English
Language : 

S912XHZ512F1VAG Datasheet, PDF (728/978 Pages) Freescale Semiconductor, Inc – Covers MC9S12XHZ384, MC9S12XHZ256
◁
Chapter 20 Voltage Regulator (S12VREG3V3V5)
20.2 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.
Table 20-1 shows all signals of VREG_3V3 associated with pins.
Table 20-1. Signal Properties
Name
VDDR
VDDA
VSSA
VDD
VSS
VDDPLL
VSSPLL
VREGEN (optional)
Function
Power input (positive supply)
Quiet input (positive supply)
Quiet input (ground)
Primary output (positive supply)
Primary output (ground)
Secondary output (positive supply)
Secondary output (ground)
Optional Regulator Enable
Reset State
—
—
—
—
—
—
—
—
Pull Up
—
—
—
—
—
—
—
—
NOTE
Check device level specification for connectivity of the signals.
20.2.1 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.
20.2.2 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.
20.2.3 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 (100 nF...220 nF, X7R
ceramic).
In shutdown mode an external supply driving VDD/VSS can replace the voltage regulator.
MC9S12XHZ512 Data Sheet, Rev. 1.06
728
Freescale Semiconductor
 ▷