S12 Clock, Reset and Power Management Unit (S12CPMU)
MC9S12G Family Reference Manual Rev.1.27
354 NXP Semiconductors
• The Internal Reference Clock (IRC1M) provides a1MHz clock.
10.1.1 Features
The Pierce Oscillator (XOSCLCP) contains circuitry to dynamically control current gain in the output
amplitude. This ensures a signal with low harmonic distortion, low power and good noise immunity.
• Supports quartz crystals or ceramic resonators from 4MHz to 16MHz.
• High noise immunity due to input hysteresis and spike filtering.
• Low RF emissions with peak-to-peak swing limited dynamically
• Transconductance (gm) sized for optimum start-up margin for typical crystals
• Dynamic gain control eliminates the need for external current limiting resistor
• Integrated resistor eliminates the need for external bias resistor.
• Low power consumption: Operates from internal 1.8V (nominal) supply, Amplitude control limits
power
The Voltage Regulator (IVREG) has the following features:
• Input voltage range from 3.13V to 5.5V
• Low-voltage detect (LVD) with low-voltage interrupt (LVI)
• Power-on reset (POR)
• Low-voltage reset (LVR)
The Phase Locked Loop (PLL) has the following features:
• highly accurate and phase locked frequency multiplier
• Configurable internal filter for best stability and lock time.
• Frequency modulation for defined jitter and reduced emission
• Automatic frequency lock detector
• Interrupt request on entry or exit from locked condition
• Reference clock either external (crystal) or internal square wave (1MHz IRC1M) based.
• PLL stability is sufficient for LIN communication, even if using IRC1M as reference clock
The Internal Reference Clock (IRC1M) has the following features:
• Frequency trimming
(A factory trim value for 1MHz is loaded from Flash Memory into the IRCTRIM register after
reset, which can be overwritten by application if required)
• Temperature Coefficient (TC) trimming.
(A factory trim value is loaded from Flash Memory into the IRCTRIM register to turned off TC
trimming after reset. Application can trim the TC if required by overwriting the IRCTRIM
register).
•
Other features of the S12CPMU include
• Clock monitor to detect loss of crystal
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