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SP2EH_23EH_0_060

6

SHuTDOwN MODE

The

SP211EH and SP213EH both feature

a control input which will disable the device

and reduce power supply to less than 0µA,

making the parts ideal for battery-powered

systems. In the "shutdown" mode the

receivers and transmitters will both be tri-

stated. The V+ output of the charge pump

will discharge to Vcc and the V- output will

discharge to ground.

For complete shutdown to occur and the

0µA power drain to be realized, the follow-

ingconditionsmustbemet:

SP211EH:

• +5V must be applied to the SD pin.

• ENABLE must be either 0V, +5V or not

connected

• the transmitter inputs must be either

+5.0V or not connected

• Vcc must be +5V

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

SP213EH:

• 0V must be applied top the SD pin

• ENABLE must be either 0V, +5.0V or

not connected

• the transmitter inputs must be either

+5.0V or not connected

• Vcc must be +5V

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

ENAblE

SP211EH and SP213EH feature an enable

input, which allows the receiver outputs to

be either tri–stated or enabled. This can be

especially useful when the receiver is tied

directly to a shared microprocessor data

bus. For the

SP211EH, enable is active

low; that is, 0V applied to the ENABLE pin

will enable the receiver outputs. For the

SP213EH, enable is active high; that is, +5V

applied to the ENABLE pin will enable the

receiver outputs.

wAKE-uP FuNCTION

The

SP213EH has a wake-up feature that

keeps two receivers (R4 and R5) in an en-

abled state when the device is in shutdown

mode.Withonlythereceiversactiveduring

shutdown, the devices draw 5-0µA of sup-

ply current.

Atypical application of this function would be

where a modem is interfaced to a computer

in a power-down mode. The ring indicator

signal from the modem could be passed

through an active receiver in the

SP213EH

that is itself in the shutdown mode. The ring

indicator signal would propagate through

the

SP213EH to the power management

circuitry of the computer to power up the

microprocessor and the

SP213EH drivers.

After the supply voltage to the

SP213EH

reaches +5.0V, the SHUTDOWN pin can

be disabled, taking the

SP213EH out of the

shutdown mode.

All receivers that are active during shutdown

maintain 500mV (typical) of hysteresis.

SD EN

Power

Up/Down

Receiver

Outputs





Up

Enable



0

Up

Tri-state

0



Down

Enable

0

0

Down

Tri-State

Table2.SP213EHWake-UpTruthTable

SD EN

Power

Up/Down

Receiver

Outputs

0

0

Up

Enable

0



Up

Tri-state



0

Down

Enable





Down

Tri-State

Table 3. SP2EH Receiver Truth Table