Is there a device that can...

[Arie de Muynck]

"Frank Bemelman" ...

"Winfield Hill" ...

Current-switched level shifting, by contrast, saves two resistors
and also has a few other advantages (there is a requirement that
the switched voltage be higher than the logic-control voltage).

. hv in ---+-- E C ------- out
. | B Q2 switched
. R2 2.7k | pnp
. | |
. '-----+
. |
. C
. logic ----- B Q1
. control E npn
. 5.0V |
. R1 4.3k
. |
. gnd

The current provided by R1 is the desired base-drive current, plus
the base discharge current Vbe/R2. The base-drive current level is
provided independently of any changes in the switched power voltage.
The circuit is suitable for switching high voltages, for example
if Q1 is a mpsA42, up to 300V can be switched. If Q2 is a MOSFET,
chose R2/R1 to provide about 12V of gate voltage for the ON state.

Hey, I like that one. You just saved me 500 resistors per year
Now I have to find a way to buy the Guru a cup of coffee and a
donut...

If EVER that BC junction shorts you will blow the micro.
Done it, got bitten, came back...

Arie de Muynck

 

[Frank Bemelman]

"Arie de Muynck" <no.spam.please@xxx.com> schreef in bericht
news:42aadf61$1$70907$e4fe514c@news.xs4all.nl...

"Frank Bemelman" ...
"Winfield Hill" ...

Current-switched level shifting, by contrast, saves two resistors
and also has a few other advantages (there is a requirement that
the switched voltage be higher than the logic-control voltage).

. hv in ---+-- E C ------- out
. | B Q2 switched
. R2 2.7k | pnp
. | |
. '-----+
. |
. C
. logic ----- B Q1
. control E npn
. 5.0V |
. R1 4.3k
. |
. gnd

The current provided by R1 is the desired base-drive current, plus
the base discharge current Vbe/R2. The base-drive current level is
provided independently of any changes in the switched power voltage.
The circuit is suitable for switching high voltages, for example
if Q1 is a mpsA42, up to 300V can be switched. If Q2 is a MOSFET,
chose R2/R1 to provide about 12V of gate voltage for the ON state.

Hey, I like that one. You just saved me 500 resistors per year
Now I have to find a way to buy the Guru a cup of coffee and a
donut...

If EVER that BC junction shorts you will blow the micro.
Done it, got bitten, came back...

Ai, there goes the coffee and the donut.

--
Thanks, Frank.
(remove 'q' and 'invalid' when replying by email)