Chopper stabilization stable switchpoints throughout operating tempera

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

Chopper stabilization stable switchpoints throughout operating tempera

Datasheet Thumbnail

Top Searches for this datasheet

A3250 A3251 Field-Programmable, Chopper-Stabilized Unipolar Hall-Effect Switches
Chopper stabilization stable switchpoints throughout operating temperature range Externally programmable operate point (through pin) On-board voltage regulator operation On-chip protection against: Supply transients Output short-circuits Reverse-battery condition
A3250 A3251 field-programmable, chopperstabilized, unipolar Hall-effect switches designed high-temperature applications. These devices chopper-stabilization technique eliminate offset inherent single-element devices. A3250 A3251 externally programmable devices. devices have wide range programmability magnetic operate point (BOP) while hysteresis remains fixed. This advanced feature allows optimization sensor switchpoint drastically reduce effects variations found production environment, such magnet device placement tolerances. These devices provide on-chip transient protection. Zener clamp power supply protects against overvoltage conditions supply line. These devices also include short-circuit protection output. output A3250 switches when subjected south-polarity magnetic field with flux density that exceeds threshold switches HIGH when
Package: SOT89 (suffix (suffix
Continued next page. scale
Functional Block Diagram
Program/Lock Programming Logic
Regulator
Offset Adjust Sample Hold Dynamic Offset Cancellation VOUT
Current Limit Low-Pass Filter
3250-DS Rev.
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Three package styles provide magnetically optimized package most applications. Type miniature SOT89/TO-243AA surface mount package that thermally enhanced with exposed ground tab, type three-lead ultramini through-hole mounting. packages lead (Pb) free, with 100% matte plated leadframes (suffix, -T).
Description (continued) field drops below magnetic release point, output A3251 opposite polarity, switching HIGH southpolarity magnetic field that switching when field drops below other differences devices power-on state. A3250 powers-on HIGH state, while A3251 powers-on state. Selection Guide
Part Number
A3250ELT-T A3250ELTTR-T A3250EUA-T A3250LLT-T A3250LLTTR-T A3250LUA-T A3251ELT-T A3251ELTTR-T A3251EUA-T A3251LLT-T A3251LLTTR-T A3251LUA-T
1Pb-based
Pb-free1
Packing2
Bulk, pieces/bag 7-in. reel, 1000 pieces/reel Bulk, pieces/bag Bulk, pieces/bag 7-in. reel, 1000 pieces/reel Bulk, pieces/bag Bulk, pieces/bag 7-in. reel, 1000 pieces/reel Bulk, pieces/bag Bulk, pieces/bag 7-in. reel, 1000 pieces/reel Bulk, pieces/bag
Package
Surface mount through hole Surface mount through hole Surface mount through hole Surface mount through hole
VOUT Power-On
High
Running3
High
High
High
variants being phased product line.
Certain variants cited this footnote production have been determined LAST TIME BUY. This classification indicates that sale this device currently restricted existing customer applications. device should purchased design applications because obsolescence near future probable. Samples longer available. Status change: October 2006. Deadlilne receipt LAST TIME ORDERS: April 2007. These variants include: A3250ELT, A3250ELTTR, A3250EUA, A3251ELT, A3251ELTTR, A3251EUA, A3251LLT, A3251LLTTR, A3251LUA. Certain variants cited this footnote production have been determined DESIGN. This classification indicates that sale this device currently restricted existing customer applications. device should purchased design applications because obsolescence near future probable. Samples longer available. Status change: 2006. These variants include: A3250LLT, A3250LLTTR, A3250LUA.
2Contact Allegro additional packing options. south polarity magnetic field sufficient strength.
Absolute Maximum Ratings
Characteristic Supply Voltage Reverse Supply Voltage Zener Overvoltage Output Current Magnetic Flux Density Operating Ambient Temperature Maximum Junction Temperature Storage Temperature Symbol VRCC IOUT TJ(max) Tstg Range Range Notes Rating 26.5 Unlimited Units
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Characteristic ELECTRICAL CHARACTERISTICS Supply Voltage1 Output Saturation Voltage Output Leakage Current VOUT(sat) IOFF ICC(off) Supply Current ICC(on) Output Rise Time Output Fall Time Chopping Frequency Power-Up Time Output Current Limit1,2 IOUT(lim) Symbol
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Test Conditions Min. Typ. Max. Units
OPERATING CHARACTERISTICS valid over operating VCC, unless otherwise specified
Running mode IOUT Switch state VOUT Switch state A3250; BRP; VOUT HIGH A3251; BOP; VOUT HIGH A3250; BOP; VOUT A3251; BRP; VOUT RLOAD CLOAD RLOAD CLOAD
HIGH
10.0 10.0
VOUT HIGH Short-circuit protection A3250; BRP, A3251; BRP,
Power-On State MAGNETIC CHARACTERISTICS Initial Operate Point Temperature Drift Hysteresis (BOP BRP)
Bhys gauss Package range Package range
