MIC2550 Micrel Semiconductor, MIC2550 Datasheet - Page 7

• Manufacturer Part Number: MIC2550
• Description: Universal Serial Bus Transceiver Advance Information
• Manufacturer: Micrel Semiconductor

Block Diagram
Applications Information
The MIC2550 is designed to provide USB connectivity in
mobile systems where system supply voltages are not avail-
able to satisfy USB requirements. The MIC2550 can operate
down to supply voltages of 2.5V and still meet USB physical
layer specifications. As shown in the system diagram, the
MIC2550 takes advantage of USB’s supply voltage, V
operate the transceiver. The system voltage, V
set the reference voltage used by the digital I/O lines (VP, VM,
RCV, OE#, SPD, and SUS pins) interfacing to the system.
Internal circuitry provides translation between the USB and
system voltage domains. V
voltage rail for the system.
In addition, a 3.3V, 10% termination supply voltage, V
provided to support speed selection. A 0.47 F (minimum)
capacitor from V
A 1.5K resistor is required between this pin and the D+ or D–
lines to respectively specify full-speed or low-speed opera-
tion.
Suspend
When the suspend pin (SUS) is high, power consumption is
reduced to a minimum. V
VM are still functional to enable the device to detect USB
activity. For minimal current consumption in suspend mode,
it is recommended that OE# = 1.
October 4, 1999
MIC2550
TRM
to ground is required to ensure stability.
TRM
IF
will typically be the main supply
is not disabled. RCV, VP and
SPD
RCV
SUS
OE#
VIF
VM
VP
VOLTAGE DOMAIN
SYSTEM I/F
IF
, is used to
BUS
TRM
, to
, is
GND
INTERNAL
Regulator
CIRCUITS
7
USB VOLTAGE DOMAIN
TO
External ESD Protection
The use of ESD transient protection devices is not required
for operation, but is recommended.
Nonmultiplexed Bus
To save pin count for the USB logic controller interface, the
MIC2550 was designed with V
To interface the MIC2550 with a nonmultiplexed data bus,
resistors can be used for low cost isolation as shown in
Figure 6.
Figure 6. MIC2550 Interface to
USB Logic
Controller
Nonmultiplexed Data Bus.
(SIE)
VBUS
VTRM
D–
D+
V
V
V
V
MO
PO
M
P
10k
10k
P
and V
V
V
P
M
MIC2550
M
as bidirectional pins.
MIC2550
Micrel