suggestion for MC34063 similar spec but with disable

looking for suggestions for a switch mode chip, similar spec to MC34063 but with a disable pin.
I can kind of do it with MC34063 with additional transistor, but it still doesn't switch completely off,
and it needs this added transistor part.

input voltage nominal 12V (max possible 15V), output adjustable 8.5-10.5V, buck topology.
current will be < 200mA
buck/boost might be needed though

bonus if the chip might also include the switch diode.
should also price about the same as a MC34063, so nothing exotic.

Thanks

may be LM78S40?

Thanks, but the switching part is similar to 34063, forgot I actually got one of these left in my parts bin...now i recall I experimented with some and confoundedly
found the switcher to be less robust than MC34063 for some strange reason and gave up on them.

I have not yet found a single chip solution for this. So I guess using an external transistor is the way it must be.

Anyway, the method being used to disable the switcher is by switching ON a PNP connected between VCC and via a resistor to pin 5 (comparator input) thus biasing
it over 1.25V and in theory should switch the switcher off, which it does,.....but every now and then a switching pulse escapes through enough for an
output voltage of 3V instead of desirable 0V......so not entirely off is it?

but every now and then a switching pulse escapes through enough for an
output voltage of 3V instead of desirable 0V......so not entirely off is it?

Click to expand...

The behaviour isn't comprehensible according to the functional description of 34063 behaviour in AN920. No new output pulse will be scheduled while comparator output is off.

disable the switcher is by switching ON a PNP connected between VCC and via a resistor to pin 5 (comparator input)

Click to expand...

It is possible to switch off 34063 by the way of giving several volts to pin 3 (timing capacitor).