DISCONTINUED PRODUCT Shown for Reference Only 3055 Data Sheet 27680 3055 MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC MULTIPLEXED TWO-WIRE HALL-EFFECT SENSOR ICs The UGN3055U Hall-effect sensor is a digital magnetic sensing IC capable of communicating over a two-wire power/signal bus. Using a sequential addressing scheme, the device responds to a signal on the bus and returns the diagnostic status of the IC, as well as the status of each monitored external magnetic field. As many as 30 sensors can function on the same two-wire bus. This IC is ideal for multiple sensor applications where minimizing the wiring harness size is desirable or essential. X 1 2 3 BUS GROUND SWITCH IN LOGIC Dwg. PH-005 Pinning is shown viewed from branded side. The device consists of high-resolution bipolar Hall-effect switching circuitry, the output of which drives high-density CMOS logic stages. These logic stages decode the address pulse and enable a response at the appropriate address. The combination of magnetic-field or switch-status sensing, low-noise amplification of the Hall-transducer output, and high-density decoding and control logic is made possible by the development of a new sensor BiMOS fabrication technology. This unique magnetic sensing IC operates within specifications between -20°C and +85°C. Alternate magnetic and temperature specifications are available upon request. It is supplied in a 60 mil (1.54 mm) thick, three-pin plastic SIP. Each package is clearly marked with a two-digit decimal device address (xx). FEATURES ■ Complete Multiplexed Hall-Effect IC with Simple Sequential Addressing Protocol ■ Allows Power and Communication Over a Two-Wire Bus (Supply/Signal and Ground) ■ Up to 30 Hall-Effect Sensors Can Share a Bus ■ Sensor Diagnostic Capabilities ■ Magnetic-Field or Switch-Status Sensing ABSOLUTE MAXIMUM RATINGS at TA = +25°C Supply Voltage, VBUS ........................... 24 V ■ Low Power of BiMOS Technology Favors Battery-Powered and Mobile Applications ■ Ideal for Automotive, Consumer, and Industrial Applications Magnetic Flux Density, B ............ Unlimited Operating Temperature Range, TA .......................... -20°C to +85°C Storage Temperature Range, TS .............................. -55°C to +150°C Package Power Dissipation, PD .................................... 750 mW Always order by complete part number: UGN3055U . 3055 MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC OPERATIONAL CHARACTERISTIC over operating temperature range. Electrical Characteristics Limits Symbol Min. Typ. Max. Units VBUS — — 15 V IS 12 15 20 mA VBUS = 6 V IQH — — 2.5 mA VBUS = 9 V IQL — — 2.5 mA I QH–IQL IQ — — 300 µA Addr 1 — 30 — LOW to HIGH VCLH — — 8.5 V HIGH to LOW VCHL 6.5 — — V Hysteresis VCHYS — 0.8 — V Clock Period tCLK 0.1 1.0 — ms Address LOW Voltage VL VRST 6 VCHL V Address HIGH Voltage VH VCLH 9 VBUS V VRST 2.5 3.5 5.5 V VBUS = 9 V th 100 — — µs VBUS = 6 V tl 100 — — µs LOW to HIGH tplh 10 — — µs HIGH to LOW tphl — — 10 µs No Magnetic Field (VOUT = HIGH) ROUTH 40 — 75 kΩ Mag. Field Present (VOUT = LOW) ROUTL — — 50 Ω *Turn-On BOP 50 150 300 G Turn-Off BRP -25 100 300 G BHYS 0 50 75 G Power Supply Voltage Signal Current Quiescent Current Address Range Clock Thresholds Power-On Reset Voltage Settling Time Propagation Delay Pin 3 Input Resistance Magnetic Characteristics Magnetic Thresholds Hysteresis (BOP–B RP) *Alternate magnetic switch point specifications are available on request. Please contact the factory. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 W Copyright © 1988, 1991, Allegro MicroSystems, Inc. 3055 MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC SENSOR LOCATION FUNCTIONAL BLOCK DIAGRAM (±0.005” [0.13 mm] die placement) ACTIVE AREA DEPTH 0.015" 0.38 mm 1 0.071" 1.80 mm NOM BUS REG COMP COMP 0.084" 2.13 mm CLOCK CMOS LOGIC RESET 3 A BRANDED SURFACE 1 2 SWITCH IN (OPTIONAL) 3 2 GROUND Dwg. FH-009 Dwg. MH-002A DEFINITION OF TERMS Sensor Address Each bus sensor has a factory-specified predefined address. At present, allowable sensor addresses are integers from 1 to 30. LOW-to-HlGH Clock Threshold (VCLH) Minimum voltage required during the positive-going transition to increment the bus address and trigger a diagnostic response from the bus sensors. This is also the maximum threshold of the on-chip comparator, which monitors the supply