CM2400-01 Datasheet, PDF (11/14 Pages) California Micro Devices Corp – Universal Serial Bus Transceiver with Level Translator

CM2400-01
Functional Description (cont’d)
Detailed in Table 4 and Table 5 are the operating
modes selected when MODE is set to LOW and HIGH.
When MODE = HIGH, the differential input data inter-
face mode is selected. The two driver inputs function
as V_MO and V_PO. When MODE = LOW, the single-
ended input data interface mode is selected. The two
driver inputs function as FSE0 and V_O.
MODE
V_O
L
L
(single-ended)
L
H
FSE0
L
H
L
Result
Logic ‘0’
SE0
Logic ‘1’
H
H
SE0
Table 4: Operating Mode (OE = L)
Detection of a V_BUS voltage is accomplished via an
internal Comparator with hysteresis. The output from
this Comparator is fed via the level translator to ensure
compatibility with processor core voltages and output
to pin USB_DET. When V_BUS is over 4.1V, USB_DET
is HIGH. When V_BUS is under 3.6V, USB_DET is LOW.
The CM2400-01HB USB transceiver includes an enu-
meration pin (ENUM) which internally connects V_PU to
V_REG when enabled. This allows a processor running
at a core voltage different than 3.3V to switch the pull-
up resistor in and out without the need for external cir-
cuitry.
MODE
V_O
H
L
(differential)
L
H
H
FSE0
L
H
L
H
Result
SE0
Logic ‘0’
Logic ‘1’
Undefined
Table 5: Operating Mode (OE = L)
Table 6 details the receiving function when OE is HIGH
(driver disabled). RCV denotes the signal level on the
output RCV just before an SE0 state occurs. This level
is stable during the SE0 period.
D+/D-
RCV
V_P
V_M
Differential Logic ’0’
L
L
H
Differential Logic ’1’
H
H
L
SE0
RCV* L
L
Table 6: Receiving Function (SPND = L)
Note 1: Denotes RCV is stable in last state before
SE0 condition.
© 2003 California Micro Devices Corp. All rights reserved.
10/01/03 430 N. McCarthy Blvd., Milpitas, CA 95035-5112 L Tel: [phone] L Fax: [phone] L www.calmicro.com 11