RTL8111C-VB-GR View Datasheet(PDF) - Realtek Semiconductor

Part Name

Description

MFG CO.

RTL8111C-VB-GR

INTEGRATED GIGABIT ETHERNET CONTROLLER FOR PCI EXPRESS™ APPLICATIONS

Realtek Semiconductor 

RTL8111C

Datasheet

7. Switching Regulator

The RTL8111C incorporates a state-of-the-art switching regulator which requires a well-designed PCB

layout in order to achieve good power efficiency and lower the output voltage ripple and input overshoot.

7.1. PCB Layout

• The input 3.3V power trace connected to pin 63 (VDDSR) should be wider than 40mils.

• The bulk de-coupling capacitors (C82 and C83) should be placed within 200mils (0.5cm) of pin 63 to

prevent input voltage overshoot.

• The output power trace out of pin 1 (SROUT12) should be wider than 60mils.

• Keep L20 within 200mils (0.5cm) of pin1.

• Keep C18 and C19 within 200mils (0.5cm) of L20 to ensure stable output power and better power

efficiency.

• Both C18 and C82 are strongly recommended to be ceramic capacitors.

Note: Violation of the above rules will damage the IC.

Figure 10. Switching Regulator Illustration

7.2. Inductor and Capacitor Parts List

Inductor Type

4R7GTSD32

(best efficiency)

6R8GTSD32

6R8GTSD53

Table 24. Inductor and Capacitor Parts List

Q at 500KHz ESR at 500KHz (MΩ)

Max I (mA)

57.15

281

1100

67.35

313

59.7

375

900

1510

Output Ripple (mV)

12.6

12

10.4

Capacitor Type

Capacitance ESR at 500KHz (MΩ) Output Ripple (mV)

22µF 1210 TDK

21.5µF

24.25

9.6

22µF 1210 X5R

22.15µF

24.90

10.4

Note: Capacitors (C18 & C82) are suggested to be ceramic due to their low ESR value.

Load Transient (mV)

81.0

73.0

Integrated Gigabit Ethernet Controller for PCI Express

25

Track ID: JATR-1076-21 Rev. 1.5

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