Product Highlights

Cost -effective linear/RCC replacement

cost and number of components the lowest, constant voltage (CV) or constant voltage/constant current (CV/CC) solution [123 123 ]

Extremely simple circuit configuration

Light 75%of the power supply reduces transportation costs

First CV/CC solution to eliminate 10 to 20

Low -system costs of secondary components

Combining main clamping, feedback, IC power supply and circuit

compensation function -minimized external component

Completely integrated short -circuit and disconnection automatic automatic circuit automatic automatic circuit automatic automatic circuit automatic Restart

Circle fault protection-save the cost of external components

42 kHz operation simplifies EMI filter design

Many performances higher than linear/RCC

The scope of general input can run globally

Power consumption decreased by 70% -reduced

The size of the shell is significant

CV/CC output characteristics without second feedback

System -level heat -limiting protection

Meet all single -point failure requirements

additional clamp capacitors

The control current in the CC area provides inherent soft start [123 ]

Optional light feedback increases the output voltage accuracy

ECOSMART-Very Energy-saving

When inputting 265 volts, consumes lt; 300 MW

Meet the requirements of Blue Angel, Energy Star, and EC requirements

No-influenza response resistor-maximize efficiency

Application

Replace linear transformers in all applications ≤3W [ 123]

Mobile phone, rope phone, PDA, digital charger

camera, MP3/portable audio equipment, shaving knife, etc.

Household electrical appliances, white home appliances and consumer electronics products

TV spare power and other auxiliary power supply

Explanation

Linkswitch is specifically for replacing low -power linear switches The design of the same or lower system transformers/RCC chargers and adapters have higher performance and energy efficiency costs.

LNK500

is the low -cost version of LNK501, and the tolerance has a larger output CC characteristics. Linkswitch introduces a revolutionary design of low -power switching power supply Patent topology and linear adapter. Compared with the traditional brick , it is compared to traditional bricks . The efficiency is as high as 75%and lt; 300 MW is empty power consumption, the link switch solution passes the lineSexual design can save enough energy for end users to fully pay the full power supply year in less than a year. Linkswitch integrates 700V power MOSFET, PWM control, high -voltage startup, current limit and heat shutdown circuit, and integrated to a single -piece integrated circuit.

Table 1. Note: 1. The output power designed by a closed adapter is measured at 50 ° C's ambient temperature.

2. See Figure 1 (b) (only CV design) and typical (CV/CC charger design) power points characteristics.

3. Use high reflection voltage transformers to design enhanced power capacity -please refer to the precautions part of the key application.

4. See part of the ordering information.

Pointing function description

Drainage (D) Sales: Power MOSFET Demonstration. Provide internal operation startup current. Internal current limit detection point current.

Control (C) pin: The duty cycle error placing the large and the feedback current input pin current limit control. The internal parallel adjuster is connected to the internal bias current during normal operation. It is also used as a connection point for power bypass and automatic restart/compensation capacitor.

Source quotation: The output MOSFET source connection for high -voltage power supply is returned. Public and reference direction of the first -side control circuit

Linkswitch function description

The relationship between the duty cycle, current limit, working frequency and control pin current is as follows. Show graph 4. Figure 5 shows a typical power summary below to describe the schematic diagram of the connection switch.

Power Electricity

During the power -power period, when the vehicle identification number (VIN) was first applied (Figure 5), the control pin capacitor C1 was connected to the drainage pipe and control through the switching of the high -voltage current source of the high -voltage current source of the power supply. Sales (see Figure 2). When the control pin voltage reaches about 5.6 volt for the power pins, the high -voltage current source is turned off, the internal control circuit is activated, and the MOSFET internal MOSFET in the high level is switched. The charge stored on C1 at this point is used to supply internal consumption chips.

Hengliu (CC) operation

Therefore, a voltage reflex transformer winding increases, and the feedback control current IC increases. As shown in Figure 4, the internal current limit increases as IC increases, and when IC reaches ILIM, it is equal to IDCT. The internal current limit and IC characteristics are designed to provide similarly constant power output currents increased as the power supply output voltage increases.

