181
CHAPTER 13 PLL FREQUENCY SYNTHESIZER
User’s Manual U15104EJ2V0UD
13.3 Registers Controlling PLL Frequency Synthesizer
The PLL frequency synthesizer is controlled by the following four registers.
• PLL mode select register (PLLMD)
• PLL reference mode register (PLLRF)
• PLL unlock F/F judge register (PLLUL)
• PLL data transfer register (PLLNS)
(1) PLL mode select register (PLLMD)
This register selects the input pin and division mode of the PLL frequency synthesizer.
PLLMD is set with a 1-bit or 8-bit memory manipulation instruction.
Reset input clears this register to 00H.
In the STOP mode, only bits 3 and 2 (VCOHDMD and VCOLDMD) retain the previous value. Bits 1 and 0
(PLLMD1 and PLLMD0) are reset to 0.
In the HALT mode, it holds the value immediately before the HALT mode was set.
Figure 13-2. Format of PLL Mode Select Register (PLLMD)
VCOH
Selection of disable status of VCOH pin
DMD
0
Connected to pull-down resistor.
1
High-impedance state
VCOL
Selection of disable status of VCOL pin
DMD
0
Connected to pull-down resistor.
1
High-impedance state
PLLMD1 PLLMD0
Selection of division mode of PLL frequency synthesizer and VCO input pin
0
0
Disables VCOL and VCOH pins
Note
0
1
Direct division (VCOL pin and MF mode)
1
0
Pulse swallow (VCOH pin and VHF mode)
1
1
Pulse swallow (VCOL pin and HF mode)
Note
This does not mean that the PLL is disabled. The VCOH and VCOL pins become the status specified
by bit 3 (VCOHDMD) and bit 2 (VCOLDMD). The EO0 and EO1 pins go low.
Remark
Bits 4 to 7 are fixed to 0 by hardware.
7
0
6
0
5
0
4
0
<3>
VCOHDMD
<2>
VCOLDMD PLLMD1 PLLMD0
Symbol
PLLMD
R/W
R/W
After reset
00H
Address
FFA0H
<1>
<0>