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DM9161B

Layout Guide

Version: DM9161B-LG-V10

August 9, 2007

6. Crystal Selection Guide

•

A crystal can be used to generate the 25MHz reference clock instead of an oscillator. The crystal must be a

fundamental type, series-resonant, connect to XT1 and XT2, and shunt each crystal lead to ground with a
22pF capacitor as shown in Figure 6.

PARAMETER SPEC

Type Fundamental,

series-resonant

Frequency

25 MHz +/- 0.01%

Equivalent Series Resistance

25 ohms max

Load Capacitance

22 pF type.

Case Capacitance

7 pF max.

Power Dissipation

1mW max.

Table 6-1: Crystal Specifications

XT1

XT2

AGND

C18

22pf

25M

C19

22pf

Figure 6

Crystal Circuit Diagram

Содержание dm9161b

Страница 1: ...DM9161B Layout Guide Version DM9161B LG V10 1 August 9 2007 DM9161B Layout Guide Version 1 0 Technical Reference Manual Davicom Semiconductor Inc August 9 2007 ...

Страница 2: ...not be placed near important signal traces such as RX receive pair and TX transmit pair band gap resistor magnetic and board edge Traces routed from the DM9161B RX pair to the 10 100M magnetic and the RJ45 connector should run symmetrically directly identically and closely no more than 2mm The same rule is applied to traces routed from the DM9161B TX pair Magnetic RJ 45 RX RX TX TX d1 d2 d1 d1 2mm...

Страница 3: ... route any digital signal between the DM9161B RX and TX pairs to the RJ 45 Keep the two pairs away from all the other active signals and the chassis ground It should be no power or ground plane in the area under the network side of the 10 100M magnetic and the area under the RJ 45 connector Any terminated pins of the RJ 45 connector pins 4 5 7 and 8 see Figure 1 and the magnetic see Figure 1 shoul...

Страница 4: ...ase TX Application Figure 1 1 and 1 2 illustrate the two types of the specific magnetic interconnect and how to connect with Davicom DM9161B These magnetic are not pin to pin compatible Please must be considered when using the DM9161B in auto MDIX mode Figure 1 1 Figure 1 2 ...

Страница 5: ...d be less than 100m Vpp The 0 1 0 01µF decoupling capacitor should be connected between each DVDD DGND set and AVDD AGND set and be placed as close as possible to the pins of DM9161B The conservative approach is to use two decoupling capacitors on each DVDD DGND set and AVDD AGND set One 0 1µF is for low frequency noise and the other 0 01µF is for high frequency noise on the power supply The AVDD ...

Страница 6: ...og ground domain and digital ground domain the analog ground domain and digital ground domain connected line is far away the AGND pins of DM9161B see Figure 4 All AGND pins pin 5 6 46 could not directly short each other see Figure 3 3 It must be directly connected to analog ground domain see Figure 3 2 Analog ground domain area is as large as possible Figure 3 1 Analog ground domain Digital ground...

Страница 7: ... used should have an impedance 100Ω at 100MHz and 200mA above A suitable bead is the Panasonic surface mound bead part number EXCCL4532U or an equivalent A 10µF 0 1µF and 0 01µF electrolytic bypass capacitors should be connected between VDD and GND at the device side of each of the ferrite bead Should separate analog power planes from noisy logic power planes Figure 4 ...

Страница 8: ...g table are electrical equivalents but may not be pin to pin equivalents Manufacturer Part Number Pulse Engineering PE 68515 H1102 YCL PH163112 PH163539 Halo TG110 S050N2 TG110 LC50N2 Bel Fuse S558 5999 W2 MAGCOM HS9016 HS9024 GTS FC 618SM Table 5 1 10 100M Magnetics Sources Parameter Values Units Test Condition Tx RX turns ratio 1 1 CT 1 1 Inductance 350 µH Min Insertion loss 1 1 dB Max 1 100 MHz...

Страница 9: ...resonant connect to XT1 and XT2 and shunt each crystal lead to ground with a 22pF capacitor as shown in Figure 6 PARAMETER SPEC Type Fundamental series resonant Frequency 25 MHz 0 01 Equivalent Series Resistance 25 ohms max Load Capacitance 22 pF type Case Capacitance 7 pF max Power Dissipation 1mW max Table 6 1 Crystal Specifications 42 43 XT1 XT2 AGND AGND C18 22pf Y1 25M C19 22pf Figure 6 Cryst...

Страница 10: ...d direct as possible between the DM9161B and MAC controller Maximum shorter than 20cm These MII signals are as follows CRS COL TXD3 TXD2 TXD1 TXD0 TXEN TXCLK TXER RXER RXCLK RXDV RXD0 RXD1 RXD2 RXD3 MDC MDIO TXD 0 3 and TXCLK length mismatch does not exceed 2cm RXD 0 3 and RXCLK length mismatch does not exceed 2cm All signal trace should be considered to have characteristic impedance of 50 Ohm ...

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