NLSX5011

http://onsemi.com

10

IMPORTANT APPLICATIONS INFORMATION

Level Translator Architecture

The

NLSX5011

auto−sense

translator

provides

bi−directional logic voltage level shifting to transfer data

in multiple supply voltage systems. These level translators

levels on the input and output sides of the translator. When

The NLSX5011 translator consists of bi−directional

channels that independently determine the direction of the

data flow without requiring a directional pin. One−shot

circuits are used to detect the rising or falling input signals.

In addition, the one−shots decrease the rise and fall times

of the output signal for high−to−low and low−to−high

transitions.

Input Driver Requirements

Auto−sense translators such as the NLSX5011 have a

wide bandwidth, but a relatively small DC output current

rating. The high bandwidth of the bi−directional I/O circuit

is used to quickly transform from an input to an output

driver and vice versa. The I/O ports have a modest DC

current output specification so that the output driver can be

over driven when data is sent in the opposite direction. For

proper operation, the input driver to the auto−sense

translator should be capable of driving 2 mA of peak output

current. The bi−directional configuration of the translator

results in both input stages being active for a very short time

period. Although the peak current from the input signal

circuit is relatively large, the average current is small and

consistent with a standard CMOS input stage.

Enable Input (EN)

The NLSX5011 translator has an Enable pin (EN) that

provides tri−state operation at the I/O pins. Driving the

Enable pin to a low logic level minimizes the power

operation occurs when the EN pin is equal to a logic high

Over−Voltage Tolerant (OVT) protection.

Uni−Directional versus Bi−Directional Translation

The NLSX5011 translator can function as a

non−inverting uni−directional translator. One advantage of

using the translator as a uni−directional device is that each

I/O pin can be configured as either an input or output. The

configurable input or output feature is especially useful in

applications such as SPI that use multiple uni−directional

I/O lines to send data to and from a device. The flexible I/O

port of the auto sense translator simplifies the trace

connections on the PCB.

Power Supply Guidelines

anywhere between 0.9 and 4.5 V. Design flexibility is

competitive auto sense translators has a restriction that the

0.4) V.

The sequencing of the power supplies will not damage

the device during power−up operation. In addition, the I/O

either supply voltage is equal to 0 V. For optimal

performance, 0.01 to 0.1

mF decoupling capacitors should

capacitors are a good design choice to filter and bypass any

noise signals on the voltage lines to the ground plane of the

PCB. The noise immunity will be maximized by placing

the capacitors as close as possible to the supply and ground

pins, along with minimizing the PCB connection traces.

The NLSX5011 translators have a power down feature

that provides design flexibility. The output ports are

This feature causes all of the I/O pins to be in the power

saving high impedance state.