XC68HC705JB3 Motorola, XC68HC705JB3 Datasheet - Page 79

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

10.4.1 Voltage Regulator
MC68HC05JB3
REV 1
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.
This regulator can be switched off by user program to save power when the device
is in suspend mode. Please note that if the regulator is off, the D– line should be
tied to another voltage source with an external pull-up resistor.
VROFF — USB 3.3V Voltage Reference
DDRC
$0006
The 3.3V Voltage Regulator for the USB transmitter and external D– pull-up can
be switched off to reduce power consumption when device is in suspend mode.
reset:
1 = Disable 3.3V regulator.
0 = Enables 3.3V regulator.
W
R
Transceiver
4.4V
Regulator
OCMPO
Figure 10-11. Regulator Electrical Connections
external resistor. Figure 10-11 shows the worst case electrical
BIT 7
3.3V
LS
0
pullup resistor connected between a data line and a voltage
VROFF
UNIVERSAL SERIAL BUS MODULE
BIT 6
0
VROFF
R1
November 5, 1998
BIT 5
0
USB Data Lines
R1 = 1.5K
R2 = 15K
USB Cable
BIT 4
0
5%
5%
DDRC3
GENERAL RELEASE SPECIFICATION
BIT 3
0
R2
DDRC2
BIT 2
0
R2
Host
Hub
DDRC1
or
BIT 1
0
MOTOROLA
DDRC0
BIT 0
0
10-11