Constant pressure (CV) operation

When IC exceeds IDC, it is usually 2 mA (Figure 4), a maximum duty ratio decreased. The IC value depends on the power provision voltage, occupyingThe peak current of the air -ratio control limit connection is lower than the internal current limit value. At this moment, the power is converted from CC to CV operation. In the typical universal input design, the minimum input voltage conversion occurs at about 30%of the duty cycle. Therefore, when the initial (Figure 5) is selected (Figure 5) to perform the IC value as the VOUT value, it is equal to the IDCT at the minimum power input voltage. The final choice When the remaining circuit is designed, R1 is generated. When the duty cycle drops to about 4%, the frequency decreases, thereby reducing energy consumption under light load conditions.

Automatic restart operation

When a failure occurs, such as output short circuit or open circuit circuit to prevent external current flow into control device pins, the capacitor C1 discharges 4.7V. At 4.7V, it is automatically restarted to be activated, which will turn off the MOSFET and make the control circuit in a low -current standby mode. When restarting automatically, Linkswitch will regain the power regularly in order to restore the power supply and stay away when the fault is recovered normally.

The above feature provides a CV/CC power supply side voltage or current feedback that does not require the output of the secondary power supply. The output voltage adjustment is affected by the voltage tracking effect on the C2. The reflective output voltage is affected. This tracking is introduced by a value of the transformer leakage. The peak of the filtering sensing voltage of the resistor R2 and the capacitor C2 reduces this error. This circuit provides a better output load regulating linear transformer with a standard transformer structure, making it an ideal power solution in many low power consumption applications. If the stricter load adjustment needs, you can use the concentrated output current characteristics provided by the optocoupler configuration during static. The optional feedback diagram 6 shows the connection switching regulations using light coupling feedback to increase the output voltage. At one side, add R3, C3, and optocoupler U1 to the schematic diagram and Figure 5. Page 3 and R1 form a divisioner to limit U1 episodes to transmit pole voltage. On the secondary side, the voltage detection circuit component R4, VR1 and U1 LED provide voltage feedback signals. In the example shown, a simple Zener (VR1) reference is usually required for accurate TL431 references, but it still provides ± 5%output voltage tolerance and cable voltage compensation. If necessary. R4 provides bias for VR1. This regulating output voltage is equal to the total voltage of VR1 Qina plus U1 LED's positive voltage drop. R5 is an optional low -value resistor, which is used to limit the U1 LED peak current, because the output ripples. The manufacturer regards the U1 current and refer to the VR1 slope resistance to determine that R5 is required. U1 sets the anode of the collector to D1 with an anode of the ground. This connection keeps the optical pipe quiet in the electrical position in the circuit. If the optometry is the opposite, it will become an exchange node on the cathode side of the D1, generating an additional co -mode EMI current through its internal parasitic capacitors.

The feedback configuration in FIG. 6 is just a resistor compressioner consists of R1 and R3, D1, R2, C1, and C2 rectify, filtering and smoothing the winding voltage signal once. Therefore, optocoupler can effectively adjust the resistance to control the DC voltage on the R1. Therefore, the feedback link switch controls the current receiving current. When the power supply is working under the constant current (CC), for example, when the battery is charged, the output voltage is lower than the voltage feedback threshold defined by U1 and VR1. In this area, the circuit's behavior and the reflection voltage mentioned earlier are limited with the output voltage and the internal current of the connection switch to adjust to provide similar CC output features. Note that the value of R1 in the similar output characteristic graph in the CC area is equal to the value graph 6 of the R1+R3. When the output reaches the voltage feedback threshold, U1 and VR1 are turned on. Any further increased power output voltage generates a U1 transistor current increased, which will increase the voltage of the percentage of reflection. As a result, the control current of the link switch is maintained. Therefore, the output voltage adjustment is maintained. Generally, the value of R1 and R3 is equal. However, increasing R3 (at the same time decreases R1 to maintain R1+R3 constant) to increase the circular gain in the CV area and improve load adjustment. The degree of R3 increased the voltage and losses of the transistor of light to be tested before completing the design. The values u200bu200bof C2 and C3 are the frequency of dividing circuits set by R1, R3, and U1 at the switch in addition to ensuring that they are sufficiently large enough on voltage impedance. The values u200bu200bof C3 and C3 are usually selected in Figure 6 that the value of C2 in FIG. 5. Although the voltage is based on the relative value of R1, the rated value may be reduced and the R2 discussed above. Typical applications see the value of the component in section.

