UNITRODE UC1625/UC2625/UC3625 handbook
Contents
1. UC3625 UC1625 UC2625 UC3625 VMOTOR 2N3906 IRF9350 3kQ TO OTHER CHANNELS Le 8 Le REQUIRED FOR BRAKE AND FAST REVERSE TO OTHER CHANNELS 3m 1029 IRF532 21 2 D Cy Se Ry REQUIRED FOR HALL AVERAGE SENSORS CURRENT SENSING 4 0 02Q Figure 13 45V 8A brushless DC motor drive circuit N Channel power MOSFETs are used for low side driv ers while P Channel power MOSFETs are shown for high side drivers Resistors are used to level shift the UC3625 open collector outputs driving emitter follow ers into the MOSFET gate A 12V zener clamp insures that the MOSFET gate source voltage will never exceed 12V Series 10Q gate resistors tame gate reactance preventing oscillations and minimizing ringing The oscillator timing capacitor should be placed close to pins 15 and 25 to keep ground current out of the capac itor Ground current in the timing capacitor causes oscil lator distortion and slaving to the commutation signal The potentiometer connected to pin 1 controls PWM duty cycle directly implementing a crude form of speed control This control is often referred to as voltage mode b2. lt E c o us run o x a pan 0 o o 0 75 50 25 0 25 50 75 100 125 Temperature 9C Figure 6 Soft start discharge current vs temperature APPLICATION INFORMATION cont Power Stage Design The UC3625 is useful in a wide variety of applications including high power in robotics and machinery The power output stages used in such equipment can take a number of forms according to the intended perfor mance and purpose of the system Below are four differ ent power stages with the advantages and disadvantages of each shown For high frequency chopping fast recovery circulating diodes are essential Six are required to clamp the wind ings These diodes should have a continuous current rating at least equal to the operating motor current since diode conduction duty cycle can be high For low voltage systems Schottky diodes are preferred In higher voltage systems diodes such as Microsemi UHVP high voltage platinum rectifiers are recom mended In a pulse by pulse current control arrangement current sensing is done by resistor Rg through which the tran sistor s currents are passed Fig A B and C In these UC1625 UC2625 UC3625 ISENSE V 0 0 I SENSE2 ISENSE1 V Figure 7 Current sense amplifier transfer function cases Rp is not needed The low side
3. 5962 9168901M XA mus UNITRODE application i UC1625 lU INFO UC2625 available UC3625 Brushless DC Motor Controller FEATURES e Drives Power MOSFETs or Power Darlingtons Directly e 50V Open Collector High Side Drivers e Latched Soft Start e High speed Current Sense Amplifier with Ideal Diode e Pulse by Pulse and Average Current Sensing e Over Voltage and Under Voltage Protection e Direction Latch for Safe Direction Reversal e Tachometer e Trimmed Reference Sources 30mA e Programmable Cross Conduction Protection e Two Quadrant and Four Quadrant Operation TYPICAL APPLICATION 2200pF lt Cosc DESCRIPTION The UC3625 family of motor controller ICs integrate most of the functions required for high performance brushless DC motor con trol into one package When coupled with external power MOSFETs or Darlingtons these ICs perform fixed frequency PWM motor control in either voltage or current mode while implementing closed loop speed control and braking with smart noise rejection safe direction reversal and cross conduction protection Although specified for operation from power supplies between 10V and 18V the UC1625 can control higher voltage power devices with external level shifting components The UC1625 contains fast high current push pull drivers for low side powe
4. TI UC1625J883B OBSOLETE CDIP J 28 TBD Call TI Call TI UC1625L OBSOLETE LCCC FK 28 TBD Call TI Call TI UC1625L883B OBSOLETE LCCC FK 28 TBD Call TI Call TI UC2625DW ACTIVE SOIC DW 28 20 Green RoHS amp CUNIPDAU Level 2 260C 1 YEAR no Sb Br UC2625DWTR ACTIVE SOIC DW 28 1000 Green RoHS amp CU NIPDAU Level 2 260C 1 YEAR no Sb Br UC2625N ACTIVE PDIP N 28 13 TBD Call TI Level NA NA NA UC2625Q ACTIVE PLCC FN 28 37 TBD Call TI Level 2 220C 1 YEAR UC2625QTR ACTIVE PLCC FN 28 750 TBD Call TI Level 2 220C 1 YEAR UC3625DW ACTIVE SOIC DW 28 20 Green RoHS amp CUNIPDAU Level 2 260C 1 YEAR no Sb Br UC3625DWTR ACTIVE SOIC DW 28 1000 Green RoHS amp CU NIPDAU Level 2 260C 1 YEAR no Sb Br UC3625N