Ordering number : ENA0604 LB11921T Monolithic Digital IC Three-Phase Brushless Motor Driver http://onsemi.com Overview The LB11921T is a pre-driver IC designed for variable-speed control of 3-phase brushless motors. It can be used to implement a motor drive circuit with the desired output capacity (voltage, current) by using discrete transistors for the output stage. It implements direct PWM drive for minimal power loss. Since the LB11921T includes a built-in VCO circuit, applications can control the motor speed arbitrarily by varying the external clock frequency. Functions • Direct PWM drive output • Speed discriminator + PLL speed control circuit • Speed lock detection output • Built-in VCO circuit • Forward/reverse switching circuit • Braking circuit (short braking) • Full complement of on-chip protection circuits, including lock protection, current limiter, and thermal shutdown protection circuits. Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Maximum supply voltage Output current Symbol Conditions VCC max IO max Ratings Unit 8 V UH, VH, WH, UL, VL, WL output 10 mA W Allowable power dissipation 1 Pd max1 Independent IC 0.4 Allowable power dissipation 2 Pd max2 Mounted on a circuit board* 0.9 W Operating temperature Topr -20 to +80 °C Storage temperature Tstg -55 to +150 °C * Mounted on a specified board: 114.3mm×76.1mm×1.6mm, glass epoxy. 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 11707 MS IM 20060327-S00010 No.A0604-1/18 LB11921T Allowable Operating Ranges at Ta = 25°C Parameter Symbol Conditions Ratings Unit FG Schmitt output applied voltage VFGS 0 to 7 V FG Schmitt output current IFGS 0 to 5 mA Lock detection applied voltage VLD 0 to 7 V Lock detection output current ILD 0 to 20 mA Supply voltage VCC 4.4 to 7.0 V Electrical Characteristics at Ta = 25°C, VCC = 5V Parameter Symbol Ratings Conditions min Supply current 1 ICC1 Supply current 2 ICC2 unit typ max 23 32 mA In stop mode 2.1 2.9 mA Output Block Output saturation voltage 1-1 VOsat1-1 At low level: IO = 500μA 0.1 0.2 V Output saturation voltage 1-2 VOsat1-2 At low level: IO = 5mA 0.3 0.5 V Output saturation voltage 2-1 VOsat2-1 At high level: IO = -500μA VCC-0.2 VCC-0.1 V Output saturation voltage 2-2 VOsat2-2 At high level: IO = -5mA VCC-0.4 VCC-0.2 V -2 -0.1 μA Hall Amplifier Input bias current IHB(HA) Common-mode input voltage range 1 VICM1 When Hall-effect sensors are used Common-mode input voltage range 2 VICM2 When one-side biased inputs are used 0.5 VCC-2.0 VCC 0 V V (Hall-effect IC applications) Hall input sensitivity Sine wave 50 mVp-p ΔVIN(HA) 9 15 26 mV Input voltage low → high VSLH 4 7 13 mV Input voltage high → low VSHL -13 -8 -4 mV Hysteresis PWM Oscillator Output high-level voltage VOH(PWM) 2.75 3.0 3.25 V Output low-level voltage VOL(PWM) 1.45 1.65 1.9 V Oscillator frequency f(PWM) Amplitude V(PWM) C = 680pF 1.1 1.35 1.6 Vp-p Output high-level voltage VOH(CSD) 3.15 3.5 3.85 V Output low-level voltage VOL(CSD) 0.9 1.1 1.3 V External capacitor charge current ICHG1 -9.0 -6.5 -3.9 μA External capacitor discharge current ICHG2 2.4 4.0 6.0 μA 23 kHz CSD Oscillator Oscillator frequency f(RK) C = 0.047μF Amplitude V(RK) 2.1 2.4 2.65 Vp-p Output high-level voltage VOH(C) 2.00 2.30 2.55 V Output low-level voltage VOL(C) 1.55 1.80 2.05 V 1.2 MHz 0.7 Vp-p 20 Hz VCO Oscillator C pin Oscillator frequency f(C) Amplitude V(C) 0.3 0.5 Continued on next page. No.A0604-2/18 LB11921T Continued from preceding page. Parameter Symbol Ratings Conditions min typ unit max Current Limiter Operation Limiter VRF 0.24 0.26 0.28 V 150 180 °C 30 °C Thermal Shutdown Operation Thermal shutdown operating TSD Design target value * ΔTSD Design target value * temperature Hysteresis Low-voltage Protection Circuit Operating voltage VSDL Release voltage VSDH 3.55 3.93 4.23 V Hysteresis ΔVSD 0.12 0.19 0.26 V VIO(FG) -10 3.40 3.74 4.00 V FG Amplifier Input offset voltage Input bias current IB(FG) -1 10 