mc68hc05jb4p Freescale Semiconductor, Inc, mc68hc05jb4p Datasheet - Page 77

• Manufacturer Part Number: mc68hc05jb4p
• Description: Mc68hc705jb4 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

10.4.1 Voltage Regulator
10.4.2 USB Transceiver
10.4.2.1 Output Driver Characteristics
MC68HC05JB4
REV 2
USB registers. The following will detail the function of the regulator, transceiver
and control logic. See Section 10.5 for the register discussion.
The USB data lines are required by the USB Specification to have a maximum
output voltage between 2.8V and 3.6V. The data lines are also required to have an
external 1.5K
source between 3.0V and 3.6V. Since the power provided by the USB cable is
specified to be between 4.4V and 5.0V, an on-chip regulator is used to drop the
voltage to the appropriate level for sourcing the USB transceiver and external
pullup resistor. An output pin driven by the regulator voltage is provided to source
the 1.5K
connection for the voltage regulator.
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
OL
of 0.3 V with a 1.5 k
Transceiver
Regulator
Figure 10-11. Regulator Electrical Connections
4.4V
external resistor. Figure 10-11 shows the worst case electrical
3.3V
LS
Freescale Semiconductor, Inc.
pullup resistor connected between a data line and a voltage
For More Information On This Product,
UNIVERSAL SERIAL BUS MODULE
load to ground. The output swings between the differential
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R1
February 24, 1999
load to 3.6 V and in its high state is above the V
USB Data Lines
R1 = 1.5K
R2 = 15K
USB Cable
5%
5%
GENERAL RELEASE SPECIFICATION
R2
R2
Host
Hub
or
OH