UPD17073 NEC, UPD17073 Datasheet - Page 137

• Manufacturer Part Number: UPD17073
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
• Manufacturer: NEC

15.4.3
to the error out pin (EO).
f
15.4.4 Unlock FF
to the UP or DOWN request signal output from the phase comparator.
be detected when one of the request signals has gone low.
function of the PLL unlock FF register.
15-2 (Read & Reset).
is 1/f
r
are as follows:
As shown in Figure 15-8, the charge pump outputs the UP and DOWN request signals from the phase comparator
Therefore, the relations among the outputs of the error out pins, divided frequency f
When f
When f
When f
As shown in Figure 15-8, the unlock FF detects the unlock status of the PLL frequency synthesizer in response
In the unlock status, either one of the UP or DOWN request signals goes low. Therefore, the unlock status can
In the unlock status, the unlock FF is set to 1.
The status of the unlock FF is detected by the PLL unlock FF register. Figure 15-10 shows the configuration and
The unlock FF is set at the cycle of the selected reference frequency f
The unlock FF is reset when the contents of the PLL unlock FF register is read by the instruction shown in Table
Therefore, the unlock FF must be detected at a cycle longer than the cycle of the reference frequency f
The delay of the up and down request signals of the phase comparator is fixed to about 1 s.
r
).
Charge pump
Remark U: Undefined
r
r
r
reset
> f
< f
= f
At
PLL unlock FF register
N
N
N
: Low-level output
: High-level output
: Floating
Power-ON
Clock stop
CE
R: Retained
Name
Figure 15-10. Configuration of PLL Unlock FF Register
b
0
0
3
Flag symbol
b
0
0
2
b
0
0
1
U
R
R
0
1
b
U
P
L
L
L
0
(BANK1)
Unlock FF = 0: PLL lock status
Unlock FF = 1: PLL unlock status
Fixed to "0"
Address
6DH
Reset
Read/
Write
R &
Detects unlock FF status
r
.
N
, and reference frequency
PD17072,17073
r
(which
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