ron
Junior Member level 3
Hi All,
Has anyone used any of the Astec/Texas Instruments Point-of-Load Switching Converters sucessfully at all ???
I am currently evaluating both the Astec ATHk12 and Texas PTH12020 Modules (Almost Identical) which are 12V Input, 1 to 5.5V Output (adjustable), 18 Amps maximum output current.
I am currently pulling my hair out at the moment with these, as I am having a problem with the 'Inhibit' input pin. According to the datasheets for these modules, leaving this pin open circuit will cause the module to operate completely normally, and pulling the same pin low will cause the module to switch off.
I only need to drive a simple 0.5 ohm metal heater strip with the output from this module, but am finding that the module will not operate with this load unless the 'Inhibit' pin is touched with my finger or simply with a scope probe for example. It is though this pin is kind of floating or something.
Adding a 100k external pullup to this pin does seem to cause the module to work everytime, but the datasheet firmly states that the module has its own internal pullup and only needs to be left open circuit for completely normal operation. I can even actually see the pullup on the module (50k) but cant get the module to work correctly without doing things to the inhibit pin.
Looking at this pin with the scope also seems to show some sort of induced waveform on it, at the same frequency as the converter is running at (350khz). I am currently convinced that it must have some sort of design problem, but surely they must of sold thousands of these things and are not that careless are they ?????
Can anyone shed some light on this matter at all as even Astec are puzzled too at the moment.
Any advice from users of these little modules would be Very Gratefully Appreciated. Please help me !!!!!!!
Thanks.
Ron
Has anyone used any of the Astec/Texas Instruments Point-of-Load Switching Converters sucessfully at all ???
I am currently evaluating both the Astec ATHk12 and Texas PTH12020 Modules (Almost Identical) which are 12V Input, 1 to 5.5V Output (adjustable), 18 Amps maximum output current.
I am currently pulling my hair out at the moment with these, as I am having a problem with the 'Inhibit' input pin. According to the datasheets for these modules, leaving this pin open circuit will cause the module to operate completely normally, and pulling the same pin low will cause the module to switch off.
I only need to drive a simple 0.5 ohm metal heater strip with the output from this module, but am finding that the module will not operate with this load unless the 'Inhibit' pin is touched with my finger or simply with a scope probe for example. It is though this pin is kind of floating or something.
Adding a 100k external pullup to this pin does seem to cause the module to work everytime, but the datasheet firmly states that the module has its own internal pullup and only needs to be left open circuit for completely normal operation. I can even actually see the pullup on the module (50k) but cant get the module to work correctly without doing things to the inhibit pin.
Looking at this pin with the scope also seems to show some sort of induced waveform on it, at the same frequency as the converter is running at (350khz). I am currently convinced that it must have some sort of design problem, but surely they must of sold thousands of these things and are not that careless are they ?????
Can anyone shed some light on this matter at all as even Astec are puzzled too at the moment.
Any advice from users of these little modules would be Very Gratefully Appreciated. Please help me !!!!!!!
Thanks.
Ron