
2003 California Micro Devices Corp. All rights reserved.
10
430 N. McCarthy Blvd., Milpitas, CA 95035-5112
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Tel: 408.263.3214
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Fax: 408.263.7846
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www.calmicro.com
10/01/03
CM2400-01
Functional Description
The CM2400-01HB USB Transceiver supports 3 differ-
ent power supply configurations, which can be config-
ured
dynamically.
Table 1
configurations. In Normal Mode the internal regulator
produces 3.3V from V
BUS
to power the internal drivers
and receivers associated with the USB protocol.
details
the
various
Table 1: Power Supply Connections
There are three power supply configurations for the
CM2400-01HB: Normal mode, Disable mode and
Sharing mode. These three modes can be changed
dynamically.
Normal mode occurs when the V
CC
and V
BUS
inputs
are both connected to a source. V
BUS
is tied to a 5V
source for 5V operation. The internal regulator of the
CM2400-01HB provides 3.3V output on V
REG
. The
V
CC
input is connected to an independent source that
can range from 1.65V to 3.3V.
When V
CC
is not connected and V
BUS
is connected,
the device is in Disable mode. The D+ and D- pins are
in tri-state and power consumption drops to a suspend
state level.
In Sharing mode, V
CC
is connected while V
BUS
is
below 3.6V. The D+ and D- pins are in tri-state and the
CM2400 allows external signals (<3.6V) to share these
two lines. The CM2400-01HB is designed to draw
almost zero current from the D+ and D- lines while in
sharing mode. In this mode, V
P
and V
M
are driven high
while RCV and USB_DET are driven low.
In Disable and Sharing Mode, all input/output pins fol-
low the states defined in
Table 2
.
Table 2: Pin States in Disable or Sharing Mode
Table 3
lists the functions of the modes associated with
suspend and OE pins. When Suspend is low and OE is
high, signal levels on D+ and D- are determined by
other USB devices and pull-up/down resistors. In Sus-
pend Mode (SPND = HIGH) the differential receiver is
inactive and output RCV is always LOW. Out of sus-
pend signaling is detected via the single-ended receiv-
ers V
P
and V
M
. During suspend and while the output is
still enabled (OE = LOW), D+ and D- lines are driven to
their intended states.
Table 3: Function Selection.
V
BUS
V
CC
CONFIGURATION
Connected
Connected
Normal Mode
Connected
Not Connected
Disable Mode
Not Connected
Connected
Sharing Mode
PIN
Sharing Mode
State
Disable Mode
State
V
BUS
V
BUS
< 3.6V
4.1V to 5.5V
V
REG
Pulled Down
3.3V Out
V
CC
Present
Not Present
V
PU
High-Z (off)
High-Z (off)
D+, D-
High-Z
High-Z
V
P
, V
M
H
Invalid
RCV
L
Invalid
USB_DET
L
Invalid
Inputs
High-Z
High-Z
SUSPEND
OE
D+ / D-
RCV
V
P
/V
M
Function
L
L
Driver & Receiver Active
Active
Active
Normal driving mode. Differential receiver active
L
H
Receiving
Active
Active
Driver Tri-stated. Differential receiver active.
H
L
Driving
Inactive
RCV=L
Active
Driving during ’suspend’. Differential receiver inactive.
H
H
High-Z
Inactive
RCV=L
Active
Low-power state.