Unitrode UC1637/UC2637/UC3637 handbook
Contents
1. UC3637ND 0 0 mus UNITRODE G VC1637 o 0 2637 UC3637 Switched Mode Controller for DC Motor Drive FEATURES Single or Dual Supply Operation 2 5V to 20V Input Supply Range 5 Initial Oscillator Accuracy 10 Over Temperature Pulse by Pulse Current Limiting Under Voltage Lockout Shutdown Input with Temperature Compensated 2 5V Threshold Uncommitted PWM Comparators for Design Flexibility Dual 100mA Source Sink Output Drivers BLOCK DIAGRAM DESCRIPTION The UC 1637 is a pulse width modulator circuit intended to be used for a variety of PWM motor drive and amplifier applications requiring either uni directional or bi directional drive circuits When used to replace conventional drivers this circuit can increase efficiency and reduce component costs for many applications All necessary circuitry is included to generate an analog error signal and modulate two bi directional pulse train outputs in proportion to the error signal magnitude and polarity This monolithic device contains a sawtooth oscillator error amplifier and two PWM comparators with 100mA output stages as standard features Protection circuitry includes under voltage lockout pulse by pulse current limiting and a shutdown port with a 2 5V temperature compensated threshold The UC1637 is characterized for operation over the full military temperature range of 55 C to 125 C while the UC2637 and UC3637 are characterized for2. 2 2 OV 10 0 5 10 0 5 uA VTH VTH Input Range 5 2 Vs 2 Vs 2 Vs 2 V Error Amplifier Input Offset Voltage VCM OV 1 5 5 1 5 10 mV Input Bias Current VCM OV 0 5 5 0 5 5 uA Input Offset Current VCM OV 0 1 1 0 1 1 uA Common Mode Range Vs 2 5 to 20V Vs 2 Vs VS 2 VS V Open Loop Voltage Gain RL 10k 75 100 80 100 dB Slew Rate 15 15 V us Unity Gain Bandwidth 2 2 MHz CMRR Over Common Mode Range 75 100 75 100 dB PSRR Vs 2 5 to 20V 75 110 75 110 dB UC1637 UC2637 UC3637 ELECTRICAL CHARACTERISTICS Unless otherwise stated these specifications apply for Ta 55 C to 125 C for the UC1637 25 C to 85 C for the UC2637 and 0 C to 70 C for the UC3637 Vs 15V Vs 15V 5V VTH 5V RT 16 7 CT 1500pF TA Ty PARAMETERS TEST CONDITIONS UC1637 UC2637 UC3637 UNITS MIN TYP MAX MIN TYP MAX Error Amplifier Continued Output Sink Current VPIN 17 OV 50 20 50 20 mA Output Source Current VPIN 17 OV 5 11 5 11 mA High Level Output Voltage 13 13 6 13 13 6 V Low Level Output Voltage 14 8 13 14 8 13 V PWM Comparators Input Offset Voltage Vom 0V 20 20 mV Input Bias Current Vom 0V 2 10 2 10 uA Input Hysteresis Vom OV 10 10 mV Common Mode range Vs 5V to 20V Vs 1 Vs 2 Vs 1 5 2 V Current Limit Input Offs
3. the power in put into the motor is increased Figure 3A shows this con figuration Case B Small Deadtime Voltage on Pin 9 gt Pin 11 A small differential voltage between Pin 9 and 11 provides the necessary time delay to reduce the chances of mo mentary short circuit in the output stage during transi tions especially where power amplifiers are used Refer to Figure 3B Case C Increased Deadtime and Deadband Mode Voltage on Pin 9 Pin 11 With the reduction of stiffness and position accuracy the power input into the motor around the null point of the servo loop can be reduced or eliminated by widening the window of the comparator circuit to a degree of accep tance Where position accuracy and mechanical stiffness is unimportant deadband operation can be used This is shown in Figure 3C 4 Vs Vs R2 R3 R1 R2 R3 Vs Vs R3 Ri R2 R3 UC1637 OSCILLATOR AA PIN 2 ERROR SIGNAL PIN 17 Figure 2 Comparator Biasing Output Drivers Each output driver is capable of both sourcing and sinking 100mA steady state and up to 500mA on a pulsed basis for rapid switching of either POWERFET or bipolar tran sistors Output levels are typically Vs 0 2V 50mA low level and Vs 2 0V 50mA high level Error Amplifier The error amplifier consists of a high slew rate 15V us op amp with a typical 1MHz bandwidth and low output im pedance Depending on the Vs supply voltage the com mon
