A1172 Micropower Ultra-Sensitive Hall-Effect Switch Features and Benefits Description ▪ Micropower operation ▪ Operation with either north or south pole— no magnetic orientation required during assembly ▪ 1.65 to 3.5 V battery operation ▪ Chopper stabilization ▫ Superior temperature stability ▫ Extremely low switchpoint drift ▫ Insensitive to physical stress ▪ Solid state reliability ▪ Small size: WLCSP (≈ 1 mm × 1 mm × 0.5 mm) ▪ Complementary, push-pull outputs eliminate need for pull-up resistor Package: 4 pin WLCSP (suffix CG) The A1172 is an ultra-sensitive, pole-independent Hall-effect switch with a latched digital output. It features operation at low supply currents and voltages, making it ideal for batteryoperated electronics. The 1.65 to 3.5 V operating supply voltage and unique clocking algorithm reduce the average operating power requirements to less than 15 μW with a 2.75 V supply. The A1172 has two push-pull output structures. Omnipolar activation for the output function is available on each output structure. As such, either a north or south pole of sufficient strength turns the available outputs off or on. The A1172 contains two complementary outputs. Therefore, for a fixed magnetic field, one output will be in a high voltage state and one output will be in a low voltage state. Improved stability is made possible through dynamic offset cancellation using chopper stabilization, which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress. This device Continued on the next page… Not to scale Engineering samples available on a limited basis. Contact your local sales or applications support office for additional information. Functional Block Diagram VDD Clock / Logic Amp Sample and Hold Dynamic Offset Cancellation VOUTPS Latch Low-Pass Filter GND 1172-DS, Rev. 5 VOUTPN Latch A1172 Micropower Ultra-Sensitive Hall-Effect Switch Description (continued) includes, on a single silicon chip, a Hall-voltage generator, a smallsignal amplifier, chopper stabilization, a latch, and a MOSFET output. The A1172 device offers magnetically optimized solutions, suitable for most applications. The wafer level chip scale package (WLCSP) is approximately only 1 mm by 1 mm by 0.5 mm. This package is smaller than most plastic packages and reduces the printed circuit board area consumed by micropower Hall-effect switches. Selection Guide Part Number Package1 4 bumped wafer-level chip-scale A1172ECGLT2 package (WLCSP) 1Contact Allegro™ for additional packing options. 2Allegro Pb-free Packing* Pb-free chip with high-temperature solder balls (RoHS compliant) 4000 pieces per reel products sold in WLCSP package types are not intended for automotive applications. Absolute Maximum Ratings Characteristic Supply Voltage Symbol Rating Units VDD Notes 5 V V Reverse Supply Voltage VRDD –0.3 Output Off Voltage VOUTx 5 V Reverse Output Voltage VROUTx –0.3 V IOUTx(Sink) –1 mA IOUTx(Source) 1 mA Output Current Magnetic Flux Density B Operating Ambient Temperature TA Maximum Junction Temperature Storage Temperature Unlimited G –40 to 85 ºC TJ(max) 165 ºC Tstg –65 to 170 ºC Range E Terminal List Table Pin-out Diagram A1 A2 B1 B2 (Bump-down view) Name Number VOUTPS A1 Push-pull output Function VOUTPN A2 Inverted push-pull output GND B1 Ground VDD B2 Connects power supply to chip Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 2 A1172 Micropower Ultra-Sensitive Hall-Effect Switch OPERATING CHARACTERISTICS Characteristic Symbol Test Conditions Min. Typ.1 Max. Units Electrical Characteristics valid over full operating voltage range and TA = 25°C Supply Voltage Range2 Output On Voltage Period Chopping Frequency Supply Slew Rate3 Supply Current VDD Operating, TA= 25°C VOUT(SAT) NMOS on, IOUT = 1 mA, VDD = 2.75 V VOUT(HIGH) PMOS on, IOUT = 1 mA, VDD = 2.75 V 1.65 – 3.5 V – 100 300 mV – mV VDD–300 VDD–100 tPERIOD – 50 100 ms fC – 200 – kHz 20 – – V/ms IDD(EN) SR Chip awake (enabled) – – 2.0 mA IDD(DIS) Chip asleep (disabled) – – 8.0 μA VDD = 1.80 V – 4 8 μA VDD = 3.5 V – 6 12 μA IDD(AV) Magnetic Characteristics4 at TA = 25°C and 1.8 V ≤ VDD ≤ 3.5 V Operate Point Release Point Hysteresis BOPS – 32 55 G BOPN –55 –32 – G BRPS 6 26 – G BRPN – –26 –6 G – 6 – G BHYS BHYS = BOPX – BRPX 1Typical values at VDD = 2.75 V. Performance may vary for individual units, within the specified maximum and minimum limits. operate and release points vary with supply voltage. 3If SR < SR(min), then valid device output might be delayed for one Period, t PERIOD , of device. 41 gauss (G) is exactly equal to 0.1 millitesla (mT). 2Magnetic Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 3 A1172 Micropower Ultra-Sensitive Hall-Effect Switch THERMAL CHARACTERISTICS may require derating at maximum conditions* Characteristic Symbol Test Conditions RθJA Package Thermal Resistance Value Units On 1-layer PCB 347 ºC/W On 4-layer PCB 147 ºC/W *Additional thermal information is available on the Allegro website. Power Dissipation versus Ambient Temperature 1600 Power Dissipation, PD (mW) 1400 1200 1000 R QJ A 800 =1 42 ºC /W 600 RQ 400 JA = 34 7 ºC /W 200 0 20 40 60 80 100 120 Temperature (°C) 140 160 180 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 A1172 Micropower Ultra-Sensitive Hall-Effect Switch Operating Characteristics Saturation Voltage versus Temperature 300 VDD = 1.65V VDD = 2.75V VDD = 3.5V VOUT(SAT) (mV) 250 200 150 100 50 0 -60 -40 -20 0 20 40 60 80 100 TA (°C) Saturation Voltage versus Supply