FIG. 7 shows the output characteristics of optocoupler feedback. The packaging line defined by the dotted line indicates that the DC output voltage and current tolerance of the power supply (unit and exceeding the input voltage range) are not used in the worst case of the worst case. A typical display of the inherent (non -optocoupler) output characteristic of the star. This is removed by U1, R4 and VR1. Coupling feedback leads to the characteristics represented by solid lines. Loading arrow diagram 7 indicates that the trajectory of the output characteristics usually appears in the battery charging cycle. When the output voltage increases, the characteristics are the same, but when the voltage feedback threshold is reached. If the voltage feedback threshold is higher than the output voltage transition point with inherited CC-TO-CV, it is shown in Figure 7. Figure 8 shows the voltage feedback threshold to set the voltage below the CC to CV transition point. In this case, with the rise of the output voltage, the second feedback circuit has obtained control before the CC to CV. In the actual battery charging application, this is only to limit the output voltage to a lower value.

However, in the laboratory table test, it is often more convenient to test the output characteristics output current from the low voltage and gradually increase the load. In this case, optocouple feedback adjustment output voltage until the peak output power curve is likeFigure 8 shown. In these cases, the output current will continue to rise until the peak power point is reached, and the optocoupler will be turned off. Once the optocoupler is turned off, the control pins feedback current is determined by R1 and R3 and the output current, so it is folded back to the inherent CC characteristics, as shown in the figure. Because this type of load conversion usually does not occur in the battery charger, the output current will never exceed the constant current value in the inherent practical application. In some applications, it is necessary to avoid excessive output current, which has nothing to do with the direction of load changes. To achieve this goal, the minimum voltage feedback threshold should be set to VO (MAX). This will ensure that the inherent characteristics of the CC to CV transition point will always occur below the voltage feedback threshold. However, the output voltage tolerance increases, because the CV characteristic tolerance lower than the VO (MAX) tolerance is added to the tolerance of the optocouple feedback circuit.

Application Example

The circuit shown in FIG. 9 shows a typical connection switch with a typical approximately constant voltage/constant current (CV/CC) charger. The design can provide a 2.75 W power nominal peak power point voltage of 5.5 V and the current of 500 mAh. Within the input range, the efficiency is greater than 70%85 volt communication to 265 volts. Bridge rectifier BR1 rectifies the exchange input. The resistor, whether the RF1 is an easy melting type, provides a side short -circuit protection circuit. Use C1 and C2 to smooth the AC electricity after rectifiers. Together with C1 and C2 to form an inductors L1 filtering electromagnetic interference with PI filter. The switch frequency is 42KHz allowed to use such a simple EMI filter without a Y capacitor, and it still meets the international EMI standard. When power is powered, a high -voltage DC power connection switch (U1) pin appears. Then control the internal charging drainage pipe between the connected switching high -voltage current source and controlling sales through the connected switching high -voltage current source. Relative to the power pins, the internal current source is closed. This internal control circuit is activated, high -voltage MOSFET starts to switch, and uses the energy in C3 to power the IC. When the MOSFET is connected, the high -voltage DC bus is connected to one end of the transformer at once, and the other end is connected to the main circuit. When the current is storage on the side of the anti -gravic transformer T1, energy storage. When the MOSFET is closed, the energy is transmitted to each switching cycle at the output end. The secondary side of the transformer via D6 rectifier filtering and C5 provides DC output for the load. Linkswitch completely starts from the first side through the constant voltage and constant current control. This is to monitor the side VOR (voltage output reflection). The diode D5 and the capacitor C4 constitute the primary clamping network. Both of them limited the peak leakage leakage voltage in C4 to provide a voltage, which is equivalent to the error caused by Vor Plus by the parasitic leakage. The resistor R2 filter the leakage peak and reduce the VOR value. The resistor R1 converts this voltage into a current input control pin to adjust the output. During the CV operation, the duty occupation ratio was controlled. When the current entering the control pin exceeds about 2 mAh, the duty cycle began to decrease to reach controlThe pin current is 30%at 2.3 mA. Under light or vacant conditions, when the duty cycle reaches about 4%, the switching frequency is reduced to lower energy consumption. If the output load increases exceeding the peak power point (defined at 0.5 · L · i2 · F), the output voltage and VOR decrease. This reduces control pins current will reduce the internal link switch current limit (current restriction control) to provide approximately constant current output characteristics. If the load increases and the control pin current drops to about 1 mA, the control pin capacitor C3 will discharge, and the power supply enters the automatic restart state.

