a3250eua-t Allegro MicroSystems, Inc., a3250eua-t Datasheet

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a3250eua-t

Manufacturer Part Number
a3250eua-t
Description
Field-programmable, Chopper-stabilized Unipolar Hall-effect Switches
Manufacturer
Allegro MicroSystems, Inc.
Datasheet
Features and Benefits
▪ Chopper stabilization for stable switchpoints throughout
▪ Externally programmable operate point (through VCC
▪ On-board voltage regulator for 4.2 V to 24 V operation
▪ On-chip protection against:
Package: 3 pin SOT89 (suffix LT) and
3 pin SIP (suffix UA)
Not to scale
3250-DS Rev. 4
operating temperature range
pin)
▫ Supply transients
▫ Output short-circuits
▫ Reverse-battery condition
VCC
Amp
Field-Programmable, Chopper-Stabilized
Functional Block Diagram
Program/Lock
Programming
Logic
Low-Pass
Filter
Offset Adjust
Unipolar Hall-Effect Switches
Description
The A3250 and A3251 are field-programmable, chopper-
stabilized, unipolar Hall-effect switches designed for use in
high-temperature applications. These devices use a chop-
per-stabilization technique to eliminate offset inherent in
single-element devices.
The A3250 and A3251 are externally programmable
devices. The devices have a wide range of programmabil-
ity of the magnetic operate point (B
remains fixed. This advanced feature allows for optimiza-
tion of the sensor switchpoint and can drastically reduce
the effects of variations found in a production environment,
such as magnet and device placement tolerances.
These devices provide on-chip transient protection. A Zener
clamp on the power supply protects against overvoltage
conditions on the supply line. These devices also include
short-circuit protection on the output.
The output of the A3250 switches LOW when subjected
to a south-polarity magnetic field with a flux density that
exceeds the threshold for B
Continued on the next page…
Current Limit
Regulator
A3250 and A3251
OP
GND
, and switches HIGH when the
OP
) while the hysteresis
VOUT

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a3250eua-t Summary of contents

Page 1

Features and Benefits ▪ Chopper stabilization for stable switchpoints throughout operating temperature range ▪ Externally programmable operate point (through VCC pin) ▪ On-board voltage regulator for 4 operation ▪ On-chip protection against: ▫ Supply transients ▫ ...

Page 2

... OUT A (ºC) 2 Power-On Running High Low Low High Rating 26.5 – Unlimited – –40 to 150 165 –65 to 170 Function Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Units ºC ºC ºC ºC 2 ...

Page 3

... G –35 – 5 5 – ≥350 G – 6 – Bit – 1 – Bit – 7.0 – – – V – – – – –5 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com ...

Page 4

... Program Code -50 - 100 T (°C) A Average B vs Program Code: 16 -50 - 100 T (°C) A Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 130 160 130 160 A 130 160 4 ...

Page 5

... Average B vs. Temperature OP -40°C to 25°C and 150°C to 25°C Code 1 Code 8 Code 16 -40°C to 25°C T (°C) A Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 100 130 160 150°C to 25°C 5 ...

Page 6

... OUT(SAT 3 out -50 - (°C) A Average I vs. Temperature CC(off -50 - 100 T (°C) A 100 130 160 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com @ 3.8 V CC(off) @ 12.0 V CC(off) @ 26.5 V CC(off) 130 160 6 ...

Page 7

... Power Dissipation 100 120 Temperature (°C) A3251 Hysteresis of ΔV OUT Switching Due to Δ HYS . RP Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Value Units 165 ºC/W 180 ºC/W 78 ºC/W 140 160 180 V OUT(off) ...

Page 8

... The effect of the degradation of the SNR is higher jitter, also known as signal repeatability. However, the jitter in a continuous-time device can be 5X that of the A3250/A3251. Regulator Amp 8 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com ...

Page 9

... Min. Typ. 4.5 5 – 500 20 – 20 – 100 300 11 – 5 – Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com t Max. Units 5 – mA – μs – μs – μs – ...

Page 10

... Bit 2 is ignored, and so remains 0.Two pulse pulse is maintained for a longer PH Address Enable Blow Encode 00001 ( Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com , 2 10 ...

Page 11

... Figure 5. Pulse sequence to select addresses V+ Falling edge of final B address digit pulses 65 pulses 0 Enable Address Encode Lock Bit Figure 6. Pulse sequence to encode lock bit Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com t Blow t 11 ...

Page 12

... Typical application circuit will have a drop S , should be chosen 100 Ω A VCC V Supply VOUT C A3250/A3251 BYP 0.1 μF GND A Maximum separation 5 mm from C to device BYP Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 1.2 kΩ 12 ...

Page 13

... V CC(est) CC(max) CC(est) CC(max) and V requires enhanced CC(est) CC(max) ≥ then operation between V CC(est) CC(max) is reliable under these conditions. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com . First, D(max) . CC(est) , then reli- and CC(est) 13 ...

Page 14

... Exact case and lead configuration at supplier discretion within limits shown A Hall element (not to scale; location controlling dimensions inches) B Active Area Depth 0.775 [.0305] nominal B 2.24 .0880 NOM 1.20 .047 0.89 .035 0.44 .017 0.35 .014 1.60 .063 1.40 .055 2X 1.50 .059 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 14 ...

Page 15

... The in for ma tion in clud ed herein is believed rate and reliable. How ev er, Allegro MicroSystems, Inc. assumes no re spon si bil i ty for its use; nor for any in fringe ment of patents or other rights of third parties which may result from its use. ...

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