DM9161A

10/100 Mbps Fast Ethernet Physical Layer Single Chip Transceiver

21

Final

Version: DM9161A-DS-F01

October 16, 2009

7.2.11 Power Reduced Mode

The Signal detect circuit is always turned on to monitor whether there is any signal on the media. In case of cable

disconnection,, DM9161A will automatically turn off the power and enter the Power Reduced mode, regardless of its operation

mode being N-way auto-negotiation or forced mode. While in the Power Reduced mode, the transmit circuit will continue

sending out fast link pulse with minimum power consumption. If a valid signal is detected from the media, which might be N-way

fast link pulse, 10Base-T normal link pules, or 100Base-TX MLT3 signals, the device wakes up and resumes normal operation

mode.

Automatic reduced power down mode can be disabled by writing Zero to Reg.16.4.

7.2.12 Power Down Mode

Power Down mode is entered by setting Reg.0.11 to ONE or pulling PWRDWN pin high, which disables all transmit and

receive functions, and MII interface functions except the MDC/MDIO management interface.

7.2.13 Reduced Transmit Power Mode

Additional transmit power reduction can be gained by designing with 1.25:1 turns ration magnetic on its TX side and using a

8.5KΩ resistor on BGRES and BGRESG pins, and the TX+/TX- pulled high resistors being changed from 50Ω to 78Ω. This

configuration could reduce about 20% of transmit power.

7.3 HP Auto-MDIX Functional Description

The DM9161A supports the automatic detect cable connection type, MDI/MDIX (straight through/cross over). A

manual configuration by register bit for MDI or MDIX is still accepted.

When set to automatic, the polarity of MDI/MDIX controlled timing is generated by a 16-bits LFSR. The switching cycle time is

located from 200ms to 420ms. The polarity control is always switch until detect received signal. After selected MDI or MDIX, the

polarity status can be read by register bit (20.7).(See page33,8.12 specified config register-20 bit 7)7.3.1 Function Setting.

Pin 39 is used to enable HP Auto-MDIX function.

Pull pin 39 low will enable it, and pull pin 39 high will disable it.

Specified config Register 20 bit 4 (20, 4) is used by programmer to disable HP Auto-MDIX function. Write register

20 bit 4 to “ 1 “ will disable HP Auto-MDIX function. Its default value is “ 0 “. When the register 20 bit 4 (20, 4) is set to “ 1 “, the

register 20 bit 5(20, 5) is used to select straight through or cross over mode, “ 0 “ is for straight through, and “ 1 “ is for cross

over.

RX + /- from DM9161A

RX+/- to RJ45

TX + /- from DM9161A

TX+/- to RJ45

* MDI : __________

* MDIX : - - - - - - - - -

This feature is able to detect the required cable connection type.( straight through or crossed over ) and make correction

automatically