Micro Power 3 V Linear Hall Effect Sensor ICs

with Tri-State Output and User Selectable Sleep Mode

A1391, A1392,

A1393, and A1395

11

Allegro MicroSystems, LLC

115 Northeast Cutoff, Box 15036

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

www.allegromicro.com

Device Supply Ratiometry Application Circuit

Figures 2 and 3 present applications where the VCC pin is con-

nected together with the VREF pin of the A139x. Both of these

pins are connected to the battery, Vbat2. In this case, the device

output will be ratiometric with respect to the battery voltage.

The only difference between these two applications is that the

S¯¯L¯¯E¯¯E¯¯P¯ pin in figure 2 is connected to the Vbat2 potential, so the

device is always in the active mode. In figure 3, the S¯¯L¯¯E¯¯E¯¯P¯ pin is

toggled by the microprocessor; therefore, the device is selectively

and periodically toggled between active mode and sleep mode.

In both figures, the device output is connected to the input of an

A-to-D converter. In this configuration, the converter reference

voltage is Vbat1.

It is strongly recommended that an external bypass capacitor be

connected, in close proximity to the A139x device, between the

VCC and GND pins of the device to reduce both external noise

and noise generated by the chopper-stabilization circuits inside of

the A139x.

Vbat1

VCC

OUT

GND

GND

SLEEP

VREF

Vbat2

A139x

Micro-

processor

Supply pin

I/O

I/O

Figure 2. Application circuit showing sleep mode disabled and output ratiometirc to the

A139x supply.

Figure 3. Application circuit showing microprocessor-controlled sleep mode and output ratiome-

tirc to the A139x supply.

Vbat1

Vbat2

processor

Supply pin

I/O

I/O

VCC

OUT

GND

GND

SLEEP

VREF

Micro-

A139x