PROGRAMMING CHARACTERISTICS Programmable Values3 Number Programming Bits Resolution BOP(prog) BRES Switchpoint Programming lock
TRANSIENT PROTECTION CHARACTERISTICS Supply Zener Voltage Supply Zener Current Reverse Battery Current
IRCC VRCC TJ(max)
-5.0
exceed TJ(max): Additional information power derating provided applications section. Short-circuit protection intended continuous operation; permanent damage result. Device used below guaranteed unipolar switch. responsibility programmer verify that desired switchpoint been achieved.
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Typical Characterization Data
data taken with A3250 devices, average lots, pieces
Average Program Code:
Average Program Code:
Average
(°C)
Average
(°C)
Average Program Code:
Average Program Code:
Average
Average
(°C)
(°C)
Average Program Code:
Average Program Code:
Average
(°C)
Average
(°C)
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Typical Characterization Data
data taken with A3250 devices, average lots, pieces
Average Temperature Program Code:
Average BHYS
Average Temperature Program Code:
Average BHYS
(°C)
(°C)
Average Temperature Program Code:
Average Temperature -40°C 25°C 150°C 25°C
Code Code Code
Average BHYS
(°C)
Average
-40°C 25°C
150°C 25°C
(°C)
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Typical Characterization Data
data taken with A3250 devices, average lots, pieces
Average ICC(on) Temperature
Average ICC(off) Temperature
ICC(off)
ICC(off) 12.0 ICC(off) 26.5
ICC(on) (mA)
ICC(on)
ICC(off) (mA)
ICC(on) 12.0 ICC(on) 26.5
(°C)
(°C)
Average VOUT(SAT) Temperature Iout
VOUT(SAT) (mV)
(°C)
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
THERMAL CHARACTERISTICS require derating maximum conditions, application information
Characteristic Package Thermal Resistance Symbol Test Conditions Package 1-layer with copper limited solder pads Package 1-layer with copper limited solder pads Package 2-layer with 0.94 copper each side Value Units
Power Derating Curve
Power Dissipation
VCC(max)
Power Dissipation,
1900 1800 1700 1600 1500 1400 1300 1200 1100 1000
Maximum Allowable
-lay
1-layer PCB, Package (RJA 1-layer PCB, Package (RJA 2-layer PCB, Package (RJA VCC(min)
1-la 1-la kage
Temperature (°C)
Hysteresis Curves
A3250
Hysteresis VOUT Switching VOUT(off)
A3251
Hysteresis VOUT Switching VOUT(off)
Switch High
Switch High
Switch
Switch
VOUT
VOUT
VOUT(on)(sat)
VOUT(on)(sat)
BHYS
BHYS
Output voltage relation sensed magnetic flux density south polarity magnetic field sufficient strength. Transition through must precede transition through BRP.
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Functional
Chopper-Stabilized Technique Hall sensor based Hall element, small sheet semiconductor material which constant bias current flows when constant voltage source applied. output takes form voltage measured across width Hall element, negligible value absence magnetic field. When magnetic field applied with flux lines right angles current Hall element, small signal voltage directly proportional strength magnetic field occurs output Hall element. This small signal voltage disproportionally small relative offset produced input device. This makes very difficult process signal maintain accurate, reliable output over specified temperature voltage range. Therefore, important reduce distortion signal that could amplified when signal processed. Chopper stabilization unique approach used minimize input offset Hall This technique removes source output drift temperature mechanical stress, produces reduction offset comparison other, conventional methods. This offset reduction chopping technique based signal modulation-demodulation process. undesired offset signal separated from magnetically-induced signal frequency domain. offset (and low-frequency noise) component signal seen signal distortion added after signal modulation process taken place. Therefore, offset modulated remains low-frequency component. Consequently, signal demodulation process acts modulation process offset, causing magneticallyinduced signal recover original spectrum baseband while offset becomes high-frequency signal. Then, signal passes using low-pass filter, while modulated offset suppressed. advantage this approach significant offset reduction, which desensitizes Hall against effects temperature mechanical stress. disadvantage that this technique features demodulator that uses sample-and-hold block store recover signal. This sampling process slightly degrade (signal-to-noise ratio) producing replicas noise spectrum baseband. This degradation function ratio between white noise spectrum sampling frequency. effect degradation higher jitter, also known signal repeatability. However, jitter continuous-time device that A3250/A3251.
Regulator
Chopper stabilization circuit (dynamic quadrature offset cancellation)
Sample Hold
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Programming Protocol
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
