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© Semiconductor Components Industries, LLC, 2016 1 Publication Order Number: June 2016 - Rev. 1 LV8728MR/D LV8728MR Stepper Motor Driver, PWM, Constant-Current Control, 1/128 step Overview The LV8728MR is a PWM current-controlled micro step stepper motor driver. This driver can perform eight types of excitation mode from Full step to 1/128 step and can drive simply by the CLK input. Function Single-channel PWM current control stepper motor driver BiCDMOS process IC Output on-resistance (upper side: 0.3 ; lower side: 0.25 ; total of upper and lower: 0.55 ; Ta = 25C, IO = 2.0A) Full, Half, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128 step excitation mode are selectable Advance the excitation step with the only step signal input Available forward reverse control IO max = 2.0A Over-current protection circuit Thermal shutdown circuit Input pull down resistance With reset pin and enable pin. Typical Applications Printer (Multi-function printer, 3D printer, etc.) Security camera Scanner Stage light www.onsemi.com
ORDERING INFORMATION
Ordering Code: LV8728MR-AH Package MFP30KR (Pb-Free / Halogen Free) Shipping (quantity/packing) 1000 / Tape & Reel Maximum Ratings (Note 1) Parameter Symbol Conditions Ratings Unit Maximum supply voltage VM max VM , VM1 , VM2 36 V Maximum output current I O max Per 1ch 2.0 A Maximum logic input voltage V IN max ST , MD1 , MD2 , MD3 , OE , RST , FR , STEP 6 V Maximum FDT input voltage VFDT max 6 V Maximum VREF input voltage VREF max 6 V Maximum MO input voltage V MO max 6 V Maximum DOWN input voltage V DOWN max 6 V Allowable power dissipation (Note 2) Pd max 1.55 W Operating temperature Topr -30 to +85 C Storage temperature Tstg -55 to +150 C 1. Stresses exceeding those listed in the Absolute Maximum Rating table may damage the device. If any of these limits are exceeded , device functionality should not be assumed, damage may occur and reliability may be affected. MFP30KR (375mil) † For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. http://www.onsemi.com/pub_link/Collateral/BRD8011-D.PDF
www.onsemi.com Recommended Operating Ranges (Note 3) Parameter Symbol Conditions Ratings Unit Supply voltage range VM VM , VM1 , VM2 9 to 32 V Logic input voltage V IN ST , MD1 , MD2 , MD3 , OE , RST , FR , STEP 0 to 5 V FDT input voltage range VFDT 0 to 5 V VREF input voltage range VREF 0 to 3 V 3. Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond the Recommended Operating Ranges limits may affect device reliability. Electrical Characteristics at Ta=25°C, VM=24V, VREF=1.5V unless otherwise noted. (Note 4) Parameter Symbol Conditions Ratings Unit min typ max Standby mode current drain I Mst ST = “L” , VM+VM1+VM2 70 100 A Current drain IM ST = “H”, OE = “H”, no load VM+VM1+VM2 3.3 4.6 mA Thermal shutdown temperature TSD Guaranteed by design 150 180 200 C Thermal hysteresis width TSD Guaranteed by design 40 C Logic pin input current I INL ST , MD1 , MD2 , MD3 , OE , RST , FR , STEP , VIN = 0.8V 3 8 15 A IINH ST , MD1 , MD2 , MD3 , OE , RST , FR , STEP , VIN = 5V 30 50 70 A Logic input voltage High V INH ST , MD1 , MD2 , MD3 , OE , RST , FR , STEP 2.0 5.0 V Low V INL 0 0.8 V FDT pin high level voltage Vfdth 3.5 V FDT pin middle level voltage Vfdtm 1.1 3.1 V FDT pin low level voltage Vfdtl 0.8 V Chopping frequency Fch Cosc1 = 100pF 70 100 130 kHz OSC1 pin charge/discharge current Iosc1 7 10 13 A Chopping oscillation circuit threshold voltage Vtup1 0.8 1 1.2 V Vtdown1 0.3 0.5 0.7 V VREF pin input voltage Iref VREF = 1.5V -0.5 A DOWN output residual voltage V OlDOWN Idown = 1mA 40 100 mV MO pin residual voltage V OlMO Imo = 1mA 40 100 mV Hold current switching frequency Fdown Cosc2 = 1500pF 1.12 1.6 2.08 Hz OSC2 pin charge/discharge current Iosc2 7 10 13 A Hold current switching frequency threshold voltage Vtup2 0.8 1 1.2 V Vtdown2 0.3 0.5 0.7 V VREG1 output voltage Vreg1 4.7 5 5.3 V VREG2 output voltage Vreg2 18 19 20 V Output on-resistance Ronu I O = 2.0A, upper side ON resistance 0.3 0.42 Ω Rond I O = 2.0A, lower side ON resistance 0.25 0.35 Ω Output leakage current I Oleak V M = 36V 50 A Diode forward voltage VD I D = -2.0A 1.1 1.4 V Current setting reference voltage VRF VREF = 1.5V, Current ratio 100% 0.285 0.3 0.315 V 4. Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product performance may not be indicated by the Electrical Characteristics if operated under different conditions.
