U209B

Features • • • • • • • • • Internal Frequency-to-voltage Converter Externally Controlled Integrated Amplifier Automatic Soft Start with Minimized “Dead Time” Voltage and Current Synchronization Retriggering Triggering Pulse Typically 155 mA Internal Supply-voltage Monitoring Temperature-compensated Reference Source Current Requirement ≤ 3 mA 1. Description The integrated circuit U209B is designed as a phase-control circuit in bipolar technology with an internal frequency-to-voltage converter. The device includes an internal open-loop amplifier, which means it can be used for motor speed control with tacho feedback. The U209B is a 14-pin shrink version of the U211B with reduced features. Using the U209B, the designer is able to realize sophisticated as well as economic motor control systems. Figure 1-1. Block Diagram 14(16) Voltage/Current detector 1(1) Automatic retriggering Output pulse 4(4) Phase Control IC for Tacho Applications U209B 5(5) Control amplifier 6(6) Phase control unit 9(9) ϕ = f (V11) Supply voltage limitation Reference voltage Voltage monitoring 3(3) -VS 2(2) GND 10(10) + 13(15) Soft start -VS 11(11) Pin numbers in brackets refer to SO16 Package 12(12) Frequencyto-voltage converter U209B 7(7) 8(8) 4765C–INDCO–02/07 Figure 1-2. 2 D1 18 k Ω 2W R1 M R4 470 k W 1 Voltage/Current detector Automatic retriggering Output pulse 220 Ω 5 6 + Reference voltage Voltage monitoring Supply voltage limitation 2 Control amplifier 3 C2 -V S GND 13 C1 C 10 22 µ F 25 V 2.2 µF 16 V N 3.3 nF R 2 680 k Ω 4 R13 VM = 230 V ~ L 14 U209B Block Diagram with Typical Circuitry for Speed Regulation R3 220 k Ω R9 47 k Ω R12 100 k Ω Set speed voltage R 10 56 k Ω R 11 100 k Ω C9 10 2.2 µF/16 V 9 Phase control unit ϕ = f (V 11) Soft start -V s 11 R8 2 MΩ R7 22 k Ω C8 220 nF C3 2.2 µF 16 V 12 8 Frequencyto-voltage converter U209B 7 220 nF C5 1 nF 1 kΩ Speed sensor R5 C4 Actual speed voltage C7 2.2 µF 16 V C6 4765C–INDCO–02/07 100 nF R6 68 k Ω U209B 2. Pin Configuration Figure 2-1. Pinning DIP14 Isync GND -VS Output VRP CP F/V 1 2 3 4 5 6 7 14 13 12 11 10 9 8 Vsync VRef Csoft CTR/OPO OP+ OPCRV Table 2-1. Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Pin Description Symbol Isync GND -VS Output VRP CP F/V CRV OPOP+ CTR/OPO Csoft VRef Vsync Function Current synchronization Ground Supply voltage Trigger pulse output Ramp current adjust Ramp voltage Frequency-to-voltage converter Charge pump OP inverting input OP non-inverting input Control input/OP output Soft start Reference voltage Voltage synchronization 3 4765C–INDCO–02/07 Figure 2-2. Pinning SO16 Isync GND -VS Output VRP CP F/V CRV 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 Vsync VRef NC NC Csoft CTR/OPO OP+ OP- Table 2-2. Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Pin Description Symbol Isync GND -VS Output VRP CP F/V CRV OPOP+ CTR/OPO Csoft NC NC VRef Vsync Function Current synchronization Ground Supply voltage Trigger pulse output Ramp current adjust Ramp voltage Frequency-to-voltage converter Charge pump OP inverting input OP non-inverting input Control input/OP output Soft start Not connected Not connected Reference voltage Voltage synchronization 4 U209B 4765C–INDCO–02/07 U209B 3. Description 3.1 Mains Supply The U209B is equipped with voltage limiting and can therefore be supplied directly from the mains. The supply voltage between pin 2 (+ pol/⊥) and pin 3 builds up across D1 and R1, and is smoothed by C1. The value of the series resistance can be approximated using: VM – VS R 1 = -------------------2 IS Further information regarding the design of the mains supply can be found in the section “Design Calculations for Mains Supply” on page 9. The reference voltage source on pin 13 of typically -8.9 V is derived from the supply voltage and represents the reference level of the control unit. Operation using an externally stabilized DC voltage is not recommended. If the supply cannot be taken directly from the mains because the power dissipation in R1 would be too large, the circuit as shown in Figure 3-1 should be used. Figure 3-1. Supply Voltage for High Current Requirements ~ U209B 24 V~ 1 