SP238ACX datasheet(6/17 Pages) SIPEX

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Date: 8/3/04

+ 5V Powered Multi-Channel RS-232 Drivers/Receivers

FEATURES…

Themulti–channelRS-232linedrivers/receiverspro-

videsavarietyofconfigurationstofitmostcommuni-

cation needs, especially those applications where

±12V is not available. The SP230A, SP235A/B,

SP236A/B, SP240A/B, and SP241A/B feature a

shutdownmodewhichreducesdevicepowerdissipa-

tion to less than 5

µW. All feature low power CMOS

operation, which is particularly beneficial in battery-

powered systems. The SP235A/B use no external

components and are ideally suited where printed

circuit board space is limited.

All products in the Series include two charge pump

voltage converters which allow them to operate from

a single +5V supply. These converters convert the

+5V input power to the

±10V needed to generate

the RS-232 output levels. An internal charge pump

converter produces the necessary –12V supply.

All drivers and receivers meet all EIA RS-232D

and CCITT V.28 specifications.

The Series are available for use over the commer-

cial, industrial and military temperature ranges.

They are packaged in plastic DIP and SOIC

packages. For product processed and screened to

MIL–M–38510 and MIL–STD–883C require-

ments, please consult the factory.

THEORY OF OPERATION

The SP230A/B–241A/B series devices are made up

ofthreebasiccircuitblocks–1)transmitter,2)receiver

and 3) charge pump. Each model within the series

incorporates variations of these circuits to achieve the

desired configuration and performance.

Driver/Transmitter

The drivers are inverting transmitters, which accept

TTL or CMOS inputs and output the RS-232 signals

withaninvertedsenserelativetotheinputlogiclevels.

Typically the RS-232 output voltage swing is

±9V.

Evenunderworst-caseloadingconditionsof3k

Ωand

2500pF, the output is guaranteed to be

±5V, which is

consistent with the RS-232 standard specifications.

The transmitter outputs are protected against infi-

nite short-circuits to ground without degradation

in reliability.

The drivers of the SP230A, SP235A/B, SP236A/B,

SP240A/B and SP241A/B can be tri-stated by using

theSHUTDOWNfunction.Inthis“power-off”state,

the output impedance will remain greater than 300

Ohms, again satisfying the RS-232 specifications.

Should the input of the driver be left open, an internal

400k

Ω pull–up resistor to V

CC forces the input high,

thus committing the output to a low state.

The slew rate of the transmitter output is internally

limited to a maximum of 30V/

µs in order to meet the

Table 1. EIA Standards Definition

20kbps

100kbps

10Mbps

64kbps

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