mV 1 μA Output high-level voltage VOH(FG) IFGI = -0.1mA, No load 3.6 3.95 4.3 V Output low-level voltage VOL(FG) IFGI = 0.1mA, No load 0.7 1.05 1.4 V 180 250 mV 2.34 kHz FG input sensitivity Gain: 100× Schmitt amplitude for the next stage 3 100 mV Operating frequency range Open-loop gain Reference voltage f(FG) = 2kHz VB(FG) 45 51 -5% VCC/2 5% dB 0.2 0.4 V 10 μA 1.1 V V FGS Output Output saturation voltage Output leakage current VO(FGS) IL(FGS) IO(FGS) =2mA VO = VCC Speed Discriminator Output Output high-level voltage VOH(D) Output low-level voltage VOL(D) VCC-1.0 VCC-0.7 0.8 Counts V 512 Speed Control PLL Output Output high-level voltage VOH(P) 3.25 3.50 3.85 V Output low-level voltage VOL(P) 1.25 1.60 1.85 V 0.25 0.4 V 10 μA +6.25 % Lock Detection Output saturation voltage Output leakage current VOL(LD) IL(LD) ILD = 10mA VO = VCC Lock range -6.25 Integrator Input offset voltage Input bias current VIO(INT) -10 10 mV IB(INT) -0.4 0.4 μA V Output high-level voltage VOH(INT) IINTI = -0.1mA, No load 3.45 3.7 3.95 Output low-level voltage VOL(INT) IINT = 0.1mA, No load 1.1 1.3 1.5 45 51 -5% VCC/2 Open-loop gain Gain-bandwidth product Reference voltage Design target value * VB(INT) *: Design target value and no measurement was made. V dB 1.0 MHz 5% V Continued on next page. No.A0604-3/18 LB11921T Continued from preceding page. Parameter Symbol Ratings Conditions min unit typ max FIL Output Output source current IOH(FIL) -17 -13 -7 μA Output sink current IOL(FIL) 7 12 17 μA Input high-level voltage VIH(S/S) 2.0 VCC V Input low-level voltage VIL(S/S) 0 1.0 V Input open voltage VIO(S/S) VCC-0.5 VCC V Hysteresis ΔVIN(S/S) 0.13 0.22 0.31 V Input high-level current IIH(S/S) VS/S = VCC 10 Input low-level current IIL(S/S) VS/S = 0V Pull-up resistance S/S Pin μA -10 0 -135 -93 RU(S/S) 37 53.5 Input high-level voltage VIH(F/R) 2.0 VCC V Input low-level voltage VIL(F/R) 0 1.0 V Input open voltage VIO(F/R) VCC-0.5 VCC V Hysteresis ΔVIN(F/R) Input high-level current IIH(F/R) VF/R = VCC Input low-level current IIL(F/R) VF/R = 0V Pull-up resistance RU(F/R) Input high-level voltage VIH(BR) 2.0 Input low-level voltage VIL(BR) Input open voltage VIO(BR) Hysteresis ΔVIN(BR) 0.13 μA 70 kΩ F/R Pin 0.13 0.22 0.31 V -10 0 10 μA -135 -93 37 53.5 μA 70 kΩ VCC V 0 1.0 V VCC-0.5 VCC V 0.22 0.31 V 10 μA 70 kΩ BR Pin Input high-level IIH(BR) VBR = VCC Input low-level current IIL(BR) VBR = 0V Pull-up resistance -10 0 -135 -93 RU(BR) 37 53.5 Input high-level voltage VIH(CLK) 2.0 VCC V Input low-level voltage VIL(CLK) 0 1.0 V VCC-0.5 VCC V μA CLK Pin Input open voltage VIO(CLK) Hysteresis ΔVIN(CLK) Design target value * Input high-level current IIH(CLK) VCLK = VCC Input low-level current IIL(CLK) VCLK = 0V Input frequency Pull-up resistance 0.13 0.22 0.31 V -10 0 10 μA -135 -93 37 53.5 f(CLK) RU(CLK) μA 2.34 kHz 70 kΩ *: Design target value and no measurement was made. No.A0604-4/18 LB11921T Package Dimensions unit : mm (typ) 3253B Allowable Power Dissipation, Pd max - W 0.5 5.6 7.6 19 36 1 18 0.15 0.18 Mounted on a specified board: 114.3mm×76.1mm×1.6mm, glass epoxy 1.0 0.9 0.8 0.6 0.504 Independent IC 0.4 0.224 0.2 0.08 (1.0) (0.63) 1.2max (0.5) Pd max - Ta 1.2 9.75 0 -20 0 20 40 60 80 Ambient Temperature, Ta -°C 100 ILB01797 SANYO : TSSOP36(275mil) IN1+ IN1- IN2+ IN2- IN3+ IN3- VCC WH WL VH VL UH UL GND RF RFGND FGIN+ FGIN- Pin Assignment 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 CLK F/R BR FGS LD DOUT POUT INT.REF INT.IN INT.OUT PWM FIL R C CSD NC 18 FGOUT 1 S/S LB11921T Top view Three-Phase Logic Truth Table (A high (H) input is the state where IN+ > IN–.) F/R=L F/R=H Output IN1 IN2 IN3 IN1 IN2 IN3 PWM - 1 H L H L H L VH UL 2 H L L L H H WH UL 3 H H L L L H WH VL 4 L H L H L H UH VL 5 L H H H L L UH WL 6 L L H H H L VH WL No.A0604-5/18 LB11921T IN3- IN3+ IN1IN2+ IN2- CSD IN1+ Block Diagram VCC HALL HYS AMP CSD OSC WH VH LOGIC PRI DRIVER F/R F/R UH WL VL UL LOGIC BR BR TSD S/S RES RF INT OUT COMP + RFGND - INT IN CURR LIM S/S 1.3VREF VCC LVSD INT REF PWM OSC PWM POUT LD LD SPEED DISCRI DOUT SPEED PLL 1/512 FG FILTER FGS R VCO PLL VCO C - + FIL FGOUT CLK FIL + - VCC CLK FGIN+ FGIN- GND No.A0604-6/18 LB11921T Pin Functions Pin No. Symbol 1 S/S Pin Description Start/stop control Equivalent Circuit VCC Low: 0V to 1.0V 50kΩ High: 2.0V to VCC Goes high when left open. Low for start. 