XC68HC705JB3 Motorola, XC68HC705JB3 Datasheet - Page 82

• Manufacturer Part Number: XC68HC705JB3
• Description: MICROCONTROLLER
• Manufacturer: Motorola

GENERAL RELEASE SPECIFICATION
10.4.3.3 Data Signal Rise and Fall Time
10.4.4 USB Control Logic
MOTOROLA
10-14
measured with the same capacitive load used for maximum rise and fall times and
is measured at the crossover points of the data lines as shown in Figure 10-14.
For low speed transmissions, the jitter time for any consecutive differential data
transitions must be within
differential data transitions. These jitter numbers include timing variations due to
differential buffer delay, rise/fall time mismatches, internal clock source jitter, and
to noise and other random effects.
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
75 ns (minimum) into a capacitive load (C
capacitive load of 350 pF. The rising and falling edges should be smooth
transitional (monotonic) when driving the cable to avoid excessive EMI.
The USB control logic manages data movement between the CPU and the
transceiver. The control logic handles both transmit and receive operations on the
USB. It contains the logic used to manipulate the transceiver and the endpoint
registers. The logic contains byte count buffers for transmit operations that load
the active transmit endpoints byte count and use this to determine the number of
bytes to transfer. This same buffer is used for receive transactions to count the
number of bytes received and, upon the end of the transaction, transfer that
number to the receive endpoints byte count register.
DIFFERENTIAL
DATA LINES
t
Period
Figure 10-15. Data Signal Rise and Fall Time
C
C
L
L
DIFFERENTIAL
DATA LINES
UNIVERSAL SERIAL BUS MODULE
CONSECUTIVE
TRANSITIONS
Figure 10-14. Data Jitter
November 5, 1998
25 ns and within
LOW SPEED: 75 ns at C
10%
TRANSITIONS
PAIRED
RISE TIME
t
L
R
) of 50 pF and 300 ns (maximum) into a
CROSSOVER
POINTS
90%
L
= 50 pF, 300 ns at C
10 ns for any set of paired
90%
FALL TIME
t
L
F
= 350 pF
10%
MC68HC05JB3
REV 1