Ordering number : EN6197C LB1927 Monolithic Digital IC For Office Automation Equipment http://onsemi.com 3-phase Brushless Motor Driver Overview The LB1927 is a 3-phase brushless motor driver well suited for drum and paper feed motors in laser printers, plain-paper copiers and other office automation equipment. Direct PWM drive allows control with low power losses. Peripheral circuitry including speed control circuit and FG amplifier is integrated, thus allows drive circuit to be constructed with a single chip. Features • 3-phase bipolar drive (30V, 2.5A) • Direct PWM drive technique • Built-in diode for absorbing output lower-side kickback • Speed discriminator and PLL speed control • Speed lock detection output • Built-in forward/reverse switching circuit • Built-in protection circuitry includes current limiter, overheat protection, motor restraint protection, etc. Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Maximum supply voltage Symbol Conditions VCC max Ratings Unit 30 Maximum output current IO max T ≤ 500ms Allowable power dissipation 1 Pd max 1 Independent IC Allowable power dissipation 2 Pd max 2 With an arbitrary large heat sink Operating temperature Storage temperature V 2.5 A 3 W 20 W Topr -20 to +80 °C Tstg -55 to +150 °C Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Semiconductor Components Industries, LLC, 2013 May, 2013 N1908 MS JM/O0702AS(OT)/D1099TH(KI)/62599RM(KI) No.6197-1/11 LB1927 Allowable Operating Ranges at Ta = 25°C Parameter Symbol Conditions Ratings Unit Power supply voltage range 1 VCC 9.5 to 28 V Regulator voltage output current IREG -30 to 0 mA LD output current ILD 0 to 15 mA Electrical Characteristics at Ta = 25°C, VCC = VM = 24V Ratings Parameter Symbol Conditions min typ Unit max Power supply current 1 ICC1 23 30 mA Power supply current 2 ICC2 In STOP mode 3.5 5.0 mA Output saturation voltage 1 VOsat1 IO = 1.0A, VO (SINK) +VO (SOURCE) 2.0 2.5 V Output saturation voltage 2 VOsat2 IO = 2.0A, VO (SINK) +VO (SOURCE) 2.6 3.2 V Output leak current IOleak 100 μA Lower-side diode forward voltage 1 VD1 ID = -1.0A 1.2 1.5 V Lower-side diode forward voltage 2 VD2 ID = -2.0A 1.5 2.0 V Output 5V regulator voltage output Output voltage VREG IO = -5mA 5.00 5.35 V Voltage fluctuation ΔVREG1 VCC = 9.5 to 28V 4.65 30 100 mV Load fluctuation ΔVREG2 IO = -5 to -20mA 20 100 mV Hall amplifier Input bias current IHB Common mode input voltage range VICM -2 Hall input sensitivity μA -0.5 1.5 VREG-1.5 80 V mVp-p Hysteresis width ΔVIN Input voltage L→H VSLH 12 mV Input voltage H→L VSHL -12 mV 15 24 42 mV PWM oscillator Output High level voltage VOH (PWM) 2.5 2.8 3.1 V Output Low level voltage VOL (PWM) 1.2 1.5 1.8 V Oscillator frequency F (PWM) Amplitude V (PWM) 1.05 1.30 1.55 Vp-p C = 3900pF 18 kHz CSD circuit Operating voltage VOH (CSD) 3.6 3.9 4.2 V External capacitance charge ICHG -17 -12 -9 μA current Operating time T (CSD) C = 10μF Design target value 3.3 s VRF VCC-VM 0.45 0.5 TSD Design target value (junction temperature) 150 180 °C ΔTSD Design target value (junction temperature) 50 °C Current limiter operation Limiter 0.55 V Thermal shutdown operation Thermal shutdown operating temperature Hysteresis width FG amplifier Input offset voltage VIO (FG) Input bias current IB (FG) Output High level voltage VOH (FG) IFGO = -0.2mA Output Low level voltage VOL (FG) IFGO = 0.2mA FG input sensitivity GAIN 100 times Next-stage Schmitt comparator Design target value -10 +10 mV -1 +1 μA 0.8 1.2 V 100 180 250 mV 2 kHz 45 51 VREG-1.2 VREG-0.8 V 3 mV width Operation frequency range Open-loop gain f (FG) = 2kHz dB Continued on next page. No.6197-2/11 LB1927 Continued from preceding page. Ratings Parameter Symbol Conditions min typ VREG-1.0 VREG-0.7 Unit max Speed discriminator Output High level voltage VOH (D) IDO = -0.1mA Output Low level voltage VOL (D) IDO = 0.1mA 0.8 Count number V 1.1 V 512 PLL output Output High level voltage VOH (P) IPO = -0.1mA Output Low level voltage VOL (P) IPO = 0.1mA VOL (LD) ILD = 10mA VREG-1.8 VREG-1.5 VREG-1.2 V 1.2 1.5 1.8 V 0.15 0.5 Lock detection Output Low level voltage Lock range 6.25 V % Integrator Input bias current IB (INT) Output High level voltage VOH (INT) IINTO = -0.2mA -0.4 Output Low level voltage VOL (INT) IINTO = 0.2mA Open-loop gain f (INT) = 1kHZ Gain bandwidth product Design target value Reference voltage Design target value VREG-1.2 0.8 45 -5% +0.4 μA 1.2 V