3.5kΩ The hysteresis is about 0.22V 1 2 CLK External clock signal input Low: 0V to 1.0V VCC 50kΩ High: 2.0V to VCC Goes high when left open. The hysteresis is about 0.22V. f = 2.34kHz, maximum 3.5kΩ 2 3 F/R Forward/reverse control Low: 0V to 1.0V VCC High: 2.0V to VCC 50kΩ Goes high when left open. Low for forward. The hysteresis is about 0.22V. 3.5kΩ 3 BR Brake pin (short braking operation) Low: 0V to 1.0V VCC High: 2.0V to VCC Goes high when left open. High or open for brake mode operation. The hysteresis is about 0.22V. 50kΩ 4 3.5kΩ 4 Continued on next page. No.A0604-7/18 LB11921T Continued from preceding page. Pin No. Symbol 5 FGS Pin Description Equivalent Circuit FG schmitt comparator circuit output VCC This is an open collector output. 5 6 LD Speed lock detection output VCC Goes low when the motor speed is within the speed lock range (±6.25%). 6 7 DOUT Speed discriminator output V CC Acceleration → high, deceleration → low 7 8 POUT Speed control system PLL output VCC Outputs the phase comparison result for CLK and FG. 8 Integrating amplifier non-inverting input (1/2 VCC potential) 10 INT IN VCC Integrating amplifier inverting input 30kΩ INT REF 500Ω 9 500Ω 10 30kΩ 9 Continued on next page. No.A0604-8/18 LB11921T Continued from preceding page. Pin No. Symbol 11 INT OUT Pin Description Equivalent Circuit Integrating amplifier output VCC 40kΩ 11 12 PWM PWM oscillator frequency setting. Connect a capacitor between this pin and ground. VCC 300Ω 7.5kΩ 12 13 FIL VCO system PLL output filter connection VCC 300Ω 13 14 R Set the value of the charge/discharge current from the VCO circuit C pin. VCC Insert a resistor between this pin and ground. 300Ω 14 Continued on next page. No.A0604-9/18 LB11921T Continued from preceding page. Pin No. Symbol 15 C Pin Description Equivalent Circuit VCO oscillator connection VCC Insert a capacitor between this pin and ground. The oscillation frequency of the C pin must not exceed 1.2MHz. 300Ω 15 16 CSD Set the operating time of the constrained-rotor protection circuit. Reset circuit VCC Insert a capacitor between this pin and ground. This pin also functions as the logic circuit block power-on reset pin. 300Ω 16 17 NC There is unconnected pin, and can be used for wiring. 18 FGOUT FG amplifier output VCC This pin is connected to the FG Schmitt comparator circuit internally in the IC. 40kΩ 18 FG Schmitt comparator 20 + FGIN FG amplifier inverting input VCC 300Ω FGOUT FG amplifier noninverting input. Insert a capacitor between this pin and ground. 20kΩ FGIN- The 1/2 VCC potential. 500Ω 500Ω 19 20 20kΩ 19 Continued on next page. No.A0604-10/18 LB11921T Continued from preceding page. Pin No. Symbol 21 RF GND Pin Description Equivalent Circuit Output current detection reference VCC Connect to GND of the external resistor Rf. 21 22 RF Output current detection Connect a low resistance resistor Rf between this VCC pin and Rf GMD pin. This resistor sets the maximum output current IOUT to be 0.26/Rf. 22 23 GND GND pin 24 UL Outputs (that are used to drive external 25 UH transistors). 26 VL Duty cycle is controlled on the UH, VH, and WH 27 VH side of these output. 28 WL 29 WH VCC 50kΩ 24 26 28 30 VCC 25 27 29 Power supply Connect a capacitor between this pin and ground for stabilization. 31 IN3- Hall-effect device inputs. 32 IN3+ The input is seen as a high-level input when IN+ 33 IN2- > IN-, and as a low-level input for the opposite 34 IN2+ state. 