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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com

SP207E_00_072309

FEATuRES

The SP207E, SP208E, SP211E and

SP213E multi–channeltransceiversfitmost

RS-232/V.28communicationneeds.Allof

thesedevicesfeaturelow–powerCMOScon-

struction and

ExAR–proprietary on-board

charge pump circuitry to generate RS-232

signal-voltages, making them ideal for appli-

cations where +9V and -9V supplies are not

available.Thehighlyefficientchargepump

is optimized to use small and inexpensive

0.µFchargepumpcapacitors,savingboard

space and reducing overall circuit cost.

Each device provides a different driver/

receiver combination to match standard

application requirements. The

SP207E is

a 5-driver, 3-receiver device, ideal for DCE

applications such as modems, printers or

other peripherals.

SP208Eisa4-driver/4-

receiver device, ideal for providing hand-

shaking signals in V.35 applications or other

general-purpose serial communications.

The

SP211E and SP213E are each 3-driver,

5-receiver devices ideal for DTE serial ports

on a PC or other data-terminal equipment.

The

SP211E and SP213E feature a low–

powershutdownmode,whichreducespower

supply drain to µA. The

SP213E includes a

Wake-Upfunctionwhichkeepstworeceivers

activeintheshutdownmode,unlessdisabled

by the EN pin.

Thefamilyisavailablein28and24pinSO

(wide)andSSOP(shrink)smalloutlinepack-

ages.Devicescanbespecifiedforcommer-

cial(0˚Cto+70˚C)andindustrial/extended

(–40˚Cto+85˚C)operatingtemperatures.

THEORY OF OPERATION

Exar RS-232 transceivers contain three

basiccircuitblocks—a)transmitter/driver,

b) receiver and c) the

ExAR–proprietary

charge pump.

SP211E and SP213E also

include SHUTDOWN and ENABLE func-

tions.

Transmitter/Drivers

The drivers are single-ended inverting trans-

mitters,whichaccepteitherTTLorCMOS

inputs and output the RS-232 signals with

an inverted sense relative to the input logic

levels. Should the input of the driver be left

input high, thus committing the output to a

logic- (MARK) state. The slew rate of the

transmitter output is internally limited to a

maximum of 30V/µs in order to meet the

EIA/RS-232andITUV.28standards.The

transition of the output from high to low also

meets the monotonicity requirements of the

standard even when loaded. Driver output

voltage swing is ±7V (typical) with no load,

and ±5V or greater at maximum load. The

transmitter outputs are protected against

infinite short–circuits to ground without

degradation in reliability.

The drivers of the

SP211E, and SP213E

canbetri–statedbyusingtheSHUTDOWN

function. In this “power-off” state the charge

pump is turned off and V

µA typical. Driver output impedance will

remain greater than 300Ω, satisfying the

RS-232andV.28specifications.For

SP211E

SHUTDOWNisactivewhenpin25isdriven

high. For

SP213ESHUTDOWNisactive

when pin 25 is driven low.

Receivers

The receivers convert RS-232 level input

signalstoinvertedTTLlevelsignals.Because

signals are often received from a transmis-

sion line where long cables and system

interference can degrade signal quality, the

inputs have enhanced sensitivity to detect

weakened signals. The receivers also fea-

ture a typical hysteresis margin of 500mV for

cleanreceptionofslowlytransitioningsignals

in noisy conditions. These enhancements

ensure that the receiver is virtually immune

to noisy transmission lines.