A1202 and A1203: Continuous-Time Bipolar Switch Family
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Description The Allegro® A1202 and A1203 Hall-effect bipolar switches are next-generation replacements and extension of the popular Allegro A3133 and A3132 bipolar switch product line. Overall, the A120x family, produced with BiCMOS technology, consists of continuous-time devices that feature fast power-on time and low-noise operation. Device programming is performed after packaging, to ensure increased switchpoint accuracy by eliminating offsets that can be induced by package stress. Unique Hall element geometries and low-offset amplifiers help to minimize noise and to reduce the residual offset voltage normally caused by device overmolding, temperature excursions, and thermal stress. The A120x Hall-effect bipolar switches include the following on a single silicon chip: voltage regulator, Hall-voltage generator, small-signal amplifier, Schmitt trigger, and NMOS output transistor. The integrated voltage regulator permits operation from 3.8 to 24 V. The extensive on-board protection circuitry makes possible a ±30 V absolute maximum voltage rating for superior protection in automotive and motor commutation A1202-DS, Rev. 16 Features and Benefits Continuous-time operation Fast power-on time Low noise Stable operation over full operating temperature range Reverse battery protection Solid-state reliability Factory-programmed at end-of-line for optimum performance Robust EMC performance High ESD rating Regulator stability without a bypass capacitor Continuous-Time Bipolar Switch Family Continued on the next page… Packages: 3 pin SOT23W (suffix LH), and 3 pin SIP (suffix UA) Functional Block Diagram Not to scale A1202 and A1203 Amp Regulator GND VCC VOUT Gain Offset Trim Control To all subcircuits

A1202 Continuous-Time Bipolar Switch Family and A1203 Allegro MicroSystems, Inc. 2 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com applications, without adding external components. All devices in the family are identical, except for magnetic switchpoints. The small geometries of the BiCMOS process allow these devices to be provided in ultrasmall packages. The package styles available provide magnetically optimized solutions for most applications. Package LH is a SOT23W, a miniature low-profile surface-mount package, while package UA is...

A1202 Continuous-Time Bipolar Switch Family and A1203 Allegro MicroSystems, Inc. 3 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Pin-out Diagrams Terminal List Name Description Number Package LH Package UA VCC Connects power supply to chip 1 1 VOUT Output from circuit 2 3 GND Ground 3 2 1 2 3 GND VOUT VCC Package LH Package UA 1 2 3 GND VOUT VCC

A1202 Continuous-Time Bipolar Switch Family and A1203 Allegro MicroSystems, Inc. 4 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com OPERATING CHARACTERISTICS over full operating voltage and ambient temperature ranges, unless otherwise noted Characteristic Symbol Test Conditions Min. Typ. Max. Units Electrical Characteristics Supply Voltage1 VCC Operating, TJ < 165°C 3.8 – 24 V Output Leakage Current IOUTOFF VOUT = 24 V, B < BRP – – 10 ìA Output On Voltage VOUT(SAT) IOUT = 20 mA, B > BOP – 215 400 mV Power-On Time2 tPO Slew rate...

A1202 Continuous-Time Bipolar Switch Family and A1203 Allegro MicroSystems, Inc. 5 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information Characteristic Symbol Test Conditions Value Units Package Thermal Resistance RèJA Package LH, 1-layer PCB with copper limited to solder pads 228 ºC/W Package LH, 2-layer PCB with 0.463 in.2 of copper area each side connected by thermal vias 110 ºC/W Package UA, 1-layer PCB with copper limited to solder pads 165...

A1202 Continuous-Time Bipolar Switch Family and A1203 Allegro MicroSystems, Inc. 8 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Functional Description Bipolar Device Switching The devices of the A120X family provide highly sensitive switching for applications using magnetic fields of alternating polarities, such as ring magnets. There are three switching modes for bipolar devices, referred to as latch, unipolar switch, and negative switch. Mode is determined by the switchpoint characteristics of the individual device. The...

A1202 Continuous-Time Bipolar Switch Family and A1203 Allegro MicroSystems, Inc. 9 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com the field is reduced beyond the BOP level, the device switches back to the low state. The typical output behavior of the A120x devices is latching. That is, switching to the low state when the magnetic field at the Hall element exceeds the operate point threshold, BOP . At this point, the output voltage is VOUT(SAT). When the magnetic field is reduced to below the release point threshold, BRP , the device...

A1202 Continuous-Time Bipolar Switch Family and A1203 Allegro MicroSystems, Inc. 10 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com The choice between continuous-time and chopper-stabilized designs is solely determined by the application. Battery management is an example where continuous-time is often required. In these applications, VCC is chopped with a very small duty cycle in order to conserve power (refer to figure 4). The duty cycle is controlled by the power-on time, tPO, of the device. Because continuous-time devices have the...

A1202 Continuous-Time Bipolar Switch Family and A1203 Allegro MicroSystems, Inc. 11 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Power Derating Power Derating The device must be operated below the maximum junction temperature of the device, TJ(max). Under certain combinations of peak conditions, reliable operation may require derating supplied power or improving the heat dissipation properties of the application. This section presents a procedure for correlating factors affecting operating TJ. (Thermal data is also available on the...