NEC mPD780344 Series User Manual page 462

8-bit single-chip microcontrollers
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Subsystem clock oscillator characteristics (T
Resonator
Recommended Circuit
Crystal
XT2
XT1
resonator
R
C4
External
clock
XT2
Notes 1. Indicates only oscillator characteristics.
2. Time required to stabilize oscillation after reset or STOP mode release.
Cautions 1. When using the subsystem clock oscillator, wire as follows in the area enclosed by the broken
lines in the above figures to avoid an adverse effect from wiring capacitance.
• Keep the wiring length as short as possible.
• Do not cross the wiring with the other signal lines.
• Do not route the wiring near a line through which a high fluctuating current flows.
• Always make the ground point of the oscillator capacitor the same potential as V
• Do not ground the capacitor to a ground pattern through which a high current flows.
• Do not fetch signals from the oscillator.
2. The subsystem clock oscillator is designed as a low-amplitude circuit for reducing current
consumption, and is more prone to malfunction due to noise than the main system clock
oscillator. Particular care is therefore required with the wiring method when the subsystem
clock is used.
Remark For the resonator selection and oscillator constant, customers are requested to either evaluate the
oscillation themselves or apply to the resonator manufacturer for evaluation.
Capacitance (T
= 25°C, V
A
Parameter
Symbol
Input
C
IN
capacitance
I/O
C
IO
capacitance
Remark Unless specified otherwise, the characteristics of alternate-function pins are the same as those of port
pins.
462
CHAPTER 25 ELECTRICAL SPECIFICATIONS
= −40 to +85°C, V
A
Parameter
Oscillation
Note 1
frequency (f
)
XT
Oscillation
C3
stabilization time
XT1 input frequency (f
XT1
XT1 input high-/low-level width (t
= V
= 0 V)
DD
SS
f = 1 MHz
Unmeasured pins returned to 0 V.
f = 1 MHz
Unmeasured pins
returned to 0 V.
User's Manual U15798EJ2V0UD
= 1.8 to 5.5 V)
DD
Conditions
V
= 1.8 to 5.5 V
DD
V
= 4.5 to 5.5 V
DD
Note 2
V
= 1.8 to 5.5 V
DD
Note 1
)
XT
, t
)
XTH
XTL
Conditions
P00 to P07, P20 to P27, P32 to
P35, P40 to P43, P80 to P87,
P90 to P97, P100 to P107, P110
to P113
P30, P31, P70 to P73
MIN.
TYP.
MAX.
Unit
32
32.768
35
kHz
1.2
2
s
10
s
32
35
kHz
µ s
5
15
.
SS1
MIN.
TYP.
MAX. Unit
15
pF
15
pF
20
pF

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