SP231A Datasheet, PDF (6/8 Pages) Sipex Corporation – Enhanced RS-232 Line Drivers/Receivers

+5V INPUT
7
V_CC
T₁ IN
2
400k Ω
T₁
5
T₂ IN
1
400k Ω
T₂
18
R₁OUT
R₂OUT
Do not make
connection to
these pins
Internal
-10V Power
Supply
Internal
+10V Power
Supply
3
R₁
4
5k Ω
20
8 _{C 1+}
13
C 1-
12
V-
17 _V-
14
V+
R₂
19
5k Ω
SP233A
GND
GND
C ₂ + ¹¹
C 2 + ¹⁵
C 2 - ¹⁰
16
C2 -
6
9
T ₁OUT
T ₂OUT
R ₁IN
R ₂IN
+5V INPUT
7
V_CC
T₁ IN
2
400k Ω
T₁
5
T₂ IN
1
400k Ω
T₂
18
R₁OUT
R₂OUT
Do not make
connection to
these pins
Internal
-10V Power
Supply
Internal
+10V Power
Supply
3
R₁
4
5k Ω
20
13 _{C 1+}
14 _{C 1-}
10
V-
17
V-
8
V+
R₂
19
5k Ω
SP233ACT
GND
GND
C ₂ + ¹²
C 2 + ¹⁵
C 2 - ¹¹
16
C2 -
6
9
T ₁OUT
T ₂OUT
R ₁IN
R ₂IN
Figure 4. Typical Circuits using the SP233ACP and SP233ACT
Shutdown (SD) and Enable (EN)
SP310A/SP312A Only
Both the SP310A and SP312A have a shut-down/
standby mode to conserve power in battery-pow-
ered systems. To activate the shutdown mode,
which stops the operation of the charge pump, a
logic “0” is applied to the appropriate control line.
For the SP310A, this control line is ON/OFF (pin
18). Activating the shutdown mode also puts the
SP310A transmitter and receiver outputs in a high
impedance condition (tri-stated). The shutdown
mode is controlled on the SP312A by a logic “0”
on the SHUTDOWN control line (pin 18); this also
puts the transmitter outputs in a tri–state mode.
The receiver outputs can be tri–stated separately
during normal operation or shutdown by a logic
“1” on the ENABLE line (pin 1).
Wake–Up Feature (SP312A Only)
The SP312A has a wake–up feature that keeps
all the receivers in an enabled state when the
device is in the shutdown mode. Table 1 defines
the truth table for the wake–up function.
After the ring indicator signal has propagated
through the SP312A receiver, it can be used to
trigger the power management circuitry of the
computer to power up the microprocessor, and
bring the SD pin of the SP312A to a logic high,
taking it out of the shutdown mode. The receiver
propagation delay is typically 1µs. The enable
time for V⁺ and V^– is typically 2ms. After V⁺ and
V^– have settled to their final values, a signal can
be sent back to the modem on the data terminal
ready (DTR) pin signifying that the computer is
ready to accept and transmit data.
Pin Strapping — SP233ACT Only
The SP233A packaged in the 20–pin SOIC
package (SP233ACT) has a slightly different
pinout than the SP233A in other package
configurations. To operate properly, the following
pairs of pins must be externally wired together:
the two V– pins (pins 10 and 17)
the two C₂+ pins (pins 12 and 15)
the two C₂– pins (pins 11 and 16)
With only the receivers activated, the SP312A
typically draws less than 5µA supply current
(10µA maximum). In the case of a modem
interfaced to a computer in power down mode,
the Ring Indicator (RI) signal from the modem
would be used to "wake up" the computer,
allowing it to accept data transmission.
All other connections, features, functions and
performance are identical to the SP233A as
specified elsewhere in this data sheet.
SD EN
0
0
0
1
1
0
1
1
Power
Up/Down
Down
Down
Up
Up
Receiver
Outputs
Enable
Tri–state
Enable
Tri–state
SP231ADS/01
Table 1. Wake-up Function Truth Table.
SP231A Enhanced RS-232 Line Drivers/Receivers
© Copyright 2000 Sipex Corporation
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