2 3 4 5 R1 C1 3.2 Phase Control The function of the phase control is largely identical to that of the well known integrated circuit U2008B. The phase angle of the trigger pulse is derived by comparing the ramp voltage (which is mains synchronized by the voltage detector) with the set value on the control input pin 4. The slope of the ramp is determined by C2 and its charging current. The charging current can be varied using R2 on pin 5. The maximum phase angle αmax can also be adjusted by using R2. When the potential on pin 6 reaches the nominal value predetermined at pin 11, a trigger pulse is generated whose width tp is determined by the value of C2 (the value of C2 and hence the pulse width can be evaluated by assuming 8 µs/nF). The current sensor on pin 1 ensures that, for operation with inductive loads, no pulse is generated in a new half cycle as long as a current from the previous half cycle is still flowing in the opposite direction to the supply voltage at that instant. This makes sure that “gaps” in the load current are prevented. The control signal on pin 11 can be in the range 0 V to -7 V (reference point pin 2). If V11 = -7 V, the phase angle is at maximum = αmax, i.e., the current flow angle is at minimum. The minimum phase angle αmin is when V11 = Vpin 2. 5 4765C–INDCO–02/07 3.3 Voltage Monitoring As the voltage is built up, uncontrolled output pulses are avoided by internal voltage surveillance. At the same time, all latches in the circuit (phase control, soft start) are reset and the soft-start capacitor is short-circuited. Used with a switching hysteresis of 300 mV, this system guarantees defined start-up behavior each time the supply voltage is switched on or after short interruptions of the mains supply. 3.4 Soft Start As soon as the supply voltage builds up (t1), the integrated soft start is initiated. Figure 3-2 shows the behavior of the voltage across the soft-start capacitor, which is identical with the voltage on the phase control input on pin 11. This behavior guarantees a gentle start-up for the motor and automatically ensures the optimum run-up time. C3 is first charged up to the starting voltage Vo with typically 30 µA current (t2). By reducing the charging current to approximately 4 µA, the slope of the charging function is also substantially reduced, so that the rotational speed of the motor only slowly increases. The charging current then increases as the voltage across C3 increases giving a progressively rising charging function which accelerates the motor with increasing rotational speed. The charging function determines the acceleration up to the set-point. The charging current can have a maximum value of 50 mA. Figure 3-2. Soft Start VC3 V12 V0 t1 t2 t tot t1 t2 t1 + t2 t3 ttot t3 t = build-up of supply voltage = charging of C3 to starting voltage = dead time = run-up time = total start-up time to required speed 6 U209B 4765C–INDCO–02/07 U209B 3.5 Frequency-to-voltage Converter The internal frequency-to-voltage converter (f/V converter) generates a DC signal on pin 9 which is proportional to the rotational speed, using an AC signal from a tacho generator or a light beam whose frequency is in turn dependent on the rotational speed. The high impedance input with a switch-on threshold of typically -100 mV gives very reliable operation even when relatively simple tacho generators are employed. The tacho frequency is given by: n f = ----- p(Hz) 60 n = revolution per minute p = number of pulses per revolution The converter is based on the charge pumping principle. With each negative half wave of the input signal, a quantity of charge determined by C5 is internally amplified and then integrated by C6 at the converter output on pin 9. The conversion constant is determined by C5, its charging voltage of Vch, R6 (pin 9) and the internally adjusted charge amplification Gi. k = Gi × C5 × R6 × Vch The analog output voltage is given by where: Vo Vch Gi =k× f = 6.7 V = 8.3 The values of C5 and C6 must be such that for the highest possible input frequency, the maximum output voltage V0 does not exceed 6 V. The Ri on pin 8 is approximately 