Studying all necessary information of tny284 tny285 tny286 tny287 tny288 tny289 tny290


1. TNY284 TNY285 TNY286 TNY287 TNY288 TNY289 TNY290 packet, Output power table.

It has 3 packet options. D packet, P packet , K packet

TNY284PN has smallest out power 6W, TNY287PN has 13W output power, TNY288PN has 16W output power, TNY289PN has 19W output power, TNY290PN has 20W output power . So you can replace TNY284PN by TNY287PN because of TNY287PN bigger output power  and the opposite that, you can not replace TNY290PN by TNY288PN because TNY288PN has smaller output power. 

3. Pin Functional Description of  TNY284 TNY285 TNY286 TNY287 TNY288 TNY289 TNY290

DRAIN (D) Pin: This pin is the power MOSFET drain connection. It provides internal operating current for both start-up and steady-state operation

BYPASS/MULTI-FUNCTION (BP/M) Pin: This pin has multiple functions: • It is the connection point for an external bypass capacitor for the internally generated 5.85 V supply. • It is a mode selector for the current limit value, depending on the value of the capacitance added. Use of a 0.1 μF capacitor results in the standard current limit value. Use of a 1 μF capacitor results in the current limit being reduced to that of the next smaller device size. Use of a 10 μF capacitor results in the current limit being increased to that of the next larger device size for TNY285-290. • It provides a shutdown function. When the current into the bypass pin exceeds ISD, the device latches off until the BP/M voltage drops below 4.9 V, during a power-down or, when the UV function is employed with external resistors connected to the BP/UV pin, by taking the UV/EN pin current below IUV minus the reset hysteresis (Typ. 18.75 μA). This can be used to provide an output overvoltage function with a Zener connected from the BYPASS/MULTIFUNCTIONAL pin to a bias winding supply

ENABLE/UNDERVOLTAGE (EN/UV) Pin: This pin has dual functions: enable input and line undervoltage sense. During normal operation, switching of the power MOSFET is controlled by this pin. MOSFET switching is terminated when a current greater than a threshold current is drawn from this pin. Switching resumes when the current being pulled from the pin drops to less than a threshold current. A modulation of the threshold current reduces group pulsing. The threshold current is between 75 μA and 115 μA. The ENABLE/UNDERVOLTAGE pin also senses line undervoltage conditions through an external resistor connected to the DC line voltage. If there is no external resistor connected to this pin, TinySwitch-4 detects its absence and disables the line undervoltage function

SOURCE (S) Pin: This pin is internally connected to the output MOSFET source for high-voltage power return and control circuit common

4. Real Application Example ciruit


when first start input voltage 220VDC , F1 fuse to protect circuit, then 220VDC line goes through input noise filter block including C1 capacitor, RT1 thermistor, L1 coil. After noise filter block, 220VAC is converted to 300VDC line by Bridge rectifier. Use c2 capacitor to flatten 300 VDC voltage, the 300VDC voltage goes to T1 pulse transformer, the rest of the primary coil of pulse transformer connects to D pin of TNY290PN. the S pin of TNY290PN connects to GND of 300VDC line. Inside TNY90PN has a mosfet and a pulse generator, when output voltage of the circuit changes, the feedback block measures its changement of voltage than it feedbacks information to EN/UV pin of TNY290PN. therefore, the pulse generator inside TNY290PN will change frequency and pulse width to G pin of mosfet, and then that will make output voltage stable. You can see output voltage will be calculated by this principle below.

when the mosfet switch on and off 300V DC voltage at high frequency, there will be a induction current created in primary coil of T1 pulse transformer. This current opposites to 300VDC volatge and harm to Mosfet. So to protect (D) Drain pin of mosfet from this opposite current, there is a block including VR1 P6KE150A, D1 diode UF4006. At secondary coils of T1 pulse transformer, the output voltage of 9,10 coil is converted to DC voltage by D4 diode STPS30L60 , then it is flatted by output voltage flat block. At 4,5 secondary coil of T1 pulse transformer, the output voltage is converted to DC voltage and goes to BP/M pin of TNY290PN. Output voltage 5VDC goes through current limit resistor R9 47r to supply power PC817 opto. From 5VDC output , using the voltage divider circuit (R6 R7 resistors) and voltage of r7 resistor goes to TL431 IC. inside TL431 has a voltage reference 2.5VDC, so if ouput voltage increase, the Voltage of r7 resistor will be higher than 2.5VDC , TL431 will open, PC817 opto will work, the EN/UV pin will be 0VDC. The pulse generator block will change pwm pulse to G pin of Mosfet inside TNY290PN, so output voltage will be stable at 5VDC.

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