current limit control does not require any secondary side

current sensor element (sensor, transistor, photoelectric component axis and related components). Remove the auxiliary induction circuit has greatly improved efficiency and reducing the relevant benefits of reducing the size of the shell.

Key application precautions

Design output power

Table 1 (Homepage) provides the conditions specified in the continuous output power of the given device. The output (CV/CC) of the charger is usually at the typical output peak power point. On the contrary, non-charger applications (only suitable for CV, suitable for many converters, such as as adapter, spare/auxiliary power supply and other embedded AC-DC converters) Specify the supply in the worst case.

In order to help the designer, the power table reflects these differences. For CV/CC design, the typical power column and CV design should use the minimum power column, which are separate. In addition, the data is based on the following content:

1. The minimum DC input bus voltage is 90 V or higher. This filter capacitor input and 1 μF/W corresponding to the universal 3 μF/W is used for 230 VAC or 115 VAC input multiples input level.

2. Designed a intermittent mode anti -gratitude converter. Continuous mode design can lead to unstable circuit and not recommended. Typical output power chart, the nominal value of the primary inductance and the i2, is it hypothetical? For minimum output power numbers, the primary inductance is reduced by 10%, and the minimum I2F value is hypothetical. For empty load consumption lt; 300 mW, the assumed range is 40 V to 60 V. It is used for air -loading lt; 500 MW and higher output power capabilities, and the range is 60 V to 100 V.

3. 5V secondary output with Schottky rectifier diode.

4. Suppose the efficiency is 70%.

5. This part is a copper area with sufficient welding of the plate installation and source of the source, so that the mold temperature is kept or lower than 100 ° C.

6. The output cable of 0.2 #8486; total resistance. In addition to the heat environment (sealing shell, ventilation, open framework, etc.), Linkswitch dependencies in the application of maximum power capabilitiesInput voltage specified by the transformer iron heart size, efficiency, primary inductor tolerance, minimum value, input storage capacitance, output voltage, output diode forward voltage drop, etc., as shown in Table 1.

Transformer design

In order to provide about CV/CC output, the transformer should be designed as discontinuous; all energy is stored at MOSFET to close the time. The energy transmission in the intermittent mode has nothing to do with the line voltage. The peak power point before entering the Hengliu operation is defined as the maximum power transformer transmitted. The transmitted power is given by the expression p u003d 0.5 · I2 · F. In the formula, L is the primary inductance, I2 is the main peak current square and F is the switching frequency. To simplify the analysis, the data table parameter table specifies the twelve F coefficient. This is the square and switch frequency of current limit to the feedback parameter DCT company. This provides a peak power point for power supply due to Linkswitch. Because the primary inductor tolerance is a part of the expression that determines the peak output power point (CC starting characteristics). This parameter should be well controlled. In order to estimate the ± 25%inductance tolerance of the total constant flow to a winding, the tolerance should be ± 10%or better. This is the size of the low -cost center of the low -cost center of the use of standards that can be implemented. Smaller gaps are possible, but non -standard, tight iron oxygen aluminum tolerance is required. Other gap techniques, such as the thin -film gap, allow more close tolerances (± 7%or higher) and peak power tolerance. Please consult your transformer supplier guide. The core gap should be the same. The uneven rock core cracks, especially if the gap is small, may lead to the non -linear of the inductance constant current area with magnetic flux density (partial saturation). Verify a uniform gap, a current waveform is recommended to check from the DC power supply. This gradient is defined as di/dt u003d v/l, and the entire MOSFET should be kept on time. Any changes in the slope The slope indicates uneven gaps. The measurement of the LCR bridge should not be limited to relying; usually these instruments are measured only at a current. This is not enough to produce a sufficient high -energy magnetic core density to show uneven gaps.

