AN8031 PANASONIC | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 21
Technical content
In supplying electric power from commercial power supply to various electrical equipment, there is a possi- bility that the harmonic distortion generated in the power line may give obstruction to the power facilities or other electrical equipment. The use of active filter is one of the methods to solve the harmonic distortion problems. The AN8031 is a monolithic IC which incorporates the control and protection functions into one package so that the active filter can be constructed easily. It is most suitable for the measures against the harmonic distortion problems such as lighting equipment. n Features
- Self-excited peak current mode is adapted.
- Built-in protection circuit for preventing the overvolt- age generated under a small load
- Easy constant setting with enlarged dynamic range of multiplier and error amplifier.
- Using totem pole output circuit which allows the power MOSFET to be directly driven.
- Built-in low voltage protection circuit which ensures the on-resistance during the power MOSFET operation.
- Timer circuit is built in for realizing automatic start. n Applications
- Lighting equipment and switching power supply equipment n Block Diagram SIP009-P-0000C 0.3+0.1 –0.05 23.3±0.3 6.0±0.3 2.4±0.25 3.3±0.25 1.5±0.25 0.5±0.1 2.541.5±0.25 1.4±0.3 3.0±0.3 30° Unit: mm SV CC Under voltage clamper 1 V B V REF 10 V/8 V 2.5 V 2.5 V
2.6 VCurrent
comp. Error amp. OVP comp. CS2 EI5 MPI 3 EO 4 GND 7 Over voltage clamper One shot Timer Drive Multiplier 2.5 V PV CC V OUT
Parameter Symbol Range Unit Supply voltage V CC 0 to 34 V n Absolute Maximum Ratings Parameter Symbol Rating Unit Supply voltage V CC 35 V CS allowable application voltage V CS - 0.5 to +7V MPI allowable application voltage VMPI - 0.5 to +7V EI allowable application voltage V EI - 0.5 to +7V Output allowable current I O –150 mA Peak output current I OP –1A V B allowable flow-in current I BI +5m A V B allowable flow-out current I BO -5m A Power dissipation P D 874 mW Operating ambient temperature * Topr -30 to +85 °C Storage temperature * Tstg -55 to +150 °C n Recommended Operating Range n Electrical Characteristics at Ta = 25°C Parameter Symbol Conditions Min Typ Max Unit Error detection feedback threshold VEITH1 2.35 2.50 2.65 V voltage 1 Error detection low-level output voltageV EOL IEO = 0 mA, VEI = 5 V ¾ 1.0 1.6 V Error detection high-level output voltageV EOH IEI = 0 mA, VEI = 0 V 5.0 5.7 ¾ V Error detection input bias current IEI V EI = 0 V ¾- 0.3 -1.0 mA Error detection output supply current IEO V EI = 0 V, VEO = 1 V 0.25 0.50 0.75 mA n Pin Descriptions Pin No. Symbol Description 1S V CC Control system supply-voltage pin
2 CS Comparator input pin
3 MPI Multiplier input pin
4 EO Error amplifier output pin / multiplier input pin
5 EI Error amplifier inverting input pin / overvoltage protection input pin
6V B Transformer-reset detection pin
7 GND Grounding pin
9P V CC Power system supply-voltage pin Note) *: Expect for the operating ambient temperature and storage temperature, all ratings are for Ta = 25°C.
n Electrical Characteristics (continued) at Ta = 25°C Parameter Symbol Conditions Min Typ Max Unit Multiplier input D-range (upper limit) VMPIH V EO = 5 V 4.0 4.5 ¾ V Multiplier output D-range (upper limit)V MPOH V EO = 5 V 4.8 5.4 ¾ V Multiplier gain G MP 1.0 1.2 1.4 1/V Multiplier input bias current I MPI V MPI = 0 V ¾- 1.5 -3.0 mA Coil detection input threshold voltage VBTH 1.2 1.5 1.8 V Coil detection hysteresis width dV B 50 100 200 mV Coil detection high-level clamp voltageV BH IB = 5 mA 7.0 7.5 8.0 V Coil detection low-level clamp voltageV BL IB = -5 mA - 0.3 - 0.2 0 V Current detection input offset voltage VCSOFF ¾ 3.5 15 mV Current detection input bias current ICS V CS = 0 V ¾- 0.5 -2.0 mA Overvoltage detection input V OVP 2.45 2.60 2.75 V threshold voltage V OVP - VEITH1 ¾ 70 100 130 mV Low-level output voltage V OUTL IOUT = 100 mA ¾ 0.9 1.5 V High-level output voltage V OUTH IOUT = -100 mA 9.2 10.2 ¾ V Standby output voltage V OUTSTB IOUT = 10 mA ¾ 0.8 1.5 V Standby current I CCSTB V CC = 7 V 40 80 120 mA Operation current without load I CC V CC = 12 V ¾ 6.0 10.0 mA
- Design reference data Note) The characteristics listed below are reference values based on the IC design and are not guaranteed. Parameter Symbol Conditions Min Typ Max Unit Error detection feedback V EITH2 Ta = -25°C to +85°C 2.3 2.7 V threshold voltage 2 Error detection open-loop gain G AV 85 dB Error detection gain band width f BW 1.0 MHz Multiplier input D-range (lower limit) VMPIL V EO = 5 V 0 V Multiplier output D-range (lower limit)V MPOL V EO = 5 V 0 V Current detection - output delay td CS 200 ns Overvoltage detection - output delay tdOVP 500 ns Output rise time t r V CC = 12 V, VOUT = 10% fi 90% 50 ns Output fall time t f V CC = 12 V, VOUT = 90% fi 10% 50 ns Timer delay time td TIM 400 ms
n Terminal Equivalent Circuits Pin No. Equivalent circuit Description I/O 1S V CC :I The supply voltage terminal for control system. It monitors the supply voltage and has operating threshold value for start/stop.
