mc9s12vr48 Freescale Semiconductor, Inc, mc9s12vr48 Datasheet - Page 125

• Manufacturer Part Number: mc9s12vr48
• Description: S12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

4.2
This section lists and describes the signals that connect off chip as well as internal supply nodes and special
signals.
4.2.1
Pin RESET is an active-low bidirectional pin. As an input it initializes the MCU asynchronously to a
known start-up state. As an open-drain output it indicates that an MCU-internal reset has been triggered.
4.2.2
These pins provide the interface for a crystal to control the internal clock generator circuitry. EXTAL is
the input to the crystal oscillator amplifier. XTAL is the output of the crystal oscillator amplifier. If
XOSCLCP is enabled, the MCU internal OSCCLK_LCP is derived from the EXTAL input frequency. If
OSCE=0, the EXTAL pin is pulled down by an internal resistor of approximately 200 kΩ and the XTAL
pin is pulled down by an internal resistor of approximately 700 kΩ.
4.2.3
Pin VSUP is the power input of VREGAUTO. All currents sourced into the regulator loads flow through
this pin.
Off-chip decoupling capacitors (10uF plus 220 nF(X7R ceramic)) between VSUP and VSS can smooth
ripple on VSUP.
4.2.4
Pins VDDA and VSSA
Internal precision reference circuits are supplied from these signals.
An off-chip decoupling capacitor (10uF plus 220 nF(X7R ceramic)) between VDDA and VSSA can
improve the quality of this supply.
VDDA has to be connected externally to VDDX.
4.2.5
This supply domain is monitored by the Low Voltage Reset circuit.
VDDX has to be connected externally to VDDA.
Freescale Semiconductor
Signal Description
RESET
EXTAL and XTAL
VSUP — Regulator Power Input Pin
VDDA, VSSA — Regulator Reference Supply Pins
VDDX, VSSX— Pad Supply Pins
Freescale recommends an evaluation of the application board and chosen
resonator or crystal by the resonator or crystal supplier.
The loop controlled circuit (XOSCLCP) is not suited for overtone
resonators and crystals.
,
are used to supply the analog parts of the regulator.
MC9S12VR Family Reference Manual, Rev. 2.2
Preliminary - Subject to Change Without Notice
NOTE
Clock, Reset and Power Management (S12CPMU_UHV)
125