Micro Power 3 V Linear Hall Effect Sensor ICs

with Tri-State Output and User Selectable Sleep Mode

A1391, A1392,

A1393, and A1395

14

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Application Circuit with Multiple Hall Devices and a Single A-to-D Converter

Multiple A139x devices can be connected to a single micro-

processor or A-to-D converter input. In this case, a single

device is periodically triggered and put into active mode by

the microprocessor. While one A139x device is in active

mode, all of the other A139x devices must remain in sleep

mode. While these devices are in sleep mode, their outputs

are in a high-impedance state. In this circuit configuration,

the microprocessor reads the output of one device at a time,

according to microprocessor input to the S¯¯L¯¯E¯¯E¯¯P¯ pins.

When multiple device outputs are connected to the same

microprocessor input, pulse timing from the microproces-

sor (for example, lines A1 through A4 in figure 6) must be

configured to prevent more than one device from being in the

awake mode at any given time of the application. A device

output structure can be damaged when its output voltage is

forced above the device supply voltage by more than 0.1 V.

Figure 6. Application circuit showing multiple A139x devices, controlled by a single microprocessor.

VCC

OUT

GND

GND

SLEEP

VREF

Vbat2

A139x

Vbat2

Vbat2

Vbat2

A1

A2

A3

A4

Supply pin

Microprocessor

I/O

Vbat1

A1

A2

A3

A4

Cfilter

VCC

OUT

GND

GND

SLEEP

VREF

A1391x

VCC

OUT

GND

GND

SLEEP

VREF

A139x

VCC

OUT

GND

GND

SLEEP

VREF

A139x