The TOPswitch flyback controller is a voltage mode flyback controller by Power integrations. It is the single most popular offline flyback controller in the world in terms of number of different SMPS’s that use it. It is a superb part, so why does app note 57 by Power integrations (attached) claim that it can be compensated by a “type 2” compensator? (A voltage mode flyback needs a type 3 compensator –surely?)
AN47 by power integrations:
https://ac-dc.power.com/sites/default/files/product-docs/an47.pdf
(top left of page 15 speaks of “type 2”, plus elsewhere in article)
O o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o
The Power integrations topswitch operate with a kind of “adjusted voltage mode”, do you agree?
If you look at fig 6 , page 4 of the topswitch-jx datasheet (below), then you see that as the control pin current (the error current), increases, the peak current level decreases, aswell as the duty cycle decreasing.
Such a decrease in peak primary current does not occur in “pure voltage mode” converters. Therefore, this is why the topswitch-jx is an “adjusted voltage mode” converter. Do you agree with this?
TOPswitch-jx datasheet:
https://ac-dc.power.com/sites/defaul..._datasheet.pdf
….the clever use of this “adjusted voltage mode” control by the topswitch-jx means that a type 2 compensator can be used to stabilise a flyback in ccm that uses topswitch-jx.
AN-47 by power integrations discusses how a type 2 compensator can be used with a power integrations topswitch-x.
AN-47 App Note on topswitch:
https://ac-dc.power.com/sites/defaul...-docs/an47.pdf
We know that topswitch-jx is of superb quality, because Dr Christophe Basso, probably amongst the world’s best SMPS writers, has set aside a whole chapter of his latest book “Designing control loops for linear and switching power supplies” “ to the topswitch-jx feedback loop.
AN47 by power integrations:
https://ac-dc.power.com/sites/default/files/product-docs/an47.pdf
(top left of page 15 speaks of “type 2”, plus elsewhere in article)
O o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o
The Power integrations topswitch operate with a kind of “adjusted voltage mode”, do you agree?
If you look at fig 6 , page 4 of the topswitch-jx datasheet (below), then you see that as the control pin current (the error current), increases, the peak current level decreases, aswell as the duty cycle decreasing.
Such a decrease in peak primary current does not occur in “pure voltage mode” converters. Therefore, this is why the topswitch-jx is an “adjusted voltage mode” converter. Do you agree with this?
TOPswitch-jx datasheet:
https://ac-dc.power.com/sites/defaul..._datasheet.pdf
….the clever use of this “adjusted voltage mode” control by the topswitch-jx means that a type 2 compensator can be used to stabilise a flyback in ccm that uses topswitch-jx.
AN-47 by power integrations discusses how a type 2 compensator can be used with a power integrations topswitch-x.
AN-47 App Note on topswitch:
https://ac-dc.power.com/sites/defaul...-docs/an47.pdf
We know that topswitch-jx is of superb quality, because Dr Christophe Basso, probably amongst the world’s best SMPS writers, has set aside a whole chapter of his latest book “Designing control loops for linear and switching power supplies” “ to the topswitch-jx feedback loop.
