LC877917A Datasheet, PDF (26/29 Pages) Sanyo Semicon Device – 8-bit 1-chip Microcontroller

LC877917A
Characteristics of a Sample Main System Clock Oscillation Circuit
Given below are the characteristics of a sample main system clock oscillation circuit that are measured using a
SANYO-designated oscillation characteristics evaluation board and external components with circuit constant values
with which the oscillator vendor confirmed normal and stable oscillation.
Table 1 Characteristics of a Sample Main System Clock Oscillator Circuit with a Ceramic Oscillator
Nominal
Frequency
Vendor
Name
Oscillator Name
Circuit Constant
C1
C2
Rf1
Rd1
[pF] [pF]
[Ω]
[Ω]
Operating
Voltage
Range
[V]
Oscillation
Stabilization Time
typ
max
[ms]
[ms]
Remarks
CSTCR4M00G53-R0
(15) (15) Open
1k
2.4 to 3.6
0.04
-
4.00MHz Murata
CSTLS4M00G53-B0
(15) (15) Open
1k
2.4 to 3.6
0.03
-
Internal
C1, C2
The oscillation stabilization time refers to the time interval that is required for the oscillation to get stabilized after
VDD goes above the operating voltage lower limit (see Figure 4).
• Till the oscillation gets stabilized after the instruction for starting the main clock oscillation circuit is executed.
• Till the oscillation gets stabilized after the HOLD mode reset.
• Till the oscillation gets stabilized after the HOLD mode reset with CFSTOP(the OCR register bit0)=0.
Characteristics of a Sample Subsystem Clock Oscillator Circuit
Given below are the characteristics of a sample subsystem clock oscillation circuit that are measured using a SANYO-
designated oscillation characteristics evaluation board and external components with circuit constant values with
which the oscillator vendor confirmed normal and stable oscillation.
Table 2 Characteristics of a Sample Subsystem Clock Oscillator Circuit with a Crystal Oscillator
Nominal
Frequency
Vendor
Name
Oscillator Name
Circuit Constant
C3
C4
Rf2 Rd2
Operating
Voltage
Range
Oscillation
Stabilization Time
typ
max
Remarks
[pF] [pF] [Ω]
[Ω]
[V]
[s]
[s]
CL=7.0pF
9
9
Open
-
2.4 to 3.6
1.0
2.0
Normal XT
32.768KHz
Epson
Toyocom
MC-306
mode
CL=7.0pF
2
2
Open
-
2.4 to 3.6
2.0
3.0
Low Amp XT
mode
The oscillation stabilization time refers to the time interval that is required for the oscillation to get stabilized after the
instruction for starting the subclock oscillation circuit is executed and to the time interval that is required for the
oscillation to get stabilized after the HOLD mode with EXTOSC (the OCR register bit6)=1 is reset (see Figure 4).
Note: The components that are involved in oscillation should be placed as close to the IC and to one another as
possible because they are vulnerable to the influences of the circuit pattern.
CF1
CF2
Rf1
Rd1
C1
C2
CF
XT1
C3
XT2
Rf2
Rd2
C4
X’tal
Figure 1 CF Oscillator Circuit
Figure 2 XT Oscillator Circuit
0.5VDD
Figure 3 AC Timing Measurement Point
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