ACTIVE PDIP N 28 13 TBD Call TI Level NA NA NA UC3625Q ACTIVE PLCC FN 28 37 TBD Call TI Level 2 220C 1 YEAR UC3625QTR ACTIVE PLCC FN 28 750 TBD Call TI Level 2 220C 1 YEAR The marketing status values are defined as follows ACTIVE Product device recommended for new designs LIFEBUY TI has announced that the device will be discontinued and a lifetime buy period is in effect NRND Not recommended for new designs Device is in production to support existing customers but TI does not recommend using this part in a new design PREVIEW Device has been announced but is not in production Samples may or may not be available OBSOLETE TI has discontinued the production of the device 2 Eco Plan The planned eco friendly classification Pb Fre
5. allow for a wide variety of uses They can be connected to the Isense to Tach Out through a filter to an external command volt age to a D A converter for computer control or to an other op amp for more elegant feedback loops The error amplifier is compensated for unity gain stability so E A Out can be tied to E A In for feedback and major loop compensation E A Out and PWM In drive the PWM comparator For voltage mode PWM systems PWM In can be connected to RC Osc The PWM comparator clears the PWM latch commanding the outputs to chop The error amplifier can be biased off by connecting E A In to a higher voltage than E A In When biased off E A Out will appear to the application as a resistor to ground E A Out can then be driven by an external am plifier GND All thresholds and outputs are referred to the GND pin except for the PD and PU outputs UC1625 UC2625 UC3625 H1 H2 H3 The three shaft position sensor inputs con sist of hysteresis comparators with input pull up resis tors Logic thresholds meet TTL specifications and can be driven by 5V CMOS 12V CMOS NMOS or open collectors Connect these inputs to motor shaft position sensors that are positioned 120 electrical degrees apart If noisy signals are expected zener clamp and filter these inputs with 6V zeners and an RC filter Suggested filtering components are 1kQ and 2nF Edge skew in the filter is not a problem because sensors normally genera
6. circulating di odes go to ground and the current sense terminals of the UC3625 IsgNsE1 and IsgNsEo are connected to Rs through a differential RC filter The input bias current of the current sense amplifier will cause a common mode offset voltage to appear at both inputs so for best accu racy keep the filter resistors below 2kQ and matched The current that flows through Rs is discontinuous be cause of chopping It flows during the on time of the power stage and is zero during the off time Conse quently the voltage across Rs consists of a series of pulses occurring at the PWM frequency with a peak value indicative of the peak motor current To sense average motor current instead of peak cur rent add another current sense resistor Rp in Fig D to measure current in the low side circulating diodes and operate in four quadrant mode pin 22 high The nega tive voltage across Rp is corrected by the absolute value current sense amplifier Within the limitations im posed by Table 1 the circuit of Fig B can also sense average current UC1625 UC2625 UC3625 APPLICATION INFORMATION cont FIGURE A FIGURE B FIGURE C FIGURE D 2 4 SAFE POWER CURRENT SENSE QUADRANT QUADRANT BRAKING REVERSE PULSE BY PULSE AVERAGE FIGURE A YES NO NO NO YES NO FIGURE B YES YES NO IN 4 QUAD MODE ONLY YES YES FIGURE C YES YES YES IN 4 QUAD MODE ONLY YES NO FIGURE D YES YE
7. first 50us of a tran sition from propagating to the output transistors and causing cross conduction or chatter The UC3625 also contains six flip flops corresponding to the six output drive signals One of these flip flops is set every time that an output drive signal is turned on and UC1625 UC2625 UC3625 tation cycle additional commutations are not possible Although this will effectively set a maximum rotational speed the maximum speed can be set above the high est expected speed preventing false commutation and chatter Vcc This device operates with supplies between 10V and 18V Under voltage lockout keeps all outputs off be low 7 5V insuring that the output transistors never turn on until full drive capability is available Bypass Vcc to ground with an O 1uF ceramic capacitor Using a 10uF electrolytic bypass capacitor as well can be beneficial in applications with high supply impedance Vref This pin provides regulated 5 volts for driving Hall effect devices and speed control circuitry Vrer will reach 5V before Vcc enables ensuring that Hall effect devices powered from Vgpgre will become active before the UC3625 drives any output Although Vpger is current limited operation over 30mA is not advised For proper performance Vref should be bypassed with at least a 0 1uF capacitor to ground cleared two PWM oscillator cycles after that drive signal is turned off The output of each flip flop is used to inhibit driv
