enCoRe™ V CY7C643xx, enCoRe™ V LV CY7C604xx TRM, Document No. 001-32519 Rev *H
77
External Crystal Oscillator (ECO)
freely switch between the ECO and ILO. It should be written
as early as possible after a POR or XRES event.
For additional information, refer to the
10.3.4
Related Registers
■
■
PRTxDR Registers register on page 56
■
PRTxIE Registers register on page 56
.
10.4
Usage Modes and
Guidelines
This block operates at extremely low current levels, making
it vulnerable to coupled noise. Take care to avoid coupling
noise from neighboring signal pins. The block is designed to
accept a wide variety of 6- or 12-pF crystals. There are four
distinct operating power modes:
■
Power-down (PDM)
■
Startup mode (SPM)
■
High-power mode (HPM)
■
Low-power mode (LPM)
There are specific sequences that are used to switch
between each mode; typically a small delay is required after
each instruction.
Figure 10-3. Power Mode State Machine
