_______________Detailed Description

The MAX563 consists of three sections: charge-pump

voltage converters, transmitters (drivers), and

receivers. Both the transmitters and the receivers are

inverting.

+3V to ±6V, Dual Charge-Pump Voltage

Converter

Two charge pumps either invert or double the incoming

ters. The first charge pump uses capacitor C1 to

reservoir capacitor. The second charge pump uses

capacitor C2 to invert V+; this negative voltage is

stored on the V- capacitor.

When

SHDN is low, the charge pumps are turned off,

Ω resistor, and V-

rises to GND.

It is possible to draw some power from the V+ and V-

pins for external use. However, doing so diminishes the

charge-pump output voltages and reduces noise mar-

gins, so it is not recommended.

EIA/TIA-562 Transmitters

The MAX563’s drivers are inverting level translators that

convert +3V logic inputs to EIA/TIA-562 voltage levels.

With a VCC supply of only 3.0V, the driver outputs

deliver the EIA/TIA-562 ±3.7V minimum specification

under worst-case conditions—when both transmitters

are loaded with 3k

Ω receivers (either EIA/TIA-232 or

EIA/TIA-562).

The transmitters are fast: the guaranteed data rate with

standard loads is 116kbps, which is the highest rate

commonly used by PC-to-PC communication software,

such as LapLink. The highest practical data rate may

be reduced if the other communicating device (RS-562

or RS-232) is not as fast, or if the cables present an

excessive capacitive load (>1000pF). Each transmitter

is designed to drive a single receiver; transmitters can

be paralleled to drive multiple receivers.

When

SHDN is low, the driver outputs are turned off.

Their output leakage currents are less than 10µA when

pulled to GND or when driven to ±15V. This enables

two transmitters to be connected to the same line, pro-

vided that one of them is always disabled by taking

SHDN low.

+3.3V-Powered, EIA/TIA-562 Dual Transceiver

with Receivers Active in Shutdown

4

_______________________________________________________________________________________

______________________________________________________________Pin Description

10, 13

NAME

FUNCTION

EN

Receiver enable. Connect

EN to GND to enable receivers, and take EN high to disable receivers.

CMOS receiver outputs. These outputs are active regardless of the state of

SHDN. They

are enabled when

EN is low, and disabled (Hi-Z) when EN is high.

C1+

Positive terminal of positive charge-pump capacitor.

11, 12

V+

PIN

1

2

C1-

Negative terminal of positive charge-pump capacitor.

CMOS driver inputs.

C2+

Positive terminal of inverting charge-pump capacitor.

16

C2-

Negative terminal of inverting charge-pump capacitor.

GND

V-

GND when

SHDN is low.

3

4

5

Ground.

EIA/TIA-562 voltage-level transmitter outputs. These outputs are disabled (Hi-Z) when

SHDN is low.

17

EIA/TIA-562 and EIA/TIA-232 voltage-level receiver inputs.

6

7

8, 15

9, 14

+3.0V to +3.6V supply voltage.

18

SHDN

Shutdown control. Connect to GND to shut down the charge pumps and the transmitters.

Take high to turn on the charge pumps and to enable the transmitters.