8. F capacitor between Isensey and IsENSE2 Input resistors should be kept small and matched to maintain gain accuracy OV Coast This input can be used as an over voltage shutdown in put as a coast input or both This input can be driven by TTL 5V CMOS or 12V CMOS PIN DESCRIPTIONS cont PDA PDB PDC These outputs can drive the gates of N Channel power MOSFETs directly or they can drive the bases of power Darlingtons if some form of current limiting is used They are meant to drive low side power devices in high current output stages Current available from these pins can peak as high as 0 5A These out puts feature a true totem pole output stage Beware of exceeding IC power dissipation limits when using these outputs for high continuous currents These outputs pull high to turn a low side device on active high PUA PUB PUC These outputs are open collector high voltage drivers that are meant to drive high side power devices in high current output stages These are active low outputs meaning that these outputs pull low to command a high side device on These outputs can drive low voltage PNP Darlingtons and P channel MOSFETs directly and can drive any high voltage de vice using external charge pump techniques trans former signal coupling cascode level shift transistors or opto isolated drive high speed opto devices are recom mended See applications PWR Vcc This supply pin carries the current sourced by
9. PWM using the RC Osc pin to select the monostable time constant F The voltage on the RC Osc pin is normally a ramp of about 1 2V peak to peak centered at approximately 1 6V This ramp can be used for voltage mode PWM control or can be used for slope compensation in cur rent mode control Sstart Any time that Vcc drops below threshold or the sensed current exceeds the over current threshold the soft start latch is set When set it turns on a transistor that pulls down on SsrAnr Normally a capacitor is con nected to this pin and the transistor will completely dis charge the capacitor A comparator senses when the NPN transistor has completely discharged the capacitor and allows the soft start latch to clear when the fault is removed When the fault is removed the soft start ca pacitor will charge from the on chip current source PIN DESCRIPTIONS cont Sstart clamps the output of the error amplifier not al lowing the error amplifier output voltage to exceed Sstart regardless of input The ramp on RC Osc can be applied to PWM In and compared to E A Out With Sstart discharged below 0 2V and the ramp minimum being approximately 1 0V the PWM comparator will keep the PWM latch cleared and the outputs off As Sstart rises the PWM comparator will begin to duty cycle modulate the PWM latch until the error ampli fier inputs overcome the clamp This provides for a safe and orderly motor start up from an off or fault conditi
10. S YES IN 4QUADMODE ONLY YES YES APPLICATION INFORMATION cont e VM gt 45V VM 12V e _VM gt 45V ke Lo VM gt 45V Figure 10 Power NPN high side driver UC1625 UC2625 UC3625 To Other gt gt _ Channels PWR Vcc a D a PDA Power Darlington To Current Sense Resistor Figure 11 Power NPN low side driver For drives where speed is critical P Channel MOSFETs can be driven by emitter followers as shown in Fig 8 Here both the level shift NPN and the PNP must with stand high voltages A zener diode is used to limit gate source voltage on the MOSFET A series gate re sistor is not necessary but always advisable to control overshoot and ringing High voltage optocouplers can quickly drive high voltage MOSFETs if a boost supply of at least 10 volts greater than the motor supply is provided See Fig 9 To protect the MOSFET the boost supply should not be higher than 18 volts above the motor supply For under 200V 2 quadrent applications a power NPN driven by a small P Channel MOSFET will perform well as a high side driver as in Fig 10 A high voltage small signal NPN is used as a level shift and a high volt age low current MOSFET provides drive Although the NPN will not saturate if used within its limitations the base emitter resistor on the NPN is still the speed limiting compon
