E749BPJ 查看數據表（PDF） - Semtech Corporation

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E749BPJ

Octal Pin Electronics Driver/Receiver

Semtech Corporation 

Edge749

TEST AND MEASUREMENT PRODUCTS

Application Information (continued)

Also, either the pull up or pull down resistor could be

used to terminate the transmission from the DUT to the

pin electronics in an effort to minimize any reflections.

VHIGH A

VLOW A

DATA IN A

DVR EN*A

DATA IN B

DVR EN*B

VHIGH B

VPULL UP

DUT

VLOW B

VPULL DOWN

Figure 9. Driver with Pull Up/Pull Down

Trinary Driver with Termination

Two Logic Family Driver

Many test systems support exactly two families of driver

and receiver levels and select between family A and family

B settings on a per-pin basis, typically using an analog

multiplexer (See Figure 11). Common examples of these

families are:

Family A = TTL

Family B = CMOS

or

Family A = TTL

Family B = ECL

The Edge749 supports this system architecture with

minimal hardware and the elimination of the per-pin

analog multiplexer. The drive and receive levels need to

be generated once per system, then distributed and

buffered suitably.

Other combinations are also possible. For example, two

parallel drivers can be configured to implement one

trinary driver with a pull down (or pull up) dynamic

termination (see Figure 10).

VHIGH A

VLOW A

DATA IN A

Parametric Functions

Two drivers in parallel also offer the possibility of

connecting force and sense parametric circuitry to the

DUT without adding additional circuitry to the controlled

impedance DUT line. For example, Figure 12 shows the

second driver being utilized to force a current and

measure a voltage.

DVR EN*A

DATA IN B

VHIGH B

VTERMINATION

Notice that the VHIGH and VLOW pins are used from

DUT different drivers to allow the force and sense functions

to be active simultaneously.

DVR EN*B

Figure 10. Trinary Driver with Termination

Revision 3 / October 21, 2002

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