Abstract: Analyzes one kind to use the TOP234Y multi-purpose monolithic integrated circuit switching power supply with 8051 monolithic integrated circuit union design multiway switch power source’s plan, simultaneously introduced that TOP34Y the internal structure and the principle of work, give this switching power supply’s main circuit and peripheral circuit’s design method.
Key word: Switching power supply TOP234Y 8051 monolithic integrated circuits
Introduction
The power source is always in each kind of electronic installation the essential constituent, whether does its performance fit and unfit quality direct relation electronic installation’s technical specification and work reliably safely. The monolithic switching power supply then demonstrated since coming out its superiority, is formidable the design develops in each kind of high efficiency, the low power switching power supply’s superiority component. Along with in the production, the life automaticity’s unceasing enhancement, the switching power supply also develops toward the intellectualized direction, controls the switching power supply by the micro controller unifies the monolithic switching power supply and the monolithic integrated circuit control, even more has manifested switching power supply’s reliability and the flexibility. This article introduces one kind of TOPSwitch-FX series and the monolithic integrated circuit union design switching power supply.
1 TOPSwitch-FX series synopsis
The TOPSwitch-FX series is American PI Corporation promotes has the high performance-to-price ratio 5 end monolithic switching power supply integrated circuit, including TOP232P/G/Y-TOP234P/G/Y.
1.1 TOPSwitch-FX series pin function
TOP234Y uses to-220-7B seal, some 5 pins, respectively are the control carry C, multi-purpose to carry M, source S, the turn-on frequency choice to carry F, drain electrode D. Various base pins’ function is as follows:
The control carries C: The erroneous amplifier and the feedback electric current’s input end, uses in the dutyfactor control.
Figure 1
Multi-purpose carries M: Line pressure, undervoltage protection input end; The connection line voltage forward feed reduces the biggest dutyfactor; Outside the current limitation supposes the fixed end; The far-end opens/closes the remote control and the synchronization; Will forbid the chip function this end and the S end pipe nipple, causes its work under the simple 3 end pattern.
Source S: Connects the internal MOSFET power tube’s source, initial cascade control electric circuit’s public end and reference point.
The turn-on frequency choice carries F: Uses in the selection switch frequency the input end, this end and S look carefully Lian Ke to obtain the 130kHz turn-on frequency, this is helpful in reduces high-frequency transformer’s volume. This end and the C end connection may obtain the 65kHz turn-on frequency. Waits for an opportunity under the pattern to choose half frequency (65kHz) the working pattern to be able to drop to the power source power loss lowly. P does not have the turn-on frequency choice with G series TOPSwith to carry F.
Drain electrode D: Connects the internal high-pressured MOSFT power tube’s drain electrode, provides the start bias electric current through the internal switch high pressure current supply.
1.2 TOPSwitch-FX series internal structure
The TOPSwitch-FX series’s internal structure like disputes 1 to show, is mainly composed of the below part: The control voltage terminal, the base crack datum potential source, the frequency jitter oscillator, the parallel adjuster/error amplifier, the PDM keyer, the overflow comparator, the gate actuation level and the output stage, the shape has the hysteresis characteristics overheated protection circuit, the shutdown/to restart the dynamic electricity road, the high-tension current fountainhead, the soft starting circuit gradually, to owe the voltage comparator, the current limitation regulator, the line detector, the multi-purpose end internal circuits automatically. Its principle of work is adjusts the dutyfactor through the feedback electric current.
2 TOP234Y and 8051 switching power supply design
The author designs the switching power supply has 3 group output voltages, respectively is U01 (5V,2.5A), U02 (5V,150mA), U03 (12V,1A), total output 25W. In which U02 is mainly other peripheral device component which is 8051 or 8051 must increase (for example EEPROM) supplies power, U01 and U03 are to need the great voltage big electric current the equipment power supply. In the design mainly uses 1 TOP234Y, 3 optical coupler LTV817A and 1 8051 monolithic integrated circuits. The concrete designa circuit and device parameter as shown in Figure 2.
2.1 main circuit designs
Will be called the main circuit besides TOP234Y and 8051 electric circuit. The analog input electric current to exchange 85V~265V, suitably in majority application situations. For withstanding possibly the thunder stroke voltage which sneaks into from the electrical network, is exchanging input end parallel 1 varistor VSR, and joins 1 fuse, assures the entire electric circuit’s security. For suppression circuit’s electromagnetic interference, enters the electromagnetic interference filter in the exchange side string (to be composed of C0, L1) suppresses switching power supply’s rising time as well as the transformer vibration and so on noise which produces.
After the alternating current passes through the bridge-type rectifier and the C1 rectification filter, has the high-pressured cocurrent to give a high-frequency transformer’s winding power supply. VS1 and VD1 can the peak voltage clamp which produces the leakage inductance to the security value, and can weaken the ringing voltage. VS1 uses the back breakdown voltage is the 200V P6KF200 transient voltage blanker, VD0 uses 1A/600V UF4006 ultra-fast to restore the diode. C1 is the security electric capacity, meets between the direct-current high pressure end and the place, can filter the syntype disturbance which a time winding, two winding coupling capacity produces.
