Datasheet
MCF5227x ColdFire
®
Microprocessor Data Sheet, Rev. 8
Electrical Characteristics
Freescale Semiconductor34
5.12 SSI Timing Specifications
This section provides the AC timings for the SSI in master (clocks driven) and slave modes (clocks input). All timings are given
for non-inverted serial clock polarity (SSI_TCR[TSCKP] = 0, SSI_RCR[RSCKP] = 0) and a non-inverted frame sync
(SSI_TCR[TFSI] = 0, SSI_RCR[RFSI] = 0). If the polarity of the clock and/or the frame sync have been inverted, all the timings
remain valid by inverting the clock signal (SSI_BCLK) and/or the frame sync (SSI_FS) shown in the figures below.
P side Impedance Driven Z
P
6.25 8.25 11.25 Ω
M side Impedance Driven Z
M
6.25 8.25 11.25 Ω
Impedance Matching P/M Z
Matching
— 0.17 0.23 Ω
Pulldown Resistance
1
R
PD
30k 50k 70k Ω
1
The pulldown resistors are included to provide a method to keep DP and DM signals in a known quiescent state
if desired when the USB port is not being used or when the USB cable is not connected. These on-chip
resistors should not be used to provide the 15-kΩ host-mode pulldowns called for in Chapter 7 of the USB
Specification, Rev. 1.1 or Rev. 2.0.
Table 24. USB On-Chip Transceiver Full Speed AC Characteristics
Characteristic Condition Symbol Min Typ Max Unit
Rise Time 10–90% t
LH
71117.5ns
Fall Time 90–10% t
HL
71117.5ns
Rise/Fall Matching —
Matching
20 40 60 ps
Rise/Fall Matching, DP and DM —
Pad-to-Pad
330 360 640 ps
TIme Skew Between DP and DM — t
SKE
100 140 210 ps
Table 25. USB On-Chip Transceiver Low Speed AC Characteristics
Characteristic Condition Symbol Min Typ Max Unit
Rise Time 10–90% t
LH
75 — 300 ns
Fall Time 90–10% t
HL
75 — 300 ns
Rise/Fall Matching
Matching
80 — 125 %
Table 26. SSI Timing—Master Modes
1
Num Characteristic Symbol Min Max Unit Notes
S1 SSI_MCLK cycle time t
MCLK
4 × 1/f
SYS
—ns
2
S2 SSI_MCLK pulse width high / low 45% 55% t
MCLK
S3 SSI_BCLK cycle time t
BCLK
4 × 1/f
SYS
—ns
3
S4 SSI_BCLK pulse width 45% 55% t
BCLK
Table 23. USB On-Chip Transceiver DC Characteristics (continued)
Characteristic Condition Symbol Min Typ Max Unit
t
LH
t
HL
--------
t
LH
t
HL
--------
t
LH
t
HL
--------
t
LH
t
HL
--------