Integrated 10/100/1000M Ethernet Transceiver
Track ID: JATR-8275-15 Rev. 1.1
Regulators and Power Sequence
9.1. Switching Regulator (RTL8211F(I))
The RTL8211F(I) incorporates a state-of-the-art switching regulator that requires a well-designed PCB
layout in order to achieve good power efficiency and lower the output voltage ripple and input overshoot.
The switching regulator 1.0V output pin (REG_OUT) should be connected only to DVDD10 and AVDD10
(do not provide this power source to other devices).
• The input 3.3V power trace connected to DVDD33 must be wider than 40mils
• The bulk de-coupling capacitors (Cin1 and Cin2) must be placed within 200mils (0.5cm) of DVDD33
to prevent input voltage overshoot
• The output power trace out of REG_OUT must be wider than 60mils
• Lx (2.2µH/4.7µH) must be kept within 200mils (0.5cm) of REG_OUT
• Cout1 and Cout2 must be kept within 200mils (0.5cm) of Lx to ensure stable output power and better
• For switching regulator stability, the capacitor Cout1 and Cout2 must be a ceramic (X5R) capacitor.
Cin1 and Cin2 are recommended to be ceramic capacitors
• Place Lx and Cin1 on the same layer as the RTL8211F(I). Do not use vias on DVDD33 and REG_OUT
Note: Violation of the above rules will damage the IC.
Figure 10. Switching Regulator