www.onsemi.com Package Dimensions unit : mm SOIC30 W / MFP30KR (375 mil) CASE 751CH ISSUE A SOLDERING FOOTPRINT* NOTE: The measurements are not to guarantee but for reference only. (Unit: mm) 9.75 0.50 1.15 1.00 0.10
2.45 MAX
(2.25)0.1 0.1S S 0.65 0.2 0.25 +0.15 −0.05 0~10
15.55 MAX
15.2 0.1 1.0 (0.6) 0.35 +0.15 −0.05 0.15 7.9 0.1 10.5 0.3 (5.1) (4.4) LASER MARKED INDEX
www.onsemi.com Pin Assignment VREG2 VM OUT1A PGND1 VM1 RF1 OUT1B NC OUT2A RF2 VM2 PGND2 OUT2B GND VREF VREG1 ST MD1 MD2 MD3 OE RST GND FR STEP OSC1 OSC2 FDT DOWN MO Pd max – Ta 0.2 0.4 0.6 0.8 1.2 1.4 1.6 1.8 -20 0 20 40 60 80 100 Allowable power dissipation, Pdmax - W Ambient temperature, Ta - C Mounted on a board (76.1mm×114.3mm×1.6, Glass epoxy) Independent IC 1.55 0.8 0.806 0.416
www.onsemi.com Block Diagram Output control logic Current select circuit Current select circuit Oscillator circuit TSD UVLO RF2 ST Regulator 2 VREF GND VM VREG1 PGND2 DOWN Decay Mode setting circuit Regulator 1 PGND1 MD1 MD2 MD3 FR STEP RST OE FDT OSC1 MO OUT2B OUT2A VM2 VM1 OUT1B OUT1A RF1 VREG2 OSC2 Output preamplifier stage Output preamplifier stage Output preamplifier stage Output preamplifier stage
www.onsemi.com Pin Functions Pin No. Pin Name Pin Func tion Equivalent Circuit STEP FR RST OE MD3 MD2 MD1 Step clock pulse signal input pin Forward / Reverse signal input pin Reset signal input pin Output enable signal input pin Excitation mode switching pin Excitation mode switching pin Excitation mode switching pin
29 ST Chip enable pin
Channel 1 Power ground pin Channel 1 motor power supply pin Channel 1 current sense resistor pin Channel 1 output B pin Channel 2 output A pin Channel 2 current sense resistor pin Channel 2 motor power supply pin Channel 2 Power ground pin Channel 2 output B pin
15 VREF Constant-current control reference
voltage input pin. Continued on next page
www.onsemi.com Continued from preceding page Pin No. Pin Name Pin Func tion Equivalent Circuit
1 VREG2 Internal regulator capacitor
connection pin.
