Part (A) Driving LEDs and DC Motors by Sourcing and Sinking Current from a Logic Gate Sourcing Current Sinking Current

Transcription

1 Name Name ME430 Mechatronics Lab 2: Transistors, H Bridges, and motors The lab team has demonstrated: Part (A) Driving LEDs and DC Motors by Sourcing and Sinking Current from a Logic Gate Sourcing Current Sinking Current Part (B) Driving DC Motors using Logic Gates and Transistors NPN BJT transistor N channel MOSFET transistor Darlington Chip (ULN2003) Part (C) Using 2 Volt Power Supplies to Drive Lamps and Fans MOSFETs BJTs Darlingtons Part (D) Using a Darlington to drive multiple LEDs Dancing lights Part (E) Bi directional Control of Motors with H Bridge chips DC Motor with bi directional 5V drive circuit Linear actuator DC motor with bi directional 2V drive circuit Stepper Motor at 5V with 2 sets of bi directional phases ME430 Mechatronics: Lab 2

2 Part (A) Driving LEDs and DC Motors by Sourcing and Sinking Current from a Logic Gate In the Intro to Transistors video lecture, you also learned about sourcing and sinking current from a logic gate. Sinking the current allows much higher current levels. In this part we would like to build the two configurations and verify that they work. () Sourcing Current First, rebuild the simple current sourcing circuit you built for the beginning of Lab. sure that one works before you move on. Recall that it looks like Make We would like to modify the circuit to also drive (by sourcing the current from the 7404) a DC (brushed) motor. These are the ordinary looking silver grey motors. On the sketch below, show how you are planning to add the motor to the circuit: ME430 Mechatronics: Lab 2 2

3 Now that you have a plan, go ahead and wire the circuit. The LED should still turn on when you push the button. But does the motor spin? (It may or may not, depending on the motor. You can try to turn it by hand to get it started.) When we are sourcing current from the chip, we don t get very much current. Get this checked off on the front page. (2) Sinking Current There is a much better chance that we will be able to drive the LED and the motor if we sink the current to the chip instead. Refer to your notes on the video lecture Intro to Transistors, and sketch a circuit which uses a basic switch and a 7404 chip, but which sinks the current to the chip. (The LED and the motor will be on when the button is not pressed, and off when it is pressed. That s ok.) Once you have a sketch, go ahead and wire the circuit. Does the motor spin? What if you give it a push? Get this checked off on the front page. ME430 Mechatronics: Lab 2 3

4 Part (B) Driving DC Motors using Logic Gates and Transistors Clearly, we are not getting enough power from the 7404 logic chip to drive a motor. So, we will use the logic chip merely as input to a transistor. The transistor will act as an electronic switch to turn the power to the motor on and off. In this part, our goal is to use three kinds of transistors as electronic switches: an NPN BJT (Bipolar junction transistor) transistor, an N channel MOSFET (metal oxide semiconductor field effect transistor) transistor, and a Darlington chip (which contains many transistors). Note: saying MOSFET transistor is redundant since the T stands for transistor, but, much like saying PIN number, it is common practice. () NPN BJT transistor Sketch a circuit that has a basic switch and a 7404 NOT gate. Source the current to an LED off of pin 2 of the Use pin 4 of the 7404 to drive an NPN BJT transistor. Refer to your notes on the Intro to Transistors video to complete the circuit diagram. Don t forget to measure the resistance of your motor to properly size the resistors in the circuit. Now go ahead and build the circuit. There are extra resistors of various sizes in the grey cabinet. Demonstrate that the LED and motor work when you press the button and get it checked off on the front page. ME430 Mechatronics: Lab 2 4

5 (2) N channel MOSFET transistor MOSFETs are even easier to use than BJTs, because you don t need to figure any currents or size any resistors the MOSFETs act as voltage controlled switches. Sketch a circuit that has a basic switch and a 7404 NOT gate. Source the current to an LED off of pin 2 of the Use pin 4 of the 7404 to drive an N channel MOSFET transistor. Refer to your notes on the Intro to Transistors video to complete the circuit diagram. Now go ahead and build the circuit. Demonstrate that the LED and motor work when you press the button and get it checked off on the front page. ME430 Mechatronics: Lab 2 5

