SMSC LAN8720, LAN8720i Table of Contents

Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support

Datasheet

Table of Contents

Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.1 General Terms and Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.2 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.3 Architectural Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.3.1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Chapter 2 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.1 Package Pin-out Diagram and Signal Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Chapter 3 Pin Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.1 MAC Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2 LED Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.3 Management Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.4 General Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.5 10/100 Line Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.6 Analog Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.7 Power Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Chapter 4 Architecture Details. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.1 Top Level Functional Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.2 100Base-TX Transmit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.2.1 100M Transmit Data Across the MII/RMII Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.2.2 4B/5B Encoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.2.3 Scrambling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.2.4 NRZI and MLT3 Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.2.5 100M Transmit Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.2.6 100M Phase Lock Loop (PLL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.3 100Base-TX Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.3.1 100M Receive Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.3.2 Equalizer, Baseline Wander Correction and Clock and Data Recovery . . . . . . . . . . . . . 21 4.3.3 NRZI and MLT-3 Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.3.4 Descrambling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.3.5 Alignment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.3.6 5B/4B Decoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.3.7 Receive Data Valid Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.3.8 Receiver Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.3.9 100M Receive Data Across the MII/RMII Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.4 10Base-T Transmit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.4.1 10M Transmit Data Across the MII/RMII Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.4.2 Manchester Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.4.3 10M Transmit Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.5 10Base-T Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.5.1 10M Receive Input and Squelch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.5.2 Manchester Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.5.3 10M Receive Data Across the MII/RMII Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.5.4 Jabber Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.6 MAC Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.6.1 RMII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.7 Reference Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4.7.1 REF_CLK In Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4.7.2 REF_CLK OUT Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

