LAN9221i SMSC [SMSC Corporation], LAN9221i Datasheet - Page 134

• Manufacturer Part Number: LAN9221i
• Description: High-Performance 16-bit Non-PCI 10/100 Ethernet Controller with Variable Voltage I/O
• Manufacturer: SMSC [SMSC Corporation]

Revision 2.6 (12-04-08)
6.6
SYMBOL
t
t
t
t
FIFO_SEL
A[2:1]
nCS, nRD
Data Bus
t
t
t
t
csdv
acyc
t
csh
asu
adv
don
doff
doh
ah
In this mode the upper address inputs are not decoded, and any burst read of the LAN9221/LAN9221i
will read the RX Data FIFO. This mode is enabled when FIFO_SEL is driven high during a read
access. This is normally accomplished by connecting the FIFO_SEL signal to a high-order address
line. This mode is useful when the host processor must increment its address when accessing the
LAN9221/LAN9221i. Timing is identical to a PIO Burst Read, and the FIFO_SEL signal has the same
timing characteristics as the address lines.
In this mode, performance is improved by allowing an unlimited number of back-to-back read cycles.
RX Data FIFO Direct PIO Burst Reads can be performed using Chip Select (nCS) or Read Enable
(nRD). When either or both of these control signals go high, they must remain high for the period
specified.
Note that address lines A[2:1] are still used, and address bits A[7:3] are ignored.
Note: The “Data Bus” width is 16 bits.
Note 6.5
Note: An RX Data FIFO Direct PIO Burst Read cycle begins when both nCS and nRD are asserted.
RX Data FIFO Direct PIO Burst Reads
DESCRIPTION
nCS, nRD Deassertion Time
nCS, nRD Valid to Data Valid
Address Cycle Time
Address, FIFO_SEL Setup to nCS, nRD Valid
Address Stable to Data Valid
Address, FIFO_SEL Hold Time
Data Buffer Turn On Time
Data Buffer Turn Off Time
Data Output Hold Time
The cycle ends when either or both nCS and nRD are deasserted. They may be asserted and
deasserted in any order.
Figure 6.5 RX Data FIFO Direct PIO Burst Read Cycle Timing
When VDDVARIO is 3.3V or 2.5V, the maximum T
1.8V, the maximum T
Table 6.6 RX Data FIFO Direct PIO Burst Read Cycle Timing
doff
DATASHEET
time is 9ns.
134
High-Performance 16-bit Non-PCI 10/100 Ethernet Controller with Variable Voltage I/O
MIN
13
45
0
0
0
0
doff
time is 7ns. When VDDVARIO is
TYP
SMSC LAN9221/LAN9221i
Note 6.5
MAX
30
40
Datasheet
UNITS
ns
ns
ns
ns
ns
ns
ns