6 (3) Darlington Chip (ULN2003) Darlington chips are prepackaged, paired BJTs, which are intended to be used as switches. Sketch a circuit that has a basic switch and a 7404 NOT gate. Source the current to an LED off of pin 2 of the Use pin 4 of the 7404 to drive the Darlington chip. Refer to your notes on the Intro to Transistors video to complete the circuit diagram. Now go ahead and build the circuit. Demonstrate that the LED and motor work when you press the button and get it checked off on the front page. ME430 Mechatronics: Lab 2 6

7 Part (C) Using 2 Volt Power Supplies to Drive Lamps and Fans In Part (B), we used transistors to drive the motor because we needed more current than the NOT gate could provide. Now we are going to use transistors to drive devices that need a higher voltage. It is very common for motors and other actuators to require higher drive voltages. We will modify the circuits from before to control a 2 Volt power supply for the load in this case lamps (not LEDs) and fans. () MOSFETs First, diagram a circuit that will let you run a lamp with a MOSFET, still using a 5 Volt power supply for everything. This is almost identical to the MOSFET circuit you used in Part (B), but you will use a lamp instead of the motor. (The lamps look a lot like clear LEDs, except that you can see a filament inside of them. The lamps are in the grey cabinet! IR emitters look like lamps, and are in your lab kit. Don t use an IR emitter here!) Now build this circuit and make sure that the lamp turns on. The light will be rather dim, because you are running it from a 5V supply instead of the 2V it wants. You can check yourself off on this part! Lamp is lit from 5V, although dim ME430 Mechatronics: Lab 2 7

8 Next, modify the circuit you drew to light the lamp from a 2V supply. (Notice how easy the modification is! This is why MOSFETs are wonderful.) Note that the power to the NOT chip is still running at 5V! The 2V supplies are red, and are in the grey cabinet at the back of the room. (On the front they say one voltage, but on the back they say 2V.) Remember the power to the NOT chip is still 5V try not to burn up too many NOT chips Also, make sure that the ground for the 2V supply is the same as the ground for the 5V supply connect the two grounds together. If you don t do this, the two ground voltages could actually be different and your circuit might not work. Build this circuit and make sure that the light is brighter than it was before. yourself off on this part, too. You can check Lamp is lit from 2V, and is pretty bright now. For the last piece of this section, we are going to replace the lamp in the circuit with a fan. The fans are black, have a frame that is about 3 x3, and are in the grey cabinet at the back of the room. The circuit a direct swap of the lamp and the fan, except that running fans backwards can break them! Make sure that the red lead on the fan goes to the +2V line! Once you have this working, demonstrate it to your instructor and get this section checked off on the front page. (2) BJTs The MOSFETs were really easy to use, but they are much more expensive than the BJTs. So, we will need to be able to use BJTs to do the same tasks we accomplished with the MOSFET. Remember that, for the BJTs, we need an input resistor to control the current. The lamps we purchased were called 2 volt, 35 ma, incandescent, lamps. They draw 35 ma when they are running. This means that we need to choose a resistor to make the current into the base one tenth of the load current, or 3.5 ma. The voltage drop between the base and the emitter of the BJT is 0.7 V, so the resistor will see a voltage drop of 4.3 V. What resistor size should you choose if you could choose an arbitrary value? Now go to the cabinet and pick a real resistor. Build the BJT circuit to drive the lamp at 2V. What size did you pick? You can check this part off yourself: Got the lamp running at 2V with a BJT ME430 Mechatronics: Lab 2 8