11. e RoHS or Green RoHS amp no Sb Br please check http www ti com productcontent for the latest availability information and additional product content details TBD The Pb Free Green conversion plan has not been defined Pb Free RoHS TI s terms Lead Free or Pb Free mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances including the requirement that lead not exceed 0 196 by weight in homogeneous materials Where designed to be soldered at high temperatures TI Pb Free products are suitable for use in specified lead free processes Green RoHS amp no Sb Br TI defines Green to mean Pb Free RoHS compatible and free of Bromine Br and Antimony Sb based flame retardants Br or Sb do not exceed 0 196 by weight in homogeneous material 3 MSL Peak Temp The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications and peak solder temperature Important Information and Disclaimer The information provided on this page represents TI s knowledge and belief as of the date that it is provided TI bases its knowledge and belief on information provided by third parties and makes no representation or warranty as to the accuracy of such information Efforts are underway to better integrate information from third parties TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructi
12. e to the opposing output see below In this way it is impossible to turn on driver PUA and PDA at the same time It is also impossible for one of these drivers to turn on without the other driver having been off for at least two PWM oscillator clocks EDGE FINDER PULL UP FROM DECODER PULL DOWN Figure 1 Cross conduction prevention UC1625 UC2625 UC3625 TYPICAL CHARACTERISTICS 100kHz lt gt E Oo c ab c o o o p x LL 3 x 5 o 4 amp gt o a 6 a 2 o 0 01 Cosc uF 75 50 25 0 25 50 75 100 125 Temperature C Figure 2 Oscillator frequency vs Cosc and Hosc 100us Soft Start Current pA 15 75 50 25 0 25 50 75 100 125 Temperature C Figure 3 Tachometer on time vs Ry and Cr Figure 5 Soft start pull up current vs temperature TYPICAL CHARACTERISTICS cont
13. ecause the potentiometer position sets the aver age motor voltage This controls speed because UNITRODE CORPORATION 7 CONTINENTAL BLVD e MERRIMACK NH 03054 TEL 603 424 2410 FAX 603 424 3460 m UDG 99045 steady state motor speed is closely related to applied voltage Pin 20 Tach Out is connected to pin 7 SPEED IN through an RC filter preventing direction reversal while the motor is spinning quickly In two quadrant opera tion this reversal can cause kinetic energy from the mo tor to be forced into the power MOSFETs A diode in series with the low side MOSFETs facilitates PWM current control during braking by insuring that braking current will not flow backwards through low side MOSFETSs Dual current sense resistors give continu ous current sense whether braking or running in four quadrant operation an unnecessary luxury for two quadrant operation The 68kQ and 3nF tachometer components set maxi mum commutation time at 140us This permits smooth operation up to 35 000 RPM for four pole motors yet gives 140us of noise blanking after commutation K Texas PACKAGE OPTION ADDENDUM INSTRUMENTS www ti com 19 Jul 2005 PACKAGING INFORMATION Orderable Device Status Package Package Pins Package Eco Plan Lead Ball Finish MSL Peak Temp Type Drawing Qty 5962 9168901MXA OBSOLETE CDIP J 28 TBD Call TI Call TI UC1625J OBSOLETE CDIP J 28 TBD Call TI Call
