Ultralow Power +3.3 V, RS-232

Notebook PC Serial Port Drivers/Receivers

ADM560/ADM561

Rev. B

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FEATURES

RS-232 compatible

Operates with 3 V or 5 V logic

Ultralow power CMOS: 1.3 mA operation

Low power shutdown: 0.2 μA

Suitable for serial port mice

116 kbps data rate

1 μF charge pump capacitors

Single +3 V to +3.6 V power supply

Two receivers active in shutdown (ADM560)

APPLICATIONS

Notebook computers

Peripherals

Modems

Printers

Battery-operated equipment

FUNCTIONAL BLOCK DIAGRAM

7

16

15

14

12

13

17

11

T1

2

6

T2

3

20

T3

1

24

21

T4

28

R1

9

8

R2

4

5

R3

27

26

R4

23

22

R5

18

25

SHDN (ADM561)

19

10

C1+

C1–

C2+

V+

V–

C2–

+

+

GND

+3.3V TO +6.6V

VOLTAGE

DOUBLER

+6.6V TO –6.6V

VOLTAGE

INVERTER

0.1µF

C3

1µF

6.3V

1µF

10V

1µF

10V

C4

1µF

10V

EIA/TIA-232

OUTPUTS

EIA/TIA-232

INPUTS

SHDN (ADM560)

ADM560/

ADM561

+3.3V INPUT

CMOS

INPUTS

CMOS

OUTPUTS

EN (ADM560)

EN (ADM561)

Figure 1.

GENERAL DESCRIPTION

The ADM560/ADM561 are four driver/five receiver interface

devices designed to meet the EIA-232 standard and operate with

a single +3.3 V power supply. The devices feature an on-board

dc-to-dc converter, eliminating the need for dual ±5 V power

supplies. This dc-to-dc converter contains a voltage doubler

and voltage inverter, both of which internally generate ±6.6 V

from the input +3.3 V power supply.

The ADM560 and the ADM561 consume only 5 mW making

them ideally suited for battery and other power-sensitive appli-

cations. A shutdown facility is also provided to reduce the power

to 0.66 μW.

The ADM560 contains active low shutdown and an active high

receiver enable signal. In shutdown mode, two receivers remain

active, thereby allowing monitoring of peripheral devices. This

feature allows the device to be shut down until a peripheral

device begins communication. The active receivers alert the

processor, and then take the ADM560 out of shutdown mode.

The ADM561 features active high shutdown and an active

low receiver enable. In this device, all receivers are disabled

in shutdown.

The ADM560/ADM561 are fabricated using CMOS technology

for minimal power consumption. They feature a high level of

over-voltage protection and latch-up immunity. The receiver

inputs can withstand up to ±25 V levels. The transmitter inputs

can be driven from either 3 V or 5 V logic levels. This allows

operation in mixed 3 V/5 V power supply systems.

The ADM560/ADM561 are packaged in a 28-lead SOIC and

a 28-lead SSOP package.