Datasheet

FUNCTIONAL DESCRIPTION
TUSB2551A
www.ti.com ...................................................................................................................................................................................................... SCES790 – JUNE 2009
TERMINAL FUNCTIONS
TERMINAL
NO. I/O DESCRIPTION
NAME
RGT PW
System interface supply voltage. Used to provide reference supply voltage for system I/O interface
V
CC(I/O)
15 1 I
signaling.
Speed. Edge-rate control: A logic HIGH operates at edge rates for full-speed operation. A logic LOW
SPEED 1 2 I
operates at edge rates for low-speed operation.
RCV 2 3 O Receive data. Output for USB differential data.
If OE = 1, VP = Receiver output (+)
VP 3 4 I/O
If OE = 0, VP = Driver input (+)
If OE = 1, VM = Receiver output ( – )
VM 4 5 I/O
If OE = 0, VM = Driver input ( – )
SOFTCON 5 6 I Soft connect. Controls state of V
PU(3.3)
. See V
PU(3.3)
pin description for details.
GND 6 7 Ground reference
SUSPEND 7 8 I Suspend. Active high. Turns off internal circuits to reduce supply current.
NC 8, 16 No internal connection
Output enable. Active low. Enables the transceiver to transmit data onto the bus. When inactive, the
OE 9 9 I
transceiver is in the receive mode.
D – , D+ 10, 11 10, 11 I/O Differential data lines conforming to the USB standard
3.3-V reference supply. Requires a minimum 0.1- µ F decoupling capacitor for stability. A 1- µ F capacitor is
V
reg(3.3)
12 12 O
recommended.
Pullup supply voltage. Used to connect 1.5-k Ω pullup speed detect resistor.
V
PU(3.3)
13 13 O
If SOFTCON = 1, V
PU(3.3)
is high impedance. If SOFTCON = 0, V
PU(3.3)
= 3.3 V.
V
CC(5.0)
14 14 I USB bus supply voltage. Used to power USB transceiver and internal circuitry.
FUNCTION SELECTION
SUSPEND OE D+, D – RCV VP, VM FUNCTION
0 0 Driving Active Active Normal transmit mode
0 1 Receiving Active Active Normal receive mode
1 0 Hi-Z 0 Not active Low power state
1 1 Hi-Z 0 Active Receiving during suspend (low power state)
(1)
(1) During suspend, VP and VM are active to detect out-of-band signaling conditions.
TRUTH TABLE DURING NORMAL MODE
OE = 0
INPUT OUTPUT
RESULT
VP VM D+ D – RCV
0 0 0 0 X
(1)
SE0
0 1 0 1 0 Logic 0
1 0 1 0 1 Logic 1
1 1 1 1 X
(1)
Undefined
OE = 1
INPUT OUTPUT
RESULT
D+ D – VP VM RCV
0 0 0 0 X
(1)
SE0
0 1 0 1 0 Logic 0
1 0 1 0 1 Logic 1
1 1 1 1 X
(1)
Undefined
(1) X = Undefined
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