SP231ADS/01

SP231A Enhanced RS-232 Line Drivers/Receivers

© Copyright 2000 Sipex Corporation

6

20

19

R IN

R OUT

2

R

1

34

R IN

R OUT

1

1

18

T IN

2

T OUT

2

2

5

T IN

1

T OUT

1

9

GND

400k

Ω

400k

Ω

14

13

C +

C -

V-

V-

V+

1

1

11

7

V

CC

+5V INPUT

12

2

1

5k

Ω

5k

Ω

17

10

C +

C +

C -

C -

2

2

GND

6

8

15

16

2

2

Do not make

connection to

these pins

Internal

-10V Power

Supply

Internal

+10V Power

Supply

SP233ACT

20

19

R IN

R OUT

2

R

1

34

R IN

R OUT

1

1

18

T IN

2

T OUT

2

2

5

T IN

1

T OUT

1

9

GND

400k

Ω

400k

Ω

13

8

C +

C -

V-

V-

V+

1

1

10

7

V

CC

+5V INPUT

11

2

1

5k

Ω

5k

Ω

17

12

C +

C +

C -

C -

2

2

GND

6

14

15

16

2

2

Do not make

connection to

these pins

Internal

-10V Power

Supply

Internal

+10V Power

Supply

SP233A

Figure 4. Typical Circuits using the SP233ACP and SP233ACT

Table 1. Wake-up Function Truth Table.

SD

EN

Power

Up/Down

Receiver

Outputs

0

0

1

1

0

1

0

1

Down

Down

Up

Up

Enable

Tri–state

Enable

Tri–state

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.

With only the receivers activated, the SP312A

typically draws less than 5

µA supply current

(10

µA 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.

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 1

µs. The enable

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 C

the two C

All other connections, features, functions and

performance are identical to the SP233A as

specified elsewhere in this data sheet.