mandatory Schottky diodes ?

[coresta]

Hi , are these mandatory even for low output power with 12v psu only ? cheers

 

[BWRX]

Do you mean diodes in parallel with the output FETs?

If so, they are not necessarily mandatory. They shouldn't hurt anything if they are used though.

 

[coresta]

yes Brian , those Dh and Do on Tripath sheets

 

[BWRX]

If you operate the chips close to their maximum voltage or with a lower impedance load they are recommended because the output inductor can cause the switching node voltage to swing above the supply voltage or below ground. The diodes clamp the switching node voltage in case that happens. They can also carry the inductor current during dead time (particularly for the lower FET).

Schottky diodes with a low forward voltage drop and low junction capacitance will be the most effective.

 

[FastEddy]

Schottky Diodes Mandatory? ... well, no.

Essential for "golden ear" audio equipment? ... well, yes, sometimes.

http://en.wikipedia.org/wiki/Schottky_diode ... " this diode can cease conduction faster than an ordinary PN rectifier diode. This property in turn allows a smaller device area, which also makes for a faster transition. This is another reason why Schottky diodes are useful in switch-mode power converters; the high speed of the diode means that the circuit can operate at frequencies in the range 200 kHz to 2 MHz, allowing the use of small inductors and capacitors with greater efficiency than would be possible with other diode types. ..."

http://en.wikipedia.org/wiki/Walter_H._Schottky ... He discovered / invented the diode. A hardware hacker of the first water ... And one of my heros.