Differences between upd75402a and upd75402 – NEC PD75402A User Manual
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CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS
5.2.4
Differences Between
µ
PD75402A and
µ
PD75402
Part of the clock generation circuit differs between the
µ
PD75402A and the
µ
PD75402.
The
µ
PD75402 does not include the sections enclosed in dotted lines.
Fig. 5-16 Clock Generation Circuit - Differences between
µ
PD75402A and
µ
PD75402
*
Instruction execution
Remarks
1.
f
XX
= System clock frequency
2.
f
X
= external clock frequency
3.
PCC: Processor clock control register
4.
1 clock cycle (t
CY
) of
Φ
is 1 machine cycle of an instruction.
Internal Bus
V
DD
X1
X2
System
Clock
Oscillation
Circuit
f
XX
or f
X
STOP
Oscillation
1/2
1/16 to 1/512
Frequency Divider
Selector
Frequency
Divider
• CPU
• INT0 Noise
Eliminator
• Clock Output
Circuit
HALT F/F
S
R
Q
RESET Input Falling Edga
Detection Signal
RESET Input Rising Edge
Detection Signal
Standby Release Signal from
Interrupt Control Circuit
STOP F/F
Q
S
R
Clear
all bits
Clear
PCC2
0
PCC1
PCC2
PCC3
HALT*
STOP*
PCC
• Basic Interva Timer (BT)
• Clock Output Circuit
• Serial Interface
• INT0 Noise Eliminator
• Clock Output Circuit
4
1/4
1/6
Φ