CY8C28xxx PSoC Programmable System-on-Chip TRM, Document No. 001-52594 Rev. *G
95
Phase-Locked Loop (PLL)
11.2.2
OSC_CR2 Register
The Oscillator Control Register 2 (OSC_CR2) is used to
configure various features of internal clock sources and
clock nets.
Bit 7: PLLGAIN.
This is the only bit in the OSC_CR2 regis-
ter that directly influences the PLL. When set, this bit keeps
the PLL in Low Gain mode.
If this bit is held low, the lock time is less than 10 ms. If this
bit is held high, the lock time is on the order of 50 ms. After
lock is achieved, it is recommended that this bit be forced
high to decrease the jitter on the output. If longer lock time is
tolerable, the PLLGAIN bit can be held high all the time.
Bit 4: SLP_EXTEND.
This bit allows for extended sleep
intervals, up to 16s.
Bit 3: WDR32_SE.
If an external 32 kHz crystal is used,
this bit allows a choice between the ECO or the ILO as the
source of the watchdog timer and sleep timer
Bit 2: EXTCLKEN.
When the EXTCLKEN bit is set, the
external clock becomes the source for the internal clock
tree, SYSCLK, which drives most PSoC device clocking
functions. All external and internal signals, including the 32
kHz clock, whether derived from the Internal Low Speed
Oscillator (ILO) or the crystal oscillator, are synchronized to
this clock source. If an external clock is enabled, PLL mode
should be off. The external clock input is located on port
P1[4]. When using this input, the pin drive mode should be
set to High-Z (not High-Z analog).
Bit 1: RSVD.
Reserved bit - This bit should always be 0.
Bit 0: SYSCLKX2DIS.
When SYSCLKX2DIS is set, the
IMO’s doubler is disabled. This will result in a reduction of
overall device power, on the order of 1 mA. It is advised that
any application that does not require this doubled clock
should have it turned off. During emulation with the In-Circuit
Emulator (ICE), the IMO’s doubler is always active regard-
less of the status of SYSCLKX2DIS.
For additional information, refer to the
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Access
1,E2h
PLLGAIN
SLP_EXTE
ND
WDR32_SE
EXTCLKEN
RSVD
SYSCLKX2
DIS
RW : 00
Summary of Contents for CY8C28 series
Page 65: ...64 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G RAM Paging ...
Page 125: ...124 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Page 311: ...310 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G IDAC_CR0 1 FDh ...
Page 317: ...316 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Page 393: ...392 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...
Page 477: ...476 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G Digital Clocks ...
Page 561: ...560 CY8C28xxx PSoC Programmable System on Chip TRM Document No 001 52594 Rev G ...