ez80f91 ZiLOG Semiconductor, ez80f91 Datasheet - Page 279

• Manufacturer Part Number: ez80f91
• Description: Ez80 Acclaimplus!? Connectivity Assp Ez80f91 Assp
• Manufacturer: ZiLOG Semiconductor

PS027001-0707
PLL Normal Operation
for the number of consecutive reference clock cycles. The lock criteria is selected in the
PLL Control Register, PLL_CTL0[LDS_CTL]. When the locked condition is met, this
block outputs a logic High signal (lock) that interrupts the CPU.
By default (after system reset) the PLL is disabled and SCLK = XTAL oscillator. Ensuring
proper loop filter, supply voltages and external oscillator are correctly configured, the PLL
is enabled. The SCLK/Timer cannot choose the PLL as its source until the PLL is locked,
as determined by the lock detect block. By forcing the PLL to be locked prior to enabling
the PLL as a SCLK/Timer source, it is assured to be stable and accurate.
Figure 58
displays the programming flow for normal PLL operation.
Figure 58. Normal PLL Programming Flow
Set SCLK MUX to PLL (PLL_CTL0)
{Charge Pump & Lock criteria}
PLL_DIV_L then PLL_DIV_H
Disable Lock Interrupt Mask
Execute Application Code
Execute instructions with
SCLK = XTAL Oscillator
Upon Lock Interrupt:
{Interrupts & PLL}
POR/System
{PLL Divider}
(PLL_CTL1)
PLL_CTL0
PLL_CTL1
Program:
Enable:
Reset
Product Specification
Phase-Locked Loop
eZ80F91 ASSP
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