operate switchpoint, field-programmed. coded series voltage pulses through used bitfields onboard registers. effect device output monitored, registers cleared repeatedly until required achieved. make setting permanent, bitfield-level solid state fuses blown, finally, device-level fuse blown, blocking further coding. necessary program release switchpoint, because difference between referred hysteresis, BHYS fixed. range values between BOP(min) BOP(max) scaled increments. actual change magnetic flux represented each increment indicated BRES (see Operating Characteristics table; however, testing only method verifying resulting BOP). programming, increments individually identified using data bits, which physically represented bitfields onboard registers. setting these bitfields, corresponding calibration value programmed into device. Three voltage levels used programming device: voltage, minimum required sustain register settings; mid-level voltage, used increment address counter device; high voltage, used separate sets pulses (when short duration) blow fuses (when long duration). fourth voltage level, essentially used clear registers between pulse sequences. pulse values shown Programming Protocol Characteristics table figure
Td(P) Td(0) Td(1)
Figure Pulse amplitudes durations
Additional information device programming programming products available www. allegromicro.com. Programming hardware available purchase, programming software available free charge.
Code Programming. Each bitfield must individually set.
pulse sequence must transmitted each bitfield that being more than bitfield being pulse sequences must sent, after other, without allowing fall zero (which clears registers). same pulse sequence used provisionally bitfields used permanently bitfield-level fuses. only difference that when provisionally setting bitfields, fuse-blowing pulse sent pulse sequence.
PROGRAMMING PROTOCOL CHARACTERISTICS, unless otherwise noted Characteristic Symbol Programming Voltage1 Programming Current2 td(0) Pulse Width td(1) td(P) Pulse Rise Time Pulse Fall Time
1Programming bypass
Test Conditions Minimum voltage range during programming
Min.
Typ.
Max.
Units
Maximum supply current during programming time between programming bits Pulse duration time) enable, address, fuse blowing lock bits Pulse duration time) fuse blowing VPM; VPL;
voltages measured pin. capacitor with minimum capacitance must connected from device order provide current necessary blow fuse.
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
vertently setting bitfield Instead, blowing devicelevel fuse protects bitfields from being accidentally future. When provisionally trying calibration value, pulse sequence used, using decimal values. sequence setting value shown figure When permanently setting values, bitfields must individually, must programmed binary 101. (0001002, which 410), then (0000012, which 110). ignored, remains 0.Two pulse sequences permanently setting calibration value shown figure final pulse maintained longer period, enough blow corresponding bitfield-level fuse.
pulse sequences consist following groups pulses: enable sequence. bitfield address sequence. When permanently setting bitfield, long fuse-blowing pulse. (Note: Blown fuses cannot reset.) When permanently setting bitfield, level must allowed drop zero between each pulse sequence, order clear registers. However, when provisionally setting bitfields, must maintained between pulse sequences, order maintain prior bitfield settings while preparing additional bitfields. Bitfields that evaluated zeros. bitfield-level fuses value bitfields never blown. This prevents inadV+
Enable Address Optional Monitoring Clear
Figure Pulse sequence provisionally calibration value
Address Enable Address Encode 001002 (410) Blow Enable Blow Encode 000012 (110)
Figure Pulse sequence permanently encode calibration value (101 binary, bitfield address bitfield address
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Enabling Addressing Mode. first segment code keying sequence used enable bitfield addressing mode. shown figure this segment consists short pulse, seven more pulses, short pulse, with supply interruptions. This sequence designed prevent device from being programmed accidentally, such noise supply line.
Minimum pulses
Figure Addressing mode enable pulse sequence
Address Selection. After addressing mode enabled,
target bitfield address, indicated series pulses, shown figure When provisionally trying value, this sequence followed short pulse, which serves delimit address corresponding bitfield. When permanently setting bitfield, pulse continued longer period time, suffienct only bitfield also blow bitfield fuse.
Address Address Address
Figure Pulse sequence select addresses
Falling edge final address digit
Lock Programming. After desired calibration value
programmed, corresponding bitfield-level fuses blown, device-level fuse should blown. lock (bitfield address should encoded have fuse blown. This done same manner permanently setting other bitfields, shown figure
pulses Enable Address Encode Lock Blow pulses
Figure Pulse sequence encode lock
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Application Information