For the typical EE13 core of the center -legged gap in the center, the gap is 0.08 mm (ALG of 190 NH/T2) allows primary inductance tolerance to maintain ± 10%in standard large -scale production. This allows EE13 to be used in the design of up to 2.75 W. The air -load power consumption is less than 300 MW. If the film gap is used and then increases to 3W. Move to a larger core, EE16, for example, allows the output of 3W in the center of the center. The ratio ratio of the transformer turns should be selected to give VOR (output voltage from the secondary turns to the primary turns to reflect the ratio of 40 V to 60 V. The design does not require the 300 MW empty load consumption index. It can be designed to design the transformer as long as the non -continuous mode is maintained. This increases the output power capability. For example, the 230 VAC input design of the EE19 transformer is very high -frequency omnidirectional (VOR)The magnetic core greater than 70 volts can provide a typical output power of up to 5.5 watts. Note: The output characteristics of the linear CC area are affected by VOR. If this is an important aspect of application, the output characteristics should be checked before completing the design.

The output characteristics change

Equipment tolerance and external circuits control the tolerance of the overall link switch output characteristics. It is estimated that the peak power point of 3W design is ± 10%voltage and the current limit of ± 25%, which is used for high -batch production. This includes the tolerance and line deviation of the device and the transformer. Low -power design may be poor in lineivity.

When the output load is reduced from the peak power point, due to the large tracking error, the output voltage will rise to the load terminal. The sources of these errors include output cable voltage drop, output diode positive voltage and leakage, which is the main reason. When the load is reduced, the peak current of the main work is reduced, and the leakage also reduces the inductance energy, which reduces the clamping capacitor. A leakage sense is 50 μH, and the output voltage generally increases to more than 30%. When it is very light or empty, the output current is usually less than 2 mA. Due to the peak of the leakage, the output voltage rising auxiliary equipment is charged. This rising voltage can be used with a small pre -load, which has little effect on the power consumption. The output voltage load changes can be used through the entire load range by increasing the optocoupler and auxiliary reference (Figure 6). The auxiliary reference is designed to provide a voltage that maintains the correct constant flow characteristics of the correct constant flow characteristics of only higher than the normal peak power point. The schematic diagram shown in the component selection of Figure 5 outlines that the key components need to connect the switching power supply.

Die Diode – D1

Dya D1 should be a fast type (TRR LT; 250 ns) or a super fast type (TRR LT; 50 ns), and the rated voltage is 600 V or higher. The first choice of recovery type is usually low. It is not recommended to use diode; they may cause excessive discharge bells and connection switches to reverse bias.

Clamping capacitor – C2

Capacitor C2 should be 0.1 μF, 100 V capacitor. Low -cost is recommended to use metal plastic film types. The impact of tolerance on the output characteristics is very small. Therefore, any standard ± 5%, ± 10%, or ± 20%tolerance is acceptable. It is not recommended to use ceramic capacitors. This commonly used electronics such as Y5U or Z5U instability is related to voltage or temperature, which may lead to output instability. Ceramic capacitors with high stability medium can be expensive than metallic film types.

Control pin capacitor-C1

Capacitor C1 is used to start the power connection switch and set the automatic restart frequency. The value of the battery's design loading this component should be 0.22 μF and the resistance of the resistance is 1 μF. This ensures that the output voltage is sufficient to reach the specified value during the startup period. Any capacitor type can be acceptable, and the rated voltage is 10 V or more.

