A1172

A1172 Micropower Ultra-Sensitive Hall-Effect Switch Features and Benefits ▪ 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 Description 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 Package: 4 pin WLCSP (suffix CG) Not to scale Continued on the next page… Engineering samples available on a limited basis. Contact your local sales or applications support office for additional information. Functional Block Diagram VDD Clock / Logic Sample and Hold Dynamic Offset Cancellation Latch Low-Pass Filter VOUTPS Amp Latch VOUTPN GND 1172-DS A1172 Description (continued) Micropower Ultra-Sensitive Hall-Effect Switch 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 A1172ECGLT Package Pb-free Pb-free chip with high-temperature solder balls (RoHS compliant) Packing* 4000 pieces per reel 4 bumped wafer-level chip-scale package (WLCSP) *Contact Allegro for additional packing options. Absolute Maximum Ratings Characteristic Supply Voltage Reverse Supply Voltage Output Off Voltage Reverse Output Voltage Output Current Magnetic Flux Density Operating Ambient Temperature Maximum Junction Temperature Storage Temperature Symbol VDD VRDD VOUTx VROUTx IOUTx(Sink) IOUTx(Source) B TA TJ(max) Tstg Range E Notes Rating 5 –0.3 5 –0.3 –1 1 Unlimited –40 to 85 165 –65 to 170 Units V V V V mA mA G ºC ºC ºC Terminal List Table Pin-out Diagram A1 B1 A2 B2 Name VOUTPS VOUTPN GND VDD Number A1 A2 B1 B2 Push-pull output Inverted push-pull output Ground Function (Bump-down view) Connects power supply to chip Allegro MicroSystems, Inc. 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 Supply Voltage Range2 Output On Voltage Mode Cycle Period Chopping Frequency Symbol VDD VOUT(SAT) VOUT(HIGH) tPeriod fC IDD(EN) Test Conditions Operating, TA= 25°C NMOS on, IOUT = 1 mA, VDD = 2.75 V PMOS on, IOUT = 1 mA, VDD = 2.75 V Min. 1.65 – – – Typ.1 – 100 50 200 – – 4 6 32 –32 26 –26 6 Max. 3.5 300 – 100 – 2.0 8.0 8 12 55 – – –6 – Units V mV mV ms kHz mA μA μA μA G G G G G Electrical Characteristics valid over full operating voltage range and TA = 25°C VDD–300 VDD–100 Chip awake (enabled) Chip asleep (disabled) VDD = 1.80 V VDD = 3.5 V – – – – – –55 6 – Supply Current IDD(DIS) IDD(AV) Magnetic Characteristics3 at TA = 25°C and 1.8 V ≤ VDD ≤ 3.5 V Operate Point Release Point Hysteresis 1Typical 2Magnetic BOPS BOPN BRPS BRPN BHYS BHYS = BOPX – BRPX – 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. 31 gauss (G) is exactly equal to 0.1 millitesla (mT). Allegro MicroSystems, Inc. 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 Operating Characteristics Saturation Voltage versus Temperature 300 250 VOUT(SAT) (mV) VDD = 1.65V VDD = 2.75V VDD = 3.5V 200 150 100 50 0 -60 -40 -20 0 20 TA (°C) 40 60 80 100 Saturation Voltage versus Supply Voltage 300 250 VOUT(SAT) (mV) 85°C -40°C 25°C 200 150 100 50 0 1 1.5 2 2.5 VCC (V) 3 3.5 4 Allegro MicroSystems, Inc. 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 Average Supply Current versus Temperature 12 10 8 6 4 2 0 -60 -40 -20 0 20 TA (°C) 40 60 80 100 VDD = 1.65V VDD = 2.75V VDD = 3.5V IDD(AV) (uA) Average Supply Current versus Supply Voltage 12 10 8 IDD(AV) (μA) 85°C -40°C 25°C 6 4 2 0 1 1.5 2 2.5 VCC (V) 3 3.5 4 Allegro MicroSystems, Inc. 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 Period versus Temperature 100 90 80 70 tperiod (ms) VDD = 1.65V VDD = 2.75V VDD = 3.5V 60 50 40 30 20 10 0 -60 -40 -20 0 20 TA (°C) 40 60 80 100 Period versus Supply Voltage 100 90 80 70 tperiod (ms) 85°C -40°C 25°C 60 50 40 30 20 10 0 1 1.5 2 2.5 VCC (V) 3 3.5 4 Allegro MicroSystems, Inc. 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 Functional Description Low Average Power Internal timing circuitry activates the sensor for 50 μs and deactivates it for the remainder of the period (50 ms). A short awake time allows stabilization prior to the sensor 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. tPeriod Awake Sleep 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). 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. 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. I DD(EN) I DD(DIS) 0 Sample and Output Latched The push-pull outputs are capable of sourcing or sinking a maximum of 1 mA. 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. Operation The VOUTPS output switches low (turns on) when a magnetic field perpendicular to the Hall sensor exceeds the operate point, (A) VOUTPS V+ Switch to High Switch to High Switch to Low Switch to Low VOUT(HIGH) V+ Switch to High (B) VOUTPN VOUT(HIGH) Switch to High Switch to Low Switch to Low VOUT VOUT(SAT) 0 BRPN BRPS B– 0 B+ 0 B– BHYS 0 B+ BHYS VOUT VOUT(SAT) 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). BOPN BHYS BOPS BHYS Allegro MicroSystems, Inc. 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 Applications It is strongly recommended that an external bypass capacitor be connected (in close proximity to the Hall sensor) 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 0.1 μF capacitor is typical. Extensive applications information on magnets and Hall-effect sensors is available in the following notes: • Hall-Effect IC Applications Guide, AN27701 • Hall-Effect Devices: Gluing, Potting, Encapsulating, Lead Welding and Lead Forming AN27703.1 • Soldering Methods for Allegro Products (SMD and ThroughHole), AN26009 All are provided in Allegro Electronic Data Book, AMS-702, and on the Allegro Web site, www.allegromicro.com. VS CBYP 0.1 μF Sensor Outputs VOUTPS VOUTPN A1172 GND VDD Figure 2. Typical Application Circuit Allegro MicroSystems, Inc. 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 Package CG, 4-Bump WLCSP 0.955 1 2 X A A 0.955 B B .160 A 0.500 1 2 0.500 C SEATING PLANE 4X 0.05 C 0.200 PCB Layout Reference View 0.555 MAX C 0.227 All dimensions nominal, not for tooling use Dimensions in millimeters Exact configuration at supplier discretion within limits shown 0.228 B 0.500 A B 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 1 0.500 2 Copyright ©2008, Allegro MicroSystems, Inc. The products described herein are manufactured under one or more of the 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; and other patents pending. Allegro MicroSystems, Inc. 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, Inc. 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, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9