LMD18245T National Semiconductor, LMD18245T Datasheet
LMD18245T
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LMD18245T Summary of contents
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... DS(ON) Applications n Full, half and microstep stepper motor drives n Stepper motor and brushed DC motor servo drives n Automated factory, medical and office equipment Order Number LMD18245T See NS Package Number TA15A DS011878 March 2006 of typically 0.3 per power switch = 155˚C ...
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... See Table 1. www.national.com Top View 15-Lead TO-220 Molded Power Package Order Number LMD18245T See NS Package Number TA15A Pin 12, SGND: Ground return node of all signal level circuits. Pin 13, CS OUT: Output of the current sense amplifier. The current sense amplifier sources 250 µA (typical) per ampere of total forward current conducted by the upper two switches of the power bridge ...
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... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. DC Voltage at: OUT and OUT 2 CC COMP OUT, RC, M4, M3, M2, M1, BRAKE, DIRECTION, CS OUT, and DAC REF DC Voltage PGND to SGND Continuous Load Current ...
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Electrical Characteristics The following specifications apply for V perature range, −40˚C T +125˚C. All other limits apply for T J Symbol Parameter CURRENT SENSE AMPLIFIER Current Sense Offset DIGITAL-TO-ANALOG CONVERTER (DAC) Resolution Monotonicity Total Unadjusted Error Propagation Delay I DAC ...
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Typical Performance Characteristics RDS(ON) vs Temperature RDS(ON) vs Supply Voltage Supply Current vs Supply Voltage RDS(ON) vs Load Current 01187829 01187831 01187833 5 01187830 Current Sense Output vs Load Current 01187832 Supply Current vs Temperature 01187834 www.national.com ...
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Functional Descriptions TYPICAL OPERATION OF A CHOPPER AMPLIFIER Chopper amplifiers employ feedback driven switching of a power bridge to control and limit current in the winding of a motor (Figure 1). The bridge consists of four solid state power switches ...
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Functional Descriptions (a) 01187803 (b) 01187804 (e) 01187807 (f) 01187808 FIGURE 1. Chopper Amplifier Chopping States: Full V and (e), Winding Current Decays During a Change in the Direction of the Winding Current (c) and (f), and the (Continued) Applied ...
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Functional Descriptions THE LMD18245 CHOPPER AMPLIFIER The LMD18245 incorporates all the circuit blocks needed to implement a fixed off-time chopper amplifier. These blocks include: an all DMOS, full H-bridge with clamp diodes, an amplifier for sensing the load current, a ...
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Functional Descriptions (Continued) 01187810 01187811 FIGURE 2. The DMOS H-Bridge 9 www.national.com ...
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Functional Descriptions FIGURE 3. Decay Paths for Initial Winding Current During a Change in the Direction of the Winding Current THE CURRENT SENSE AMPLIFIER Many transistor cells in parallel make up the DMOS power switches. The current sense amplifier (Figure ...
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Functional Descriptions THE DIGITAL-TO-ANALOG CONVERTER (DAC) The DAC sets the threshold voltage for chopping D/16, where D is the decimal equivalent (0–15) DAC REF of the binary number applied at M4 through M1, the digital inputs of ...
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Applications Information POWER SUPPLY BYPASSING Step changes in current drawn from the power supply occur repeatedly during normal operation and may cause large voltage spikes across inductance in the power supply line. Care must be taken to limit voltage spikes ...
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The Typical Application Figure 7 shows the typical application, the power stage of a chopper drive for bipolar stepper motors. The 20 k and 2.2 nF capacitor connected between RC and ground set the off-time at about 48 µs, and ...
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The Typical Application wave drive. The motor takes one full step at each change of direction of either winding current. Figure 9 shows the wind- Top Trace: Phase A Winding Current at 1A/div Bottom Trace: Phase B Winding Current at ...
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The Typical Application Top Trace: Phase A Winding Current at 1A/div Bottom Trace: Phase B Winding Current at 1A/div Horizontal: 1 ms/div *500 steps/second M4 A through through BRAKE A = ...
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The Typical Application HALF STEP DRIVE WITHOUT TORQUE COMPENSATION To make the motor take half steps, windings A and B can be energized in the sequence A*B A* A*B* B* AB* A The motor takes one half ...
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The Typical Application HALF STEP DRIVE WITH TORQUE COMPENSATION To make the motor take half steps, the windings can also be energized with sinusoidal currents (Figure 12). Controlling the winding currents in the fashion shown doubles the step resolution without ...
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The Typical Application |cos 0˚ FORWARD 45˚ 90˚ 135˚ 180˚ 225˚ REVERSE 270˚ | 315˚ REPEAT FIGURE 13. Lookup Table for Half Step Drive with Torque Compensation www.national.com (Continued DIRECTION 0.707 11 ...
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The Typical Application QUARTER STEP DRIVE WITH TORQUE COMPENSATION Figure 14 shows the winding currents and lookup table for a quarter step drive (four microsteps per full step) with torque compensation. Top Trace: Phase A Winding Current at 1A/div Bottom ...
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Test Circuit and Switching Time Definitions www.national.com 01187828 20 ...
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... Deutsch Tel: +49 (0) 69 9508 6208 English www.national.com Français Tel: +33 ( 8790 15-Lead TO-220 Power Package (T) Order Number LMD18245T NS Package Number TA15A 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system affect its safety or effectiveness ...