35 IN1- If noise on the Hall-effect device signals is a 36 IN1+ problem, insert capacitors between the corresponding IN+ and IN- inputs. VCC 500Ω 32 34 36 500Ω 31 33 35 No.A0604-11/18 LB11921T Sample Application Circuit 1 (P-channel + N-channel, Hall-effect sensor application) 24V IN2- IN3+ IN3- VCC WH 26 25 24 23 22 21 20 19 FGIN- IN2+ 27 FGIN+ IN1- 28 RFGND 29 RF 30 GND 31 UL 32 UH 33 VL 34 VH 35 WL 36 IN1+ 5V S/S CLK F/R BR FGS LD DOUT POUT INT.REF INT.IN INT.OUT PWM FIL R C CSD NC FGOUT LB11921T 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 S/S CLK F/R BR FGS LD No.A0604-12/18 LB11921T Sample Application Circuit 2 (PNP + NPN, Hall-IC application) 24V 23 22 21 20 19 FGIN- 24 FGIN+ 25 RFGND 26 RF 27 GND IN3+ 28 UL IN2- 29 UH IN2+ 30 VL IN1- 31 VH 32 WL 33 WH 34 VCC 35 IN3- 36 IN1+ 5V S/S CLK F/R BR FGS LD DOUT POUT INT.REF INT.IN INT.OUT PWM FIL R C CSD NC FGOUT LB11921T 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 S/S CLK F/R BR FGS LD No.A0604-13/18 LB11921T LB11921T Overview 1. Speed Control Circuit This IC implements speed control using the combination of a speed discriminator circuit and a PLL circuit. The speed discriminator circuit outputs (This counts a single FG period.) an error signal once every two FG periods. The PLL circuit outputs an error signal once every one FG Period. As compared to the earlier technique in which only a speed discriminator circuit was used, the combination of a speed discriminator and a PLL circuit allows variations in motor speed to be better suppressed when a motor that has large load variations is used. The FG servo frequency (fFG) is controlled to have the equal frequency with the clock signal (fCLK) which is input through the CLK pin. fFG = fCLK 2. VCO Circuit The LB11921T includes a built-in VCO circuit to generate the speed discriminator circuit reference signal. The reference signal frequency is given by the following formula. fVCO = fCLK × 512 fVCO: Reference signal frequency fCLK: Externally input clock frequency The range over which the reference signal frequency can be varied is determined by the resistor and capacitor components connected to the R and C pins (pins 14 and 15) and by the VCO loop filter constant (the values of the external components connected to pin 13). Reference value at VCC = 5V fFG in the high-speed R(kΩ) C(pF) 1.5kHz 5.6 330 2.0kHz 5.6 220 rotation mode The components connected to the R, C, and FIL pins must be connected with lines to their ground pin (pin 23) that are as short as possible. 3. Output Drive Circuit To reduce power loss in the output, this IC adopts the direct PWM drive technique. The output transistors (which are external to the IC) are always saturated when on, and the motor drive output is adjusted by changing the duty with which the output is on. The PWM switching is performed on the UH, VH, and WH pins. The PWM switching side in the output can be selected to be either the high or low side depending on how the external transistors are connected. 4. Current Limiter Circuit The current limiter circuit limits the (peak) current at the value I = VRF/Rf (VRF = 0.26V (typical), Rf: current detection resistor). The current limitation operation consists of reducing the output duty to suppress the current. High accuracy detection can be achieved by connecting the RF and RFGND pin lines near the ends of the current detection resistor (Rf). 5. Speed Lock Range The speed lock range is ±6.25% of the fixed speed. When the motor speed is in the lock range, the LD pin (an open collector output) goes low. If the motor speed goes out of the lock range, the motor on duty is adjusted according to the speed error to control the motor speed to be within the lock range. 