ML4423IP

July 2000 ML4423* 1, 2, or 3-Phase Variable Speed AC Motor Controller GENERAL DESCRIPTION The ML4423 provides the PWM sinewave drive signals necessary for controlling three phase AC induction motors as well as single and two phase split capacitor AC induction motors. A constant voltage/frequency ratio can be maintained over a frequency range of greater than 10:1, providing 15Hz to 150Hz control. The output variable frequency AC voltages are sensed and fed back to the controller to track the sinewave frequency and amplitude set at the speed control input. Direction, on two and three phase motors, is controlled by changing the relative phase difference between the motor windings: 90× for two phase motors and 120× and 240× for three phase motors. To protect the motor, power devices, high voltage drivers and control circuitry, the ML4423 includes fixed period, pulse by pulse variable duty cycle current limit, deadtime circuitry, and undervoltage lockout. The ML4423 has selectable output voltage swing of 5V or 12V for interfacing to different high side drivers and power devices. FEATURES s s s s s s s s s Drives single, two, and three phase AC motors Greater than 10:1 variable speed control range Constant V/F ratio with programmable end points Reverse capability for two and three phase motors Low distortion PWM sinewave drive Eliminates run capacitors in PSC motors Coast function for quick power disable Low cost interface for various gate drivers PWM current limit, undervoltage lockout, and programmable deadtime 12V ±20% operation with onboard 8V reference s (* Indicates Part Is End Of Life As Of July 1, 2000) BLOCK DIAGRAM 27 SINE A-C FB A 1 FB C 2 5V/12 SELECT FB B 3 + – + – + – + – 28 SINE B-C 13 CT 15 F/R 18 3PH/2PH COAST 14 PWM OSCILLATOR RDT 9 25 HA PWM SINE WAVE CONTROL HB GATING LOGIC & OUTPUT DRIVERS HC LA LB LC 24 22 23 21 19 20 16 CO 12 SINE A GENERATOR VSPEED 5 VMIN 4 RSPEED 6 SINE C GENERATOR UVLO SPEED CONTROL SINE B GENERATOR 26 VDD REFERENCE GND 17 8 RREF VREF + COMP ISENSE 0.5V – 7 1 ML4423 PIN CONFIGURATION ML4423 28-Pin Narrow PDIP (P28N) 28-Pin SOIC (S28) SENSE A SENSE C SENSE B VMIN VSPEED RSPEED VREF RREF RDT 1 2 3 4 5 6 7 8 9 28 27 26 25 24 23 22 21 20 19 18 17 16 15 CGM2 CGM1 VDD 5V/12V SELECT HA HC HB LA LC LB 3PH/2PH GND ISENSE F/R SINE A-C 10 SINE B-C 11 CO 12 CT 03 COAST 14 TOP VIEW 2 ML4423 PIN DESCRIPTION PIN NAME FUNCTION PIN NAME FUNCTION 1 FB A Differential input which, in conjunction with FB C, feeds back the voltage applied across motor winding A-C. Input which feeds back the voltage applied to motor winding C. Reference voltage for windings A and B. Differential input which, in conjunction with FB C, feeds back the voltage applied across motor winding B-C. The voltage on this pin sets the minimum sinewave amplitude at low speeds. The voltage on this pin sets the frequency and amplitude of the sinewaves generated at SINEA and SINEB. An external resistor to ground provides a variable current to the sinewave generator. The current is proportional to VSPEED. 8V reference output which can be used for setting VSPEED and VMIN. An external resistor to ground provides a constant current used for setting the PWM frequency in conjunction with CT. An external resistor to ground sets the deadtime in the output stage to prevent cross-conduction in the power devices. A test output for observing the internally generated sinewave used for motor winding A-C. A test output for observing the internally generated sinewave used for motor winding B-C. An external capacitor to ground sets the sinewave frequency in conjunction with VSPEED and RSPEED. 