Oki Dr.63514, User Manual, Page: 84 / 101

Chapter 4. Additional Usage Notes
4-9
(5) Clock circuit
These clocks can be selected from the following.
Low-speed (XT) Internal (32.768kHz)
External (user cable USR.XT pin)
High-speed (OSC) Internal (2MHz)
External (user cable USR.OSC pin)
A built-in voltage conversion circuit converts the external clock input to the internal “H” level from VDD,
the positive power supply voltage (0.9 to 5.5V).
These selected clocks are output to user cable for monitoring. These pins have output signal levels of
5V.
HC541
HC541
150K
Ω
150K Ω
External
low-speed
clock
USR.OSC
(User cable)
USR.XT
(User cable)
High-speed
OSC clock
to OSC pin on
evaluation chip
to XT pin on
evaluation chip
OSC.OUT
(User cable)
XT.OUT
(User cable)
Low-speed
XT clock
Internal high-speed clock
Internal 5V
power supply
External
high-speed
clock
OSC.SEL
IN
EXT
XT.SEL
IN
EXT
2MHz
65.536kHz
1/2
VDD
+
-
operational
amplifier
+
-
+5V
+
-
+5V
HC541
+5V
HC541
+5V
Internal low-speed clock
5.1K Ω
5.1K Ω
Figure 4-9 clock control part