XC68HC705JB3 Motorola, XC68HC705JB3 Datasheet - Page 80

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

GENERAL RELEASE SPECIFICATION
10.4.2 USB Transceiver
10.4.2.1 Output Driver Characteristics
10.4.2.2 Low Speed (1.5 Mbs) Driver Characteristics
10.4.3 Receiver Characteristics
MOTOROLA
10-12
The USB transceiver provides the physical interface to the USB D+ and D– data
lines. The transceiver is composed of two parts: an output drive circuit and a
differential receiver.
The USB transceiver uses a differential output driver to drive the USB data signal
onto the USB cable. The static output swing of the driver in its low state is below
the V
of 2.8 V with a 15 k
high and low state are well balanced to minimize signal skew. Slew rate control on
the driver is used to minimize the radiated noise and cross talk. The driver’s
outputs support three-state operation to achieve bi-directional half duplex
operation. The driver can tolerate a voltage on the signal pins of –0.5 V to 3.8 V
with respect to local ground reference without damage.
The rise and fall time of the signals on this cable are greater than 75 ns to keep
RFI emissions under FCC class B limits, and less than 300 ns to limit timing
delays and signaling skews and distortions. The driver reaches the specified static
signal levels with smooth rise and fall times, and minimal reflections and ringing
when driving the cable. This driver is used only on network segments between low
speed devices and the ports to which they are connected.
USB data transmission is done with differential signals. A differential input receiver
is used to accept the USB data signal. A differential 1 on the bus is represented by
D+ being at least 200 mV more positive than D– as seen at the receiver, and a
differential 0 is represented by D– being at least 200 mV more positive than D+ as
seen at the receiver. The signal cross over point must be between 1.3V and 2.0V.
V
V
SE
SE
OL
(max)
(min)
V
of 0.3 V with a 1.5 k
SS
Figure 10-12. Low Speed Driver Signal Waveforms
(1.5 Mb/s)
ONE BIT
TIME
UNIVERSAL SERIAL BUS MODULE
load to ground. The output swings between the differential
November 5, 1998
load to 3.6 V and in its high state is above the V
REFLECTIONS AND RINGING
LEVELS WITH MINIMAL
PASS OUTPUT SPEC
SIGNAL PINS
MC68HC05JB3
REV 1
OH