4. 25 C to 85 C and 0 C to 70 C respectively ABSOLUTE MAXIMUM RATINGS Note 1 Supply Voltage EVs siiis 00 ia eed eee eb 20V Output Current Source Sink Pins 4 7 500mA Analog Inputs Pins 1 2 3 8 9 10 11 12 13 14 15 16 5 Error Amplifier Output Current Pin 17 20 Oscillator Charging Current Pin 18 2mA Power Dissipation at TA 25 C Note 2 1000mWw Power Dissipation at Tc 25 Note 2 2000mW Storage Temperature Range 65 C to 150 C Lead Temperature Soldering 10 300 Note 1 Currents are positive into negative out of the specified terminal Note 2 Consult Packaging Section of Databook for thermal limitations and considerations of package AIN AIN 11 110 2 5V SHUT SHUTDOWN ed Ap AOUT E A OUTPUT 6 97 98 Bin BIN Note Fault latches are reset dominant UC1637 UC2637 CONNECT
5. ION DIAGRAM UC3637 DIL 18 TOP VIEW PLCC 20 LCC 20 J or N Package TOP VIEW V Q L Packages VtH 1 ISET PACKAGE PIN 2 FUNCTION FUNCTION VTH CT vs S 14 DOWN VTH Vs 6 13 c L NV AOUT I z 3 Aout 4 E A Bout 7 Bin 8 IS 2 Bour O1 i 9 10 11 12 13 SOIC 20 TOP VIEW BIN DW Package AN VTH ISET AIN E A C L OUTPUT C L iua SHUTDOWN DOWN E A OUTPUT ISET 2 3 Eee eee ee ELECTRICAL CHARACTERISTICS Unless otherwise stated these specifications apply for Ta 55 C to 125 C for the UC1637 25 C to 85 C for the UC2637 and 0 C to 70 C for the UC3637 Vs 15V Vs 15V VTH 5V VTH 5V RT 16 7kO 1500pF TA TJ PARAMETER TEST CONDITIONS UC1637 UC2637 UC3637 UNITS MIN TYP MAX MIN TYP MAX Oscillator Initial Accuracy TJ 25 C Note 6 9 4 10 10 6 9 10 11 kHz Voltage Stability Vs 5 to 20V VPIN 1 5 7 5 7 VPIN 3 3V Temperature Stability Over Operating Range Note 3 0 5 2 0 5 2 VTH Input Bias Current VPIN 2 6V 10 0 1 10 10 0 1 10 uA VTH Input Bias Current VPIN
6. any license either express or implied is granted under any patent right copyright mask work right or other intellectual property right of TI covering or relating to any combination machine or process in which such semiconductor products or services might be or are used Tl s publication of information regarding any third party s products or services does not constitute Tl s approval warranty or endorsement thereof Copyright 1999 Texas Instruments Incorporated
7. et Voltage VoM OV Ty 25 190 200 210 180 200 220 mV Input Offset Voltage T C 0 2 0 2 Input Bias Current 10 1 5 10 1 5 uA Common Mode Range Vs 2 5V to 20V Vs Vs 3 Vs VS 3 V Shutdown Shutdown Threshold Note 4 2 3 2 5 2 7 2 8 2 5 2 7 V Hysteresis 40 40 mV Input Bias Current 14 Vs to Vs 10 0 5 10 0 5 uA Under Voltage Lockout Start Threshold Note 5 4 15 5 0 4 15 5 0 V Hysteresis 0 25 0 25 mV Total Standby Current Supply Current 8 5 15 8 5 15 mA Output Section Output Low Level ISINK 20 14 9 13 14 9 13 V ISINK 100mA 14 5 13 14 5 13 Output High Level ISOURCE 20 13 13 5 13 13 5 V ISOURCE 100mA 12 13 5 12 13 5 Rise Time Note 3 CL Inf TJ 25 100 600 100 600 ns Fall Time Note 3 CL Inf TJ 25 100 300 100 300 ns Note 3 These parameters although guaranteed over the recommended operating conditions are not 100 tested in production Note 4 Parameter measured with respect to 4 Vs Pin 6 Note 5 Parameter measured at Vs Pin 6 with respect to Vs Pin 5 Note 6 Rr and Cr referenced to Ground FUNCTIONAL DESCRIPTION Following is a description of each of the functional blocks shown in the Block Diagram Oscillator The oscillator consists of two comparators a charging and discharging current source a current source set ter minal ISET and a flip flop The upper and lower threshold of the oscillator waveform is
8. he latest version of relevant information to verify before placing orders that information being relied on is current and complete All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement including those pertaining to warranty patent infringement and limitation of liability TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with Tl s standard warranty Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty Specific testing of all parameters of each device is not necessarily performed except those mandated by government requirements CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH PERSONAL INJURY OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE CRITICAL APPLICATIONS TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN LIFE SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER S RISK In order to minimize risks associated with the customer s applications adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards Tl assumes no liability for applications assistance or customer product design TI does not warrant or represent that