The high-frequency transformer uses EEL25. And strengthens the magnetic field coupling degree for the reduced high-frequency transformer volume, two windings used have piled up one on top of another the type winding. In a two winding’s group voltage after VD2, C2, L2 and C3 rectification filter obtains voltage which needs. Because the monolithic switching power supply’s turn-on frequency is high, therefore after outputting the electric valve shuts off in the reverse recovery procedure, will have the switch noise, easy to damage the electric valve, but by anti- will accommodate the RC electric circuit which the part will be composed, although can protect the diode and reduct noise certain function, but the effect will be not very ideal, but also the power production will lose on the resistor, therefore here will select the inductor to replace the resistor. Uncertain skin inductor L2 selects 3.3VμH puts on the heart inductor, may filter VD2 the switch noise which produces in the reverse recovery procedure. Based on the above consideration, secondary’s several other groups outputs use this method filter and the denoising. A feedback winding not only direct achievement group output voltage, moreover was also TOP234Y provides has needed the bias. C6 is the protective condenser, uses in filtering the disturbance which by, a two winding coupling condenser causes.
Figure 2
2.2 control circuit design
The control circuit mainly points to monolithic integrated circuit switching power supply component TOP234Y and the monolithic integrated circuit 8051 peripheral circuits. The switching power supply part mainly by TOP234Y (U1), linear optical coupler LTV817A (U2) is composed. The control section mainly by monolithic with 8051, linear optical coupler LTV817A (U3, U4), presses a key SB to be composed.
Using TOP234Y M end. May pass through composes following three forms the switching circuit, like Figure 3 (a) ~ (c) shows. Figure 3 (a) is the belt limiting current hypothesis ON activation way passes/breaks the electric circuit, Figure 3 (b) is the belt limiting current hypothesis OFF activation way passes/breaks the electric circuit, Figure 3 (c) is the zone lines sensor’s OFF activation way passes/breaks the electric circuit. In chart switching valve QR then uses the artillery coupler also to be possible to use the hand switch. And “ON activates” is refers to, when ON/OFF end for high level the switching power supply activates, otherwise the low level activates named “OFF activation”. What this article uses is the first control mode, the line is simple, the part are relatively few.
When the switch presses a key SB presses down the VD5 breakover, TOP234Y M and the S connection, the electric circuit work in three end patterns, the multi-purpose ends and the turn-on frequency choice end does not have an effect. By now U02 had the voltage output and was 8051 power supplies, after 8051 undergo the initial program replacement, the normal work, winds through on U3 the electric current to cause the optical coupler connection, afterward 8051 examine P1.0 to pull to the low level, after the procedure receives the interrupt, changes over to the TOP234Y start-up procedure, then gives P1.1yi a signal to actuate U4, thus multi-purpose carries TOP234Y M and the turn-on frequency choice carries the F connection, causes TOP234Y maintains at the connection condition, normal work.
When needs to shut off (the TOP234Y shutdown, may press down SB not completely), equally after U3 the signaling examines for 8051,8051 P1.0 the low level signal, will change over to the shutdown procedure, according to need, this period 8051 may also carry out other operation, for instance the preserved data, the safe stop are moving external instrumentation and so on. after 8051 operations complete, then changes over to the shutdown procedure, gives the signal from P1.1, cuts off U4, as the matter stands the TOP234Y drain electrode electric current is only 0.6μA, the power loss is small.
If 8051 this switching power supply power supply, when changes supplies power by other equipment, then may in 8051 establish fixed time the start-up procedure, predetermined time, P1.1 output signal directly TOP234Y M and F end pipe nipple, TOP234Y along with it start. The output voltage may drive the external instrumentation, thus realizes fixed time automatically moves, if turning on remote control procedure and equipment, but may also realize the far-end remote control fixed time to start.
Also has many methods based on 8051 switching power supply design, for example, in shown in Figure 2 in the design drawing, with 8051 controls TOP234Y the source S end, the control to carry C and the turn-on frequency choice carries F the make-and-break to be possible to realize the turn-on frequency cut, end may realize the 65kHz turn-on frequency F the termination C, chooses this kind of half frequency work in the video frequency control to be possible to further reduce the equipment to the video noise sensitive degree.
Figure 3
in 2.3 design uses should pay attention to the question
(1), because switching power supply’s soft starting time and 8051 replacement initialization time may play the delayed action, therefore, presses a key on SB not to need to add against vibration electric circuit, this also needs to press SB, for switching power supply and 8051 by enough time start, but cannot only be clicks on to press a key gently, otherwise is unable to start.
(2), if presses a key SB, U3 and U4 is away from TOP234Y the M end to be not very near, then must merge electric capacity CN to eliminate time switch’s noise.
3 conclusions
The TOPSwitch-FX series interior integrated power switch MOSFET and each kind of protection circuit, coordinates the exterior electric circuit to be possible to realize reaches 14 kind of control functions, but (limited to 8051) does not unify this electric circuit with the micro controller the use to be able to realize multi-purpose and manifests the design the flexibility. This article only gives the partial functions to realize the method, more TOPSwitch-FX wait for with the micro controller union design’s electric circuit further develops.