VREG-0.8 V 51 dB 450 kHz VREG/2 5% V 10 MHz Crystal oscillator Operating frequency range fOSC Low level pin voltage VOSCL IOSC = -0.5mA 3 High level pin current IOSCH VOSC = VOSCL+0.3V 1.65 V 0.4 mA Start/stop pin High level input voltage range VIH (S/S) 3.5 VREG V Low level input voltage range VIL (S/S) 0 1.5 V Input open voltage VIO (S/S) VREG-0.5 Hysteresis width ΔVIN High level input current IIH (S/S) V (S/S) = VREG Low level input current IIL (S/S) V (S/S) = 0V VREG V 0.35 0.50 0.65 V -10 0 10 μA -280 -210 μA Forward/reverse pin High level input voltage range VIH (F/R) Low level input voltage range VIL (F/R) Input open voltage VIO (F/R) Hysteresis width ΔVIN 3.5 VREG V 0 1.5 V VREG-0.5 VREG V 0.50 0.65 V -10 0 +10 μA -280 -210 0.35 High level input current IIH (F/R) V (F/R) = VREG Low level input current IIL (F/R) V (F/R) = 0V μA No.6197-3/11 LB1927 Package Dimensions unit : mm (typ) 3147C Pd max -- Ta Allowable power dissipation, Pd max -- W 24 With an arbitrary large heat sink 20 16 12 8 4 3 Without heat sink 0 -20 0 20 40 60 80 100 Ambient temperature, Ta -- °C Pin Assignment OUT1 F/R IN3+ IN3- IN2+ IN2- IN1+ IN1- GND1 S/S 28 27 26 25 24 23 22 21 20 19 FGIN+ FGIN- FGOUT 18 17 16 LD 15 LB1927 1 2 3 OUT2 OUT3 GND2 4 5 VCC VM 6 7 VREG PWM 8 9 10 CSD XI XO INTOUT INTIN POUT DOUT 11 12 13 14 Top view Relationship between crystal oscillator frequency fOSC and FG frequency fFG is as follows. fFG (servo) = fOSC/ (ECL divide-by-16×count number) = fOSC/8192 Truth Table Source F/R = “L” Sink F/R = “H” IN1 IN2 IN3 IN1 IN2 IN3 1 OUT2→OUT1 H L H L H L 2 OUT3→OUT1 H L L L H H 3 OUT3→OUT2 H H L L L H 4 OUT1→OUT2 L H L H L H 5 OUT1→OUT3 L H H H L L 6 OUT2→OUT3 L L H H H L No.6197-4/11 LB1927 Block Diagram and Sample Application Circuit FGIN- FGOUT + LD POUT LD DOUT INTIN FG AMP – FGIN+ – LOCK DET + VREG/2 INTOUT CSD INT AMP CSD CIRCUIT + PWM OSC TSD – SPEED DISCRI + VCC VCC + CURR LIM PWM Rf VREG VM COMP FG RST PLL VREF OUT1 GND1 ECL 1/16 LOGIC VREF 1/512 DRIVER BGP OUT2 HALL HYS AMP Xtal OSC XI S/S XO S/S F/R F/R 5VREG VREG OUT3 IN1 IN2 IN3 GND2 No.6197-5/11 LB1927 Pin Description Pin No. Pin name Pin function 28 OUT1 Motor drive output pins. 1 OUT2 Connect a Schottky diode between these outputs and VCC. 2 OUT3 3 GND2 5 VM Equivalent circuit Output ground pin. Output block power supply and output current detection pin. Connect a resistor (Rf) between this pin and VCC to detect the output current as a voltage. The output current is limited according to the equation IOUT = VRF/Rf. 4 VCC 6 VREG Power supply pin (except for output block). Regulated power supply output pin (5V output). Connect a capacitor (approx. 0.1μF) between this pin and ground to stabilize the output. 7 PWM PWM frequency setting pin. Connect a capacitor between this pin and ground. C = 3900pF results in a frequency of about 18kHz. 8 CSD Lock protection circuit operation time setting pin. Connecting a capacitor of about 10μF between this pin and ground results in a protection circuit operation time of about 3.3 seconds. 9 XI Crystal oscillator pins. 10 XO Connect to quartz oscillator to generate the reference clock. When an external clock (of several MHz) is used, the clock signal should be input via a resistor of about 5.1kΩ connected in series with the XI pin. In this case, the XO pin must be left open. Continued on next page. No.6197-6/11 LB1927 Continued from preceding page. Pin No. Pin name Pin function 11 INTOUT Integrator output pin (speed control pin). 12 INTIN Integrator input pin. 13 POUT PLL output pin. 14 DOUT Equivalent circuit Speed discriminator output pin. Acceleration : High, Deceleration : Low 15 LD Speed lock detection pin. When motor rotation is within lock range (±6.25%) : Low Withstand voltage : 30V max. Continued on next page. No.6197-7/11 LB1927 Continued from preceding page. Pin No. Pin name Pin function 16 FGOUT FG amplifier output pin. 17 FGINFGIN+ FG amplifier input pin. 18 19 S/S Start/stop control pin. Equivalent circuit By connecting a capacitor (approx. 0.1μF) between FGIN+ and ground, the logic circuitry is reset. Start (Low) : 0V to 1.5V Stop (High) : 3.5V to VREG High when open. Hysteresis width : approx. 0.5V. 20 GND1 Ground pin (except for output block). 22 IN1+ IN1- Hall input pins. High when IN+ > IN-, Low when IN+ < IN-. IN2+ IN2- Hall signal should have an amplitude of at least 25 IN3+ IN3- signal noise is a problem, connect a capacitor between IN+ and IN-. 