CS8442 CS8442 Stepper Motor Driver with Buffered Speed Signal Output Features Description The CS8442 is a stepper motor driver that implements an Hbridge design to drive two coils in an eight step sequence each revolution. Each H-bridge is capable of delivering 85mA to the load. The sequencer function insures that the odometer is monotonic and that cross-conduction of each H bridges does not occur. Before the beginning of each sequence, both bridges are turned off. This “dead zone” minimizes the fly back energy generated in the inductive loads. In addition, on board clamp diodes across each output protect the output drive transistors from excessive fly back voltages. The CS8442 is fault protected against reverse battery, short circuit, and over voltage conditions. If a fault is detected, the IC shuts down. The buffered speed signal output (SENSOR OUT) is an open collector NPN capable of driving a 4.7kΩ load connected to a 5V supply. The signal is a buffered, inverted version of the speed sensor input voltage (SENSOR IN). The input voltage can be either a sine or square wave form. ■ Buffered Speed Sensor Output ■ No Cross-conduction in either H-bridge ■ Guaranteed Monotonic ■ On Chip Flyback Diodes ■ Fault Protection Overvoltage Short Circuit Protection Load Dump Protection to 60V Absolute Maximum Ratings Supply Voltage (VCC) (continuous) -40˚C to +105˚C ..................–0.5 to 24V (100ms pulse transient) -40˚C to +105˚C ......................–0.5 to 60V Input Voltage (VIN) ..............................................................–0.3 to VCC +0.3V Storage Temperature Range (TSTG)......................................–65°C to +150°C Junction Temperature.............................................................–40°C to +150°C Speed Sensor Output .....................................................................................7V ESD (Human Body Model) .........................................................................2kV Lead Temperature Soldering Wave Solder (through hole styles only) ........10 sec. max, 260°C peak Package Options 8 Lead PDIP Gnd 1 Block Diagram COILB+ COILA– COILB– SENSOR IN SENSOR IN Coil Driver A Input Comp. Sequencer VCC COILA+ SENSOR OUT COILA+ COILA- Overvoltage and Short Circuit Protection SENSOR OUT Coil Driver B COILB + COILB- ON Semiconductor 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885–3600 Fax: (401)885–5786 N. American Technical Support: 800-282-9855 Web Site: www.cherry–semi.com March, 2000 - Rev. 1 1 CS8442 Electrical Characteristics: Unless otherwise stated, these specifications apply for -40˚C to +105˚C, VCC = 6.5 to 15.5 VDC. All voltage shall be referenced to Gnd unless otherwise noted. Overvoltage shutdown of coils occurs when VCC > 16V. PARAMETER ■ Supply Supply Voltage Range Supply Current TEST CONDITIONS TA = -40°C to +105°C TA = -40°C to +25°C VCC = 15.5 VDC Outputs not loaded Overvoltage Shutdown ■ Speed Sensor Input Frequency Range Switching Threshold Hysteresis Input Bias Current Input Voltage Range Operating Input Voltage Output Saturation Voltage Output Leakage Input Clamp Current ■ Coil Output Drivers Coil Load Coil Inductance Coil Resistance Temperature * Energized Coil Voltage (Both Polarities) A and B MIN TYP MAX UNIT 6.5 6.5 15.5 24.0 35 α α mA 16 23 V 0 1.6 300 400 3.0 Hz VDC mV µA VDC VDC VIN = 0.8VDC to VCC ±1 8 -15 to VCC 0 10K Ohm Resistor in Series ICC = 1.3mA VCC = 5.5V I Clamp at VIN = 0 VDC -0.4 +25°C 198 210 Coefficient VCC = 6.5 VDC VCC = 10.0 VDC VCC = 15.5 VDC, TA= -20°C to +105°C VCC = 15.5 VDC, TA= -40°C to -20°C 275 5 * Voltage across the coils shall be measured at the specific voltages, but shall also be within linearly interpolated limits. 2 V µA mA 222 80 0.39 Ω mH %/°C ±100 VDC VDC VDC VDC µA 400 mA VCC - 1.50 VCC - 1.60 VCC - 1.75 VCC - 2.00 De-Energized Coil Leakage Current ■ Short Circuit Protection Short Circuit Threshold Coil A + Coil B Short Circuit Turn Off Delay 0.4 10 -5.0 µs CS8442 Package Pin Description PACKAGE PIN # PIN SYMBOL 8L PDIP 1 FUNCTION Gnd Ground connection. 2 COILA+ Output stage, when active, supplies current to COIL A. 3 COILA- Output stage, when active, supplies current to COIL A. 4 SENSOR IN Input signal from wheel speed or engine rpm. 5 SENSOR OUT Buffered and inverted output of SENSOR IN signal. 