SN74CBT16811C

24BIT FET BUS SWITCH WITH PRECHARGED OUTPUTS

5V BUS SWITCH WITH 2V UNDERSHOOT PROTECTION

SCDS118C − JANUARY 2003 − REVISED OCTOBER 2003

2

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

description/ordering information (continued)

The SN74CBT16811C is organized as two 12-bit bus switches with separate output-enable (1OE, 2OE) inputs.

It can be used as two 12-bit bus switches or as one 24-bit bus switch. When OE is low, the associated 12-bit

bus switch is ON, and the A port is connected to the B port, allowing bidirectional data flow between ports. When

OE is high, the associated 12-bit bus switch is OFF, and a high-impedance state exists between the A and B

ports. The B port is precharged to BIASV through the equivalent of a 10-k

Ω resistor when OE is high, or if the

device is powered down (VCC = 0 V).

During insertion (or removal) of a card into (or from) an active bus, the card’s output voltage may be close to

GND. When the connector pins make contact, the card’s parasitic capacitance tries to force the bus signal to

GND, creating a possible glitch on the active bus. This glitching effect can be reduced by using a bus switch

with precharged bias voltage (BIASV) of the bus switch equal to the input threshold voltage level of the receivers

on the active bus. This method will ensure that any glitch produced by insertion (or removal) of the card will not

cross the input threshold region of the receivers on the active bus, minimizing the effects of live-insertion noise.

This device is fully specified for partial-power-down applications using Ioff. The Ioff feature ensures that

damaging current will not backflow through the device when it is powered down. The device has isolation during

power off.

To ensure the high-impedance state during power up or power down, OE should be tied to VCC through a pullup

resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

ORDERING INFORMATION

TA

PACKAGE†

ORDERABLE

PART NUMBER

TOP-SIDE

MARKING

SSOP − DL

Tube

SN74CBT16811CDL

CBT16811C

SSOP − DL

Tape and reel

SN74CBT16811CDLR

CBT16811C

−40

°C to 85°C

TSSOP − DGG

Tube

SN74CBT16811CDGG

CBT16811C

−40 C to 85 C

TSSOP − DGG

Tape and reel

SN74CBT16811CDGGR

CBT16811C

TVSOP − DGV

Tape and reel

SN74CBT16811CDGVR

CY811C

† Package drawings, standard packing quantities, thermal data, symbolization, and PCB design

guidelines are available at www.ti.com/sc/package.

FUNCTION TABLE

(each 12-bit bus switch)

INPUT

INPUT/OUTPUT

FUNCTION

INPUT

OE

INPUT/OUTPUT

A

FUNCTION

L

B

A port = B port

H

Z

Disconnect

B port = BIASV