2 CS: I
The input terminal of comparator which detects the current value flowing in power MOSFET. The output level of multiplier and the current value of power MOSFET input from the CS terminal are compared. If the later becomes larger than the former, the V OUT is set to low level and the power MOSFET output is cut.
3 MPI: I
The input terminal of multiplier The voltage after a full-wave rectified AC input voltage are monitored.
4 EO: O
The output terminal of error amplifier / the input terminal of multiplier. The error amplifier monitors the output voltage of active filter and amplifies its error portion and outputs to the multiplier. Therefore, this terminal serves as another input terminal of the multiplier.
5 EI: I
The inverted input terminal of error amplifier / the overvoltage protection input terminal. To the noninverted input terminal, the internal reference voltage of IC (2.5 V typ.) is input. Since this terminal monitors the output voltage of the active filter, it also functions as the input ter- minal for the overvoltage protector which detects the overvoltage of output voltage and cuts off the power MOSFET. Internal bias (Approx. 7.1 V) U.V .L.O. Approx. 7.1 V To high-speed converter Approx. 7.1 V Approx. 7.1 VApprox. 7.1 V Error amplifier output Multiplier input Approx. 7.1 V Approx. 7.1 V Approx. 7.1 V Approx. 7.1 V Error amplifier output Overvoltage protection input
n Terminal Equivalent Circuits (continued) Pin No. Equivalent circuit Description I/O 6V B :I The terminal is connected via the transformer's sub-coil and resistor. The reset of transformer is detected and the trigger signal to turn on the power MOSFET is sent. Since the coil signal of transformer is input as current, the IC incorporates the circuit which clamps the upper/lower limit voltage to prevent malfunction.
7 GND: ¾
This terminal is used in common for grounding the control system and the power system. 8V OUT :O The output terminal. It is capable of driving the gate of power MOSFET directly.
9 P V CC : ¾
The supply voltage terminal for power. It determines the upper limit of output drive volt- age. Normally, it is used at the same potential of SV CC . Approx. 7.1 V Lower limit voltage clamp Upper limit voltage clamp V B Comparator input Approx. 7.1 VPV CC V B upper limit voltage clamp Power MOSFET drive block
It controls so that the input current proportional to the input voltage (C, D in figure 1) could be flown. voltage are taken into consideration. Figure 1. Application outline description
400 VDC
- Normal control (continued)
resistor is input to the multiplier input terminal of the AN8031 (MPI terminal). and input to another multiplier input (EO terminal, which also functions as output for error amplifier). signal which monitors both the input voltage and output voltage of the chopper circuit. Figure 2. Explanation of normal control operation
- Normal control (continued)
considering the power dissipation). sends the reset signal to the RS latch circuit to turn off the switching device. Figure 3. Explanation of block diagram and normal operation
- Normal control (continued)
- When the excitation energy of inductor is lost and the free resonance is started, the switching device turns on.
- The switching device will turn off when the following two elements cross each other: The product of the input voltage (EIN) and output one (EOUT ) of the chopper circuit, and the switching device current.
- The fluctuation of input voltage and load current is controlled by changing the peak value height of switching device current.
- The purposes of mixing two signals by using the multiplier are: ¾ to stabilize the control system ¾ to reduce the number of components required 3) Description of each function (1) VB
- Function It detects the discharge of the excitation energy of the inductor (reset operation) and turns on the power MOSFET at the next cycle.