Voltage 300 85°C -40°C 25°C VOUT(SAT) (mV) 250 200 150 100 50 0 1 1.5 2 2.5 3 3.5 4 VCC (V) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 5 A1172 Micropower Ultra-Sensitive Hall-Effect Switch Average Supply Current versus Temperature 12 VDD = 1.65V VDD = 2.75V VDD = 3.5V IDD(AV) (uA) 10 8 6 4 2 0 -60 -40 -20 0 20 40 60 80 100 TA (°C) Average Supply Current versus Supply Voltage 12 85°C -40°C 25°C 10 IDD(AV) (μA) 8 6 4 2 0 1 1.5 2 2.5 3 3.5 4 VCC (V) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 6 A1172 Micropower Ultra-Sensitive Hall-Effect Switch Period versus Temperature 100 VDD = 1.65V VDD = 2.75V VDD = 3.5V 90 80 tperiod (ms) 70 60 50 40 30 20 10 0 -60 -40 -20 0 20 40 60 80 100 TA (°C) Period versus Supply Voltage 100 85°C -40°C 25°C 90 80 tperiod (ms) 70 60 50 40 30 20 10 0 1 1.5 2 2.5 3 3.5 4 VCC (V) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 A1172 Micropower Ultra-Sensitive Hall-Effect Switch Functional Description Low Average Power Internal timing circuitry activates the IC for 50 μs and deactivates it for the remainder of the period (50 ms). A short awake time allows stabilization prior to the sampling and data-latching on the falling edge of the timing pulse. The output during the sleep state is latched in the last sampled state. The supply current is not affected by the output state. VOUTPN operates with the opposite output polarity. That is, the output is low (on) in the absence of a magnetic field. The output goes high (turns off) when sufficient field, of either north or south polarity, is presented to the device. tPeriod Awake I DD(EN) BOPS (or is less than BOPN). After turn-on, the output voltage is VOUT(SAT). The output transistor is capable of sinking current up to the short circuit current limit, IOM, which is a minimum of 1 mA. When the magnetic field is reduced below the release point, BRPS (or increased above BRPN), the device output switches high (turns off). The pull-up transistor brings the output voltage to VOUT(HIGH). Sleep The difference in the magnetic operate and release points is the hysteresis, BHYS , of the device. This built-in hysteresis allows clean switching of the output even in the presence of external mechanical vibration and electrical noise. Sample and Output Latched The push-pull outputs are capable of sourcing or sinking a maximum of 1 mA. Operation The VOUTPS output switches low (turns on) when a magnetic field perpendicular to the Hall element exceeds the operate point, Powering-on the device in a hysteresis region, between BOPX and BRPX, allows an indeterminate output state. The correct state is attained after the first excursion beyond BOPX or BRPX. (A) VOUTPS (B) VOUTPN Switch to High VOUT(HIGH) VOUT Switch to Low VOUT V+ Switch to Low Switch to Low Switch to Low Switch to High VOUT(HIGH) Switch to High V+ Switch to High I DD(DIS) 0 VOUT(SAT) 0 BRPS BRPN BHYS 0 BOPS BOPN B– B+ VOUT(SAT) 0 B+ 0 B– BHYS BHYS BHYS Figure 1. Switching Behavior of Omnipolar Switches. On the horizontal axis, the B+ direction indicates increasing south polarity magnetic field strength, and the B– direction indicates decreasing south polarity field strength (including the case of increasing north polarity). Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 8 A1172 Micropower Ultra-Sensitive Hall-Effect Switch Applications It is strongly recommended that an external bypass capacitor be connected (in close proximity to the Hall element) between the supply and ground of the device to reduce both external noise and noise generated by the chopper stabilization technique. As is shown in figure 2, a 0.1μF capacitor is typical. • Hall-Effect IC Applications Guide, AN27701 Extensive applications information on magnets and Hall-effect devices is available in the following notes: All are provided in Allegro Electronic Data Book, AMS-702, and on the Allegro Web site, www.allegromicro.com. • Hall-Effect Devices: Gluing, Potting, Encapsulating, Lead Welding and Lead Forming AN27703.1 • Soldering Methods for Allegro Products (SMD and ThroughHole), AN26009 VS CBYP 0.1 μF VOUTPS Outputs VOUTPN A1172 GND VDD Figure 2. Typical Application Circuit Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9 A1172 Micropower Ultra-Sensitive Hall-Effect Switch Package CG, 4-Bump WLCSP 0.955 ±0.020 1 2 1 X .160 A A 2 A 0.955 ±0.020 0.500 B B 0.500 C 0.506 4X +0.049 –0.051 C PCB Layout Reference View A1 0.05 C 0.200 ±0.030 SEATING PLANE NN YWW 0.227 0.228 D B Standard Branding Reference View N = Last two digits of device part number Y = Last digit of year of manufacture W = Week of manufacture 0.500 A B 1 2 0.500 For Reference Only, not for tooling use Dimensions in millimeters Exact configuration at supplier discretion within limits shown A Terminal #A1 mark area (substrate side) B Hall element (not to scale) C Reference view of typical layout for solder pads All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances D Branding scale and appearance at supplier discretion Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 10 A1172 Micropower Ultra-Sensitive Hall-Effect Switch Revision History Revision Revision Date Rev. 5 October 26, 2011 Description of Revision Update Selection Guide Copyright ©2008-2013, Allegro MicroSystems, LLC Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. For the latest version of this document, visit our website: www.allegromicro.com Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 11