MIC2551A MICREL [Micrel Semiconductor], MIC2551A Datasheet - Page 8

• Manufacturer Part Number: MIC2551A
• Description: USB TRANSCEIVER
• Manufacturer: MICREL [Micrel Semiconductor]

MIC2551A
Power Supply Configuration
The MIC2551A can be set up for different power supply
configurations which modify the behavior of the device. Both
V
are either removed or grounded. Table 3 depicts the behavior
under the different power supply configuration scenarios that
are explained below.
Normal Mode
V
connected to a supply voltage in the range of 1.6V to 3.6V. In
this case V
speed select resistor via V
pin.
Disconnect Mode
V
V
ting, the data lines (D+, D–) have sharing capability and may
be driven with external devices up to approximately 3.6V if
and only if SUSPEND is enabled (SUS = 1). With V
ground, D+, D– sharing mode is not permitted.
Disable Mode
V
open. All logic controlled inputs become high impedances,
thus minimal current will be supplied by V
pulled up to an external source.
Alternate Power Supply Configuration Options
I/O Interface Using 3.3V
In systems where the I/O interface utilizes a 3.3V USB
controller, an alternate solution is shown in Figure 7. No extra
components are required; however, the load on V
not exceed 10mA.
Bypass Input
V
range of 3.0V to 3.6V. The internal regulator is bypassed and
the internal circuitry is run from the V
M9999-051004
BUS
BUS
IF
BUS
BUS
BUS
is connected to a supply in a range of 1.6V to 3.6V and
is open or grounded. If V
and V
and V
is connected to the 5.0V USB bus voltage and V
is connected to the 5.0V USB bus voltage and V
3.3V
Controller
IF
Figure 7. I/O Interface Using 3.3V
TRM
TRM
V
USB
Figure 8. Powering MIC2551A
DD
have special thresholds that detect when they
are tied together to a supply voltage in the
supplies a 3.3V voltage for powering the
VIF
from External 3.3V
MIC2551A
I/O
PU
VIF
V
RCV/OE#
VTRM
VBUS
depending on the state of CON
P
/V
BUS
MIC2551A
M
/
is opened while transmit-
TRM
VTRM
VBUS
IF
input. See Figure 8.
3.3V
if the input pins are
VBUS
TRM
must
IF
IF
BUS
is
is
8
Signal Amplitude Respective to V
When operating the MIC2551A, it is necessary to provide
input signals which do not exceed V
Suspend
When the suspend pin (SUS) is high, power consumption is
reduced to a minimum. V
are still functional to enable the device to detect USB activity.
For minimal current consumption in suspend mode, it is
recommended that OE# = 1, and SPD = 0.
Speed
The speed pin (SPD) sets D+/D– output edge rates by increas-
ing or decreasing biasing current sources within the output
drivers. For low speed, SPD = 0. For full speed, SPD = 1. By
setting SPD = 0 during idle periods, in conjunction with suspend
(SUS), the lowest quiescent current can be obtained. However,
designers must provide a 300ns delay between changing SPD
from 0 to 1 and transmission of data at full speed. This delay
ensures the output drivers have arrived at their proper operating
conditions. Failure to do so can result in leading edge distortion
on the first few data bits transmitted.
External ESD Protection
The use of ESD transient protection devices is not required
for operation, but is recommended. We recommend the
following devices or the equivalent:
Cooper Electronic Technologies (www.cooperet.com)
Littelfuse (www.littelfuse.com)
Non-Multiplexed Bus
In order to save pin count for the USB logic controller
interface, the MIC2551A was designed with V
directional pins. To interface the MIC2551A with a non-
multiplexed data bus, resistors can be used for low cost
isolation as shown in Figure 9.
41206ESDA SurgX
0805ESDA SurgX
V0402MHS05
SP0503BAHT
Figure 9. MIC2551A Interface to
Non-Multiplexed Data Bus
USB Logic
Controller
(SIE)
V
V
V
V
MO
PO
TRM
M
P
is not disabled. RCV, V
10k
10k
V
V
MIC2551A
P
M
IF
IF
+ 0.3V.
P
and V
May 2004
P
and V
M
Micrel
as bi-
M