30 VREG1 Internal regulator capacitor
connection pin. MO DOWN Output pin for position detecting Output pin for holding current reduction OSC2 OSC1 Capacitor connection pin for STEP signal off detection time setting When not using the current reduction by DOWN pin, need to connect OSC2 pin to GND at 10kΩ (recommended value). Capacitor connection pin for chopping frequency setting. GND GND Ground pin
www.onsemi.com Functional Description 1. Input Pin Function Each input terminal has the function to prevent the flow of the current from an input to a power supply. Therefore, Even if a power supply (VM) is turned off in the state that applied voltage to an input terminal, the electric current does not flow into the power supply. 2. Stand-by function When ST pin is at low levels, the IC enters stand-by mode, all logic is reset and output is turned OFF. When ST pin is at high levels, the stand-by mode is released. 3. STEP pin function Input Operating mode ST STEP Low Don’t care Standby mode High Excitation step is proceeded High Excitation step is kept 4. Input Timing Tsteph/Tstepl: Clock H/L pulse width (min 500ns) Tds: Data set-up time (min 500ns) Tdh: Data hold time (min 500ns) 5. Position detection monitor function The MO position detection monitoring pin is an open drain type. When the excitation position is in the initial position, the MO output is placed in the ON state. (Refer to "Examples of current waveforms in each of the excitation modes.") MO Status ON Initial position OFF Except initial position
www.onsemi.com 6. Excitation mode setting function Set the excitation setting as shown in the following table by setting MD1 pin, MD2 pin and MD3 pin. Input Excitation mode Initial position MD3 MD2 MD1 1ch current 2ch current Low Low Low Full step 100% -100% Low Low High Half step 100% 0% Low High Low 1/4 step 100% 0% Low High High 1/8 step 100% 0% High Low Low 1/16 step 100% 0% High Low High 1/32 step 100% 0% High High Low 1/64 step 100% 0% High High High 1/128 step 100% 0% The initial position is also the default state at start-up and excitation position at counter-reset in each excitation mode. 7. Output enable function When the OE pin is set Low, the output is forced OFF and goes to high impedance. However, the internal logic circuits are operating, so the excitation position proceeds when the STEP is input. Therefore, when OE pin is returned to High, the output level conforms to the excitation position that is advanced by the STEP input. OE Operating mode Low Output OFF High Output ON 8. Reset function When the RST pin is set Low, the excitation position of the output is set to the initial position forcibly and MO pin output is turn ON state. And then by setting RST pin is High, the excitation position moves forward with the next step signal. RST Operating mode Low Reset status High Normal operation