14. ecoder logic translates the Hall signals and the Dir signal to the correct driver sig nals PUs and PDs To prevent output stage damage the signal on Dir is first loaded into a direction latch then shifted through a two bit register As long as Speed In is less than 250mV the direction latch is transparent When Speed In is higher than 250mV the direction latch inhibits all changes in direc tion Speed In can be connected to Tach Out through a filter so that the direction latch is only transparent when the motor is spinning slowly and has too little stored en ergy to damage power devices Additional circuitry detects when the input and output of the direction latch are different or when the input and output of the shift register are different and inhibits all output drives during that time This can be used to allow the motor to coast to a safe speed before reversing The shift register guarantees that direction can t be changed instantaneously The register is clocked by the PWM oscillator so the delay between direction changes is always going to be between one and two oscillator pe riods At 40kHz this corresponds to a delay of between 25us and 50us Regardless of output stage 25us dead time should be adequate to guarantee no overlap cross conduction Toggling DIR will cause an output pulse on Tach Out regardless of motor speed E A In E A In E A Out PWM In E A In and E A In are not internally committed to
15. ecommended values for Cy are 1nF to 100nF allowing times between 5us and 10ms Best ac curacy and stability are achieved with values in the cen ters of those ranges RC Brake also has another function If RC Brake pin is pulled below the brake threshold the IC will enter brake mode This mode consists of turning off all three high side devices enabling all three low side devices and disabling the tachometer The only things that in hibit low side device operation in braking are low supply exceeding peak current OV Coast com mand and the PWM comparator signal The last of these means that if current sense is implemented such that the signal in the current sense amplifier is propor tional to braking current the low side devices will brake the motor with current control See applications Sim pler current sense connections will result in uncontrolled braking and potential damage to the power devices RC Osc The UC3625 can regulate motor current using fixed frequency pulse width modulation PWM The RC Osc pin sets oscillator frequency by means of timing resistor Rosc from the RC Osc pin to Vref and capaci tor Cosc from RC Osc to Gnd Resistors 10kQ to 100kQ and capacitors 1nF to 100nF will work best but frequency should always be below 500kHz Oscillator frequency is approximately 2 Rosc Cosc Additional components can be added to this device to cause it to operate as a fixed off time PWM rather than a fixed frequency
16. ent Fig 11 shows a power NPN Darlington drive technique using a clamp to prevent deep saturation By limiting sat uration of the power device excessive base drive is mini mized and turn off time is kept fairly short Lack of base series resistance also adds to the speed of this ap proach APPLICATION INFORMATION cont UC3724N UC1625 UC2625 UC3625 VMOTOR kK lis Ke 1 2 15 TO MOTOR UDG 99047 Figure 12 Fast high side N channel driver with transformer isolation Fast High Side N Channel Driver with Transformer Isolation A small pulse transformer can provide excellent isolation between the UC3625 and a high voltage N Channel MOSFET while also coupling gate drive power In this circuit shown in Fig 12 a UC3724 is used as a trans former driver encoder that duty cycle modulates the transformer with a 150kHz pulse train The UC3725 recti fies this pulse train for gate drive power demodulates the signal and drives the gate with over 2 amp peak current Both the UC3724 and the UC3725 can operate up to 500kHz if the pulse transformer is selected appropriately To raise the operating frequency either lower the timing resistor of the UC3724 1kQ min lower the timing ca pacitor of the UC3724 500pF min or both If there is significant capacitance between transformer primary and secondary toge
17. eshold Over Operating Range 7 75 8 05 8 55 V Overvoltage Coast OV Coast Inhibit Threshold Over Operating Range 1 65 1 75 1 85 V OV Coast Restart Threshold 1 55 1 65 1 75 V OV Coast Hysteresis 0 05 0 10 0 15 V OV Coast Input Current 10 1 0 uA Logic Inputs H1 H2 H3 Low Threshold Over Operating Range 0 8 1 0 1 2 V H1 H2 H3 High Threshold Over Operating Range 1 6 1 9 2 0 V H1 H2 H3 Input Current Over Operating Range to OV 400 250 120 uA Quad Sel Dir Thresholds Over Operating Range 0 8 1 4 2 0 V Quad Sel Hysteresis 70 mV Dir Hysteresis 0 6 V Quad Sel Input Current 30 50 150 uA Dir Input Current 30 zi 30 uA PWM Amp Comparator E A In E A In Input Current To 2 5V 5 0 0 1 5 0 uA PWM In Input Current To 2 5V 0 3 30 uA Error Amp Input Offset OV VcoMMON MODE 3V 10 10 mV Error Amp Voltage Gain 70 90 dB UC1625 UC2625 UC3625 ELECTRICAL CHARACTERISTICS Unless otherwise stated these specifications apply for Ta 25 C Pwr Voc Voc 12V Rosc 20k to Vnge Cosc 2nF Rrach 33k Crach 10nF and all outputs unloaded TA Ty PARAMETER TEST CONDITIONS MIN TYP MAX UNITS PWM Amp Comparator cont E A Out Range 0 25 3 50 V Ssranr Pull up Current To OV 16 10 5 uA Ssranr Discharge Current To 2 5V 0 1 0 4 3 0 mA SSTART Resta
