SP211EH Datasheet, PDF (6/16 Pages) Exar Corporation – High Speed +5V High Performance

SHUTDOWN MODE
The SP211EH and SP213EH both feature
a control input which will disable the device
and reduce power supply to less than 10µA,
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
10µA power drain to be realized, the follow-
ing conditions must be met:
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. With only the receivers active during
shutdown, the devices draw 5-10µA of sup-
ply current.
A typical 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.
Power Receiver
SD EN Up/Down Outputs
11
Up
Enable
10
Up Tri-state
0 1 Down Enable
0 0 Down Tri-State
Table 2. SP213EH Wake-Up Truth Table
Power Receiver
SD EN Up/Down Outputs
00
Up
Enable
01
Up Tri-state
1 0 Down Enable
1 1 Down Tri-State
Table 3. SP211EH Receiver Truth Table
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com

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