27 F/R 21 24 23 26 100mVp-p (differential operation). When Hall Forward/reverse control pin. Forward (Low) : 0V to 1.5V Reverse (High) : 3.5V to VREG High when open. Hysteresis width : approx. 0.5V. No.6197-8/11 LB1927 Description of the LB1927 1. Speed control circuit The IC performs speed control through combined use of a speed discrimination circuit and PLL circuit. The speed control circuit counts FG cycles and outputs a deviation signal every 2FG cycles. The PLL circuit outputs a phase deviation signal every FG cycle. The FG servo frequency is determined by the following equation. The motor rotation speed is set by the number of FG pulses and the crystal oscillator frequency. fFG (servo) = fOSC/8192 fOSC : Crystal oscillator frequency 2. Output drive circuit In order to reduce power loss at the output, the LB1927 uses the PWM drive technique. While ON, the output transistors are always saturated, and motor drive power is adjusted by varying the output ON duty ratio. Because output PWM switching is performed by the lower-side output transistor, a Schottky diode must be connected between OUT and VCC. (If the reverse recovery time of the diode is too long, a feedthrough current will flow at the instant when the lower-side transistor goes ON.) An internal diode is provided between OUT and GND. If large output current causes a problem (waveform distortion during lower-side kickback, etc.), an external rectifying diode or Schottky diode should be connected. The output diode is integrated only on the lower side. 3. Current limiting circuit The current limiting circuit limits the peak current to the value I = VRF/Rf (VRF = 0.5V typ., Rf : current detector resistance). Current limiting is achieved by reducing the ON duty ratio of the output, which reduces the current. 4. Power save circuit In order to reduce current drain in the STOP condition, the IC goes into power save mode. In this condition, bias current to most circuits is cut off, but the 5V regulator output remains active. 5. Reference clock The reference clock for speed control can be input using one of the following two methods. (1) Using a crystal oscillator When a crystal is used for oscillation, connect the crystal, capacitors, and a resistor as shown in the figure below. XI XO C3 C4 C1 C2 R1 C1, R1 : For stable oscillation C3 : For oscillator coupling C2 : For stabilization and to prevent oscillation at upper harmonic frequencies C4 : Prevents oscillation at upper harmonic frequencies VREG (Reference values) Oscillator frequency (MHz) C1 (μF) C2 (pF) C3 (pF) C4 (pF) R1 (Ω) 3 to 5 0.1 15 47 10 330k 5 to 8 0.1 10 47 None 330k 8 to 10 0.1 10 22 None 330k The circuit configuration and values are for reference only. The crystal oscillator’s characteristics as well as the possibility of floating capacitance and noise due to layout factors must be taken into consideration when designing an actual application. No.6197-9/11 LB1927 [Precautions for wiring layout design] Since the crystal oscillator circuit operates at high frequencies, it is susceptible to the influence of floating capacitance from the circuit board. Wiring should be kept as short as possible and traces should be kept narrow. When designing the external circuitry, pay special attention to the wiring layout between the oscillator and C3 (C2), to minimize the influence of floating capacitance. The capacitor C4 is quite effective at reducing the negative resistance (gain) at high frequencies. However, care is required to avoid excessive reduction in the negative resistance at the fundamental frequency. (2) External clock input (equivalent to crystal oscillator, several MHz) When using an external signal source instead of a crystal oscillator, the clock signal should be input from the XI pin through a resistor of about 5.1kΩ connected to the pin in series. The XO pin should be left open. Signal input level Low : 0 to 0.8V High : 2.5 to 5.0V 6. Speed lock range The speed clock range is ±6.25% of the rated speed. When the motor rotation is within the lock range, the LD pin becomes Low (open collector output). When the motor rotation goes out of the lock range, the ON duty ratio of the motor drive output is varied according to the amount of deviation to bring the rotation back into the lock range. 