additional general application information, visit Allegro MicroSystems site www. allegromicro.com. Typical Application Circuit strongly recommended that external ceramic bypass capacitor, CBYP, range 0.01 connected between supply reduce both external noise noise generated chopper-stabilization technique. (The diagram right shows CBYP CBYP should installed that traces that connect A3250/A3251 greater than length. (For programming device, capacitor further away from device, including mounting board used programming device.) series resistor combination with CBYP creates filter pulses. (Additional information provided Allegro MicroSystems site.) will have drop approximately This must taken into consideration when determining minimum requirement A3250/A3251. pull-up resistor, should chosen limit current through output transistor; exceed maximum continuous output current device.
VOUT
VSupply
CBYP
A3250/A3251
Maximum separation from CBYP device
Typical application circuit
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Power Derating device must operated below maximum junction temperature device, TJ(max). Under certain combinations peak conditions, reliable operation require derating supplied power improving heat dissipation properties application. This section presents procedure correlating factors affecting operating (Thermal data also available Allegro MicroSystems site.) Package Thermal Resistance, RJA, figure merit summarizing ability application device dissipate heat from junction (die), through paths ambient air. primary component Effective Thermal Conductivity, printed circuit board, including adjacent devices traces. Radiation from through device case, RJC, relatively small component RJA. Ambient temperature, motion significant external factors, damped overmolding. effect varying power levels (Power Dissipation, PD), estimated. following formulas represent fundamental relationships used estimate Example: Reliability 150°C, package using minimum-K PCB. Observe worst-case ratings device, specifically: 165°C/W, TJ(max) 165°C, VCC(max) ICC(max) Calculate maximum allowable power level, PD(max). First, invert equation Tmax TJ(max) This provides allowable increase resulting from internal power dissipation. Then, invert equation PD(max) Tmax 15°C °C/W Finally, invert equation with respect voltage: VCC(est) PD(max) ICC(max) result indicates that, application device dissipate adequate amounts heat voltages VCC(est). Compare VCC(est) VCC(max). VCC(est) VCC(max), then reliable operation between VCC(est) VCC(max) requires enhanced RJA. VCC(est) VCC(max), then operation between VCC(est) VCC(max) reliable under these conditions.
example, given common conditions such 25°C, °C/W, then: °C/W 25°C 33°C worst-case estimate, PD(max), represents maximum allowable power level (VCC(max), ICC(max)), without exceeding TJ(max), selected
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Package 3-Pin SOT89
4.60 .181 4.40 .173 1.83 .072 1.62 .064 1.14 .0450
2.24 .0880
4.25 .167 3.94 .155
2.60 .102 2.29 .090
1.20 .047 0.89 .035
0.44 .017 0.35 .014 1.60 .063 1.40 .055
0.48 .019 0.36 .014 0.56 .022 0.44 .017 0.10 [.004] 1.50 .059
Preliminary dimensions, reference only Dimensions millimeters U.S. Customary dimensions (in.) brackets, reference only (reference JEDEC TO-243 Dimensions exclusive mold flash, gate burrs, dambar protrusions Exact case lead configuration supplier discretion within limits shown Hall element (not scale; location controlling dimensions inches) Active Area Depth 0.775 [.0305] nominal
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
A3250 A3251
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
Package 3-Pin
.164 4.17 .159 4.04
2.06 .081
.057 1.45
.062 1.57 .058 1.47
.122 3.10 .117 2.97
.085 2.16
.031 0.79
.640 16.26 .600 15.24
.017 0.44 .014 0.35
.019 0.48 .014 0.36 .050 1.27 Dimensions inches Metric dimensions (mm) brackets, reference only Dambar removal protrusion (6X)
Ejector mark opposite side Active Area Depth .0195 [0.50] Hall element (not scale) controlling dimensions inches
products described herein manufactured under more following U.S. patents: 5,045,920; 5,264,783; 5,442,283; 5,389,889; 5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; other patents pending. Allegro MicroSystems, Inc. reserves right make, from time time, such departures from detail specifications required permit improvements performance, reliability, manufacturability products. Before placing order, user cautioned verify that information being relied upon current. Allegro products authorized critical components life-support devices systems without express written approval. information included herein believed accurate reliable. However, Allegro MicroSystems, Inc. assumes responsibility use; infringement patents other rights third parties which result from use. Copyright 2004, 2006 Allegro MicroSystems, Inc.
Allegro MicroSystems, Inc. Northeast Cutoff, 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com

Chopper stabilization stable switchpoints throughout operating tempera

Top Searches for this datasheet

Other recent searches