voltage, VBUS. HlGH-to-LOW Threshold (VHL) Maximum voltage required during the negative-going transition to trigger a signal current response from the bus sensors. This is also the maximum threshold of the onchip comparator, which monitors the supply voltage, VBUS. Bus HIGH Voltage (VH) Bus HIGH voltage required for addressing. Voltage should be greater than VCLH . Address LOW Voltage (VL) Bus LOW Voltage required for addressing. Voltage should be greater than VRST and less than VCHL. Bus Reset Voltage (VRST) Voltage level required to reset individual sensors. Sensor Quiescent Current Drain (IQ) The current drain of bus sensors when active but not addressed. IQH is the maximum quiescent current drain when the sensor is not addressed and is at VH . IQL is the maximum quiescent current drain when the sensor is not addressed and is at VL. Diagnostic Phase Period on the bus when the address voltage is at VH . During this period, a correctly addressed sensor responds by increasing its current drain on the bus. This response from the sensor is called the diagnostic response and the bus current increase is called the diagnostic current. Signal Phase Period on the bus when the address voltage is at VL. During this period, a correctly addressed sensor that detects a magnetic field greater than magnetic Operate Point, BOP, responds by maintaining a current drain of IS on the bus. This response from the sensor is called the signal response and the bus current increase is called the signal current. Sensor Address Response Current (IS) Current returned by the bus sensors during the diagnostic and the signal responses of the bus sensors. This is accomplished by enabling the constant current source (CCS). Magnetic Operate Point (B OP) Minimum magnetic field required to switch ON the Hall amplifier and switching circuitry of the addressed sensor. This circuitry is only active when the sensor is addressed. Magnetic Release Point (BRP) Magnetic field required to switch OFF the Hall amplifier and switching circuitry after the output has switched ON. This is due to magnetic memory in the switching circuitry. However, when a device is deactivated by changing the current bus address, all magnetic memory is lost. Magnetic Hysteresis (BHYS) Difference between the BOP and BRP magnetic field thresholds. 3055 MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC ADDRESSING PROTOCOL The device may be addressed by modulating the supply voltage as shown in Figure 1. A preferred addressing protocol is as follows: the bus supply voltage is brought down to 0V so that all devices on the bus may be reset. The voltage is then raised to the address LOW voltage (VL) and the bus quiescent current is measured. The bus is then toggled between VL and VH (address HIGH voltage), with each positive transition representing an increment in the bus address. After each voltage transition, the bus current is monitored to check for diagnostic and signal responses from sensor ICs. Sensor Addressing When a sensor detects a bus address equal to its factory programmed address, it re- sponds with an increase in its supply current drain (called IS during the HIGH portion of the address cycle). This response may be used as an indication that the sensor is alive and well on the bus and is also called the diagnostic response. If the sensor detects an ambient magnetic field, it also responds with IS during the low portion of the address cycle. This response from the sensor is called the signal response. When the next positive transition is detected, the sensor becomes disabled, and its contribution to the bus signal current returns to IQ. Bus Current Figure 1 displays the above described addressing protocol. The top trace represents the bus voltage transitions as controlled by the bus driver (see applications note for an optimal bus driver schematic). The second trace represents the bus current contribution of sensor (address 02). The diagnostic response from the sensor indicates that it detected its address on the bus; however, no signal response current is returned, which indicates that sufficient magnetic field is not detected at the chip surface. The third trace represents the current drain of sensor 03 when a magnetic field is detected. Note both the diagnostic and signal response from the sensor. The last trace represents FIGURE 1 BUS TIMING D1 V