6 COILB- Output stage, when active, supplies current to COIL B. 7 COILB+ Output stage, when active, supplies current to COIL B. 8 VCC Supply Voltage. Application Information Table 1: Transition States Speed Sensor SENSOR IN is a PNP comparator input that accepts a sine or square wave input. Signals in excess of VCC or Ground will not damage the input as long as the input current is limited to 1.5mA. An active clamp at 0V prevents negative input voltages from disrupting normal operation. The input can withstand 150 VDC as long as the input current does not exceed 1.5mA. This is possible if a 100kΩ resistor is placed in series with the SENSOR IN. SENSOR OUT is an open collector NPN transistor that produces a buffered and inverted version of the SENSOR IN signal. It is capable of driving a 4.7kΩ load connected to a 5V supply. 1 2 3 4 5 6 7 + OFF OFF + + + + + OFF OFF Connect Coil + VCC Gnd Polarity Positive (+) Negative (-) Connect Coil Gnd VCC H Bridge Outputs A and B The eight step sequencer moves the two H bridge output drivers through 8 sequential states (Table 1, Figure 1). In State 0, current flows from COILA+ out through COIL A and back in through COILA-. The same polarity also holds for COIL B. In State 1, COIL A outputs turn off while COIL B outputs continue conducting with the same polarity. In State 2, current flows from COIL A- out through the coil and back in COIL A+. COIL B outputs continue with their original polarity. COIL A outputs maintain this polarity through States 3 and 4 during which COIL B outputs are first turned off and then reversed. COIL B’s reversed polarity continues in Stages 5 and 6. COIL A’s outputs are turned off in Stage 5 and then turned back on (positive polarity) in Stage 6. In Stage 7, COIL B is off and COILA outputs continue with a positive polarity. 0 Coil B 0 1 2 3 4 5 6 7 The polarity definition for the coil driver outputs is as follows: Sequencer STATE # State Output State Table Coil A Each H-bridge output stage consists of 4 power NPN transistors with fly back diodes (Figure 2). Each half bridge has a composite saturation voltage of 1.5V at VCC=15.5V and IOUT = 85mA. The output stage is designed to prevent cross conduction: i.e., at no time can Q1 and Q2 or Q3 and Q4 conduct. This dead zone time minimizes fly back energy and helps protect the output stages from damage. Protection Circuitry The CS8442 is protected from short circuit, over voltage and thermal runaway conditions. When any of these faults is detected, an internal flip-flop is set and both H bridges are disabled. When the fault condition is removed, the Flip-Flop is reset after the first positive going edge from the speed sensor input. 0 Short Circuit VCC + Q1 COIL A Q3 Sense Resistor – Coil + Q2 COIL B Q4 Short Circuit Gnd – Sense Resistor Figure 1: State Diagram for Coil Outputs Figure 2: Coil Driver Output 3 Overvoltage and Short Circuit Protection CS8442 Application Diagram C1 - 10µF C2 - 0.1µF C3 - 0.01µF R1 - 3.9Ω 0.5W R2 - 100kΩ R3 - 15kΩ D1 - 1A 600PIV Z1 - 50V 0.5W COIL A - 210±12Ω, 80mH COIL B - 210±12Ω, 80mH COILA+ COILA– COILB+ CS8442 SENSOR IN SENSOR OUT VCC D1 COILB– Gnd R1 IGN C2 C1 Z1 R3 Buffered Speed Signal (Open Collector Drive) R2 C3 Package Specification PACKAGE THERMAL DATA PACKAGE DIMENSIONS IN mm (INCHES) D Lead Count Metric Max Min 10.16 9.02 8L PDIP Thermal Data RΘJC typ English Max Min .400 .355 RΘJA 8L PDIP 52 typ 100 ˚C/W ˚C/W Plastic DIP (N); 300 mil wide 7.11 (.280) 6.10 (.240) 8.26 (.325) 7.62 (.300) 1.77 (.070) 1.14 (.045) 2.54 (.100) BSC 3.68 (.145) 2.92 (.115) .356 (.014) .203 (.008) 0.39 (.015) MIN. .558 (.022) .356 (.014) REF: JEDEC MS-001 D ON Semiconductor and the ON Logo are trademarks of Semiconductor Components Industries, LLC (SCILLC). ON Semiconductor reserves the right to make changes without further notice to any products herein. For additional information and the latest available information, please contact your local ON Semiconductor representative. Ordering Information Part Number CS8442XN8 Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same. Description 8L PDIP 4 © Semiconductor Components Industries, LLC, 2000