9 Next, we would like to replace the lamp with a fan. for the base. We will need to recalculate the resistor We knew the current the lamp would draw when it was running, but we will need to measure the current drawn by the fan when it is running. (It won t work to measure the fan resistance, because the fan has a diode that confuses the measurement.) Get the fan running directly from the power supply, then put the digital multimeter (DMM) in series with the fan and measure the current it draws. We measured a fan current of. If we could choose any size resistor for the base of the BJT, we would choose. However, when we went to the cabinet, we picked this resistor:. Get the fan running with this resistor and the BJT. the front page. Then have your instructor check you off on (3) Darlingtons Darlingtons (ULN2003 chips) are very simple to use for our switching purposes even at 2V. Build a circuit that uses a Darlington to drive the lamp, then replace the lamp with a fan. Make sure that the power for the load (the lamp or the fan) is connected to 2V, but the power for the NOT chip is connected to 5V. So you will need BOTH power supplies with the grounds connected together. Make sure that the COM line on the Darlington is connected to 2V (not 5V). Don t use the optional resistor on the input to the Darlington. (The COM line is connected to the internal snubber diodes on the Darlington, so that is why we need to connect it to the 2V supply. The optional resistor on the input can actually interfere with some circuits.) You can check off the lamp yourself. Lamp running from a Darlington with 2V power to the lamp. Demonstrate the fan running from a Darlington with 2V to the fan to your instructor, and get this section checked off on the front. ME430 Mechatronics: Lab 2 9

10 Part (D) Using a Darlington to drive multiple LEDs If we try to drive multiple LEDs in a source configuration with a single NOT chip, we will draw too much current from the chip and the lights will be weak. (The same would be true if we tried to drive multiple LEDs from one microcontroller.) However, it is quite straightforward to use the logic chip to drive a Darlington, and then let the Darlington control the LEDs. The Darlington has 7 switches in each chip, and they have all of the snubber diodes and resistors included in the package. Isn t it nice when they include things inside the chip for you? In this part, we will use a Darlington to drive 7 LEDs. Just for fun, we will make our LEDs in this part dance when the button is not pressed, 4 of the LEDs will be on, and 3 will be off. When the button is pressed, the on/off LEDs will switch. The figure below shows part of the circuit you need to build: Our load is the light, so replace R load with an LED and a 330 ohm resistor. If we just wire the circuit as shown, then the single LED will be on when the button is not pressed, and off when we press the button. (You should check this.) Now, if you haven t already, make the connections labeled 2, 3, 4, 5, 6, and 7 on the NOT gate, and also connect them to IN2, IN3, IN7 on the Darlington. Check that the button press still toggles the one LED on and off, so that you haven t messed anything up. These connections will make IN2, IN4, and IN6 go low when IN, IN3, IN5, and IN7 are high, and vice versa. Finally, put 6 more LEDs and resistors on OUT2, OUT3, OUT7. Each LED needs its own resistor. When you press the button, the lights should dance. Get this checked off by your instructor on the front. ME430 Mechatronics: Lab 2 0

11 Part (E) Bi directional Control of Motors with H bridge chips If we only need unidirectional control of our motors, then the transistor circuits we used in Part (B) or Part (C) are the easiest solution. If we need to run the motor forwards and backwards, then we will need bidirectional control. For this, an H bridge (L293) chip is definitely the way to go. We will have you create a bi directional control for three different motors using an H bridge chip: Table 2: H Bridge motor circuits Motor DC motor (silver grey) Linear actuator DC motor (door actuator) Stepper Motor (larger, silver and black) Type of drive 5 Volts, bi directional 2 Volts, bi directional 5 Volts, 2 sets of bi directional phases ME430 Mechatronics: Lab 2

12 () DC Motor with bi directional 5V drive circuit We want to use the H bridge chip to run a motor with 2 button switches one switch will turn the motor on or off and the other one will choose whether the motor turns clockwise or counter clockwise. Referring to the L293 datasheet on the ME430 courseware page, we see that the suggested bi directional motor circuit for an L293 looks like: There are actually three motors here one running bi directionally on the left and two running uni directionally on the right. We will only use the connections on the left hand side. Recall that if we ever want uni directional control we ll use a regular transistor. We ve pasted a version of this circuit by itself on the next page, because we are going to want to add some switches and other connections to it. In order to make sure that the right hand side of the H bridge does not interfere with the left hand side, we also connected pin 9 to ground. If you read through the datasheet a bit more, you find that pin is the enable line the signal that tells the H bridge to turn on. On the circuit drawing on the next page, add a basic switch circuit without an inverter to serve as the input to pin. This button switch will control whether the motor is on or off the motor will normally be on, but if we press the button it will shut the H bridge (and the motor) off. ME430 Mechatronics: Lab 2 2

