UPD789304 Datasheet, PDF (16/64 Pages) NEC – 8-BIT SINGLE-CHIP MICROCONTROLLER

µPD789304, 789306, 789314, 789316
5.2 Clock Generator
The specifications of the main system clock generator differ depending on the product as shown below.
(1) Main system clock generator
• Ceramic/crystal oscillation: µPD789304, 789306
This generator’s oscillation frequency range is 1.0 to 5.0 MHz. The minimum instruction execution time
can be changed from 0.4 to 1.6 µs (@ 5.0 MHz operation).
• RC oscillation: µPD789314, 789316
This generator’s oscillation frequency range is 2.0 to 4.0 MHz. The minimum instruction execution time
can be changed from 0.5 to 2.0 µs (@ 4.0 MHz operation).
(2) Subsystem clock generator (crystal oscillation)
This generator’s oscillation frequency is 32.768 kHz. The minimum instruction execution time is 122 µs (@
32.768 kHz operation).
Figure 5-1. Block Diagram of Clock Generator
Internal bus
FRC SCC
Sub oscillation mode register
(SCKM)
XT1
Subsystem fXT
XT2
clock oscillator
X1 (CL1)
X2 (CL2)
Main system
clock oscillator
1/2
Prescaler
fXT
fX
2
(fcc)
fX
2²
(
) ^fCC
2²
Prescaler
Watch timer
LCD controller/driver
Clock to peripheral
hardware
Standby
controller
Wait
controller
CPU clock
(fCPU)
STOP
MCC PCC1 CLS CSS0
Processor clock control
register (PCC)
Internal bus
Subsystem clock control
register (CSS)
Remark Pins names enclosed in parentheses are when using the RC oscillation (µPD789314, 789316).
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Data Sheet U14384EJ1V0DS