What is the jelly bean DAC du jour?

[Arlet]

I've been searching for a while for some tips to roll at least 12
channels of SD ADCs into an FPGA, with external 2nd order modulators
(mostly because the audio ADCs' PGAs aren't guaranteed stable enough
for me over -400C to +60C, and the simple sinc3 decimation filters in
industrial ADCs don't have the alias rejection I need). Any tips or
links appreciated, on the FPGA approach or on better ADCs.
Tony (remove the "_" to reply by email)

Did you look at the AD1555 ? It produces a digital bitstream, which you
could feed into your own FPGA based filter.

 

[Tony]

Did you look at the AD1555 ? It produces a digital bitstream, which you
could feed into your own FPGA based filter.

Thanks. It looks like a nice chip, but at $81 each, my 12 channels
would be about $950 over budget. I'm guessing it's an older design.

Regards,
Tony
Tony (remove the "_" to reply by email)

 

[Piglit]

Hello Folks,

Haven't used DACs in a while, did it with PWM all the time. Now I need
to design something that requires lots of low noise DC levels to be set.

What is the common jelly-bean 8-bit multi-DAC with a serial bus these days?

The requirements would be the usual. Multi-sourced if possible, lots of
channels, under 50c/channel or at least under $1/channel, 8 bits or
more, serial bus with two or at the most three wires, speed can be in
the low kHz range. A chip select would be nice but that could also be
handled by gating logic.

I have seen some nice octal 8-bitters like the TLC5628 which
unfortunately needs an extra load command line (but that would be ok).
Don't know whether that one is a mainstream part and I want to avoid
settling for a boutique part, which is why I am asking.

Then there'll be the challenge to bus the data to several dozen modules
with the DACs on them but that's a whole 'nother matter. Got to wait
until the guys tell me what the bus is going to be. Hopefully nothing
that needs lots of arbitration.

What the world needs is an 8 bit version of the TDA8444
(I2C in, 8 x 6 bit analog out, costs next to nothing)
M

 

[Joerg]

What the world needs is an 8 bit version of the TDA8444
(I2C in, 8 x 6 bit analog out, costs next to nothing)
M

It's around $2 a pop, not exactly "nothing" for an octal 6-bitter. Here
is an octal 8-bit DAC for less (around $1.50):
http://www.rohm.com/products/databook/general/pdf/bh2226fv-e.pdf

 

[Piglit]

It's around $2 a pop, not exactly "nothing" for an octal 6-bitter. Here
is an octal 8-bit DAC for less (around $1.50):
http://www.rohm.com/products/databook/general/pdf/bh2226fv-e.pdf

Almost got interested in that one (I use the 8444 in all sorts of
things and
wouldn't mind the extra resolution) but the Rohm part seems to be
unobtanium
(in findchips). Where can these beasties be found in non-enormous
quantities
for a buck and a half ?
cheers
M

 

[Joerg]

Joerg wrote:




Almost got interested in that one (I use the 8444 in all sorts of
things and
wouldn't mind the extra resolution) but the Rohm part seems to be
unobtanium
(in findchips). Where can these beasties be found in non-enormous
quantities
for a buck and a half ?

Don't know about non-enormous quantities but Digikey has 7500 of them in
stock. $1.45/2500. Usually my clients go through that qty in a jiffy.