|
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese|
ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING SAMSUNG CGM7607L monitor power supply based on KA2S series chip. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Power Supplies Specialized microcircuits of the KA2S series form the basis of power supplies for SAMSUNG monitors of the latest generation (400b, 500/500pM, CGM1706M). These include microcircuits KA2S0880/KA2S0680, KA2N0880/KA2N0680, etc. The microcircuit housing contains a pulse-width modulator with pulse current control and a high-voltage field-effect transistor. The microcircuit is equipped with a soft start system and uses external synchronization. The pulse-width modulator operates from a generator at a fixed frequency and has internal protection circuits that block the operation of the microcircuit in the event of increased or decreased supply voltage, overheating, and the occurrence of critical operating modes of the source. The main power supply devices that ensure its operation are: - mains voltage rectifier;
A typical circuit diagram for connecting the KA2N0880 microcircuit is used in the power supply of the SAMSUNG CGM7607L monitor, the circuit diagram of which is shown in here. The main circuits of the converter are presented in table. 1. Table 1
Mains voltage rectifier The voltage of the AC mains through the connector IS601, the fusible link F601, L601 is supplied to the rectifier D601 ... D604. Elements L601, C601 ... C603, BD601 form a surge filter that prevents the penetration of impulse noise into the electrical network, created by the power source during its operation. The bridge type rectifier is made on discrete elements D601 ... D604, the negative terminal of which is connected to a common wire through a resistor R606. As a result of its operation, the capacitor C607 is charged to a voltage of +300 V through the thermistor TH601. The CRT monitor degaussing device is connected through the CN603 connector, the RTH601 thermistor and the contacts of the controlled relay RL601 are connected to the filter output. The RL601 relay control winding is connected to the collector circuit of the Q605 transistor switch and is controlled by the DEGAUSS signal from the mode control processor. Trigger and Timing Circuit The PWM converter of the microcircuit is powered by applying the appropriate voltage to pin 3 of the IC601 microcircuit, which must be within the required limits. For this purpose, a circuit is connected to the AC network, consisting of elements D605, R602, C608. In the event that the voltage across capacitor C608 reaches +15 V, which corresponds to the low voltage comparator turn-on threshold (UVLO) (Fig. 1), this comparator switches the microcircuit to the on state.
This enables the operation of the internal reference voltage of the output MOSFET transistor and turns on the converter control circuits. The rectified voltage of the AC mains is supplied to the MOSFET drain (pin 1 of IC601) from the common point of the diodes D602, D603 through the chokes BD6O2, BD6O3. To facilitate the start-up mode of the converter at the first moment of switching on, when there are no feedback signals and the operating mode of the converter is close to the short-circuit mode in the load, a soft start mode is used. Operation in this mode is provided by external elements: capacitor C611 and resistor R605, which are connected to pin 5 of the microcircuit. The operation of this circuit is that while charging capacitor C611, the PWM modulator generates control signals on the MOSFET as if the converter were operating with a zero error signal; the duration of the control signal at the driver output is short. In this case, the capacitor C6O5 is charged from an internal source to the error voltage of the soft start duration corresponding to this error. As the charge progresses, the voltage on capacitor C611 reaches +5 V and the soft start circuit is turned off, and the duration of the MOSFET control signal increases; the voltage on capacitor C605 is determined by the error signal generated by the feedback circuit. In the steady state of operation, the microcircuit is powered from the feed circuit formed by the secondary winding of the T601 transformer (vyv.6-9), elements D610, R604. Reducing the voltage at the power supply pin of the microcircuit (vyv.Z IC601) is less than the value of the UVLO comparator turn-off threshold, corresponding to +10 V, turns off the converter. When current flows through the primary winding of the T601 transformer (pin 2-5), processes occur in the power source that contribute to its transfer to the steady state operation. Elements T602, C612, D607 form an external synchronization circuit for the internal oscillator of the microcircuit with SYNC_P pulses coming from the horizontal