6. Notes on the PWM Frequency The PWM frequency is determined by the capacitor (F) connected to the PWM pin. fPWM ≈ 1/(64000 × C) A PWM frequency of between 15 and 25kHz is desirable. If the PWM frequency is too low, the motor may resonate at the PWM frequency during motor control, and if that frequency is in the audible range, that resonation may result in audible noise. If the PWM frequency is too high, the output transistor switching loss will increase. To make the circuit less susceptible to noise, the connected capacitors must be connected to the GND pin (pin 23) with lines that are as short as possible. No.A0604-14/18 LB11921T 7. Hall effect sensor input signals An input amplitude of over 100mVp-p is desirable in the Hall effect sensor inputs. The closer the input waveform is to a square wave, the lower the required input amplitude. Inversely, a higher input amplitude is required the closer the input waveform is to a triangular wave. Also note that the input DC voltage must be set to be within the commonmode input voltage range. If noise on the Hall inputs is a problem, that noise must be excluded by inserting capacitors across the inputs. Those capacitors must be located as close as possible to the input pins. When the Hall inputs for all three phases are in the same state, all the outputs will be in the off state. If a Hall sensor IC is used to provide the Hall inputs, those signals can be input to one side (either the + or - side) of the Hall effect sensor signal inputs as 0 to VCC level signals if the other side is held fixed at a voltage within the common-mode input voltage range that applies when a Hall effect sensors are used. 8. Forward/Reverse Switching The motor rotation direction can be switched using the F/R pin. However, the following notes must be observed if the motor direction is switched while the motor is turning. • This IC is designed to avoid through currents when switching directions. However, increases in the motor supply voltage (due to instantaneous return of motor current to the power supply) during direction switching may cause problems. The values of the capacitors inserted between power and ground must be increased if this increase is excessive. • If the motor current after direction switching exceeds the current limit value, the PWM drive side outputs will be turned off, but the opposite side output will be in the short-circuit braking state, and a current determined by the motor back EMF voltage and the coil resistance will flow. Applications must be designed so that this current does not exceed the ratings of the output transistors used. (The higher the motor speed at which the direction is switched, the more severe this problem becomes.) 9. Brake Switching The LB11921T provides a short-circuit brake implemented by turning the output transistors for the UH, VH, and WH pins for all phases on. (The opposite side transistors are turned off for all phases.) Note that the current limiter does not operate during braking. During braking, the duty is set to 100%, regardless of the motor speed. The current that flows in the output transistors during braking is determined by the motor back EMF voltage and the coil resistance. Applications must be designed so that this current does not exceed the ratings of the output transistors used. (The higher the motor speed at which braking is applied, the more severe this problem becomes.) The braking function can be applied and released with the IC in the start state. This means that motor startup and stop control can be performed using the brake pin with the S/S pin held at the low level (the start state). If the startup time becomes excessive, it can be reduced by controlling motor startup and stop with the brake pin rather than with the S/S pin. (Since the IC goes to the power saving state when stopped, enough time for the VCO circuit to stabilize will be required at the beginning of the motor start operation.) 