6 kΩ while C5 is charging up. To obtain good linearity of the f/V converter the time constant resulting from Ri and C5 should be considerably less (1/5) than the time span of the negative half cycle for the highest possible input frequency. The amount of remaining ripple on the output voltage on pin 9 is dependent on C5, C6 and the internal charge amplification. G i × V ch × C 5 ∆ V O = -----------------------------------C6 The ripple ∆Vo can be reduced by using larger values of C6, however, the maximum conversion speed will then also be reduced. The value of this capacitor should be chosen to fit the particular control loop where it is going to be used. 7 4765C–INDCO–02/07 3.6 Control Amplifier The integrated control amplifier with differential input compares the set value (pin 10) with the instantaneous value on pin 9, and generates a regulating voltage on the output pin 11 (together with external circuitry on pin 12). This pin always tries to keep the real voltage at the value of the set voltages. The amplifier has a transmittance of typically 110 µA/V and a bipolar current source output on pin 11 which operates with typically ±100 µA. The amplification and frequency response are determined by R7, C7, C8 and R8 (can be left out). For operation as a power divider, C4, C5, R6, C6, R7, C7, C8 and R8 can be left out. Pin 9 should be connected with pin 11 and pin 7 with pin 2. The phase angle of the triggering pulse can be adjusted using the voltage on pin 10. An internal limiting circuit prevents the voltage on pin 11 from becoming more negative than V13 + 1 V. 3.7 Pulse-output Stage The pulse-output stage is short-circuit protected and can typically deliver currents of 125 mA. For the design of smaller triggering currents, the function IGT = f (RGT) can be taken from Figure 6-8 on page 15. 3.8 Automatic Retriggering The automatic retriggering prevents half cycles without current flow, even if the triacs have been turned off earlier, e.g., due to not exactly centered collector (brush lifter) or in the event of unsuccessful triggering. If necessary, another triggering pulse is generated after a time lapse of tPP = 4.5 tP and this is repeated until either the triac fires or the half cycle finishes. 3.9 General Hints and Explanation of Terms To ensure safe and trouble-free operation, the following points should be taken into consideration when circuits are being constructed or in the design of printed circuit boards. The connecting lines from C2 to pin 6 and pin 2 should be as short as possible, and the connection to pin 2 should not carry any additional high current such as the load current. When selecting C2, a low temperature coefficient is desirable. The common (earth) connections of the set-point generator, the tacho generator and the final interference suppression capacitor C4 of the f/V converter should not carry load current. The tacho generator should be mounted without influence by strong stray fields from the motor. 8 U209B 4765C–INDCO–02/07 U209B Figure 3-3. Explanation of Terms in Phase Relationship V Mains Supply π/2 VGT Trigger Pulse VL Load Voltage tp π 3/2π 2π tpp = 4.5 tp IL Load Current Φ ϕ 3.10 Design Calculations for Mains Supply The following equations can be used for the evaluation of the series resistor R1 for worst case conditions: V Mmin – V Smax R 1max = 0.85 ------------------------------------2 I tot V M – V Smin R 1min = ---------------------------2 I Smax ( V Mmax – V Smin ) P ( R1max ) = --------------------------------------------2 R1 where: VM VS Itot ISmax Ip Ix 2 = Mains voltage 230 V = Supply voltage on pin 3 = Total DC current requirement of the circuit = IS + Ip + Ix = Current requirement of the IC in mA = Average current requirement of the triggering pulse = Current requirement of other peripheral components R1 can be easily evaluated from Figure 6-10 on page 15 to Figure 6-12 on page 16. 9 4765C–INDCO–02/07 4. Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Reference point pin 2, unless otherwise specified Parameters Current requirement t ≤10 µs Synchronization current t < 10 µs t < 10 µs f/V Converter Input current t