- Method When the inductor is reset, the sub-coil provided on the inductor (bias winding) starts free resonance. It is difficult from the view point of withstanding voltage to input this voltage directly to the IC. For this reason, it is input to the V B terminal through resistor.
- Function of upper limit voltage clamper It prevents the damage when the VB terminal voltage exceeds the withstanding voltage.
- Function of lower limit voltage clamper It prevents the malfunction when the VB terminal voltage swings to negative voltage: generally, in the case of monolithic IC, malfunction (such as latch-up) occurs when the terminal voltage decreases to a value below -V BE and the parasitic device is activated.
- IC inside The VB terminal voltage is input to the comparator with hysteresis inside the IC. For this reason, if the V B terminal voltage is under the threshold value, the power MOSFET is turned on. However, if the off signal has been given to the power MOSFET by the overvoltage protection func- tion, this function precedes the former.
Figure 4. VB terminal description
- Normal control (continued)
- Regulation by clamper in/out-current value The allowable output current of the upper limit voltage clamper is -5 mA and the allow- able input current of the lower limit voltage clamper is +5 mA. Either one of these allowable values is ex- ceeded, the voltage clamp operation of the V B terminal is not guaranteed. Therefore, RB should be set so that these values are not exceeded.
- Consumption current and delay When the R B value is too large, the VB threshold could be exceeded. When the RB value is too small, the consumption current becomes too large. In order to determine the R B value prop- erly, the input voltage range and the dispersion of components should be taken into consider- ation and it should be confirmed that a stable operation can be ensured under start/overload conditions or under a small load condition. ID SDB V B lower limit voltage clamp current V B upper limit voltage clamp current Clamp upper limit voltage Time Time Lower limit voltage clamp Upper limit voltage clamp V B V B threshold value V BV CC AN8031 GND
Figure 5. Explanation of VB operation TOFF is extended by the delay amount because of low speed. is small and undershoot tends to be generated easily.
- Normal control (continued)
- Zero-cross switching Zero-cross switching can be realized by using the local resonance when turning off the power MOSFET in order to suppress the loss. By connecting the resonance capacitor C P be- tween the drain and source of the power MOSFET, and using the inductance of the transformer's pri- mary side L P, the resonance is produced after dis- charging the accumulated energy of the transformer. The capacitor for delay should be connected to the V B terminal so that the next turn-on could occur at the time when the resonance occurred and the drain voltage of the power MOSFET has reached around 0 V. However, it is necessary to take care that the zero-cross conditions could deviate since the delay amount varies depending on the conditions such as the input voltage. (2) CS The terminal for detecting the current when the power MOSFET is turned on. The current flow when the power MOSFET is turned on is equivalent to the current flow in the inductor. Therefore, the necessary power value can be controlled by controlling the peak value of the above current. The input D-range of this terminal is from 0 V to 5 V. However, since dissipation becomes larger if the power MOSFET current detecting resistance is set at larger value. A value from 0.22 W to 0.47 W is the standard considering the relationship with the S/N. The charge and discharge current to and from the parasitic capacitance of the power MOSFET, transformer or printed circuit wiring flow in the power MOSFET detection resistor at turning-on and off. Since such current generates noise and causes malfunction, it is necessary to incorporate a filter to re- move such irregular element. AN8031 Resonance capacitor Delay capacitor LP R B A B V OUT V B C B C P Delay Power MOSFET Power MOSFET On Off Resonance by LP - CP Zero-cross switching V BTH 0 V B-point voltage 0 V A-point voltage
Figure 6. CS terminal explanation
0 A Spike
V typical and output D-range is from 0 V to 5.4 V typical.
n Application Notes (continued) [2] Operation descriptions (continued) 1. Normal control (continued) 3) Description of each function (continued) (6) VCC The supply voltage terminal other than the (The characteristics of U.V.L.O. are shown in the right figure.) <Note on the methods of providing V CC >
- The method to give bias from sub-coil There is only 2 V typical difference between the start voltage 10 V typical and the stop voltage 8 V typical. Be careful that the value for C1 shown in the right figure must be set at a large value, otherwise, the IC does not easily start.