13 CT An external capacitor to ground sets the PWM triangle frequency in conjunction with the external resistor RREF. A logic low input causes all output drive transistors to turn OFF. An internal pull-up drives COAST to VDD if left unconnected. A logic high input causes phase A to lead phase B, while a logic low input causes phase A to lag phase B. An internal pull-up drives F/R to VDD if left unconnected. Motor current sense input. Signal and power ground. Leaving this pin unconnected selects 3-phase drive. Connecting this pin to VDD selects single/2-phase drive. Low side drive output for phase B. Low side drive output for phase C. Low side drive output for phase A. High side drive output for phase B. High side drive output for phase C. High side drive output for phase A. Input to select 5V or 12V output drive. Leaving this pin unconnected selects 5V output drive levels at the driver outputs. Connecting this pin to VCC selects 12V output drive levels at the driver outputs. 12V power supply input. An external capacitor to ground sets a pole in the feedback loop. An external capacitor to ground sets a pole in the feedback loop. 2 FB C 14 COAST 3 FB B 15 F/R 4 V MIN 16 17 18 I SENSE GND 3PH/2PH 5 V SPEED 6 R SPEED 19 20 21 22 23 24 25 LB LC LA HB HC HA 5V/12V SELECT 7 8 V REF R REF 9 RDT 10 SINE A-C 26 27 28 V DD C GM1 C GM2 11 SINE B-C 12 CO 3 ML4423 ABSOLUTE MAXIMUM RATINGS Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. V DD .............................................................................................. 15V Output Drive Current ........................................... ±50mA Logic Inputs (F/R, COAST) .............................. –0.3 to 7V Junction Temperature .............................................. 150ºC Storage Temperature Range ...................... –65ºC to 150ºC Lead Temperature (Soldering 10 sec) ...................... 260ºC Thermal Resistance (qJA) Plastic DIP ....................................................... 52ºC/W Plastic SOIC .................................................... 75ºC/W OPERATING CONDITIONS Temperature Range C Suffix ...................................................... 0ºC to 70ºC I Suffix .................................................... –40ºC to 85ºC V DD ........................................................... 9.6V to 14.4V ELECTRICAL CHARACTERISTICS Unless otherwise specified, VDD = 12V ± 20%, RSPEED = 160kW, RSENSE = 250mW, RREF = 200kW, C0 = 0.47mF, CPWM = 220pF, RDT = 166kW, TA = Operating Temperature Range (Note 1). SYMBOL REFERENCE VREF Output Voltage Line Regulation Total Variation Line, Temperature 7.6 7.8 8.2 V PARAMETER CONDITIONS MIN TYP MAX UNITS DIGITAL INPUTS VIL VIH Input Low Voltage Input High Voltage 2 0.8 V V OUTPUT DRIVERS VOL Output Low Voltage IOL = 20mA, 5V/12V SELECT = VDD IOL = 2mA, 5V/12V SELECT = open VOH Output High Voltage IOL = –20mA, 5V/12V SELECT = VDD IOL = –2mA, 5V/12V SELECT = open 1 0.1 VDD – 1 5 V V V V SINE WAVE GENERATOR V PP Peak Voltage Frequency Distortion VSPEED = 4.4V VSPEED = 4.4V 3.4 60 5 V Hz % PWM GENERATOR Ramp Frequency 25 kHz CURRENT LIMIT Threshold Voltage 0.4 0.5 0.6 V UNDERVOLTAGE LOCKOUT Threshold Voltage Hysteresis 7.8 8.4 0.5 9.2 V V SUPPLY I CC VCC Operating Current 10 14 20 mA Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions. 4 ML4423 FUNCTIONAL DESCRIPTION The ML4423 generates 2 reference sinewaves separated by 90º or 60º in a closed loop feedback system. These sinewaves can be varied in amplitude and frequency by the speed input. Signals across the motor windings are fed back and the ML4423 drives the external power output stage with the PWM sinewave signal necessary to cause the measured (feedback) output waveform to match the internal reference sinewaves. The ML4423 provides fixed period, variable duty cycle current limit protection, and a programmable dead time circuit to prevent cross conduction in the power output stage. An undervoltage lockout circuit turns off the external power transistors if VDD falls below 9V. SINEA and SINEB Generators The capacitor to ground on C0 sets the frequency of the sinewave according to the following relationship. C0 should be a low temperature coefficient capacitor for stable output frequency.   