Tutorial repairing battery charger circuit viper22a dip-8 viper22 and viper12a


Typical applications of VIPER22A DIP-8 VIPER22A SOP-8 

We ussually see VIPER22A in battery charger adapters, standby power supplies for TV or monitors, auxiliary supplies for motor control, etc. Mosf of problems in these circuits is VIPER22A broken.

Pin connections and function of VIPER22A DIP-8 VIPER22A SOP-8

Current and voltage conventions in VIPER22A

VDD: Power supply of the control circuit inside VIPER22A

SOURCE (S) : Power MOSFET source and circuit ground reference

Drain (D): Power MOSFET drain. Also used by the internal high voltage current source during start up phase for charging the external VDD capacitor

FB : Feedback input. The useful voltage range extends from 0 V to 1 V, and defines the peak drain MOSFET current. The current limitation, which corresponds to the maximum drain current, is obtained for a FB pin shorted to the SOURCE pin

How does VIPER22A operate in battery charger circuit ?

We first start with 220VAC input, 220VAC line goes through F1 fuse ( F1 fuse to protect circuit ). C3 capacitor and T2 coil is input voltage noise filter. After noise filter, 200VAC line comes to bridge rectifier, it converts 200VAC to 300VDC. C4 capacitor to make 300VDC flatter. The flat 300VDC Voltage goes to the primary coil of T1 pulse transformer then to Drain pin of VIPER22A. Inside VIPER22A also has a Mosfet, this Drain pin of VIPER22A is the same Drain pin of Mosfet. Then the S pin of VIPER22A connects to GND of 300VDC Voltage. The second primary coil of T1 pulse transformer creates voltage, it is converted to DC voltage by D3 diode. This converted DC Voltage connected to VDD of VIPER22A, supply power to VIPER22A. The second primary coil of T1 pulse transformer creates voltage, it is converted to DC voltage by D3 diode. This converted DC Voltage connected to VDD of VIPER22A, supplY power to VIPER22A. The manufacture also create inside VIPER22A a pulse generator block, this block create pulse to G pin of mosfet, switch on and off 300VDC voltage line at a certain frequency, so that way there will appear induction current at secondary coil of T1 pulse transformer. If you want to understand more about pulse power supply circuit working, please read reference articles linked below.

At secondary coil, the output voltage of T1 pulse is converted to DC voltage by D2 diode, and then flatted  by C1 capacitor. The D5 diode convert secondary voltage to DC voltage to supply power TSM101 IC. The TM101 and ISO1 opto are combined together to create a voltage feedback system to VIPER22A to make DC output voltage be stable. inside TMS101 has a voltage reference opam and a current reference opam. R8 and R9 resistors are combined to be a voltage divider circuit then the voltage of R9 resistor goes to TMS101 and reference to voltage reference.  The current located R7 resistor also goes to TMS101 and refernce to current refernce. TMS101 uses OR logic circuit to creat output signal to turn ON or OFF ISO1 opto. When ISO1 opto turns ON OR OFF , it transmits signal to FB pin of VIPER22A , so pulse generator will change pulse frequency and pulse width moduration to make OUTPUT DC voltage stable.

So conclusion, we have explain in easy way to understand how VIPER22A works in a pulse power supply circuit, so if you have any ideas or questions feel free to ask and comment below.

How about Viper12A? HOW does VIPER12A work in pulse power supply ? what IC CAN replace VIPER12A?

Pin connection of VIPER12A

Current and voltage conventions of VIPER12A

As you can see Pin connector, pin functions, current and voltage conventions of VIPER12A and VIPER22A are the same. So We absolutely replace VIPER12A by VIPER22A because output power supply of VIPER22A 20W is biger than outpout power supply VIPER12A 13W. in return, you can not replace VIPER22A by VIPER12A because of smaller output power supply.



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