www.onsemi.com 9. Forward / Reverse switching The internal D/A converter proceeds by a bit on the rising edge of the step signal input to the STP pin. In addition, CW and CCW mode are switched by FR pin setting. In CW mode, the channel 2 current phase is delayed by 90° relative to the channel 1 current. In CCW mode, the channel 2 current phase is advanced by 90° relative to the channel 1 current. FR Operating mode Low Clockwise (CW) High Counter-clockwise(CCW) STEP FR 1ch output 2ch output Excitation Position CW mode CW mode CCW mode 10. Decay mode setting Current Decay method is selectable as shown below by applied voltage to the FDT pin. FDT voltage Decay mode 3.5V to 5.0V SLOW Decay 1.1V to 3.1V or Open MIXED Decay 0V to 0.8V FAST Decay 11. Output current setting Output current is set as shown below by the VREF pin (applied voltage) and a resistance value between RF1 (2) pin and GND. ோாி ோி௫ The setting current value above is a 100% output current in each excitation mode. Where, I OUT : Coil current [A] RRFx : Resistor between RF1 (2) and GND [ Ω] VREF : Input voltage at the VREF pin [V] For example, when VREF = 1.1V and RF1 (2) resistance is 0.22Ω, the setting current is shown below: ை் ൌ 1.1 5ൈ0.22ሿ 12. Chopping frequency setting For constant-current control, LV8728 performs PWM operation at the chopping frequency determined by the capacitor (COSC1) connected between the OSC1 pin and GND. The calculation for the value of chopping frequency is: Where, Fch : Chopping frequency [Hz] IOSC1 : Charge/ Discharge current of OSC1pin [A]. IOSC1 is 10uA (typ) by electrical Characteristics. C OSC1 : Capacitor for chopping frequency setting [F] For example, when COSC1=100pF and IOSC1=10uA (typ), the chopping frequency is shown below: ൌ10ൈ10 ି 100ൈ10 ିଵଶሿ The higher the chopping frequ ency is, the greater the output switching loss becomes. As a result, heat generation issue arises. The lower the chopping frequency is, the lesser the heat generation becomes. However, current ripple occurs. Since noise increases when switching of chopping takes place, you need to adjust frequency with the influence to the other devices into consideration. 13. Blanking time If, when exercising PWM constant-current chopping control over the motor current, the mode is switched from decay to charge, the recovery current of the parasitic diode may flow to the current sensing resistance, causing noise to be carried on the current sensing resistance pin, and this may result in erroneous detection. To prevent this erroneous detection, a blanking period is provided to prevent the noise occurring during mode switching from being received. During the blanking time, even if noise is generated in sense resistor, a mode does not switch from CHARGE to DECAY . In this IC, the blanking time is fixed to approximately 1 s.
www.onsemi.com 14. DOWN output pin for holding current reduction The DOWN output pin is an open drain type. When DOWN pin is turned ON, the motor is holding current. DOWN Status ON Holding current OFF Normal operation To avoid to applying high current to a motor coil for long term at one position, the DOWN output may be used to reduce the reference current. The DOWN is asserted when the step clock interval is longer than TDOWN (STEP signal off detection time). With the circuit is shown in below. VREF voltage can be reduced when the DOWN is turned ON. The open-drain output in once turned ON, is turned OFF at the next rising edge of STP. For example, when V1=5V, R1=68kΩ, R2=30kΩ, R3=5kΩ, RRF1 (2) =0.22Ω, the VREF voltage is shown below: RRF1 (2) is Resistor between RF1 (2) and GND [Ω] VREF is input voltage at the VREF pin [V] When the DOWN is turned OFF 6830ሿ ை் ൌ 1.53 5ൈ0.22ሿ When the DOWN is turned ON, combined resistor of R2 and R3 is about 4.3kΩ. 684.3ሿ ை் ൌ 0.3 5ൈ0.22ሿ 15. SETP signal off detection time setting STEP signal off time is determined by the capacitor (COSC2) connected between the OSC2 pin and GND. When this function is unused, connect OSC2 pin to GND at 10kohm (recommendation). The calculation for the value of STEP signal off detection time is: 2ൈ0.4ൈ10 ଽ Where, TDOWN : STEP signal off detection time [Sec] COSC2 : Capacitor for STEP signal off time [F] For example, when COSC2=1500pF, the STEP signal off detection time is shown below: ሿ
