CS8900A
Crystal LAN™ ISA Ethernet Controller
exit from this mode, the SLEEP pin must be driven
high. Upon exit, the CS8900A performs a complete
To enter SW Suspend mode, the host must set the
SWSuspend bit (Register 15, SelfCTL, bit 8). To
reset, and then goes through a normal initialization exit SW Suspend, the host must write to the
procedure.
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.
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).
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
HWStandbyE
HWSleepE
SWSuspend
(Pin 77) (SelfCTL, Bit A) (SelfCTL, Bit 9) (SelfCTL, Bit 8) Link Activity
Low
1
1
N/A
Not Present HW Standby mode: 10BASE-T
receiver listens for link activity
Low
Low
1
0
1
1
1
N/A
N/A
0
Present
N/A
HW Standby mode: LANLED low
HW Suspend mode
Low to
High
N/A
N/A
CS8900A resets and goes through
initialization
High
High
Low
Low
N/A
N/A
N/A
N/A
N/A
N/A
0
0
N/A
N/A
N/A
N/A
Not in low-power mode
SW Suspend mode
SW Suspend mode
Not in low-power mode
1
0
0
Notes: 1. Both HW and HW Suspend take precedence over SW Suspend.
Table 8. Low-Power Mode Operation
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DS271PP3
27
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