13 ME430 Mechatronics: Lab 2 3

14 Next, we notice that pins 2 and 7 are always supposed to be opposites when 2 is high 7 should be low, and vice versa. This instructs the motor to spin clockwise or counter clockwise. We want to use just one more switch to accomplish this, so we will pick up one of the inputs before a NOT gate and one of the inputs after the NOT gate. Add this circuit to the diagram on the previous page. Hook the signal line labeled Z to pin 7 and the signal line labeled Z to pin 2. Finally, we will need to connect the power to the H bridge. V cc and V cc2 should both be at 5 volts (for this section). Add this to your circuit diagram. Now that you have everything planned out, go ahead and build the circuit. demonstrate it to your instructor and get it signed off on the front page. When it works, (2) Linear actuator DC motor with bi directional 2V drive circuit This next piece is very simple, really. Get a linear actuator (door actuator) from the grey cabinet. It has a motor in it that makes it either move out (and stay) or move in (and stay). However, unlike the motor we just connected, it runs on 2V, since it s for a car door. Replace the DC motor in your circuit with the door actuator. Read the datasheet for the L293 carefully, and figure out which of the voltage inputs on the L293 need to get changed to 2V in order to run the linear actuator. Change the inputs appropriately, and test the circuit. It s very cute really it quacks like a duck when it moves. Demonstrate this to your instructor and get it checked off on the front page. ME430 Mechatronics: Lab 2 4

15 (3) Stepper Motor at 5V with 2 sets of bi directional phases Stepper motors are more complicated to drive than ordinary brushed DC motors. Nevertheless, the L293 makes the task much simpler. From the L293 datasheet, we have a suggested circuit for a Two Phase Motor Driver: In this circuit V cc and V cc2 can be connected to the 5 volt supply, even though this shows V cc2 connected to 24V. Since this is a low power stepper motor, we could probably skip the diodes. Notice that the layout shown above is not a literal picture of the chip pin 4 is shown ME430 Mechatronics: Lab 2 5

16 right next to pin! Read the pin number and figure out where they are on the real device (all this information is in the L293 datasheet). We will want to set up two basic switches to control the L293. One of the switches goes directly to pin 2 of the L293, while the inverted signal from that switch goes directly to pin 7. The second switch (directly) goes to pin 0, and goes inverted to pin 5. Next, we need to hook four of the six stepper motor wires up to pins 3, 6,, and 4. Use your notes from the video lecture on stepper motors to understand what you need to measure in order to figure out which wires to use. Once everything is wired correctly, we should be able to make the stepper motor go through a small step by pushing the buttons in the correct 4 part sequence. The sequence is the full step sequence from the video lecture. Finally, count how many times you need to go through the 4 part sequence in order to get the motor to make one revolution. It takes times through the 4 part sequence to go one revolution. Demonstrate your working stepper motor for your instructor and get it checked off on the front page. ME430 Mechatronics: Lab 2 6

17 2N3904 Type 2N3904 Marking 2N3904 SILICON EPITAXIAL PLANAR NPN TRANSISTOR TO-92 PACKAGE SUITABLE FOR THROUGH-HOLE PCB ASSEMBLY THE PNP COMPLEMENTARY TYPE IS 2N3906 SMALL SIGNAL NPN TRANSISTOR PRELIMINARY DATA APPLICATIONS WELL SUITABLE FOR TV AND HOME APPLIANCE EQUIPMENT SMALL LOAD SWITCH TRANSISTOR WITH HIGH GAIN AND LOW SATURATION VOLTAGE TO-92 INTERNAL SCHEMATIC DIAGRAM ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit V CBO Collector-Base Voltage (I E = 0) 60 V V CEO Collector-Emitter Voltage (I B = 0) 40 V V EBO Emitter-Base Voltage (I C = 0) 6 V I C Collector Current 200 ma Ptot Total Dissipation at TC = 25 o C 625 mw T stg Storage Temperature -65 to 50 T j Max. Operating Junction Temperature 50 o C o C June 2002 /4