www.onsemi.com 16. Output current vector locus (one step is normalized to 90 degrees) Current setting ratio in each excitation mode STEP 1/128 step (%) 1/64 ste p (%) 1/32 ste p (%) 1/16 ste p (%) 1/8 ste p (%) 1/4 ste p (%) Half ste p (%) Full ste p (%) 1ch 2ch 1ch 2ch 1ch 2c h 1ch 2ch 1ch 2ch 1ch 2ch 1ch 2ch 1ch 2ch θ0 100 0 100 0 100 0 100 0 100 0 100 0 100 0 θ1 100 1 θ2 100 2 100 2 θ3 100 4 θ4 100 5 100 5 100 5 θ5 100 6 θ6 100 7 100 7 θ7 100 9 θ8 100 10 100 10 100 10 100 10 θ9 99 11 θ10 99 12 99 12 θ11 99 13 θ12 99 15 99 15 99 15 θ13 99 16 θ14 99 17 99 17 θ15 98 18 θ16 98 20 98 20 98 20 98 20 98 20 θ17 98 21 θ18 98 22 98 22 θ19 97 23 θ20 97 24 97 24 97 24 θ21 97 25 θ22 96 27 96 27 θ23 96 28 θ24 96 29 96 29 96 29 96 29 θ25 95 30 Continued on next page (Full step)
www.onsemi.com Continued from preceding page STEP 1/128 step 1/64 ste p (%) 1/32 ste p (%) 1/16 ste p (%) 1/8 ste p (%) 1/4 ste p (%) Half ste p (%) Full ste p (%) 1ch 2ch 1ch 2ch 1ch 2c h 1ch 2ch 1ch 2ch 1ch 2ch 1ch 2ch 1ch 2ch θ26 95 31 95 31 θ27 95 33 θ28 94 34 94 34 94 34 θ29 94 35 θ30 93 36 93 36 θ31 93 37 θ32 92 38 92 38 92 38 92 38 92 38 92 38 θ33 92 39 θ34 91 41 91 41 θ35 91 42 θ36 90 43 90 43 90 43 θ37 90 44 θ38 89 45 89 45 θ39 89 46 θ40 88 47 88 47 88 47 88 47 θ41 88 48 θ42 87 49 87 49 θ43 86 50 θ44 86 51 86 51 86 51 θ45 85 52 θ46 84 53 84 53 θ47 84 55 θ48 83 56 83 56 83 56 83 56 83 56 θ49 82 57 θ50 82 58 82 58 θ51 81 59 θ52 80 60 80 60 80 60 θ53 80 61 θ54 79 62 79 62 θ55 78 62 θ56 77 63 77 63 77 63 77 63 θ57 77 64 θ58 76 65 76 65 θ59 75 66 θ60 74 67 74 67 74 67 θ61 73 68 θ62 72 69 72 69 θ63 72 70 θ64 71 71 71 71 71 71 71 71 71 71 71 71 71 71 100 100 θ65 70 72 θ66 69 72 69 72 θ67 68 73 θ68 67 74 67 74 67 74 θ69 66 75 θ70 65 76 65 76 θ71 64 77 θ72 63 77 63 77 63 77 63 77 θ73 62 78 θ74 62 79 62 79 θ75 61 80 θ76 60 80 60 80 60 80 θ77 59 81 θ78 58 82 58 82 θ79 57 82 θ80 56 83 56 83 56 83 56 83 56 83 θ81 55 84 θ82 53 84 53 84 θ83 52 85 θ84 51 86 51 86 51 86 θ85 50 86 θ86 49 87 49 87 θ87 48 88 θ88 47 88 47 88 47 88 47 88 θ89 46 89 θ90 45 89 45 89 Continued on next page
www.onsemi.com Continued from preceding page STEP 1/128 step 1/64 ste p (%) 1/32 ste p (%) 1/16 ste p (%) 1/8 ste p (%) 1/4 ste p (%) Half ste p (%) Full ste p (%) 1ch 2ch 1ch 2ch 1ch 2c h 1ch 2ch 1ch 2ch 1ch 2ch 1ch 2ch 1ch 2ch θ91 44 90 θ92 43 90 43 90 43 90 θ93 42 91 θ94 41 91 41 91 θ95 39 92 θ96 38 92 38 92 38 92 38 92 38 92 38 92 θ97 37 93 θ98 36 93 36 93 θ99 35 94 θ100 34 94 34 94 34 94 θ101 33 95 θ102 31 95 31 95 θ103 30 95 θ104 29 96 29 96 29 96 29 96 θ105 28 96 θ106 27 96 27 96 θ107 25 97 θ108 24 97 24 97 24 97 θ109 23 97 θ110 22 98 22 98 θ111 21 98 θ112 20 98 20 98 20 98 20 98 20 98 θ113 18 98 θ114 17 99 17 99 θ115 16 99 θ116 15 99 15 99 15 99 θ117 13 99 θ118 12 99 12 99 θ119 11 99 θ120 10 100 10 100 10 100 10 100 θ121 9 100 θ122 7 100 7 100 θ123 6 100 θ124 5 100 5 100 5 100 θ125 4 100 θ126 2 100 2 100 θ127 1 100 θ128 0 100 0 100 0 100 0 100 0 100 0 100 0 100