10. Constraint Protection Circuit The LB11921T includes an on-chip constraint protection circuit to protect the IC and the motor in motor constraint mode. If the LD output remains high (indicating the unlocked state) for a fixed period in the start state, the PWM output (external) transistors are turned off. This time is set by the capacitance of the capacitor attached to the CSD pin. The set time (in seconds) is 15.1 × C (μF) To clear the motor constrained protection state, the application must either switch to the stop or brake state for a fixed period (about 1ms or longer), or the power must be turned off and reapplied. If the motor constrained protection circuit is not used, a 360kΩ resistor and a 3300pF capacitor must be connected in parallel between the CSD pin and ground. However, in that case, the clock disconnect protection circuit described below will no longer function. Since the CSD pin also functions as the power-on reset pin, if the CSD pin were connected directly to ground, the IC would go to the power-on reset state and motor drive operation would remain off. The power-on reset state is cleared when the CSD pin voltage rises above a level of about 0.25V. 11. Clock Disconnect Protection Circuit If the clock input goes to the no input state when the IC is in the start state, this protection circuit will operate and turn off the PWM output. If the clock is resupplied before the motor constraint protection circuit operates, the IC will return to the drive state, but if the motor constraint protection circuit does operate, the IC must either be set temporarily (approximately 1 ms or over) to the stop or brake state, or the power must be turned off and reapplied. No.A0604-15/18 LB11921T 12. Low-Voltage Protection Circuit The LB11921T includes a low-voltage protection circuit to protect against incorrect operation when VCC power is applied or if the power supply voltage falls below its operating level. The (external) all output transistors are turned off if VCC falls under about 3.74 volts, and the protection function is cleared at about 3.93 volts or higher. 13. Power Supply Stabilization Since this IC is used in applications that draw large output currents, the power-supply line is subject to fluctuations. Therefore, capacitors with capacitances adequate to stabilize the power-supply voltage must be connected between the VCC pin and ground. If diodes are inserted in the power-supply line to prevent IC destruction due to reverse power supply connection, since this makes the power-supply voltage even more subject to fluctuations, even larger capacitors will be required. 14. Ground Lines The signal system ground and the output system ground must be separated and a single ground point must be taken at the connector. Since the output system ground carries large currents, this ground line must be made as short as possible. Output system ground --- Ground for Rf, output diodes, and 24V line capacitors Signal system ground --- Ground for the IC, external components, and 5V line capacitors 15. FG Amplifier The FG amplifier is normally implemented as a filter amplifier such as that shown in the application circuits to reject noise. Since a clamp circuit has been added at the FG amplifier output, the output amplitude is clamped at about 3Vp-p, even if the gain is increased. Since a Schmitt comparator is inserted after the FG amplifier, applications must set the gain so that the amplifier output amplitude is at least 250mVp-p. (It is desirable that the gain be set so that the amplitude is over 0.5Vp-p at the lowest controlled speed to be used.) The capacitor inserted between the FGIN+ pin (pin 20) and ground is required for bias voltage stabilization. To make the connected capacitor as immune from noise as possible, connect this capacitor to the GND pin (pin 23) with a line that is as short as possible. 16. Integrating Amplifier The integrating amplifier integrates the speed error pulses and phase error pulses and converts them to the speed controlling voltage. At the same time it also sets the control loop gain and frequency characteristics. External components necessary for the integrating amplifier must be placed as close to the IC as possible to reduce influence of noise. 