5220-DS02-R datasheet(29/90 Pages) BOARDCOM

29 / 90 page

Preliminary Data Sheet

BCM5220

04/20/04

Broa d c om Co rp o r a t i o n

Document

5220-DS04-405-R

Auto Power-Down Mode

Page 17

POWER SAVING MODES

Several power saving modes are implemented in the BCM5220, which target PCMCIA and CardBus applications.

Table 5 on page 17 shows low power modes available in the BCM5220. Low power modes can be achieved either by

hardware pin or MII register programming. The table shows both hardware pin and software bits that determine the low

power modes and whether the BCM5220 keeps the clocks and the energy detect circuitry active. The BCM5220 requires a

hard reset for a minimum of 20

µs to return to normal mode from a low power mode if the clocks are not running. Allow at

least 2 ms before resuming normal operation with the BCM5220 after the device is set to run in normal mode from a low

power mode. It is necessary to choose an appropriate low power mode if the energy detection function support is required

while the BCM5220 is in low power mode.

AUTO POWER-DOWN MODE

In addition to various low power modes shown in Table 5, the BCM5220 also supports a special low power mode called Auto

Power Down Mode. Auto Power Down mode is enabled by setting bit 5 of Shadow register 1Bh. When in this mode, the

BCM5220 automatically enters the low power mode if the energy from the Link partner is lost. Similarly, the next time energy

is detected, the chip resumes full power mode. When the BCM5220 is in this low power mode, it wakes up after 2.5/5.0s

(approximately), as determined by bit 4 of Shadow register 1Bh, and send link pulse while monitoring energy from the Link

partner. If energy is detected, the BCM5220 enters full power mode and establishes link with the Link partner. Otherwise,

the wake-up mode continues for a duration of 40-600 ms (approximately) as determined by bits [3:0] of Shadow register 1Bh

before going to low power mode. See the Shadow register, Table 8 on page 23, for a details of various bits.

Table 5: Low Power Modes

Low_PWR

Reset#

Force IDDQ

Low_pwr Mode

Enable Clock

Clocks

Energy Detect

XXX

OFF

010

RUN

OFF

110

OFF

110

RUN

010

OFF

010

RUN

LOW_PWR: Pin-16 (BCM5220KPT), Pin-F1 (BCM5220KPB)

RESET#: Pin-9 (BCM5220KPT), Pin-D2 (BCM5220KPB)

FORCE IDDQ: Bit-0 of Shadow register 1Ah

LOW PWR MODE: Bit-1 of Shadow register 1Ah

ENABLE CLOCK: Bit-2 of Shadow register 1Ah

X = 1/0 or Don’t Care

5220-DS02-R 数据表(PDF) 29 Page - Broadcom Corporation.

5220-DS02-R 数据表(HTML) 29 Page - Broadcom Corporation.

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