www.onsemi.com 17. Current wave example in each excitation mode (Full, Half, 1/16, 1/128 step) Full step (CW mode) Half step (CW mode) STEP 100 -100 100 -100 (%) (%) MO STEP 100 -100 100 -100 (%) (%) MO
www.onsemi.com 1/16 step (CW mode) STEP MO I1 0 100 [%] -50 -100 I2 0 100 [%] -50 -100 1/128 step (CW mode)
www.onsemi.com 18. Current control operation FAST Decay current control: When FDT pin voltage is 0.8V or less, the constant- current control is operated in FAST Decay mode. (Sine-wave increasing direction) Coil current Fch Setting current CHARGE STEP Setting current FAST Current mode CHARGE FAST Blanking Time (Forced CHARGE) Chopping period (Sine-wave decreasing direction) Coil current Fch Setting current CHARGE STEP Setting current FAST Current mode Blanking Time FAST FAST CHARGE Blanking Time (Forced CHARGE) Chopping period The current control of FAST Decay operates with the follow sequence. The IC enters CHARGE mode at a rising edge of the chopping oscillation. The CHARGE of the blanking time is forced regardless of the magnitude of the coil current (ICOIL) and set current (IREF). The blanking time is approximately 1μs. After the period of the blanking time, The IC operates in CHARGE mode until ICOIL ≥ IREF. After that, the mode switches to the FAST Decay mode and the coil current is attenuated until the end of a chopping period. If ICOIL > IREF state exists when the end of blanking time, the coil current is attenuated by the FAST Decay mode until the end of a chopping period. Since the attenuation of the current is fast, it is early that the coil current follows the set current. However, the current ripple value may be higher.
www.onsemi.com MIXED Decay current control: When FDT pin voltage is between 1.1V and 3.1V or Open, the constant- current control is operated in MIXED Decay mode. (Sine-wave increasing direction) Coil current Fch Setting current CHARGE STEP Setting current SLOW FAST Current mode CHARGE SLOW FAST Blanking time (Forced CHARGE) (Sine-wave decreasing direction) Coil current Fch Setting current CHARGE STEP Setting current SLOW FAST Current mode Forced CHARGE FAST SLOW CHARGE Blanking time (Forced CHARGE) The current control of MIXED Decay operates with the follow sequence. The IC enters CHARGE mode at a rising edge of the chopping oscillation. The CHARGE of the blanking time is forced regardless of the magnitude of the coil current (ICOIL) and set current (IREF). The blanking time is approximately 1μs. In a period of Blanking Time, the coil current (ICOIL) and the setting current (IREF) are compared. If an ICOIL < IREF state exists during the charge period: The IC operates in CHARGE mode until ICOIL ≥ IREF. After that, it switches to SLOW DECAY mode and then switches to FAST DECAY mode in the last approximately 1μs of the period. If no ICOIL < IREF state exists during the charge period: The IC switches to FAST DECAY mode and the coil current is attenuated with the FAST DECAY operation until the end of a chopping period. The above operation is repeated. Normally, the IC operates in SLOW (+ FAST) Decay mode at the sine wave increasing direction, and the IC operates in FAST Decay mode at the sine wave decreasing direction until the current is attenuated. And then the IC operates in SLOW Decay mode when the current reaches the set value.