17. FIL Pin External Components The capacitor inserted between the FIL pin and ground is used to suppress ripple on the FIL pin voltage. Therefore, application designers must select a capacitance value that provides fully adequate smoothing of the FIL pin voltage even at the lowest external clock input frequency used. Also, the FIL pin voltage convergence time (the time until the reference signal stabilizes) when the input clock frequency is switched is shortened by connecting a resistor and a capacitor in series between the FIL pin and ground. Therefore, designers must select values for the resistor and capacitor that give the required convergence time. No.A0604-16/18 LB11921T 18. R and C Pin External Components The maximum range over which the reference signal frequency fVCO can be varied when 5V is used as the VCC supply voltage is about a factor of three. When it is desirable to make this range as wide as possible, since the values of the R pin external resistor (R) and the C pin external capacitor (C) are determined by the maximum value of the reference signal frequency (fVCO1) and the minimum value (VCCL) of the VCC power supply due to unit-to-unit variations, R and C can be determined using the following procedure as a reference. (1) Calculate R1 and C1 using the following formulas and determine values for R and C such that the conditions R ≤ R1 and C ≤ C1 will hold taking the sample-to-sample variations (including other issues such as temperature characteristics) into account. R1 = (VCCL-2.2 V)/370μA C1 = (370μA /0.9V) × (1/fVCO1) × 0.7 (2) The minimum value (fVCO2) for the reference signal frequency that can be set for the R and C values determined in step (1) can be calculated from the following formula if we let R2 and C2 be the smallest values for R and C due to the sample-to-sample variations (including other issues such as temperature characteristics). Therefore, the range over which the reference signal frequency can be set is fVCO1 to fVCO2. fVCO2 = 0.38/(R2 × C2) (3) The following are the conditions that must be met and the points that require care when determining the values of the external components connected to the R and C pins. 1. The maximum value of the set reference signal frequency must not exceed 1.2MHz. 2. The R pin voltage and the FIL pin voltage must be in the range 0.3V to (VCCL-2.2V). (VCCL is the lowest value of the VCC supply voltage given the unit-to-unit variations. VCCL is always greater than or equal to 4.4V.) However, the lower the R pin voltage, the more susceptible the system will be to ground line noise, and the reference signal frequency may become unstable as a result. Therefore the lower end of the R pin voltage range must not be used if there is much ground line noise in the system. 3. Set the value of the R pin external resistor to a value in the range 5.6kΩ to 10kΩ. Also, assure that the R pin current remains under 370μA. 4. Set the value of the C pin external capacitor to a value in the range 220pF to 1000pF. 5. When it is desirable to make the range of the reference signal frequency as wide as possible, set the values of R and C to the largest possible values. (However, those values must be lower than the calculated values R1 and C1.) Use components with the smallest sample-to-sample variations possible. The VCC voltage must be made as much higher than 5V as possible to acquire the widest possible range for the reference signal frequency. 19. NC pin Since the NC pins are electrically open with respect to the IC itself, they can be used as intermediate connection points for lines in the PCB pattern. No.A0604-17/18 LB11921T ON Semiconductor and the ON logo are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. SCILLC reserves the right to make changes without further notice to any products herein. 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