SMSC LAN8720/LAN8720i	3	Revision 1.0 (05-28-09)
	DATASHEET

Contents

LAN8720/LAN8720i Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIXSupport PRODUCT FEATURES DATASHEET Table of Contents Page Page List of Figures List of Tables Page Chapter 1 Introduction 1.1General Terms and Conventions 1.2General Description RJ45 Crystal or 1.3Architectural Overview 1.3.1Configuration Figure 1.2 LAN8720/LAN8720i Architectural Overview Chapter 2 Pin Configuration 2.1Package Pin-outDiagram and Signal Table Table 2.1 LAN8720/LAN8720i 24-PINQFN Pinout PIN NO PIN NAME Chapter 3 Pin Description 3.1MAC Interface Signals 3.2LED Signals 3.3Management Signals 3.4General Signals 3.510/100 Line Interface Signals 3.6Analog Reference 3.7Power Signals Chapter 4 Architecture Details 4.1Top Level Functional Architecture 4.2100Base-TXTransmit 4.2.1100M Transmit Data Across the MII/RMII Interface 4.2.24B/5B Encoding 4.2.3Scrambling 4.2.4NRZI and MLT3 Encoding 4.2.5100M Transmit Driver 4.2.6100M Phase Lock Loop (PLL) 4.3100Base-TXReceive 4.3.1100M Receive Input 4.3.2Equalizer, Baseline Wander Correction and Clock and Data Recovery 4.3.3NRZI and MLT-3Decoding 4.3.4Descrambling 4.3.5Alignment 4.3.65B/4B Decoding 4.3.7Receive Data Valid Signal 4.410Base-TTransmit 4.4.110M Transmit Data Across the MII/RMII Interface 4.4.2Manchester Encoding 4.4.310M Transmit Drivers 4.510Base-TReceive 4.5.110M Receive Input and Squelch 4.5.2Manchester Decoding 4.5.310M Receive Data Across the MII/RMII Interface 4.5.4Jabber Detection 4.6MAC Interface 4.6.1RMII 4.7Reference Clock 4.7.1REF_CLK In Mode 4.7.2REF_CLK OUT Mode MAC RMII 10/100 PHY Mag Figure 4.5 LAN8720 sources REF_CLK from a 25MHz crystal 4.8Auto-negotiation Page 4.8.1Parallel Detection 4.8.2Re-starting Auto-negotiation 4.8.3Disabling Auto-negotiation 4.8.4Half vs. Full Duplex 4.9HP Auto-MDIXSupport 4.10nINTSEL Strapping and LED Polarity Selection 4.11REGOFF and LED Polarity Selection 4.12PHY Address Strapping 4.13Variable Voltage I/O 4.14Transceiver Management Control 4.14.1Serial Management Interface (SMI) Figure 4.10 MDIO Timing and Frame Structure - READ Cycle Figure 4.11 MDIO Timing and Frame Structure - WRITE Cycle Chapter 5 SMI Register Mapping Page Page Page 5.1SMI Register Format Table 5.21 Register 0 - Basic Control ADDRESS DEFAULT Table 5.22 Register 1 - Basic Status Table 5.22 Register 1 - Basic Status (continued) Table 5.23 Register 2 - PHY Identifier Table 5.24 Register 3 - PHY Identifier Table 5.25 Register 4 - Auto Negotiation Advertisement Table 5.25 Register 4 - Auto Negotiation Advertisement (continued) Register 5 - Auto Negotiation Link Partner Ability Table 5.27 Register 6 - Auto Negotiation Expansion Table 5.28 Register 16 - Silicon Revision Table 5.29 Register 17 - Mode Control/Status Table 5.29 Register 17 - Mode Control/Status (continued) Table 5.30 Register 18 - Special Modes Table 5.31 Register 26 - Symbol Error Counter Register 27 - Special Control/Status Indications Register 28 - Special Internal Testability Controls Table 5.34 Register 29 - Interrupt Source Flags Table 5.34 Register 29 - Interrupt Source Flags (continued) Table 5.35 Register 30 - Interrupt Mask Table 5.36 Register 31 - PHY Special Control/Status 5.2Interrupt Management 5.2.1Primary Interrupt System 5.2.2Alternate Interrupt System 5.3Miscellaneous Functions 5.3.1Carrier Sense 5.3.2Collision Detect 5.3.3Isolate Mode 5.3.4Link Integrity Test 5.3.5Power-Downmodes 5.3.6Reset 5.3.7LED Description 5.3.8Loopback Operation XFMR Digital Ethernet Transceiver 10/100 TXD X Digital 5.3.9Configuration Signals Table 5.39 MODE[2:0] Bus DEFAULT REGISTER BIT VALUES MODE[2:0] MODE DEFINITIONS REGISTER Chapter 6 AC Electrical Characteristics 6.1Serial Management Interface (SMI) Timing 6.2RMII 10/100Base-TX/RXTimings (50MHz REF_CLK IN) 6.2.1RMII 100Base-TTX/RX Timings (50MHz REF_CLK IN) CLKIN TXD[1:0] Page Page 6.3RMII 10/100Base-TX/RXTimings (50MHz REF_CLK OUT) 6.3.1RMII 100Base-TTX/RX Timings (50MHz REF_CLK OUT) 6.3.1.2100M RMII Transmit Timing (50MHz REF_CLK OUT) TXD[1:0] Page 6.4RMII CLKIN Requirements 6.5Reset Timing 6.6Clock Circuit Chapter 7 DC Electrical Characteristics 7.1DC Characteristics 7.1.1Maximum Guaranteed Ratings 7.1.2Operating Conditions 7.1.3Power Consumption Table 7.4 Power Consumption Device Only (REF_CLK IN MODE) VDDA3.3 TOTAL POWER CURRENT Page 7.1.4DC Characteristics - Input and Output Buffers Table 7.7 LAN Interface Signals Table 7.8 LED Signals Table 7.9 Configuration Inputs Table 7.10 General Signals Internal Pull-Up / Pull-DownConfigurations Internal Pull-Up / Pull-DownConfigurations (continued) Table 7.12 100Base-TXTransceiver Characteristics Table 7.13 10BASE-TTransceiver Characteristics Chapter 8 Application Notes 8.1Application Diagram 8.1.1RMII Diagram 8.1.2Power Supply Diagram 8.1.3Twisted-PairInterface Diagram 8.2Magnetics Selection Chapter 9 Package Outline Figure 9.1 QFN, 4x4 Taping Dimensions and Part Orientation Figure 9.2 Reel Dimensions Chapter 10 Revision History