9. mode input range and the voltage output swing is within 2V of the VS supply Under Voltage Lockout An under voltage lockout circuit holds the outputs in the low state until a minimum of 4V is reached At this point all internal circuitry is functional and the output drivers are enabled If external circuitry requires a higher starting volt age an over riding voltage can be programmed through the shutdown terminal as shown in Figure 4 UC1637 UC2637 UC3637 Pins 8 11 Pins 9 Pins 11 9 UU p 4 Pins gar TL o3 kK DEADTIME 9 DAW WAS LN Pin 11 Bour A OUT AOUT Figure 3 Modulation Schemes Showing A Zero Deadtime B Deadtime and C Deadband Configurations Shutdown Comparator The shutdown terminal may be used for implementing various shutdown and protection schemes By pulling the terminal more than 2 5V below VIN the output drivers will be enabled This can be realized using an open collector zay gate or NPN transistor biased to either ground or the im l negative supply Since the threshold is temperature stabi SHUTDOWN lized the comparator can be used as an accurate low voltage lockout Figure 4 and or delayed start as in Fig R2 ure 5 In the shutdown mode the outputs are held in the low state Vs UC1637 Figure 5 Delayed Start Up VSTART Vs t
10. o within 3V of the Vs supply while providing excel lent noise rejection Figure 6 shows a typical current UC1637 sense circuit Vs 2 5V R1 lt SHUTDOWN R2 Vs 200mV UC1637 X Rs Hd Ne Figure 4 External Under Voltage Lockout Current Limit A latched current limit amplifier with an internal 200mV offset is provided to allow pulse by pulse current limiting Differential inputs will accept common mode signals from TWISTED PAIR Figure 6 Current Limit Sensing UC1637 UC2637 UC3637 wie UC1637 T E A VS OUTPUT SPEED CONTROL E A VS OUTPUT 17 10 www i POSITION COMMAND VOLTAGE POSITION FEEDBACK VOLTAGE Figure 8 Single Supply Position Servo Motor Drive UNITRODE CORPORATION 7 CONTINENTAL BLVD MERRIMACK NH 03054 TEL 603 424 2410 FAX 603 424 3460 IMPORTANT NOTICE Texas Instruments and its subsidiaries TI reserve the right to make changes to their products or to discontinue any product or service without notice and advise customers to obtain t
11. set externally by applying a voltage at pins and VTH respectively The VTH ter minal voltage is buffered internally and also applied to the ISET terminal to develop the capacitor charging current through Rr If RT is referenced to Vs as shown in Figure 1 both the threshold voltage and charging current will vary proportionally to the supply differential and the oscil lator frequency will remain constant The triangle wave form oscillators frequency and voltage amplitude is determined by the external components using the formulas given in Figure 1 _ VTH Vs UC1637 UC2637 UC3637 Is RT VTH Vs A Is 2CT VTH VrH VTH Vs Figure 1 Oscillator Setup PWM Comparators Two comparators are provided to perform pulse width modulation for each of the output drivers Inputs are un committed to allow maximum flexibility The pulse width of the outputs A and B is a function of the sign and ampli tude of the error signal A negative signal at Pin 10 and 8 will lengthen the high state of output A and shorten the high state of output B Likewise a positive error signal re verses the procedure Typically the oscillator waveform is compared against the summation of the error signal and the level set on Pin 9 and 11 MODULATION SCHEMES Case A Zero Deadtime Equal voltage on Pin 9 and Pin 11 In this configuration maximum holding torque or stiffness and position accuracy is achieved However
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Unitrode UC1637/UC2637/UC3637 handbook