- Giving bias from power supply In the case such as of fluorescent lamp inverter circuit, separate power supply is provided so as to give the bias from the separate power supply. (7) PV CC Drive current supply terminal of output block The high voltage of the power MOSFET gate drive pulse is determined by this terminal voltage. In the case of limiting the power MOSFET drive current, if the R1 is connected to the PVCC terminal and the R2 is connected to the VOUT ter- minal as shown in the right figure, the R1 + R2 limits the drive current when the power MOSFET is turned on and the R2 limits the drive current when it is turned off. In that way, the speed of turn- on and turn-off can be changed. (Stop voltage) (Start voltage) ICC V CC V 08 1 0 IC operationU.V.L.O. characteristics To fluorescent lamp inverter circuit block V CC GND AN8031 V OUT Start resistance V CC GND C1AN8031 PV CC V OUT GND Totem pole type output circuit Drive current at turning on Drive current at turning off
timer circuit does not operate as long as the overvoltage protector is operating. Figure 9. Explanation of timer operation
- Protection circuit (continued)
load current reaches zero. However, in the actual condition, the input power can not be decreased to zero. The output voltage is brought to out of control state, so that it rises. of the switching device, so that the control to stop the operation of switching device becomes impossible. tion circuit, so that the number of component to be added to the external part is drastically reduced. Figure 10. Explanation of operation Under no load condition, this voltage decreases to around 0 V. however, there is circuit delay, so that the current does not reach 0 A.
- Protection circuit (continued)
- Control reference voltage of the error amplifier: 2.50 V typical
- Detection voltage of the overvoltage comparator: 2.63 V typical [Without hysteresis] (Voltage of 5% higher than the control reference voltage of the error amplifier) If the output voltage becomes more than 5% higher than the normal control voltage at the time of start up or abnormality occurrence, the overvoltage comparator operates to cut off the switching device. The timer circuit is cut off when overvoltage is detected. This prevents the output voltage to increase further. Otherwise, the timer circuit will re-start the power MOSFET, and actuate it to increase the output voltage further at the time of the overvoltage detection. Therefore, under no load condition, the output voltage of the chopper circuit is stabilized at the value which is 5% higher than the normal control voltage and does not exceed that value. (Refer to figure 11.) The increase/decrease of the output voltage is created by the offset amount of the overvoltage com- parator.
Figure 11. Protection of overvoltage protection operation
- Protection circuit (continued)
connected to the output is charged. Under this condition the chopper circuit operates with full power. the proper output voltage is obtained, causing the overshoot of output voltage. Figure 12. Output voltage overshoot when operation starts
n Application Notes (continued) [3] Difference between the AN8031 and the AN 8032 AN8031 fi EI terminal is used in common for both the output voltage monitor function and the overvoltage detection function. AN8032 fi Exclusive-use terminal for each function (VCC terminal is used in common for both PVCC and VCC ). EI terminal : Exclusively used for the output voltage monitor function. OVP terminal: Exclusively used for the overvoltage detection function. 1) Reasons for change The excessively large overvoltage, generated when the short-circuit test between the pins of the active filter output voltage monitoring resistor, can not be suppressed. CS EO EI V OUT PV CC V CC V B MPI COM AN8031 EIN(+) EIN(-) EO(-) Output voltage monitor Overvoltage detection Excessively large overvoltage, generated when the short circuit testing, can not be suppressed. Separately require 5 to 10 external components SBD EO(+) Output voltage monitor Overvoltage detection CS EO OVP EI V OUT V CC V B MPI COM AN8032 EIN(+) EIN(-) EO(-) The control operation is stopped by the separately provided circuit for overvoltage system even if excessively large overvoltage is generated. SBD EO(+) Increase of 2 more external components 2) Countermeasures The output voltage system and the overvoltage detection system are separated from each other. Note) The OVP terminal is arranged beside the EI terminal after taking the board pattern design into consideration.
n Application Circuit Example
- Application circuit EI COM 1 mF R2 13 kW
1 M W
0.33 W 1 W 330 W 47 mF 0.1 mF 1.5 MW 10 kW EO(DC 400 V) COM 10 mF 0.01 mF 0.001 mF R10
10 M W
A D B C E F G EI5 CS2 MPI 3 V B 6 SV CC 1 PV CC 9 V OUT 8 GND7 EO4 Load
n Application Circuit Example (continued)
- Normal operation waveforms Horizontal axis 1 ms/div 10 ms/div Measuring point A (EIN) B (MPI) C (VB ) D (VOUT ) E (CS) F (EI) G (EO)
1 V/div
7 V2 V/div
12 V0.2 V/div0 V 0.8 V0.5 V/div 0 V
2.5 V50 V/div
0.5 V/div
2.5 V 0.2 V/div0 V
0.8 V 2 V/div
12 V 1 V/div
140 V20 V/div
2 V0.4 V/div
n Application Circuit Example (continued)
- Waveforms at start Horizontal axis 20 ms/div Measuring point E (CS) G (EOI)
- Waveforms at stop Horizontal axis 20 ms/div Measuring point E (CS) G (EOI)
0.2 V/div
1.2 V50 V/div
400 V0.2 V/div0 V
0.8 V50 V/div
(Conditions)
- Input voltage : 100 V (AC)
- Output voltage : 400 V (DC)
- Output current : 200 mA (resistive load 2 kW )