www.onsemi.com SLOW Decay current control: When FDT pin voltage is 3.5V or more, the constant- current control is operated in SLOW Decay mode. (Sine-wave increasing direction) Coil current Fch Setting current CHARGE STEP Setting current SLOW Current mode CHARGE SLOW Blanking Time (Forced CHARGE) Chopping period (Sine-wave decreasing direction) Coil current Fch Setting current CHARGE STEP Setting current SLOW Current mode Blanking Time SLOW SLOW Blanking Time Forced CHARGE) Blanking Time Chopping period The current control of SLOW Decay operates with the follow sequence. The IC enters CHARGE mode at a rising edge of the chopping oscillation. The CHARGE of the blanking time is forced regardless of the magnitude of the coil current (ICOIL) and set current (IREF). The blanking time is approximately 1μs. After the period of the blanking time, The IC operates in CHARGE mode until ICOIL ≥ IREF. After that, the mode switches to the SLOW Decay mode and the coil current is attenuated until the end of a chopping period. If ICOIL > IREF state exists when the end of blanking time, the coil current is attenuated by the SLOW Decay mode until the end of a chopping period. Since the attenuation of the current is slow, it may be slow that the coil current follows the set current. Or the coil current may not follow a set current.
www.onsemi.com 19. Over-current protection function This IC incorporates an over current protection circuit that, when the output has been shorted by an event such as shorting to power, shorting to ground and shorting to other output. And it switches the output to the standby mode in order to prevent the IC from being damaged. Three over-current detection modes are shown in the next page. When the over current is detected, the over current protection circuit operates. If the short status continues for the period of internal timer (≈2μs), the output of 1ch/ 2ch is turned off. If the short status exceeds the timer latch time (≈256us) set in the internal timer, the output is turned on again and detects short status again. If short is detected again, all the outputs of 1ch/ 2ch are switched to standby mode and the status is kept. To cancel the standby status, set ST=”L”. 20. Thermal shutdown function The thermal shutdown circuit is incorporated and the output is turned Off when junction temperature Tj exceeds 180°C. As the temperature falls by hysteresis, the output turned on again (automatic restoration). The thermal shutdown circuit does not guarantee the protection of the final product because it operates when the temperature exceed the junction temperature of Tjmax=150°C. TSD = 180°C (typ) ΔTSD = 40°C (typ) Fault Detection H-bridge Output state Output ON Internal counter 2µs Output ON Output OFF Over-current Detected Over-current Detected Release 1st counter start 1st counter stop 1st counter start 1st counter stop 2nd counter start 2nd counter stop Timer latch period (typ:256 µs ) Output OFF 2µs
www.onsemi.com 21. Over current detection mode Short to Power M Tr1 Tr2 Tr3 OFF Tr4 ON VM OUTA OUTB RF OFF ON M Tr1 Tr2 Tr3 OFF Tr4 ON VM OUTA OUTB RF Short-circuit Detection OFF ON 1. High current flows if OUTB short to VM and Tr4 are ON. 2. If RF voltage> setting voltage, then the mode switches to SLOW decay. 3. If the voltage between Drain and Source of Tr4 exceeds the reference voltage for 2μs, short status is detected. Short to GND (left schematic) 1. High current flows if OUTA short to GND and Tr1 are ON 2. If the voltage between Drain and Source of Tr1 exceeds the reference voltage for 2μs, short status is detected. (right schematic) 1. Without going through RF resistor, current control does not operate and current will continue to increase in CHARGE mode. 2. If the voltage between Drain and Source of Tr1 exceeds the reference voltage for 2μs, short status is detected. Load short 1. Without L load, high current flows. 2. If RF voltage> setting voltage, then the mode switches to SLOW decay. 3. During load short stay in SLOW decay mode, current does not flow and over current state is not detected. Then the mode is switched to FAST decay according to chopping cycle. 4. Since FAST state is short (≈1μs), switches to CHARGE mode before short is detected. 5. If voltage between Drain and Source exceeds the reference voltage continuously during blanking time at the start of CHARGE mode (Tr1), CHARGE state is fixed (even if RF voltage exceeds the setting voltage, the mode is not switched to SLOW decay). After 2us or so, short is detected.
www.onsemi.com Application Circuit Example Calculation for each constant setting according to the above circuit diagram is as follows. For example, when VREF=1.1V, IOSC1=10uA (typ) and COSC1=100pF Coil current ை் ൌ 1.1 5ൈ0.22ሿ Chopping frequency ൌ10ൈ10 ି 100ൈ10 ିଵଶሿ STEP signal off detection time ሿ
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