Output Drivers
To facilitate higher performance data transfer, the use of balanced CMOS active drivers for critical signals (Data,
HostAck, HostClk, PeriphAck, PeriphClk) are used ECP Mode. Because the use of active drivers can present
compatibility problems in Compatible Mode (the control signals, by tradition, are specified as open-collector), the
drivers are dynamically changed from open-collector to totem-pole. The timing for the dynamic driverchange is
specified in the IEEE 1284 Extended Capabilities Port Protocol and ISA Interface Standard, Rev. 1.14, July. 14, 1993,
available from Microsoft. The dynamic driver change must be implemented properly to prevent glitching the outputs.
t6
t3
PDATA
t1
t2
t5
nSTROBE
BUSY
t4
Parameter
min
max
units
Notes
t1
t2
t3
t4
t5
t6
DATA Valid to nSTROBE Active
nSTROBE Active Pulse Width
DATA Hold from nSTROBE Inactive
nSTROBE Active to BUSY Active
BUSY Inactive to nSTROBE Active
BUSY Inactive to PDATE Invalid
600
600
450
ns
ns
ns
ns
ns
ns
1
1
500
680
80
NOTE:
1. The data is held until BUSY goes inactive or for time t3, whichever is longer. This only
applies if another data transfer is pending. If no other data transfer is pending, the data
is held indefinitely.
FIGURE 20 - PARALLEL PORT FIFO TIMING
SMSC DS – FDC37N769
Page 133 of 137
Rev. 02-16-07
DATASHEET
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