18 l l l l l l Logic-Level Gate Drive Advanced Process Technology Dynamic dv/dt Rating 75 C Operating Temperature Fast Switching Fully Avalanche Rated Description Fifth Generation HEXFETs from International Rectifier utilize advanced processing techniques to achieve the lowest possible on-resistance per silicon area. This benefit, combined with the fast switching speed and ruggedized device design that HEXFET Power MOSFETs are well known for, provides the designer with an extremely efficient device for use in a wide variety of applications. G PD B IRLZ34N HEXFET Power MOSFET D S V DSS = 55V R DS(on) = I D = 30A The TO-220 package is universally preferred for all commercial-industrial applications at power dissipation levels to approximately 50 watts. The low thermal resistance and low package cost of the TO-220 contribute to its wide acceptance throughout the industry. Absolute Maximum Ratings Thermal Resistance TO-220AB GDS Parameter Max. Units I T C = 25 C Continuous Drain Current, V 0V 30 I T C = 00 C Continuous Drain Current, V 0V 2 A I DM Pulsed Drain Current 0 P C = 25 C Power Dissipation 68 W Linear Derating Factor 0.45 W/ C V GS Gate-to-Source Voltage ±6 V E AS Single Pulse Avalanche Energy 0 mj I AR Avalanche Current 6 A E AR Repetitive Avalanche Energy 6.8 mj dv/dt Peak Diode Recovery dv/dt ƒ 5.0 V/ns T J Operating Junction and -55 to + 75 T STG Storage Temperature Range C Soldering Temperature, for 0 seconds 300 (.6mm from case) Mounting torque, 6-32 or M3 screw. 0 lbf in (.N m) Parameter Min. Typ. Max. Units R JC Junction-to-Case 2.2 R CS Case-to-Sink, Flat, Greased Surface 0.50 C/W R JA Junction-to-Ambient 62 8/25/97

19 ULN200A-ULN2002A ULN2003A-ULN2004A SEVEN DARLINGTON ARRAYS SEVEN DARLINGTONS PER PACKAGE OUTPUT CURRENT 500mA PER DRIVER (600mA PEAK) OUTPUT VOLTAGE 50V INTEGRATED SUPPRESSION DIODES FOR INDUCTIVE LOADS OUTPUTS CAN BE PARALLELED FOR. HIGHER CURRENT TTL/CMOS/PMOS/DTL COMPATIBLE INPUTS INPUTS PINNED OPPOSITE OUTPUTS TO SIMPLIFY LAYOUT DIP6 ORDERING NUMBERS: ULN200A/2A/3A/4A SO6 DESCRIPTION The ULN200A, ULN2002A, ULN2003 and ULN2004A are high voltage, high current darlington arrays each containing seven open collector darlington pairs with common emitters. Each channel rated at 500mA and can withstand peak currents of 600mA. Suppression diodes are included for inductive load driving and the inputs are pinned opposite the outputs to simplify board layout. The four versions interface to all common logic families : ULN200A ULN2002A ULN2003A ULN2004A General Purpose, DTL, TTL, PMOS, CMOS 4-25V PMOS 5V TTL, CMOS 6 5V CMOS, PMOS ORDERING NUMBERS: ULN200D/2D/3D/4D PIN CONNECTION These versatile devices are useful for driving a wide range of loads including solenoids, relays DC motors, LED displays filament lamps, thermal printheads and high power buffers. The ULN200A/2002A/2003A and 2004A are supplied in 6 pin plastic DIP packages with a copper leadframe to reduce thermal resistance. They are available also in small outline package (SO-6) as ULN200D/2002D/2003D/2004D. February 2002 /8

