145
7641 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
PRELIMINARY
Notice: This is not a final specification.
change.
Some parametric limits are subject to
USAGE NOTES
Oscillator Connection Notice
The built-in feedback register (400
) is internally connected be-
tween pins X
IN
and X
OUT
.
Power Supply Pins Treatment Notice
Please connect 0.1
μ
F and 4.7
μ
F capacitors in parallel between
pins Vcc and Vss, and pins AVss and AVcc.
These capacitors must be connected as close as possible be-
tween the DC supply and GND pins, and also the analog supply
pin and corresponding GND pin.
Wiring patterns for these supply and GND pins must be wider than
other signal patterns.
These filter capacitors should not be placed near the LPF pins as
they will cause noise problems
Rest Pin Treatment Notice (Noise
Elimination)
If the reset input signal rises very slowly, we recommend attaching
a capacitor, such as a 1000 pF ceramic capacitor with excellent
high frequency characteristics, between the RESET pin and the
Vss pin.
Please note the following two issues for this capacitor connection.
(1) Capacitor wiring pattern must be as short as possible (within
20 mm).
(2) The user must perform an application level operation test.
LPF Pin Treatment Notice
All passive components must be located as close as possible to
the LPF pin.
0
.
1
μ
F
6
8
0
p
F
L
P
F
p
i
n
A
V
S
S
p
i
n
1
k
Fig. 124 Passive components near LPF pin
USB Transceiver Treatment (Noise
Elimination)
The USB specification ver. 1.1 requires a driver -impedance 28 to
44
.
(Refer to Clause 7.1.1.1 Full-speed (12 Mb/s) Driver Char-
acteristics in the USB specification.) In order to meet the USB
specification impedance requirements, connect a resistor (27
to 33
recommended) in series between the USB D+ pin and the
USB D- pin.
In addition, in order to reduce the ringing and control the falling/
rising timing of USB D+/D- and a crossover point, connect a ca-
pacitor between the USB D+/D- pins and the Vss pin if necessary.
The values and structure of those peripheral elements depend on
the impedance characteristics and the layout of the printed circuit
board. Accordingly, evaluate your system and observe waveforms
before actual use and decide use of elements and the values of
resistors and capacitors.
Connect a capacitor between the Ext. Cap. pin and the Vss pin.
The capacitor should have a 2.2
μ
F capacitor (Tantalum capaci-
tor) and a 0.1
μ
F capacitor (ceramic capacitor) connected in
parallel. Figure 125 for the proper positions of the peripheral
components.
X
I
N
e
n
a
b
l
e
lock
F
S
E
LS
U
S
B
C
5
enable
U
(
4
S
8
B
M
C
H
l
o
z
c
)
k
U
e
S
a
B
b
e
F
C
U
n
l
U
S
B
C
7
USB
transceiver
e
n
a
b
l
e
U
S
B
C
7
DC-DC converter
e
n
a
b
l
e
U
S
B
C
4
c
m
u
r
r
d
e
e
n
t
o
U
S
B
C
3
Ext. Cap.
2
.
2
μ
F
0
.
1
μ
F
D+
D
-
1
.
5
k
Frequency Synthesizer
N
o
t
e
1
N
o
t
e
s
1
:
2
:
I
T
n
V
e
c
r
c
e
s
=
i
s
3
t
.
3
r
s
V
,
a
c
o
u
n
e
n
s
e
d
c
e
t
p
t
o
e
n
V
d
c
c
o
.
n
h
o
v
l
t
h
e
l
a
y
o
u
t
o
f
t
h
e
p
r
i
n
t
e
d
c
i
r
c
u
i
t
b
o
a
r
d
.
Note 2
Fig.125 Peripheral circuit
In Vcc = 3.3 V operation, connect the Ext. Cap. pin directly to the
Vcc pin in order to supply power to the USB transceiver. In addi-
tion, you will need to disable the DC-DC converter in this
operation (set bit 4 of the USB control register to
“
0
”
.) If you are
using the bus powered supply in Vcc = 3.3 V operation, the DC-
DC converter must be placed outside the MCU.
Make sure the USB D+/D- lines do not cross any other wires.
Keep a large GND area to protect the USB lines. Also, make sure
you use a USB specification compliant connecter for the connec-
tion.
AVss and AVcc Pin Treatment Notice (Noise
Elimination)
An insulation connector (Ferrite Beads) must be connected be-
tween AVss and Vss pins and between AVcc and Vcc pins.