CS8900A datasheet(27/128 Pages) CIRRUS

27 / 128 page

DS271PP3

CS8900A

Crystal LAN™ ISA Ethernet Controller

CIRRUS LOGIC PRODUCT DATA SHEET

exit from this mode, the SLEEP pin must be driven

high. Upon exit, the CS8900A performs a complete

reset, and then goes through a normal initialization

procedure.

3.7.3 Software Suspend

Software (SW) Suspend mode can be used to con-

serve power in applications, like adapter cards, that

do not have power management circuitry available.

During this mode, all internal circuits are shut off

except the I/O Base Address register (PacketPage

base + 0020h) and the SelfCTL register (Register

15).

To enter SW Suspend mode, the host must set the

SWSuspend bit (Register 15, SelfCTL, bit 8). To

exit SW Suspend, the host must write to the

CS8900A’s assigned I/O space (the Write is only

used to wake the CS8900A, the Write itself is ig-

nored). Upon exit, the CS8900A performs a com-

plete reset, and then goes through a normal

initialization procedure.

Any hardware reset takes the chip out of any sleep

mode.

Table 8 summarizes the operation of the three low-

power modes.

CS8900A Configuration

CS8900A Operation

SLEEP

(Pin 77)

HWStandbyE

(SelfCTL, Bit A)

HWSleepE

(SelfCTL, Bit 9)

SWSuspend

(SelfCTL, Bit 8) Link Activity

Low

N/A

Not Present

HW Standby mode: 10BASE-T

receiver listens for link activity

Low

N/A

Present

HW Standby mode: LANLED low

Low

N/A

HW Suspend mode

Low to

High

N/A

CS8900A resets and goes through

initialization

High

N/A

Not in low-power mode

High

N/A

SW Suspend mode

Low

N/A

SW Suspend mode

Low

N/A

Not in low-power mode

Notes: 1. Both HW and HW Suspend take precedence over SW Suspend.

Table 8. Low-Power Mode Operation

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