TNY278GN-TL IC

Technical Specifications of TNY278GN-TL

Datasheet	TNY278GN-TL datasheet
Category	Integrated Circuits (ICs)
Family	PMIC – AC DC Converters, Offline Switchers
Manufacturer	Power Integrations
Series	TinySwitch?-III
Packaging	Tape & Reel (TR)
Part Status	Active
Output Isolation	Isolated
Internal Switch(s)	Yes
Voltage – Breakdown	700V
Topology	Flyback
Voltage – Start Up	–
Voltage – Supply (Vcc/Vdd)	–
Duty Cycle	65%
Frequency – Switching	132kHz
Power (Watts)	28W
Fault Protection	Current Limiting, Open Loop, Over Temperature, Over Voltage, Short Circuit
Control Features	EN
Operating Temperature	-40°C ~ 150°C (TJ)
Package / Case	8-SMD (7 Leads), Gull Wing
Supplier Device Package	SMD-8C
Mounting Type	Surface Mount

TNY278GN-TL Description

TinySwitchTM-III has a power MOSFET with 700 V, as well as an oscillator, a high-voltage switched current source, a current limit that the user can change, and a heat shutdown circuit. The ON/OFF control method used by the IC series gives creators a flexible, low-cost, and power-efficient choice.

Product Highlights

• The most flexible system with the lowest cost.
• Simple ON/OFF control, no loop correction needed.
• Current limit can be set by changing the amount of the BP/M capacitor.
• A higher current limit increases the peak power or, in applications with an open frame, the highest continuous power.
• A lower current limit makes plugs and chargers that are sealed more efficient.
• Allows the best TinySwitch-III choice to be made by switching devices without making any other changes to the circuit.
• A tight I2 f parameter tolerance lowers the cost of the system.
• Power supply to MOSFET and magnetics is increased.
• This reduces the cost of the transformer, the main clamp, and the secondary components by lowering the maximum overload power.
• ON-time extension: Extends the low line control range/hold-up time to lower the capacitance of the input bulk.
• Self-biased, so there are no windings or parts that are biased.
• Jittering the frequency lowers the cost of EMI filters.
• Pin-out makes it easier to cool the PCB.
• For low EM, the SOURCE pins are electrically quiet.

TNY278GN-TL Enhanced Safety and Reliability Features

• The need to manually reset is eliminated by accurate hysteretic thermal shutdown safety with automatic recovery.
• When there is a short circuit or an open loop fault, the improved auto-restart gives 3% of the highest power.
• Zener can turn off the output if the voltage is too high.
• A single optional resistor can be used to set the level for detecting low voltage on a line.
• A very low number of components improves stability and makes it possible to lay out a printed circuit board on only one side.
• High bandwidth allows for fast turn-on with no delay and a good response to sudden changes in load.
• Field dependability is improved by giving DRAIN and all the other pins more room to move.

TinySwitch-III Functional Description

TinySwitch-III has a built-in power source manager and a high-voltage power MOSFET switch. Instead of a more complicated PWM (pulse width modulator) algorithm, with an ON/OFF button, it regulates the output voltage.

The controller has a 700 V power MOSFET, an oscillator, an enable circuit (sense and logic), a current limit state machine, a 5.85 V regulator, a BYPASS/MULTIFUNCTIONAL pin undervoltage, overvoltage circuit, and current limit selection circuitry, overtemperature protection, a current limit circuit, leading edge blanking, and a current limit selection circuit. TinySwitch-III has new features like line undervoltage sense, automatic restart, on-time extension through adaptive switching, and frequency jitter.

Oscillator The oscillator has an average frequency of 132 kHz on the inside. The oscillator sends out two signals: the clock signal, which shows when each cycle starts, and the highest duty cycle (DCMAX) signal. So that the oscillator doesn’t give off as much EMI, it has electronics that changes the frequency by about 8 kHz peak-to-peak. By setting the frequency shift modulation rate to 1 kHz, the average and near-peak EMI emissions are kept to a minimum. The following edge of the DRAIN waveform is the best place to measure frequency jitter with an oscilloscope.

● Current Limit State Machine  and Enable Input

The EN/UV pin is linked to the enable input circuit, which is a 1.2 V low-impedance source follower output. The source follower has a current limit of 115 mA. If the current flowing out of this pin is more than the threshold current, the enable circuit’s output will be a low logic level, which means “disable.”

This state will last until the current flowing out of this pin drops below the threshold current. At the start of each cycle, the output of this enable circuit is read when the clock signal goes from low to high. If this number is high, the power MOSFET will be turned on for the current cycle. Putting it to a low number will turn off the power MOSFET.

Changes in the voltage or current of the EN/UV pin during the rest of the cycle are not taken into account because sampling only happens at the start of each cycle. At low loads, where TinySwitch-III is most likely to switch in the audible frequency range, the current limit state machine lowers the current limit in discrete steps. As the effective switching frequency goes above the hearing range, the lower current limit decreases the transformer flux density and the noise that comes from it.

The state machine keeps track of the order of enable events, uses that knowledge to figure out the load situation, and then makes small changes to the current limit. Because the source follower has a low impedance, the voltage on the EN/UV pin never drops below 1.2 V in the inactive state (except when it’s close to no-load). When this pin is connected to an optocoupler, the time it takes for the optocoupler to respond is sped up.

● 5.85 V Regulator and 6.4 V Shunt Voltage Clamp

When the MOSFET is turned off, the 5.85 V regulator draws a current from the voltage on the DRAIN pin to charge the bypass capacitor, which is linked to the BYPASS pin. This brings the bypass capacitor up to 5.85 V. The internal supply voltage point is the BYPASS/MULTIFUNCTIONS pin. When the MOSFET is on, the device runs on the power saved in the bypass capacitor.

TinySwitch-III can run constantly from the current it gets from the DRAIN pin because the internal circuitry uses very little power. A bypass capacitor with a value of 0.1 mF is enough to separate high-frequency signals and store energy. Also, a 6.4 V shunt regulator clamps the BYPASS/MULTI-FUNCTION pin at 6.4 V when an external resistance sends current to the BYPASS/MULTI-FUNCTION pin. This makes it possible to power TinySwitch-III from the outside with a bias winding, bringing the no-load power usage down to well below 50 mW.

● TinySwitch-III Operation.

In the current limit mode, TinySwitch-III devices work. When it is turned on, the oscillator starts each cycle by turning on the power MOSFET. When the current goes up to the current limit or when the DCMAX limit is reached, the MOSFET turns off.

Since the TinySwitch-III design’s maximum current limit level and frequency are always the same, the power sent to the load is proportional to the primary inductance of the transformer and peak primary current squared. So, designing the supply means figuring out the highest output power needed and calculating the primary inductance of the transformer.

Conclusion

In conclusion, the TinySwitchTM-III is a power supply option that works well and doesn’t cost too much. With its built-in parts and simple control scheme, it gives you more freedom and gets rid of the need for complicated adjustments. It makes sure that power is delivered steadily because it has improved safety features and works well. Use the TinySwitchTM-III to get the most out of your power source.

With its flexible design and improved performance, you can make solutions that work well and are reliable. For more information about the TNY278GN-TL or to place an order, you can contact ICRFQ, which is China’s top electrical parts seller. You can reach your goals with the help of our high-quality goods and low prices. Contact us today to find out more.

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