MC908JB16DWE Datasheet, PDF (180/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
t_Period
DIFFERENTIAL
DATA LINES
JITTER
CROSSOVER
POINTS
CONSECUTIVE
TRANSITIONS
PAIRED
TRANSITIONS
Figure 11-13. Data Jitter
For low-speed transmissions, the jitter time for any consecutive
differential data transitions must be within ±25ns and within ±10ns for
any set of paired differential data transitions. These jitter numbers
include timing variations due to differential buffer delay, rise/fall time
mismatches, internal clock source jitter, noise and other random effects.
11.7.2.5 Data Signal Rise and Fall Time
The output rise time and fall time are measured between 10% and 90%
of the signal. Edge transition time for the rising and falling edges of low-
speed signals is 75ns (minimum) into a capacitive load (C_L) of 200pF
and 300ns (maximum) into a capacitive load of 600pF. The rising and
falling edges should be transitioning (monotonic) smoothly when driving
the cable to avoid excessive EMI.
+ _{CL DIFFERENTIAL}
DATA LINES
+
C_L
RISE TIME
90%
10%
t_R
FALL TIME
90%
10%
t_F
LOW SPEED: 75ns at C_L = 200pF, 300ns at C_L = 600 pF
Figure 11-14. Data Signal Rise and Fall Time
Technical Data
180
Universal Serial Bus Module (USB)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor