MC3479. Stepper Motor Driver

Transcription

1 Stepper Motor Driver The M3479 is designed to drive a twophase stepper motor in the bipolar mode. The circuit consists of four input sections, a logic decoding/sequencing section, two driverstages for the motor coils, and an output to indicate the Phase drive state. Features Single Supply Operation: 7.2 to 16.5 V 35 m/oil Drive apability lamp Diodes Provided for ackemf Suppression Selectable and Full/Half Step Operation Selectable High/Low Output Impedance (Half Step Mode) TTL/MOS ompatible Inputs Input Hysteresis: 4 mv Minimum Phase Logic an e Initialized to Phase Phase Output Drive State Indication (Openollector) PbFree Package is vailable* PDIP16 P SUFFIX SE 648 MRKING DIGRM lk Full/Half Step lock F/H Step Logic V M Driver Driver V D 16 1 WL YY WW G M3479P WLYYWWG = ssembly Location = Wafer Lot = Year = Work Week = PbFree Package Phase ias/set GND Figure 1. Representative lock Diagram ORDERING INFORMTION Device M3479P M3479PG Operating Temperature Range Package Shipping T = to +7 PDIP16 PDIP16 (PbFree) 25 Units / Rail *For additional information on our PbFree strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. GND V D ias/set lk Full/Half Step lk PIN ONNETIONS (Top View) 16 V M INPUT TRUTH TLE Input Low W Full Step GND Phase Full/Half Step Input High W Half Step Hi Z Low Z Positive Edge Triggered 1

2 MXIMUM RTINGS Rating Symbol Value Unit Supply Voltage V M + 18 Vdc lamp Diode athode Voltage (Pin 1) V D V M + 5. Vdc Driver Output Voltage V OD V M + 6. Vdc Drive Output urrent/oil I OD ± 5 m Input Voltage (Logic ontrols) V in.5 to + 7. Vdc ias/set urrent I S 1 m Phase Output Voltage V O + 18 Vdc Phase Sink urrent I O 2 m Junction Temperature T J + 15 Storage Temperature Range T stg 65 to + 15 Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating onditions is not implied. Extended exposure to stresses above the Recommended Operating onditions may affect device reliability. REOMMENDED OPERTING ONDITIONS haracteristic Symbol Min Max Unit Supply Voltage V M Vdc lamp Diode athode Voltage V D V M V M Vdc Driver Output urrent (Per oil) (Note 1) I OD 35 m Input Voltage (Logic ontrols) V in Vdc ias/set urrent (Outputs ctive) I S 3 75 Phase Output Voltage V O V M Vdc Phase Sink urrent I O 8. m Operating mbient Temperature T See section on Power Dissipation in pplication Information. D ELETRIL HRTERISTIS (Specifications apply over the recommended supply voltage and temperature range, (Notes 2, 3) unless otherwise noted.) haracteristic Pins Symbol Min Typ Max Unit INPUT LOGI LEVELS Threshold Voltage (LowtoHigh) 7, 8, V TLH 2. Vdc Threshold Voltage (HightoLow) 9, 1 V THL.8 Vdc Hysteresis V HYS.4 Vdc urrent: (V I =.4 V) (V I = 5.5 V) (V I = 2.7 V) DRIVER OUTPUT LEVELS Output High Voltage (I S = 3 ) I OD = 35 m I OD =.1 m 2, 3, 14, 15 I IL 1 V OHD V M 2. V M 1.2 Output Low Voltage (I S = 3, I OD = 35 m) V OLD.8 Vdc Vdc Differential Mode Output Voltage Difference (Note 4) (I S = 3, I OD = 35 m) 14, 15 DV OD V OD Vdc Output Leakage, Hi Z State ( V OD V M, I S = 5. ) ( V OD V M, I S = 3, F/H = 2. V, =.8 V) 14, 15 I OZ1 I OZ2 LMP DIODES Forward Voltage (I D = 35 m) 1, 2, V DF Vdc Leakage urrent (Per Diode) (Pin 1 = 21 V; Outputs = V; I S = ) 3, 14, 15 I DR

3 D ELETRIL HRTERISTIS (Specifications apply over the recommended supply voltage and temperature range, (Notes 2, 3) unless otherwise noted.) haracteristic Pins Symbol Min Typ Max Unit PHSE OUTPUT Output Low Voltage (I O = 8. m) 11 V OL.4 Vdc Off State Leakage urrent (V OH = 16.5 V) I OH 1 POWER SUPPLY Power Supply urrent (I OD =, I S = 3 ) ( = V OHD, = V OLD, = V OHD, = V OLD ) ( = V OHD, = V OLD, = Hi Z, = Hi Z) ( = V OHD, = V OLD, = V OHD, = V OHD ) IS/SET URRENT To Set Phase 6 I S lgebraic convention rather than absolute values is used to designate limit values. 3. urrent into a pin is designated as positive. urrent out of a pin is designated as negative. 4. DV OD = V OD1,2 V OD3,4 where:v OD1,2 = (V OHD1 V OLD2 ) or (V OHD2 V OLD1 ), and V OD3,4 = (V OHD3 V OLD4 ) or (V OHD4 V OLD3 ). 16 I MW I MZ I MN m PKGE THERML HRTERISTIS haracteristic Symbol Min Typ Max Unit Thermal Resistance, Junctiontombient (No Heatsink) R J 45 /W SWITHING HRTERISTIS (T = + 25, V M = 12 V) (See Figures 2, 3, 4) (Notes 5, 6) haracteristic Pins Symbol Min Typ Max Unit lock Frequency 7 f K 5 khz lock Pulse Width (High) 7 PW KH 1 s lock Pulse Width (Low) 7 PW KL 1 s ias/set Pulse Width 6 PW S 1 s Setup Time ( and F/HS) t su 5. s Hold Time ( and F/HS) t h 1 s Propagation Delay (lktodriver Output) t PD 8. s Propagation Delay (ias/settodriver Output) t PSD 1. s Propagation Delay (lktophase Low) 711 t PHL 12 s Propagation Delay (lktophase High) 711 t PLH 5. s 5. lgebraic convention rather than absolute values is used to designate limit values. 6. urrent into a pin is designated as positive. urrent out of a pin is designated as negative. 3

4 + 12 V.1 F V M k ias/set lk F / HS W / W 56 k 6 3 M3479P k 1. k 1. k 1. k 1. k k + 12 V Phase ias/set Input V M Outputs PW S V M 1. V M 1. t PSD (High Impedance) Note: t r, t f (1% to 9%) for input signals are 25 ns. t PSD Figure 2. Test ircuit Figure 3. ias/set Timing (Refer to Figure 2) PIN FUNTION DESRIPTION Pin # Function Symbol Description 16 Power Supply V M Power supply pin for both the logic circuit and the motor coil current. Voltage range is to V. 4, 5, 12, 13 Ground GND Ground pins for the logic circuit and the motor coil current. The physical configuration of the pins aids in dissipating heat from within the I package. 1 lamp Diode Voltage V D This pin is used to protect the outputs where large voltage spikes may occur as the motor coils are switched. Typically a diode is connected between this pin and Pin 16. See Figure 12. 2, 3, 14, 15 Driver Outputs,, High current outputs for the motor coils. and are connected to one coil, and and to the other coil. 6 ias/set /S This pin is typically.7 volts below V M. The current out of this pin (through a resistor to ground) determines the maximum output sink current. If the pin is opened (I S < 5. ) the outputs assume a high impedance condition, while the internal logic presets to a Phase condition. 7 lock lk The positive edge of the clock input switches the outputs to the next position. This input has no effect if Pin 6 is open. 9 Full/Half Step F/HS When low (Logic ), each clock input pulse will cause the motor to rotate one full step. When high, each clock pulse will cause the motor to rotate onehalf step. See Figure 7 for sequence. 1 lockwise/ ounterclockwise This input allows reversing the rotation of the motor. See Figure 7 for sequence. 8 Output Impedance ontrol This input is relevant only in the half step mode (Pin 9 > 2. V). When low (Logic ), the two driver outputs of the nonenergized coil will be in a high impedance condition. When high the same driver outputs will be at a low impedance referenced to V M. See Figure Phase Ph This opencollector output indicates (when low) that the driver outputs are in the Phase condition ( = = V OHD, = = V OLD ). 4

5 PPLITION INFORMTION General The M3479 integrated circuit is designed to drive a stepper positioning motor in applications such as disk drives and robotics. The outputs can provide up to 35 m to each of two coils of a twophase motor. The outputs change state with each lowtohigh transition of the clock input, with the new output state depending on the previous state, as well as the input conditions at the logic controls. Outputs The outputs () are high current outputs (see Figure 5), which when connected to a twophase motor, provide two fullbridge configurations ( and are not shown in Figure 5). The polarities applied to the motor coils depend on which transistor (Q H or Q L ) of each output is on, which in turn depends on the inputs and the decoding circuitry. lk 3. V 1.5 V t PD PW LKH PW LKL Outputs F/HS, Inputs 3. V 6. V 1.5 V t su t h Note: t r, t f (1% to 9%) for input signals are 1 ns. Phase Output 1.5 V t PHL t PLH Figure 4. lock Timing (Refer to Figure 2) V M V D Q H Motor oil Q H I S /S Q L Q L R I S urrent Drivers and Logic Parasitic Diodes To, Transistors Logic Decoding ircuit W / W F/HS lk Inputs Figure 5. Output Stages The maximum sink current available at the outputs is a function of the resistor connected between Pin 6 and ground (see section on ias/set operation). Whenever the outputs are to be in a high impedance state, both transistors (Q H and Q L of Figure 5) of each output are off. 5

6 V DThis pin allows for provision of a current path for the motor coil current during switching, in order to suppress backemf voltage spikes. V D is normally connected to V M (Pin 16) through a diode (zener or regular), a resistor, or directly. The peaks instantaneous voltage at the outputs must not exceed V M by more than 6. V. The voltage drop across the internal clamping diodes must be included in this portion of the design (see Figure 6). Note the parasitic diodes (Figure 5) across each Q L of each output provide for a complete circuit path for the switched current. V F (V) I D (m) 3 Figure 6. lamp Diode haracteristics Full/Half Step When this input is at a Logic (<.8 V), the outputs change a full step with each clock cycle, with the sequence direction depending on the input. There are four steps (Phase,,, D) for each complete cycle of the sequencing logic. urrent flows through both motor coils during each step, as shown in Figure 7. When taken to a Logic 1 (>2. V), the outputs change a half step with each clock cycle, with the sequence direction depending on the input. Eight steps (Phase to H) result for each complete cycle of the sequencing logic. Phase,, E and G correspond (in polarity) to Phase,,, and D, respectively, of the full step sequence. Phase, D, F and H provide current to one motor coil, while deenergizing the other coil. The condition of the outputs of the deenergized coil depends on the input, see Figure 7 timing diagram. The output impedance control input determines the output impedance to the deenergized coil when operating in the halfstep mode. When the outputs are in Phase, D, F or H (Figure 7) and this input is at a Logic (<.8 V), the two outputs to the deenergized coil are in a high impedance condition Q L and Q H of both outputs (Figure 5) are off. When this input is at a Logic 1 (>2. V), a low impedance output is provided to the deenergized coil as both outputs have Q H on (Q L off). To complete the low impedance path requires connecting V D to V M as described elsewhere in this data sheet. ias/set This pin can be used for three functions: a) determining the maximum output sink current; b) setting the internal logic to a known state; and c) reducing power consumption. a) The maximum output sink current is determined by the base drive current supplied to the lower transistors (Q L s of Figure 5) of each output, which in turn, is a function of I S. The appropriate value of I S can be approximated using Figure 11. 6

7 lk ias/set Phase D D Phase Output (a) Full Step Mode F/HS = High Impedance = Logic " = Don t are D E F G H D (b) Half Step Mode F/HS = High Impedance = Logic " = Logic 1", = Logic " D E F G H D F/HS = Logic " = Logic 1" = Logic 1" Phase Output (c) Half Step Mode Figure 7. Output Sequence The value of R (between this pin and ground) is then determined by: R V.7 V M I S b) When this pin is opened (raised to V M ) such that I S is < 5., the internal logic is set to the Phase condition, and the four driver outputs are put into a high impedance state. The Phase output (Pin 11) goes active (low), and input signals at the controls are ignored during this time. Upon reestablishing I S, the driver outputs become active, and will be in the Phase position ( = = V OHD, = = V OLD ). The circuit will then respond to the inputs at the controls. The Set function (opening this pin) can be used as a powerup reset while supply voltages are settling. MOS logic gate (powered by V M ) can be used to control this pin as shown in Figure 12. c) Whenever the motor is not being stepped, power dissipation in the I and in the motor may be lowered by reducing I S, so as to reduce the output (motor) current. Setting I S to 75 will reduce the motor current, but will not reset the internal logic as described above. See Figure 13 for a suggested circuit. Power Dissipation The power dissipated by the M3479 must be such that the junction temperature (T J ) does not exceed 15. The power dissipated can be expressed as: P = (V M I M ) + (2 I OD ) [(V M V OHD ) + V OLD ] where V M = Supply voltage; I M = Supply current other than I OD ; I OD = Output current to each motor coil; V OHD = Driver output high voltage; V OLD = Driver output low voltage. The power supply current (I M ) is obtained from Figure 8. fter the power dissipation is calculated, the junction temperature can be calculated using: T J = (P R J ) + T where R J = Junctiontoambient thermal resistance (52 /W for the DIP, 72 /W for the FN Package); T = mbient Temperature. 7

8 .8 7 IM (m) I OD = V OLD (VOLTS) I S ( ) I OD (m) Figure 8. Power Supply urrent Figure 9. Maximum Saturation Voltage Driver Output Low For example, assume an application where V M = 12 V, the motor requires 2 m/coil, operating at room temperature with no heatsink on the I. From Figure 11, I S is determined to be 95. R is calculated: R = (12.7) V/95 R = k From Figure 8, I M (max) is determined to be 22 m. From Figure 9, V OLD is.46 V, and from Figure 1, (V M V OHD ) is 1.4 volts. P = (12.22) + (2.2) ( ) P = 1.1 W 2. T J = (1.1 W 52 /W) + 25 T J = 77.5 This temperature is well below the maximum limit. If the calculated T J had been higher than 15, a heatsink such as the Staver o. V7 Series, avid #582, or Thermalloy #612 could be used to reduce R J. In extreme cases, forced air cooling should be considered. The above calculation, and R J, assumes that a ground plane is provided under the M3479 (either or both sides of the P board) to aid in the heat dissipation. Single nominal width traces leading from the four ground pins should be avoided as this will increase T J, as well as provide potentially disruptive ground noise and I R drops when switching the motor current. 14. [V M V OHD ] (VOLTS) I S ( ) I OD (m) Figure 1. Maximum Saturation Voltage Driver Output High I OD (m) Figure 11. ias/set urrent Output Drive urrent 8

9 +V +V 1N5221 (3. V) Phase 2. k Typ 11 V M 16 1 V D 3 Motor Digital Inputs lock 7 1 M Full/Half Step GND ias/set R Set Normal Operation M1449U or equivalent Figure 12. Typical pplications ircuit M ias/set Normal Operation R R 1 Reduced Power M1449U or equivalent Suggested value for R 1 (V M = 12 V) is 15 k. R calculation (see text) must take into account the current through R 1. Figure 13. Power Reduction 9

10 PKGE DIMENSIONS PDIP16 SE 6484 ISSUE D F N L M NOTES: 1. DIMENSIONING ND TOLERNING PER SME Y14.5M, ONTROLLING DIMENSION: INH. 3. DIMENSION L TO ENTER OF LEDS WHEN FORMED PRLLEL. 4. DIMENSION DOES NOT INLUDE MOLD FLSH. INHES MILLIMETERS DIM MIN MX MIN MX D E.5 S 1.27 S F G.1 S 2.54 S J K L.3 S 7.62 S M 1 1 N K J 16X.5 (.13) M T E G 16X D.5 (.13) M T T SETING PLNE 1 M3479/D