Isolated dc-dc/minimum load

[Vindhyachal.takniki]

1. In one of my circuit I need isolated dc-dc converter.
2. Input is 4.5 to 6V & output required is 5V.
I have selected a 9V dc-dc & then will use a linear regulator to generate +5V afterward.

3. I had looked at Murata's NDY0509C , it will do the purpose. But only probelm I see is minimum load current. (55-83mA)

4. My circuit has low power consumption. System remian in sleep for most of time.
5. Does that mean I have to put a resistor to ground at output of dc-dc, so that it can maintain minimum load all the time.
e.g in my case R = 9V/83mA = 108 ohm.

6. Is there any other dc-dc for this purpose I can select

[langwadt]

1. In one of my circuit I need isolated dc-dc converter.
2. Input is 4.5 to 6V & output required is 5V.
I have selected a 9V dc-dc & then will use a linear regulator to generate +5V afterward.

3. I had looked at Murata's NDY0509C , it will do the purpose. But only probelm I see is minimum load current. (55-83mA)

4. My circuit has low power consumption. System remian in sleep for most of time.
5. Does that mean I have to put a resistor to ground at output of dc-dc, so that it can maintain minimum load all the time.
e.g in my case R = 9V/83mA = 108 ohm.

6. Is there any other dc-dc for this purpose I can select

how much power do you need?

[T3sl4co1l]

Yup.  So... don't do that?

Find a DC-DC that's actually rated for low current.  Preferably with a regulated output, no minimum load requirement, and good efficiency at light loads.  And use as small a device as you can... if it's "low power", do you *really* need three friggin watts isolated?

If nothing else, you can roll your own.  You might use one of those "micropower" switching controllers, that goes into pulse-skipping mode when lightly loaded.  Beware that the voltage sense / feedback circuit will probably need continuous power, however (usually to light an LED that throttles down the controller's output; so the LED needs maximum current (~mA?) exactly on light loads!).

Tim