A1374 View Datasheet(PDF) - Allegro MicroSystems

Part Name

Description

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A1374

High Precision, Output Pin Programmable Linear Hall Effect Sensors

Allegro MicroSystems 

A1373 and

A1374

High Precision, Output Pin Programmable

Linear Hall Effect Sensors

Pulse Generation

Several parameters can be field-programmed. To do so, a coded

series of voltage pulses through the VOUT pin is used to set

bitfields in onboard registers. The effect on the device output can

be monitored, and the registers can be cleared and set repeatedly

until the required output results are achieved. To make the setting

permanent, bitfield-level solid state fuses are blown, and finally,

a device-level fuse is blown, blocking any further coding.

Although any programmable variable power supply can be used

to generate the pulsed waveforms, Allegro highly recommends

using the Allegro Sensor Evaluation Kit, available on the Allegro

Web site On-line Store. The manual for that kit is available for

download free of charge, and provides additional information on

programming these devices.

There are three voltage levels that must be taken into account

when programming. For purposes of explanation in this docu-

ment, the signal levels are referred to simply as high program-

ming voltage, VPH, mid, VPM, and low, VPL.

The rising edge of the high level, VPH , pulse generates a state

change. The falling edge of the high level, VPH , pulse increments

the mode, register, or bitfield selection by one, when allowed to

drop below the low level, VPL , threshold. A delay on the fall-

ing edge, at the mid level, VPM , range is required to guarantee

proper programming level recognition. When it is not desirable to

increment these fields further, it is acceptable to hold the signal

at the mid level, VPM , range and then transition to another high

level, VPH, pulse. Referring to the Programming State Machine

diagram, when using Blow Fuse mode the fourth high level, VPH ,

pulse (including the key sequence to enable Blow Fuse mode),

will blow the selected key-code combination. If fuse blowing is

not desired, it is recommended to reset the A137x by toggling the

supply pin. If the high level, VPH, pulse is not generated, and the

A137x is not reset, then the next key sequence to change states

will blow the unwanted key-code combination. For multiple

register addressing without fuse blowing, Try Value mode must

be used.

PROGRAMMING PROTOCOL CHARACTERISTICS, over operating temperature range, unless otherwise noted

Characteristic

Symbol

Test Conditions

Min. Typ.

Programming Voltage1

VPL

Low voltage range, for addressing registers and

bitfields

0

–

VPM

Mid voltage range, for addressing bitfields and for

separating programming signals

14

–

VPH

High voltage range, for enabling state changes

and for fuse blowing

25

26

Max.

5

16

27

Units

V

V

V

Programming Current2

IPP tr = 11 μs; 5 V → 28 V; CPROG = 0.1 μF

–

209

–

mA

tPHE High pulse duration for enabling state change

20

–

–

μs

tPHP High pulse duration for blowing fuses

100

–

–

μs

Pulse Width

tPLA Low pulse duration for bitfield addressing

6

–

–

μs

tPME Mid pulse delay on falling edge of high pulse, VPH

15

–

–

μs

Pulse Rise Time

tPMA Mid pulse duration for bitfield addressing

6

tr

VPL to VPH or VPM; maximum may be application

dependent

5

–

–

μs

–

100

μs

Pulse Fall Time

tf

VPH or VPM to VPL; maximum may be application

dependent

5

–

100

μs

1Programming voltages are measured at pin #3, VOUT, of the A137x.

2A minimum capacitance of 0.1 μF must be connected from VOUT to the GND pin of the A137x in order to provide the current

necessary to blow the fuse.

Allegro MicroSystems, Inc.

15

115 Northeast Cutoff, Box 15036

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

www.allegromicro.com

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