18. on Tach Out Any change in the H1 H2 or H3 inputs loads data from these inputs into the position sensor latches At the same time data is loaded a fixed width 5V pulse is triggered on Tach Out The average value of the volt age on Tach Out is directly proportional to speed so this output can be used as a true tachometer for speed feedback with an external filter or averaging circuit which usually consists of a resistor and capacitor Whenever Tach Out is high the position latches are in hibited such that during the noisiest part of the commu APPLICATION INFORMATION Cross Conduction Prevention The UC3625 inserts delays to prevent cross conduction due to overlapping drive signals However some thought must always be given to cross conduction in output stage design because no amount of dead time can prevent fast slewing signals from coupling drive to a power device through a parasitic capacitance The UC3625 contains input latches that serve as noise blanking filters These latches remain transparent through any phase of a motor rotation and latch immedi ately after an input transition is detected They remain latched for two cycles of the PWM oscillator At a PWM oscillator speed of 20kHz this corresponds to 50us to 100us of blank time which limits maximum rotational speed to 100kRPM for a motor with six transitions per ro tation or 50kKRPM for a motor with 12 transitions per rota tion This prevents noise generated in the
19. ons using Tl components To minimize the risks associated with customer products and applications customers should provide adequate design and operating safeguards TI does not warrant or represent that any license either express or implied is granted under any TI patent right copyright mask work right or other TI intellectual property right relating to any combination machine or process in which TI products or services are used Information published by TI regarding third party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof Use of such information may require a license from a third party under the patents or other intellectual property of the third party or a license from TI under the patents or other intellectual property of TI Reproduction of information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties conditions limitations and notices Reproduction of this information with alteration is an unfair and deceptive business practice TI is not responsible or liable for such altered documentation Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice TI is not respon
20. put Voltage Over Operating Range 4 7 5 0 5 8 V Load Regulation OmA to 20mA Load 40 5 mV Line Regulation 10V to 18V Vcc 10 1 10 mV Short Circuit Current Over Operating Range 50 100 150 mA UC1625 UC2625 UC3625 ELECTRICAL CHARACTERISTICS Unless otherwise stated these specifications apply for Ta 25 C Pwr Voc Vcc 12V Rosc 20k to Vngre Cosc 2nF Rrach 33k Crach 10nF and all outputs unloaded TA Ty PARAMETER TEST CONDITIONS MIN TYP MAX units Miscellaneous Output Turn On Delay 1 us Output Turn Off Delay 1 us BLOCK DIAGRAM Quad Sel RC Osc PWM CLOCK PWM In E A Out E A In E A In SSTART REFERENCE ISENSE ABS VALUE ISENSE1 ISENSE2 VCC OV Coast Dir Speed In DIRECTION LATCH PWM CLOCK E RC Brake DIR COAST CHOP H1 DECODER QUAD CROSS CONDUCTION PROTECTION LATCHES 5V PUA PUB PUC Pwr Vcc PDA Tach Out UDG 99044 PIN DESCRIPTIONS Dir Speed In The position d
