38D59GCHP#U0 Renesas Electronics America, M38D59GCHP#U0 Datasheet - Page 98

• Manufacturer Part Number: M38D59GCHP#U0
• Description: IC 740/38D5 MCU QZ-ROM 80LQFP
• Manufacturer: Renesas Electronics America
• Series: 740/38000r

Specifications of M38D59GCHP#U0

• Core Processor: 740
• Core Size: 8-Bit
• Speed: 12.5MHz
• Connectivity: SIO, UART/USART
• Peripherals: LCD, LED, PWM, WDT
• Number Of I /o: 59
• Program Memory Size: 48KB (48K x 8)
• Program Memory Type: QzROM
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 85°C
• Package / Case: 80-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

38D5 Group
Rev.3.04
REJ03B0158-0304
Countermeasures against noise
(1) Shortest wiring length
1. Wiring for RESET pin
• Reason
The width of a pulse input into the RESET pin is determined by
the timing necessary conditions. If noise having a shorter pulse
width than the standard is input to the RESET pin, the reset is
released before the internal state of the microcomputer is
completely initialized. This may cause a program runaway.
Fig. 91 Wiring for the RESET pin
2. Wiring for clock input/output pins
• Reason
If noise enters clock I/O pins, clock waveforms may be
deformed.
This may cause a program failure or program runaway. Also, if a
potential difference is caused by the noise between the V
of a microcomputer and the V
clock will not be input in the microcomputer.
Make the length of wiring which is connected to the RESET
pin as short as possible. Especially, connect a capacitor across
the RESET pin and the V
wiring (within 20 mm).
• Make the length of wiring which is connected to clock I/O
• Make the length of wiring (within 20 mm) across the
• Separate the V
pins as short as possible.
grounding lead of a capacitor which is connected to an
oscillator and the V
possible.
patterns.
Reset
circuit
May 20, 2008 Page 96 of 134
V
SS
SS
pattern only for oscillation from other V
SS
Reset
circuit
pin of a microcomputer as short as
N.G.
O.K.
SS
SS
Noise
V
SS
level of an oscillator, the correct
pin with the shortest possible
RESET
V
RESET
V
SS
SS
SS
level
SS
Fig. 92 Wiring for clock I/O pins
(2) Connection of bypass capacitor across V
In order to stabilize the system operation and avoid the latch-up,
connect an approximately 0.1 µ F bypass capacitor across the V
line and the V
• Connect a bypass capacitor across the V
• Connect a bypass capacitor across the V
• Use lines with a larger diameter than other signal lines for V
• Connect the power source wiring via a bypass capacitor to the
Fig. 93 Bypass capacitor across the V
at equal length.
with the shortest possible wiring.
line and V
V
SS
line
pin and the V
line
N.G.
Noise
CC
N.G.
CC
line.
V
V
line as follows:
CC
SS
CC
X
X
V
pin.
IN
OUT
SS
SS
SS
SS
pin and the V
pin and the V
line and the V
O.K.
SS
V
V
SS
CC
O.K.
line and V
X
X
V
IN
OUT
SS
CC
CC
CC
pin
pin
CC
SS
SS