VSPEED   R SPEED =   4C 0 × 0.170V      fSINE (1) CIRCUIT BLOCKS AND COMPONENT SELECTION R REF RREF should be set to 200kW. This current along with CPWM set the PWM frequency. For RSPEED = 160kW fSINE = VSPEED 108, 800 × C 0 (2) Speed Control The voltage on VSPEED (pin 5) controls the sinewave frequency and amplitude. A 160kW resistor to ground on RSPEED (pin 6) converts the voltage on VSPEED to a current which is used to control the frequency of the output PWM sinewaves. The amplitude of the sinewaves increases linearly with VSPEED until it reahces 4.4V. Above this voltage the amplitude remains constant and only the frequency changes as shown in Figures 1 and 2. With VSPEED = 3V and C0 = 0.47mF, fSINE = 58.7Hz and can be observed at test points SINEA (pin 10) and SINEB (pin 11). PWM Generator A triangular PWM frequency will be generated on a capacitor to ground on CPWM (pin 13). The frequency is set by the following equation: fPWM = 1 200, 000 × C PWM (3) For CPWM = 220pF, fPWM = 22.7kHz. It is recommended 150 1.25 4.4V 90 NORMALIZED OUPTUT (V) 8 120 1.00 FREQUENCY (Hz) 0.75 60 RSPEED = 160 C0 = 0.47µF 30 0.50 0.25 0 2 4 VSPEED (V) 6 0 2 4 VSPEED (V) 6 8 Figure 1. Frequency vs VSPEED Figure 2. Normalized Output Voltage vs VSPEED 5 ML4423 Current Limit Motor current is sensed on ISENSE (pin 16). RLIMIT should be selected so that OUTPUT DRIVE The 6 output drivers of the ML4423 drive the H and L outputs from 0 to 12 volts (with pin 25 tied to VCC +(12V)). The outputs will drive about 10mA and are designed to drive output buffers and high side drivers requiring 12V swings. The ML4423 provides lower current 0 to 5V drive for high/low side drivers requiring 5V input signal swings with pin 25 left unconnected. RLIMIT = 0.5V IMAX (4) For a 2A current limit, RLIMIT = 0.25W. The 1kW resistor and 330pF capacitor filter (shown in figure 3) filter the high frequency flyback pulses (due to the freewheeling diode recovery currents) occurring at the output. When IMAX is reached the output power will be turned off for the remainder of the current PWM cycle, which is asynchronous with the sinewave frequency. Thus current limit is fixed-period with variable duty cycle. PROGRAMMABLE DEADTIME A dead time circuit is provided to prevent shoot through currents in the power output stage. The dead time is controlled by a resistor to ground on RDT (pin 9). The dead time selected should be large enough to prevent cross conduction between the upper and lower power devices of each inverter phase leg. tDEAD = 1.2 × 10 −11 RDB PWM SINE Controller This circuit block compares the sinewaves at SINEA and SINEB to the sampled inputs SENSEA–SENSEC and SENSEB–SENSEC, respectively. The PWM loop then drives the outputs to force these “differential” waveforms to equal the internal reference waveforms at SINEA and SINEB. The differential signals SENSEA–SENSEC and SENSEB–SENSEC will be approximately 1.7 volts zeropeak maximum. The signals at these pins should be filtered to remove the PWM frequency. The high voltages at the motor terminals are divided down to 1.7V to provide voltage feedback to the controller. In figure 3, the resistors to ground from SENSEA (pin 1) and SENSEB (pin 3) should be 1kW. SENSEC (pin 2) should have a 500W to ground because it has 1/2 the input impedance of the other 2 inputs. The 0.15mF capacitors to ground on SENSEA and SENSEB and the 0.3mF capacitor to ground on SENSEC will create a 1kHz low pass filter at these inputs. VPEAK on the motor is set by the divider ratios. For the values shown in figure 3: (VSPEED = 4.4V)   = 1.7V  99k + 1k   1k    = 1.7V  49.5k + 500    500 = 170V ( ) (6) With fPWM = 25kHz, the PWM period is 40ms. With RDB = 166k, tDEAD = 2ms (~5%). CGM1 and CGM2 These two external capacitors to ground each set a pole in the forward path of the feedback loop in conjunction with