21. r devices and 50V open collector outputs for high side power devices or level shifting circuitry The UC1625 is characterized for operation over the military tem perature range of 55 C to 125 C while the UC2625 is charac terized from 40 C to 105 C and the UC3625 is characterized from 0 C to 70 C NOTE ESD Protection to 2kV 5V TO HALL VMOTOR SENSORS 2N3906 IRF9350 3kQ TO OTHER CHANNELS UC3625 gt 8 gt Lp REQUIRED TO OTHER FOR BRAKE CHANNELS ADET 3 gt REVERSE 1029 IRF532 n 68kQ REQUIRED Rr FOR HALL e AVERAGE SENSORS CURRENT SLUS353A NOVEMBER 1999 4 SENSING 0 02Q UDG 99045 UC1625 UC2625 UC3625 ABSOLUTE MAXIMUM RATINGS CONNECTION DIAGRAM Vcc Supply Voltage 0002s 20V Pwr Voc Supply Voltage Gs hy ih ceri ytd ta ie wane er Ajo eas ey esse Eus 20V DIL 28 TOP VIEW PMII 5 ae ennt eene tater dae E ganas 0 3 to 6V J N PACKAGE E A IN EIAINC eene 0 3 to 12V or ISENSE1 ISENSE2 lt oo eoe eee 1 3 to 6V bas OV Coast Dir Speed In SSTART Quad Sel 0 3 to 8V E A COR eae dat AT A2 AG 5b oe oth pale deck REY RR 0 3 to 12V RIEA Out PU Ou
22. rt Threshold 0 1 0 2 0 3 V Current Amp Gain IsgNsE1 3V IsENSE2 5V to 7V 1 75 1 95 2 15 VN Level Shift IsENsE1 3V ISENSE2 3V 2 4 2 5 2 65 V Peak Current Threshold IseNsE1 OV Force ISENSE2 0 14 0 20 0 26 V Over Current Threshold IsENsE1 OV Force ISENSE2 0 26 0 30 0 36 V ISENSE1 ISENSE2 Input Current To OV 850 320 0 uA IsENsE1 ISENSE2 Offset Current To OV 9 42 uA Range Isense1 IsENSE2 1 2 V Tachometer Brake Tach Out High Level Over Operating Range 10k to 2 5V 4 7 5 5 8 V Tach Out Low Level Over Operating Range 10k to 2 5V 0 2 V On Time 170 220 280 us On Time Change With Temp Over Operating Range 0 1 RC Brake Input Current To OV 4 0 1 9 mA Threshold to Brake RC Brake Over Operating Range 0 8 1 0 1 2 V Brake Hysteresis RC Brake 0 09 V Speed In Threshold Over Operating Range 220 257 290 mV Speed In Input Current 30 5 30 uA Low Side Drivers Voh 1mA Down From Vcc Over Operating Range 1 60 2 1 V Voh 50mA Down From Vcc Over Operating Range 1 75 2 2 V Vol 1mA Over Operating Range 0 05 0 4 V Vol 50mA Over Operating Range 0 36 0 8 V Rise Fall Time 10 to 90 Slew Time into 1nF 50 ns High Side Drivers Vol 1mA Over Operating Range 0 1 0 4 V Vol 50mA Over Operating Range 1 0 1 8 V Leakage Current Output Voltage 50V 25 uA Fall Time 10 to 90 Slew Time 50mA Load 50 ns Oscillator Frequency 40 50 60 kHz Frequency Over Operating Range 35 65 kHz Reference Output Voltage 4 9 5 0 5 1 V Out
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24. te modified Gray code with only one output changing at a time but rise and fall times must be shorter than 20us for correct tachometer operation Motors with 60 electrical degree position sensor coding can be used if one or two of the position sensor signals is inverted IsENSE1 ISENSE2 Isense The current sense amplifier has a fixed gain of approximately two It also has a built in level shift of approximately 2 5V The signal ap pearing on Isense is Isense 2 5V 2 ABS Isense1 sense2 IsENsE1 and IsensEe are interchangeable and can be used as differential inputs The differential signal applied can be as high as 0 5V before saturation If spikes are expected on Isense1 or ISENSE2 they are best filtered by a capacitor from Isense to ground Fil tering this way allows fast signal inversions to be cor rectly processed by the absolute value circuit The peak current comparator allows the PWM to enter a cur rent limit mode with current in the windings never ex ceeding approximately 0 2V Rsense The over current comparator provides a fail safe shutdown in the unlikely case of current exceeding 0 3V Rsense Then soft start is commanded and all outputs are turned off until the high current condition is removed It is often essential to use some filter driving Isense1 and IsENSE2 to reject ex treme spikes and to control slew rate Reasonable start ing values for filter components might be 250 series resistors and a 5n
25. the PD outputs When connecting PD outputs directly to the bases of power Darlingtons the PWR Vcc pin can be current limited with a resistor Darlington outputs can also be Baker Clamped with diodes from collectors back to PWR Vcc See Applications Quad Sel The IC can chop power devices in either of two modes referred to as two quadrant Quad Sel low and four quadrant Quad Sel high When two quadrant chopping the pull down power devices are chopped by the output of the PWM latch while the pull up drivers remain on The load will chop into one commutation diode and except for back EMF will ex hibit slow discharge current and faster charge current Two quadrant chopping can be more efficient than four quadrant When four quadrant chopping all power drivers are chopped by the PWM latch causing the load current to flow into two diodes during chopping This mode exhibits better control of load current when current is low and is preferred in servo systems for equal control over accel eration and deceleration The Quad Sel input has no ef fect on operation during braking RC Brake Each time the Tach Out pulses the capaci tor tied to RC Brake discharges from approximately 3 33V down to 1 67V through a resistor The tachometer pulse width is approximately T 0 67 Ry Cr where RT and Cy are a resistor and capacitor from RC Brake to UC1625 UC2625 UC3625 ground Recommended values for Rr are 10kQ to 500kQ and r