7. PWM frequency The PWM frequency is determined by the capacitance connected to the PWM pin. f PWM ≈ 1/ (14400×C) PWM frequency in the range 15 to 25kHz is desirable. The ground side of the connected capacitor must be connected to the GND1 pin with a lead that is as short as possible. 8. Hall input signal The Hall input requires a signal with an amplitude of at least the hysteresis width (42mV max.). Taking possible noise influences into consideration, an amplitude of at least 100mV is desirable. If noise during output phase switching disrupts the output waveform, insert capacitors across the Hall signal inputs (between the + and - inputs), and position those capacitors as close as possible to the pins. 9. Forward/reverse switching Forward/reverse switching of motor rotation is carried out with the F/R pin. If this is performed while the motor is running, the following points must be observed : • Feedthrough current during switching is handled by proper circuit design. However, the VCC voltage rise during switching (caused by momentary return of motor current to power supply) must not exceed the rated voltage (30V). If problems occur, the capacitance between VCC and GND must be increased. • If the motor current after switching exceeds the current limiter value, the lower-side transistors go OFF but the upper-side transistors go into the short brake state, which causes a current flow. The magnitude of the current is determined by the motor counterelectromotive voltage and the coil resistance. This current may not exceed the rated current (2.5A). (Forward/reverse switching at high speed therefore is not safe.) 10. Motor restraint protection circuit To protect the IC and the motor itself when rotation is inhibited, a restraint protection circuit is provided. If the LD output is High (unlocked) for a certain interval in the start condition, the lower-side transistors are turned off. The length of the interval is determined by the capacitance at the CSD pin. A capacitance of 10μF results in a set interval of about 3.3 seconds. (Tolerance approx. ±30%) Set interval (s) ≈ 0.33×C (μF) If the capacitor arrangement is subject to leak current, possible adverse effects such as setting time tolerances must be taken into consideration. When the restraint protection circuit has been activated, the condition can only be canceled by setting the system to the stop condition or by turning the power off and on again (in the stop condition). When wishing not to use the restraint protection circuit, connect the CSD pin to ground. If the stop time when releasing the restraint protection is short, the capacitor charge will not be fully dissipated. This in turn will cause a shorter restraint protection activation time after the motor has been restarted. The stop time should therefore be designed to be sufficiently long, using the equation shown below (also when restarting in the motor start transient state). Stop time (ms) ≥ 15×C (μF) No.6197-10/11 LB1927 11. Power supply stabilization Because this IC provides a high output current and uses a switching drive technique, power supply line fluctuations can occur easily. Therefore, a capacitor of sufficient capacitance (several ten μF or higher) must be connected between the VCC pin and ground to assure stable operation. The ground connection of this capacitor must be connected to the GND2 pin, which is the power block ground, at a point as close as possible to the IC. If, due to problems associated with the heat sink, the (electrolytic) capacitor cannot be connected near the this pin, a ceramic capacitor of about 0.1μF must be connected near the pin. Since the likelihood of power line fluctuation increases if diodes are inserted in the power supply lines to prevent destruction of the IC if power is connected with reverse polarity, a larger capacitance will be required. 12. VREG stabilization A capacitor (about 0.1μF) must be connected to the VREG pin (the 5V regulator output), which functions as the control circuit power supply, for stabilization. The ground side of this capacitor must be connected to the GND1 pin with a lead that is as short as possible. 13. Integrating amplifier related component values The external components used in the integrating amplifier must be located as close as possible to the IC to minimize the circuit’s susceptibility to noise. These components must be located as far as possible from the motor. 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