LMD18245T/NOPB National Semiconductor, LMD18245T/NOPB Datasheet
LMD18245T/NOPB
Specifications of LMD18245T/NOPB
*LMD18245T/NOPB
LMD18245T
Available stocks
Related parts for LMD18245T/NOPB
LMD18245T/NOPB Summary of contents
Page 1
... For higher resolution applications, an external DAC can be used. Functional Block and Connection Diagram (15-Lead TO-220 Molded Power Package (T) ) © 2006 National Semiconductor Corporation Features n DMOS power stage rated at 55V and 3A continuous n Low R DS(ON) ...
Page 2
Connection Diagram Pinout Descriptions (See Functional Block and Connection Diagrams) Pin 1, OUT 1: Output node of the first half H-bridge. Pin 2, COMP OUT: Output of the comparator. If the voltage at CS OUT exceeds that provided by the ...
Page 3
... 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 ...
Page 4
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 ...
Page 5
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 ...
Page 6
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 ...
Page 7
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 ...
Page 8
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 ...
Page 9
Functional Descriptions (Continued) 01187810 01187811 FIGURE 2. The DMOS H-Bridge 9 www.national.com ...
Page 10
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 ...
Page 11
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 ...
Page 12
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 ...
Page 13
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 ...
Page 14
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 ...
Page 15
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 = ...
Page 16
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 ...
Page 17
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 ...
Page 18
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 ...
Page 19
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 ...
Page 20
Test Circuit and Switching Time Definitions www.national.com 01187828 20 ...
Page 21
... BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...