26. ther with very high output slew rate then it may be necessary to add clamp diodes from the transformer primary to 12V and ground Gen eral purpose small signal switching diodes such as 1N4148 are normally adequate The UC3725 also has provisions for MOSFET current limiting Consult the UC3725 data sheet for more infor mation on implementing this Computational Truth Table This table shows the outputs of the gate drive and open collector outputs for given hall input codes and direction signals Numbers at the top of the columns are pin numbers These ICs operate with position sensor encoding that has either one or two signals high at a time never all low or all high This coding is sometimes referred to as 120 Coding because the coding is the same as coding with position sensors spaced 120 magnetic degrees about the rotor In response to these position sense signals only one low side driver will turn on go high and one high side driver will turn on pull low at any time Table I Computational truth table INPUTS OUTPUTS H2 A Co r m Io r rirrriririr irirri ZEE EESGE a se IE S GEIES IE Lr r rir jr er ae er ce ee ee Cry ee eo ye rjr cs ew E E AE mi l SE a SE SE 2E 3L EE sE BS Se EE E E A a a E EA AE E APPLICATION INFORMATION cont 5V TO HALL SENSORS
27. tput Voltage rretan ieri ro wre omiri rea 0 3 to 50V 26lPWM In PU Output Current 0 200 mA continuous brinesdec PD Output Current 200 mA continuous Lr E A Output Current lllllssess esses 10 mA A SSENSE Isense Output Current nnana nananana 10 mA 23 OV Coast Tach Out Output Current 0 ee ee 10 mA lazQuad Sel Vner Output Current 50 mA continuous lxiriG Braka Operating Temperature Range UC1625 55 C to 125 C Operating Temperature Range UC2625 40 C to 105 C Tach Out Operating Temperature Range UC3625 0 C to 70 C Note 1 Currents are positive into and negative out of the spec ified terminal Note 2 Consult Unitrode Integrated Circuits databook for infor mation regarding thermal specifications and limitations of packages Note 3 This pinout applies to the SOIC DW PLCC Q and LCC L packages ie pin 22 has the same function on all packages ELECTRICAL CHARACTERISTICS Unless otherwise stated these specifications apply for Ta 25 C Pwr Voc Voc 12V Rosc 20k to Vnge Cosc 2nF RrAcu 33k Crach 10nF and all outputs unloaded TA Ty PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Overall Supply current Over Operating Range 14 5 30 0 mA Voc Turn On Threshold Over Operating Range 8 65 8 95 9 45 V Voc Turn Off Thr
28. ve testing or chemical analysis on incoming materials and chemicals TI and TI suppliers consider certain information to be proprietary and thus CAS numbers and other limited information may not be available for release In no event shall TI s liability arising out of such information exceed the total purchase price of the TI part s at issue in this document sold by TI to Customer on an annual basis Addendum Page 1 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries Tl reserve the right to make corrections modifications enhancements improvements and other changes to its products and services at any time and to discontinue any product or service without notice Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete All products are sold subject to Tl s terms and conditions of sale supplied at the time of order acknowledgment TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with Tl s standard warranty Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty Except where mandated by government requirements testing of all parameters of each product is not necessarily performed TI assumes no liability for applications assistance or customer product design Customers are responsible for their products and applicati
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UNITRODE UC1625/UC2625/UC3625 handbook