a gm of 1/650W. The pole should be placed at a frequency higher than the PWM frequency. gm > fPWM 2πC gm (7) APPLICATION The ML4423 provides all the signals necessary to drive the output power stage connected to the motor. The components around the ML4423 for a typical application are shown in figure 3. The motor DC supply voltage should be greater than the largest signal waveform required or output clipping may result. Figure 4 shows an alternate circuit using the IR2118. VPEAK (5) 6 12V A 0.1µF VCC 26 VREF 0.1µF RREF 7 8V REF 8 1 200kΩ SINEA UNDER VOLTAGE LOCKOUT FREQ. SPEED CONTROLLER PWM SINE CONTROLLER OUTPUT DRIVE & SHOOT THROUGH PROTECTION 24 21 22 19 23 20 CURRENT LIMIT 17 GND CGM1 0.001µF 27 28 CGM2 0.001µF 11 SINEB 15 F/R 14 18 25 5V/12V SELECT 9 RDT 166kΩ 330pF 250mΩ 3 LIN 4 5 8 7 HA LA HB LB HC LC 2 ISENSE 1kΩ RLIMIT PWR INT100 12,13,14 1 HIN 15 11 + B DRIVE +12V 2 3 100kΩ VSPEED 5 0.47µF C0 12 SINEA 10 CPWM 13 99kΩ PWM GENERATOR 220pF C Figure 3. 3-Phase Motor Controller with INT-100 High Voltage Drivers B 99kΩ 1kΩ 500Ω 49.5kΩ ML4423 SENSEA SENSEC SENSEB 0.15µF 0.15µF 1kΩ 0.30µF +12V A DRIVE 0.1µF RSPEED 160kΩ 6 AMPLITUDE +12V +VMOTOR 170–400V VMIN 100kΩ 4 SINEB 10Ω 1µF 100Ω C 16 COAST 3PH/2PH 10Ω 100Ω Note: Use Extreme caution with high voltage AC motor control and drive circuitry. When the motor is spinning at the desired speed, and the speed is rapidly reduced, the energy stored in the rotation will generate a voltage greater than the +VMOTOR node, and destruction of the power transistors, high side driver, ML4423 controller and the power supply may occur. HV POWER STAGE ML4423 7 8 170 – 360V +VMOTOR +12V + MUR150 SENSEA 1 SENSEC 2 IR2118 VCC IN HO 7 VS 6 N/C 5 22Ω 25V 1µF COM N/C VB 8 IRF740 IRF740 IRF740 330µF 400V ML4423 SENSEB 3 1 2 H A 24 25V 1.0µF 3 4 H B 22 MUR150 AC MOTOR A IR2118 1 2 VCC IN HO 7 22Ω 25V 1µF VS 6 N/C 5 COM N/C VB 8 C B H C 23 3 4 25V 1.0µF ML4423 + 1.0µF MUR150 2N3904 1 IR2118 VCC IN 2 3 4 L A 21 2N3906 25V 1.0µF VB 8 HO 7 22Ω COM N/C VS 6 N/C 5 L B 19 C21 25V 1µF Figure 4. ML4423 Output Stage Using IR2118 High Side Drivers IRF740 IRF740 22Ω 22Ω 22Ω 1kΩ 330pF 250mΩ IRF740 L C 20 ISENSE 16 RLIMIT FEEDBACK NETWORK 5V/12V SELECT RDT 25 9 240kΩ SENSEC SENSEB SENSEA +12V ML4423 PHYSICAL DIMENSIONS inches (millimeters) Package: P28N 28-Pin Narrow PDIP 1.355 - 1.365 (34.42 - 34.67) 28 PIN 1 ID 0.280 - 0.296 0.299 - 0.325 (7.11 - 7.52) (7.60 - 8.26) 1 0.045 - 0.055 (1.14 - 1.40) 0.100 BSC (2.54 BSC) 0.020 MIN (0.51 MIN) 0.180 MAX (4.57 MAX) 0.125 - 0.135 (3.18 - 3.43) 0.015 - 0.021 (0.38 - 0.53) SEATING PLANE 0º - 15º 0.008 - 0.012 (0.20 - 0.31) Package: S28 28-Pin SOIC 0.699 - 0.713 (17.75 - 18.11) 28 0.291 - 0.301 0.398 - 0.412 (7.39 - 7.65) (10.11 - 10.47) PIN 1 ID 1 0.024 - 0.034 (0.61 - 0.86) (4 PLACES) 0.050 BSC (1.27 BSC) 0.095 - 0.107 (2.41 - 2.72) 0º - 8º 0.090 - 0.094 (2.28 - 2.39) 0.012 - 0.020 (0.30 - 0.51) SEATING PLANE 0.005 - 0.013 (0.13 - 0.33) 0.022 - 0.042 (0.56 - 1.07) 0.009 - 0.013 (0.22 - 0.33) 9 ML4423 ORDERING INFORMATION PART NUMBER ML4423CP (End Of Life) ML4423CS (End Of Life) ML4423IP (End Of Life) ML4423IS (End Of Life) TEMPERATURE RANGE 0ºC to 70ºC 0ºC to 70ºC –40ºC to 85ºC –40ºC to 85ºC PACKAGE 28-Pin Narrow PDIP (P28N) 28-Pin SOIC (S28) 28-Pin Narrow PDIP (P28N) 28-Pin Narrow PDIP (P28N) © Micro Linear 2000. is a registered trademark of Micro Linear Corporation. All other trademarks are the property of their respective owners. Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376; 5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174; 5,767,653; 5,777,514; 5,793,168; 5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669; 5,825,165; 5,825,223; 5,838,723; 5.844,378; 5,844,941. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending. DS4423-01 2092 Concourse Drive San Jose, CA 95131 Tel: (408) 433-5200 Fax: (408) 432-0295 www.microlinear.com 4/21/98 Printed in U.S.A. 10