output stage to the base circuit of transistor Q601. Chains of stabilization and protection The feedback circuit is formed by an OP601 optocoupler and an IC602 low-power adjustable DC voltage regulator of parallel type. The control electrode of the IC602 microcircuit receives information about the output voltage from the divider formed by the elements R612, R610, VR601, connected to the +195 V channel. When the output voltage decreases, the current through the photo sensor of the OP601 optocoupler decreases, and, accordingly, the output current in the collector-emitter circuit of the phototransistor OP601 connected to the error signal input (pin 4 of IC601). This leads to an increase in the duration of the MOSFET control pulse and a corresponding increase in the output voltage to the required value. Thus, the principle of error control of the output voltage is implemented in the converter. The output voltage is adjusted by the VR601 resistor via the +195 V channel. A voltage exceeding +7,5 V at the error signal input (pin 4 of IC601) causes the microcircuit to stop working by triggering the supply voltage reset comparator. Elements R611, C621 are designed to reduce transients in the microcircuit, the optocoupler photosensor is powered by +14 V (2). The current control mode of the regulator (primary winding T601 pin 5-8) is implemented by the internal circuits of the microcircuit as a way to regulate the output voltage when the current in the load increases on the one hand, and on the other hand, as an element of protection against maximum currents in the load circuit. In the load current mode, this circuit turns off the MOSFET output until the next start cycle. The power supply chip IC601 has a restart function without disconnecting from the power supply. The period between successive starts during overloads is determined by the charging time of capacitor C605 from internal sources of 1 mA and 5 μA. In long-term overload mode, the converter is completely turned off using a built-in power-off comparator. Snubber circuits D602, C610, R609 and C611, D604, R610, R623 protect the MOSFET transistor from switching pulses due to the inductance of the pulse transformer windings and from exceeding the instantaneous power at the drain. Switching power supply rectifiers The surge voltage rectifiers of the secondary power sources are assembled according to a half-wave rectification scheme. The main elements of the secondary rectifier circuits are given in table. 2. Table 2
The SUSPEND and OFF signals put the power supply into low power consumption modes. With the SUSPEND command, the +12 V voltage is blocked using the Q610 transistor switch, and the +8 V voltage is removed with the OFF command. Typical malfunctions The mains fuse FH601 blows. In this case, when the monitor is turned off from the network, it is necessary to check the serviceability of the elements of the barrier filter and the mains rectifier (L601, C601...C603, D601...D604), check the serviceability of the microcircuit (pin 1,2, 601) IC608, as well as the elements damping chain (D603, R610, CXNUMX). There are no power module output voltages. Check for +300 V voltage on capacitor C607. If it is absent, check the serviceability of the elements of the mains rectifier D601 ... D604, ТН601. With the monitor turned on, check the presence of the supply voltage of the IC601 chip +16 V between pins 2 and 3. If it is absent, check the health of the elements D605, R6O2, C6O8, D610, R604. If the supply voltage is less than +10 V (the power supply is off), you should make sure that there are no malfunctions in the loads of the secondary rectifiers, the serviceability of the secondary rectifiers themselves and the elements of the feedback circuit OP601, IC6O2. If they are good, replace the IC601 chip. The output voltages are higher or lower than normal and are not regulated by the variable resistor VR601. Check the health of the elements OP601, IC602, C605, ZD602 and C606. Publication: radioradar.net
Artificial leather for touch emulation
15.04.2024 Petgugu Global cat litter
15.04.2024 The attractiveness of caring men
14.04.2024
▪ Cafe visitors are served by robots ▪ High-voltage ultra-bright LED drivers from IR ▪ B vitamins with omega-3 fatty acids slow brain aging ▪ Sleepy cows give sleeping milk
▪ section of the site Medicine. Selection of articles ▪ Michurintsy article CAR AUDIO. The art of audio ▪ article What is the largest desert on Earth? Detailed answer ▪ article Omezhnik. Legends, cultivation, methods of application ▪ article Vertical loop antenna (LOOP). Encyclopedia of radio electronics and electrical engineering
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
See other articles Section 
Latest news of science and technology, new electronics:
All languages of this page