CM2400-05 Datasheet, PDF (11/13 Pages) California Micro Devices Corp – Universal Serial Bus Transceiver with Level Translator

PRELIMINARY
CM2400-05
Functional Description (cont’d)
Detailed in Table 4 is the differential result for all varia-
tions on V_P/V_PO and V_M/V_MO.
V_P/V_PO
L
L
H
H
V_M/V_MO
L
H
L
H
Result
Logic ‘0’
SE0
Logic ‘1’
SE0
Table 4: Operating Mode (OE = L)
Table 5 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.
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 4.1 volts
USB_DET is HIGH. When V_BUS is under 3.6 volts
USB_DET is LOW.
The CM2400-05 USB transceiver includes an enumer-
ation 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.
D+/D-
RCV
V_P
V_M
Differential Logic ’0’
L
L
H
Differential Logic ’1’ H
H
L
SE0
RCV* L
L
Table 5: Receiving Function (SPND = L)
Note 1: Denotes RCV is stable in last state before
SE0 condition.
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