how to design an protection circuit which can endure the 120V surge voltage?

hi guys,

could you give me some advise about how to design a effective protection circuit as mentioned and the cicuit should consist of the simple componets only, cause the boss do not wanna spend too much money on it!! .i have tried some devices like zener diode or power TVS,but they can not solved my problem completely,and the 120v surge voltage we used as test case was defined by IEC610000-4-5,thanks a lot.

- you didn't refer to a IEC61000-4-5 test class.
- to design a protection circuit, the load characteristics must be known (overvoltage accepted without damage, power respectively load impedance)

hi FvM,thanks for your reply. there are some information about the background of the issue, the protection circuit we talk above was used for chrger port of mobile phone,and i knew the IEC61000-4-5 was used as test case for the device like charge adapter ,in fact,there is no standard for surge test can the portable device refer to ,so we have to simulate the surge might charger port faced .(some protect components like zener diode were also tested in this way)but ,the Vpeak of surge voltage was lower than requirement of IEC61000-4-5. as for the characteristics of the load ,you know ,it will change along with the changing of status of Li battery. so,i want to design a protection circuit which can work in this situation ,i hope you can understand what i say and share something useful with me. thank you .

For low voltage supply, TVS diodes are mostly providng effective surge protection. What problems do you see with TVS?

the TVS or zener diode with high power dissipation can solve my problem,but it is very expansive too，so,i have to choose the method cheap and effective.