Feedback resistor –r1

Select the value of R1 to control the power supply point of the control pins of about 2.3 mA to the peak. The actual value depends on the selection of VOR in the design process. Any 0.25 W resistor is applicable

Output diode -D2

You can use PN fast, PN ultra -fast or Schottky diode according to the efficiency target of supply. High diode. The rated voltage of the diode should be sufficient to withstand the output voltage plus the input voltage ratio through the number of turns (the typical VOR of 50 V. The diode PIV of 50 V). It is not recommended to use slow recovery diode (1N400X type).

Output capacitor — C4

The selection of capacitor C4 should make its voltage and ripples not exceed the current specification. Linkswitch layout Precautions The first connection is that the source in the link switching power supply is switching nodes, and the copper area and source are connected to C1, C2, and R1 (Figure 5) should be designed in thermal constraint to reduce electromagnetic interference coupling. Control pins capacitor C1 should be as close as possible as possible and control pins. In order to minimize the auxiliary and AC input from elementary to the auxiliary and AC input, the connection switch should stay away from the secondary side and AC input from the transformer. Linkswitch and related components around the main circuit of the transformer main circuit further reduce the coupling.

Y capacitor

If the Y -shaped capacitor is needed, it should be connected to the transformer secondary output loop pins and the negative car circuit of the primary large capacitor. Such resettlement will maximize the electromagnetic interference advantages of the Y capacitor and avoid problems.

Quick Design Examination Form

Like any power design, all connection switch design should be verified on the test table to ensure that in the worst case, it will not exceed the specifications. Note: In the Linkswitch circuit, the source is an exchange node. This should be considered in testing. The oscilloscope measurement should use the probe to the DC voltage, such as the main circuit or DC rail, but it is not a source. The input voltage of the power supply should always be powered by the isolated transformer. The following minimum value is strongly recommended to perform the following tests:

1. Maximum drain voltage -Verification VDS does not exceed 675V, the maximum input voltage and peak output power.

2. Maximum leakage current-At the highest environmental temperature, the maximum input voltage and peak output power, verify that the current waveform current is saturated and the frontier is too large. Linkswitch's shortest front edge has a hidden time of 200 nan seconds to prevent premature termination of the cycle. Confirm the current limit at the end of the end of the end of the end of 200 nanoseconds.

3. Thermal inspection-peak output power, minimum input voltage and maximum ambient temperature, verifying the link switch does not exceed the temperature specifications, transformers, output diode and output capacitorsEssence Enough changes between parts should consider the RDS (on) specified in the Linkswitch specified in the thermal data table. At the low line, the peak power, the maximum connection switch is recommended to the feet temperature of 100 ° C, considering these changes.

4. Central output characteristics-The intermediate value of using a transformer nominal the primary inductance and the input voltage is between the high and low lines. Verify the peak power point under the expected rated output current. If this happens, the design should be improved to ensure that the overall tolerance restrictions are met.

Absolutely maximum rated value (1,4)

Directory voltage -0.3 volts to 700 volts

Discovery peak current 400 Mia

Control voltage -0.3 volt to 9 volts

Control current (not more than 9 V) 100 ma

Storage temperature -65 ° C to 150 ° C

]

Work knot temperature (2) -40 ° C to 150 ° C

Lead temperature (3) 260 degrees Celsius

Note:

All voltage, TA u003d 25 ° C.

2. Usually restricted by internal circuits.

3. 1/16 inches from the shell, lasting for 5 seconds.

4. The maximum rated value can be adopted, one by one, which will not cause permanent damage to the product. Under the absolute maximum rated condition

The extended time may affect product reliability

Thermal impedance: p/g packaging:

[θja) 70 ° C/W (2), 55 ° C/W (3)

(θjc) (1) 11 ° C/W

Note:

1. Measurement on the source.

2. Welded to 0.36 square inch (232 square millimeters) 2 ounces (610 grams/square meter) copper.

3. Welded to 1 square inch (645 square millimeters). 2 ounces (610 grams/square meter) copper.