AN2727 Freescale Semiconductor / Motorola, AN2727 Datasheet - Page 8

• Manufacturer Part Number: AN2727
• Description: Designing Hardware for the HCS12 D-Family
• Manufacturer: Freescale Semiconductor / Motorola

HCS12 Power Supplies
HCS12 Power Supplies
Vdd1, Vdd2
2.5V supply for MCU core and peripheral logic.
If using the internal regulator, connect only to external decoupling capacitors.
Vddpll
2.5V supply for oscillator and PLL.
If using the internal regulator, connect only to external decoupling capacitor.
Vddr
Supply for regulator and ports A,B,E,H. Connect to VDD5.
Add 10 µF if big loads are switched.
Vddx
Supply for all other ports. Connect to VDD5.
Add 10 µF if big loads are switched.
Vdda
Supply to ATD, Port ADx and voltage regulator reference. Connect to VDD5.
Where possible, avoid connecting external pull devices or logic to VDDA or VSSA tracks.
Vrh
Reference for ATD. Connect to ATD reference potential.
The following constraint must be met to obtain full-scale, full-range ATD results:
VSSA ≤ VRL ≤ VIN ≤ VRH ≤ VDDA.
If the input level goes outside this range it will be clipped.
VRH should always be ≤ VDDA, to maintain conversion accuracy.
Avoid tracking the reference voltage through digital supply planes, and do not connect external digital pull
devices to VRH or VRL.
Designing Hardware for the HCS12 D-Family, Rev. 0
8
Freescale Semiconductor