H DIAGNOSTIC ADDRESS 01 DIAGNOSTIC ADDRESS 02 DIAGNOSTIC ADDRESS 03 DIAGNOSTIC ADDRESS 04 DIAGNOSTIC ADDRESS n DIAGNOSTIC ADDRESS 01 V CLH BUS VOLTAGE V CHL V L RESET V RESET RST t plh 0 SENSOR 02 — DIAGNOSTIC CURRENT IS SENSOR 02 CURRENT WITH NO MAGNETIC FIELD t phl I QL I QH 0 SENSOR 03 — DIAGNOSTIC AND SIGNAL CURRENTS IS SENSOR 03 CURRENT WITH MAGNETIC FIELD I QL I QH 0 I TOTAL BUS CURRENT WITH MAGNETIC FIELD AT SENSOR 03 S SENSOR 01 NOT PRESENT SENSOR 01 NOT PRESENT n • I QL n • I QH 0 Dwg. WH-005 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 3055 MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC the overall bus current drain. When no sensors are addressed, the net bus current drain is the sum of quiescent currents of all sensors on the bus (for ‘n’ sensors, the bus quiescent current drain is n * IQ). Bus Issues At present, a maximum of 30 active sensors can coexist on the same bus, each with a different address. Address 0 is reserved for bus current calibration in software. This feature allows for fail-safe detection of signal current and eliminates detection problems caused by low signal current (IS), the operation of sensors at various ambient temperatures, lot-to-lot variation of quiescent current, and the addition and replacement of sensors to the bus while in the field. Address 31 is designed to be inactive to allow for further address expansion of the bus (to 62 maximum addresses). In order to repeat the address cycle, the bus must be reset as shown in Figure 1 by bringing the supply voltage to below VRST . Sensors have been designed not to ‘wrap-around’. Magnetic Sensing The sensor IC has been designed to respond to an external magnetic field whose magnetic strength is greater than BOP. It accomplishes this by amplifying the output of an on-chip Hall transducer and feeding it into a threshold detector. In order that bus current is kept to a minimum, the transducer and amplification circuitry is kept powered down until the sensor is addressed. Hence, the magnetic status is evaluated only when the sensor is addressed. External Switch Sensing The third pin of the IC (pin 3) may be used to detect the status of an external switch when magnetic field sensing is not desired (and in the absence of a magnetic field). The allowable states for the switch are ‘open’ and ‘closed’ (shorted to sensor ground). APPLICATIONS NOTES Magnetic Actuation The left side of Figure 2 shows the wiring of the UGN3055U when used as a magnetic threshold detector. Pin 1 of the sensor is wired to the positive terminal of the bus, pin 2 is connected to the bus negative terminal, and pin 3 has no connection. Mechanical Actuation The right side of Figure 2 shows the wiring of the UGN3055U when used to detect the status of a mechanical switch. In this case, pin 3 is connected to the positive terminal of the switch. The negative side of the switch is connected to the negative terminal of the bus. When the mechanical switch is closed (shorted to ground) and the correct bus address is detected by the IC, the sensor responds with a signal current. If the switch is open, only a diagnostic current is returned. FIGURE 2 SENSOR CONNECTIONS POSITIVE BUS SUPPLY X 1 2 X 3 1 2 3 NC SWITCH BUS RETURN Dwg. EH-004 3055 MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC FIGURE 3 BUS INTERCONNECTION ADDRESS RESET ANALOG OUT INTERFACE MICROPROCESSOR UGN3055U AND UGS3055U (POSITIVE) BUS SUPPLY MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC 01 02 28 29 30 BUS RETURN Dwg. EH-005 Bus Configuration A maximum of 30 sensors may be connected across the same two wire bus as shown in Figure 3. It is recommended that the sensors use a dedicated digital ground wire to minimize the effects of changing ground potential (as in the case of chassis ground in the automotive industry). The bus was not designed to require two-wire twisted-pair wiring to the sensors; however, in areas of extreme EMI (electro-magnetic interference), it may be advisable to install a small bypass capacitor (0.01 µF for example) between the supply and ground terminals of each sensor instead of using the more expensive wiring. Bus Driver It is recommended that the bus be controlled by microprocessor-based hardware for the following reasons: • Sensor address information may be stored in ROM in the form of a look up table. • Bus faults can be