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

SP207E_00_072309

8

SHuTDOwN MODE

SP211E and SP213E feature a control input

which will shut down the device and reduce

the power supply current to less than 0µA,

making the parts ideal for battery–powered

systems. Inshutdownmodethetransmitters

will discharge to ground. Shutdown will tri-

state all receiver outputs of the

SP211E.

SP213E wAKEuP FuNCTION

On the

SP213E, shutdown will tri-state re-

ceivers -3. Receivers 4 and 5 remain active

to provide a “wake-up” function and may be

used to monitor handshaking and control

inputsforactivity.Withonlytworeceivers

active during shutdown, the

SP213E draws

only 5–0µA of supply current.

ManystandardUARTdevicesmaybecon-

figuredtogenerateaninterruptsignalbased

on changes to the Ring Indicate (RI) or other

inputs. A typical application of this function

would be to detect modem activity with the

computer in a power–down mode. The ring

indicator signal from the modem could be

passed through an active receiver in the

SP213E that is itself in the shutdown mode.

The ring indicator signal would propagate

through the

SP213E to the power manage-

ment circuitry of the computer to power up

the microprocessor and the

SP213E driv-

ers. After the supply voltage to the

SP213E

reaches +5.0V, the SHUTDOWN pin can

be disabled, taking the

SP213E out of the

shutdown mode.

All receivers that are active during shutdown

maintain 500mV (typ.) of hysteresis. All

receivers on the

SP213E may be put into

tri-state using the ENABLE pin.

SHuTDOwN CONDITIONS

For complete shutdown to occur and the

0µA power drain to be realized, the follow-

ingconditionsmustbemet:

SP211E:

• +5V must be applied to the SD pin

• ENABLE must be either Ground, +5.0V or

not connected

• the transmitter inputs must be either +5.0V

or not connected

• Receiver inputs must be >0V and <+5V

SP213E:

• 0V must be applied to the SD pin

• ENABLE must be either 0V, +5.0V or not

connected

• the transmitter inputs must be either +5.0V

or not connected

• Receiver inputs must be >0V and <+5V