MUN5333DW1T1G surge current...

[Piotr Wyderski]

Hi,

I need an array of high-side switches, not more than 50mA per channel.
The MUN5333DW1T1G would be handy. Unfortunately, the datasheet specifies
100mA max. continuous I_C only and I can\'t see anything about its surge
handling capabilities. What should I assume for an 8/20us ESD pulse?
Does 1A looks OK?

Best regards, Piotr

 

[server]

On Mon, 20 Jun 2022 18:05:23 +0200, Piotr Wyderski
<bombald@protonmail.com> wrote:

Hi,

I need an array of high-side switches, not more than 50mA per channel.
The MUN5333DW1T1G would be handy. Unfortunately, the datasheet specifies
100mA max. continuous I_C only and I can\'t see anything about its surge
handling capabilities. What should I assume for an 8/20us ESD pulse?
Does 1A looks OK?

Best regards, Piotr

Why use NPNs as high-side switches?

Single transistors seldom include ESD protection.

What\'s the application?


--

Anybody can count to one.

- Robert Widlar

 

[Piotr Wyderski]

jlarkin@highlandsniptechnology.com wrote:

> Why use NPNs as high-side switches?

The high-side switch is the PNP half. The NPN one is a level translator
from the 2.5V FPGA enable.

> Single transistors seldom include ESD protection.

There will be a 600W 14V TVS, with 29V max clamp voltage during the
surge. The question is what should be the value of the resistor between
the TVS and the high-side collector.

> What\'s the application?

A digitizer for an array of mechanical switches. The 20-50mA is the
wetting current, one switch will be tested at a time in a round-robin
fashion to limit the supply current.

Best regards, Piotr

 

[John Larkin]

On Mon, 20 Jun 2022 19:39:43 +0200, Piotr Wyderski
<bombald@protonmail.com> wrote:

jlarkin@highlandsniptechnology.com wrote:

Why use NPNs as high-side switches?

The high-side switch is the PNP half. The NPN one is a level translator
from the 2.5V FPGA enable.

Single transistors seldom include ESD protection.

There will be a 600W 14V TVS, with 29V max clamp voltage during the
surge. The question is what should be the value of the resistor between
the TVS and the high-side collector.

Zero?

What\'s the application?

A digitizer for an array of mechanical switches. The 20-50mA is the
wetting current, one switch will be tested at a time in a round-robin
fashion to limit the supply current.

Best regards, Piotr

We like TPIC6595 whan we need a lot of current-sinking drivers from an
FPGA. It\'s very rugged, controlled avalanche. You\'d still need the
PNPs.

There was a cool octal pull-up driver, UCN5815A, but it\'s unobtanium
now.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[Martin Rid]

Piotr Wyderski <bombald@protonmail.com> Wrote in message:r
> Hi,I need an array of high-side switches, not more than 50mA per channel. The MUN5333DW1T1G would be handy. Unfortunately, the datasheet specifies 100mA max. continuous I_C only and I can\'t see anything about its surge handling capabilities. What should I assume for an 8/20us ESD pulse? Does 1A looks OK? Best regards, Piotr

Have a look at Micrel eg microchip. The have some dual tsop \'s

Cheers
--


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[Piotr Wyderski]

John Larkin wrote:

There will be a 600W 14V TVS, with 29V max clamp voltage during the
surge. The question is what should be the value of the resistor between
the TVS and the high-side collector.


Zero?

When the surge is negative with respect to the collector, the situation
is under control: it will be clamped to 29V and the transistor can
withstand 50V. If the surge is positive, the PNP will be driven into the
reverse active region with sort of 5V V_EBO. I can\'t find the TVS
forward voltage at the I_MAX and so I assumed it would be prudent to
limit the I_C a bit. Indeed, zero was my initial approach, but then some
afterthoughts started coming.

We like TPIC6595 whan we need a lot of current-sinking drivers from an
FPGA. It\'s very rugged, controlled avalanche.

I love the part. FYI, you can make 8 flybacks using the TPIC6595 by
modulating the OE. Works OK up to a MHz: I gave up here, maybe it still
can go faster. The snubber is built-in, you just connect the transformer
and call it a day.

But since a PNP per channel is one part to add to the board and the
pre-biased dual is one part as well, just by connecting pins 5 and 6 you
end up with a logic-level-driven high-side switch, eliminating the HV
shift register from the BOM. And the board must be small, so it matters.

Best regards, Piotr