M3850 RENESAS [Renesas Technology Corp], M3850 Datasheet - Page 86

• Manufacturer Part Number: M3850
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
• Manufacturer: RENESAS [Renesas Technology Corp]

Rev.2.10
REJ03B0093-0210
3850 Group (Spec.A)
Notes on restarting oscillation
• Restarting oscillation
Usually, when the MCU stops the clock oscillation by STP instruc-
tion and the STP instruction has been released by an external
interrupt source, the fixed values of Timer 1 and Prescaler 12
(Timer 1 = “01
loaded in order for the oscillation to stabilize. The user can inhibit
the automatic setting by writing “1” to bit 0 of MISRG (address
0038
However, by setting this bit to “1”, the previous values, set just be-
fore the STP instruction was executed, will remain in Timer 1 and
Prescaler 12. Therefore, you will need to set an appropriate value
to each register, in accordance with the oscillation stabilizing time,
before executing the STP instruction.
<Reason>
Oscillation will restart when an external interrupt is received. How-
ever, internal clock
starts to underflow. This ensures time for the clock oscillation us-
ing the ceramic resonators to be stabilized.
Flash Memory Version
Connect the CNV
tern which is supplied to the Vss pin of the microcomputer. In
addition connecting an approximately 1 k to 5 k
to the GND could improve noise immunity. In this case as well as
the above mention, connect the pin the shortest possible to the
GND pattern which is supplied to the Vss pin of the microcom-
puter.
The CNV
flash memory. When programming in the flash memory, the im-
pedance of the V
writing to flow into the built-in flash memory. Because of this, noise
can enter easily. If noise enters the V
codes or data are read from the flash memory, which may cause a
program runaway.
Fig. 7 Wiring for the CNV
Reason
16
).
SS
/V
2005.11.14
N o t e . S h o w s t h e m i c r o c o m p u t e r ' s p i n .
PP
16
pin is the power source input pin for the built-in
”, Prescaler 12 = “FF
SS
PP
CNV
/V
pin is low to allow the electric current for
PP
is supplied to the CPU only when Timer 1
SS
pin the shortest possible to the GND pat-
SS
/(V
page 86 of 86
V
/V
PP
SS
PP
)
pin
( N o t e )
( N o t e )
PP
16
pin, abnormal instruction
”) are automatically re-
T h e s h o r t e s t
The shortest
Approx. 5k
resistor in series
Handling of Source Pins
In order to avoid a latch-up occurrence, connect a capacitor suit-
able for high frequencies as bypass capacitor between power
source pin (V
source pin (V
pin). Besides, connect the capacitor to as close as possible. For
bypass capacitor which should not be located too far from the pins
to be connected, a ceramic capacitor of 0.01 F–0.1 F is recom-
mended.
Differences among 3850 group (standard),
3850 group (spec. H), and 3850 group (spec. A)
(1) The absolute maximum ratings of 3850 group (spec. H/A) is
(2) The oscillation circuit constants of X
(3) Do not write any data to the reserved area and the reserved
(4) Fix bit 3 of the CPU mode register to “1”.
(5) Be sure to perform the termination of unused pins.
smaller than that of 3850 group (standard).
• Power source voltage Vcc = 0.3 to 6.5 V
• CNVss input voltage V
be some differences between 3850 group (standard) and 3850
group (spec. H).
bit. (Do not change the contents after reset.)
CC
CC
pin) and GND pin (V
pin) and analog power source input pin (AV
I
= –0.3 to Vcc +0.3 V
PRELIMINARY
Notice: This is not a final specification.
Some parametric limits are subject to change.
SS
IN
pin) and between power
-X
OUT
, X
CIN
-X
COUT
may
SS