Voltage Regulator (S12VREGL3V3V1)
S12XS Family Reference Manual, Rev. 1.13
492
Freescale Semiconductor
17.2
External Signal Description
Due to the nature of VREG_3V3 being a voltage regulator providing the chip internal power supply
voltages, most signals are power supply signals connected to pads.
shows all signals of VREG_3V3 associated with pins.
NOTE
Check device level specification for connectivity of the signals.
17.2.1
VDDR — Regulator Power Input Pins
Signal VDDR is the power input of VREG_3V3. All currents sourced into the regulator loads flow through
this pin. A chip external decoupling capacitor (100 nF...220 nF, X7R ceramic) between VDDR and VSSR
(if VSSR is not available VSS) can smooth ripple on VDDR.
For entering Shutdown Mode, pin VDDR should also be tied to ground on devices without VREGEN pin.
17.2.2
VDDA, VSSA — Regulator Reference Supply Pins
Signals VDDA/VSSA
,
which are supposed to be relatively quiet, are used to supply the analog parts of the
regulator. Internal precision reference circuits are supplied from these signals. A chip external decoupling
capacitor (100 nF...220 nF, X7R ceramic) between VDDA and VSSA can further improve the quality of
this supply.
17.2.3
VDD, VSS — Regulator Output1 (Core Logic) Pins
Signals VDD/VSS are the primary outputs of VREG_3V3 that provide the power supply for the core logic.
These signals are connected to device pins to allow external decoupling capacitors (220 nF, X7R ceramic).
Table 17-2. Signal Properties
Name
Function
Reset State
Pull Up
VDDR
Power input (positive supply)
—
—
VDDA
Quiet input (positive supply)
—
—
VSSA
Quiet input (ground)
—
—
VDDX
Power input (positive supply)
—
—
VDD
Primary output (positive supply)
—
—
VSS
Primary output (ground)
—
—
VDDF
Secondary output (positive supply)
—
—
VDDPLL
Tertiary output (positive supply)
—
—
VSSPLL
Tertiary output (ground)
—
—
VREGEN (optional)
Optional Regulator Enable
—
—
VREG_API
(optional)
VREG Autonomous Periodical
Interrupt output
—
—
Summary of Contents for MC9S12XS128
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