pinpointed by the microprocessor by comparing the diagnostic response to the expected response in the ROM look up table. • The microprocessor, along with an A/D converter, can also be used to self calibrate the quiescent currents in the bus and hence be able to easily detect a signal response. • The microprocessor can also be used to filter out random line noise by digitally filtering the bus responses. • The microprocessor can easily keep track of the signal responses, initiate the appropriate action; e.g., light a lamp, sound an alarm, and also pinpoint the location of the signal. Optimally, the microprocessor is used to control bus-driving circuitry that will accept TTL level inputs to drive the bus and will return an analog voltage representation of the bus current. Interface Schematic The bus driver is easily designed using a few operational amplifiers, resistors, and transistors. Figure 4 shows a schematic of a recommended bus driver circuit that is capable of providing 6 V to 9 V transitions, resetting the bus, and providing an analog measurement of the current for use by the A/D input of the microprocessor. In Figure 4, the Address pin provides a TTL-compatible input that is used to control the Bus supply. A HIGH (5 V) input switches Q1 ON and sets the bus voltage to 6 V through the resistor divider R4, R5, and the Zener Z1. A LOW input switches OFF Q2 and sets the bus voltage to 9 V. This voltage is fed into the positive input of the operational amplifier OP1 and is buffered and made available at Bus Supply (or sensor supply). Bus reset control is also available in the form of a TTL-compatible input. When this input, which is marked Reset, is HIGH, Q2 is switched ON and the positive input of the op amp is set to the saturation voltage of the transistor (approximately 0 V). This resets the bus. A linear reading of the bus current is made possible by amplifying the voltage generated across R6 (which is IBUS * R6). The amplifier, OP2, is a standard differential amplifier of gain R9/R7 (provided that R7 = R8, R9 = R10). The gain of the total transimpedance amplifier is given by: V OUT = IBUS * R6 * R9/R7 This voltage is available at the terminal marked Analog Out. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 3055 MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC Bus Control Software The processing of the bus current (available at Analog Out) is best done by feeding it into the A/D input of a microprocessor. If the flexibility provided by a microprocessor is not desired, this signal could be fed into threshold detection circuitry; e.g., comparator, and the output used to drive a display. Related References 1. G. AVERY, “Two Terminal Hall. Sensor,” ASSIGNEE: Sprague Electric Company, North Adams, MA, United States. Patent number 4,374,333; Feb. 1983. 2. T. WROBLEWSKI and F. MEISTERFIELD, “Switch Status Monitoring System, Single Wire Bus, Smart Sensor Arrangement There Of,” ASSIGNEE: Chrysler Motor Corporation, Highland Park, Ml, United States. Patent number 4,677,308; June 1987. FIGURE 4 BUS INTERFACE SCHEMATIC +15 V 1 kΩ 10 kΩ R 4 9V Z1 1 kΩ Q3 0.001 µF OP 1 BUS SUPPLY 20 kΩ R5 ADDRESS 5 kΩ 50 Ω R 6 X X Q2 Q1 RESET 5 kΩ 50 kΩ R8 50 kΩ R7 1 2 3 1 2 3 NC SWITCH 100 kΩ R 9 BUS RETURN ANALOG OUT OP 2 100 kΩ R 10 Dwg. EH-003A 3055 MULTIPLEXED TWO-WIRE HALL EFFECT SENSOR IC Dimensions in Inches (controlling dimensions) Dimensions in Millimeters (for reference only) 0.183 0.178 4.65 4.52 0.063 0.059 1.60 1.50 0.181 0.176 4.60 4.47 45° 0.086 1 2 45° 0.018 3 2.18 MAX 1 2 0.46 3 MAX 0.015 0.560 0.38 14.22 MIN MIN 0.016 0.41 SEE NOTE SEE NOTE 0.050 1.27 0.100 2.54 Dwg. MH-003C in Dwg. MH-003C mm NOTES: 1. Tolerances on package height and width represent allowable mold offsets. Dimensions given are measured at the widest point (parting line). 2. Exact body and lead configuration at vendor’s option within limits shown. 3. Height does not include mold gate flash. 4. Recommended minimum PWB hole diameter to clear transition area is 0.035” (0.89 mm). 5. Where no tolerance is specified, dimension is nominal. 6. Minimum lead length was 0.500” (12.70 mm). If existing product to the original specifications is not acceptable, contact sales office before ordering. 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 design of its products. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000