20 Featuring Unitrode L293 and L293D Products Now From Texas Instruments Wide Supply-Voltage Range: 4.5 V to 36 V Separate Input-Logic Supply Internal ESD Protection Thermal Shutdown High-Noise-Immunity Inputs Functionally Similar to SGS L293 and SGS L293D Output Current A Per Channel (600 ma for L293D) Peak Output Current 2 A Per Channel (.2 A for L293D) Output Clamp Diodes for Inductive Transient Suppression (L293D) description/ordering information The L293 and L293D are quadruple high-current half-h drivers. The L293 is designed to provide bidirectional drive currents of up to A at voltages from 4.5 V to 36 V. The L293D is designed to provide bidirectional drive currents of up to 600-mA at voltages from 4.5 V to 36 V. Both devices are designed to drive inductive loads such as relays, solenoids, dc and bipolar stepping motors, as well as other high-current/high-voltage loads in positive-supply applications. SLRS008C SEPTEMBER 986 REVISED NOVEMBER 2004 All inputs are TTL compatible. Each output is a complete totem-pole drive circuit, with a Darlington transistor sink and a pseudo- Darlington source. Drivers are enabled in pairs, with drivers and 2 enabled by,2en and drivers 3 and 4 enabled by 3,4EN. When an enable input is high, the associated drivers are enabled, and their outputs are active and in phase with their inputs. When the enable input is low, those drivers are disabled, and their outputs are off and in the high-impedance state. With the proper data inputs, each pair of drivers forms a full-h (or bridge) reversible drive suitable for solenoid or motor applications. TA 0 C to 70 C ORDERING INFORMATION PACKAGE ORDERABLE PART NUMBER HSOP (DWP) Tube of 20 L293DWP L293DWP PDIP (N) Tube of 25 L293N L293N PDIP (NE) HEAT SINK AND GROUND HEAT SINK AND GROUND L N OR NE PACKAGE L293D... NE PACKAGE (TOP VIEW),2EN A Y Tube of 25 L293NE L293NE Tube of 25 L293DNE L293DNE TOP-SIDE MARKING Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at 2Y 2A V CC V CC 4A 4Y 3Y 3A 3,4EN L DWP PACKAGE (TOP VIEW),2EN A Y NC NC NC NC NC 2Y 2A V CC V CC 4A 4Y NC NC NC NC NC 3Y 3A 3,4EN HEAT SINK AND GROUND HEAT SINK AND GROUND Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Copyright 2004, Texas Instruments Incorporated POST OFFICE BOX DALLAS, TEXAS 75265

21 SLRS008C SEPTEMBER 986 REVISED NOVEMBER 2004 description/ordering information (continued) On the L293, external high-speed output clamp diodes should be used for inductive transient suppression. A V CC terminal, separate from V CC2, is provided for the logic inputs to minimize device power dissipation. The L293and L293D are characterized for operation from 0 C to 70 C. block diagram VCC M 4 3 M M VCC2 NOTE: Output diodes are internal in L293D. A INPUTS FUNCTION TABLE (each driver) EN OUTPUT Y H H H L H L X L Z H = high level, L = low level, X = irrelevant, Z = high impedance (off) In the thermal shutdown mode, the output is in the high-impedance state, regardless of the input levels. 2 POST OFFICE BOX DALLAS, TEXAS 75265

22 SLRS008C SEPTEMBER 986 REVISED NOVEMBER 2004 APPLICATION INFORMATION 5 V 24 V 0 kω VCC 6 8 VCC2,2EN Control A A 2 Y 3 Motor 2A 7 2Y 6 3,4EN 9 Control B 3A 0 3Y 4A 5 4Y 4 Thermal Shutdown 4, 5, 2, 3 GND Figure 3. Two-Phase Motor Driver (L293D) 8 POST OFFICE BOX DALLAS, TEXAS 75265

23 SLRS008C SEPTEMBER 986 REVISED NOVEMBER 2004 IL/IL2 = 300 ma APPLICATION INFORMATION C 0.22 µf 2 L VCC D5 D + + D8 D VCC2 L IL 5 2 L2 IL2 6 D6 D D7 D3 D D8 = SES500 Figure 6. Bipolar Stepping-Motor Control mounting instructions The Rthj-amp of the L293 can be reduced by soldering the GND pins to a suitable copper area of the printed circuit board or to an external heat sink. Figure 9 shows the maximum package power P TOT and the θ JA as a function of the side of two equal square copper areas having a thickness of 35 µm (see Figure 7). In addition, an external heat sink can be used (see Figure 8). During soldering, the pin temperature must not exceed 260 C, and the soldering time must not exceed 2 seconds. The external heatsink or printed circuit copper area must be connected to electrical ground. 0 POST OFFICE BOX DALLAS, TEXAS 75265