PCB DESIGN - All In One 32 inputs with 74HC4851

[Synthex]

Ar you using the free version of diptrace ?

I use the trial version. Why ?

[TriggerThis]

Because I can count 336 pins on your board .. you can't do that with the free 250 pins version of diptrace. You must be using the trial version then ?

[Synthex]

Because I can count 336 pins on your board .. you can't do that with the free 250 pins version of diptrace. You must be using the trial version then ?

Yes ...

[Synthex]

The MAX4558CPE, an 74HC4851 alternative !!!

Very available ! : http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2018/t/or

Datasheet : http://datasheets.maxim-ic.com/en/ds/MAX4558-MAX4560.pdf

"ESD-Protected X, Y, Z and X_, Y_, Z_ Pins
±15kV (Human Body Model)
±12kV (IEC 1000-4-2, Air-Gap Discharge)
±8kV (IEC 1000-4-2, Contact Discharge) "

"Pin-Compatible with Industry-Standard 74HC4051"

"Signals on any terminal exceeding VCC or VEE are clamped by internal diodes.
Limit forward diode current to maximum current rating."

"In addition to the SCRs at the ESD-protected pins,
these devices provide internal diodes connected to the
supplies. Resistors placed in series with these diodes
limit the current flowing into the supplies during an ESD
strike. The diodes protect the X, Y, Z and X_, Y_, Z_
pins from overvoltages due to improper power-supply
sequencing."

"The MAX4558 is typical of most
CMOS analog switches. They have three supply pins:
VCC, VEE, and GND. VCC and VEE drive the internal
CMOS switches and set the limits of the analog voltage
on every switch. Internal reverse ESD-protection diodes
connect between each analog signal pin and both VCC
and VEE. If any analog signal exceeds VCC or VEE, one
of these diodes conducts. The only currents drawn
from VCC or VEE during normal operation are the leakage
currents of these ESD diodes.
Although the ESD diodes on a given signal pin are
identical and therefore fairly well balanced, they are
reverse biased differently. Each is biased by either VCC
or VEE and the analog signal. Their leakage currents
vary as the signal varies. The difference in the two
diode leakages to the VCC and VEE pins constitutes the
analog signal-path leakage current. All analog leakage
current flows between each input and one of the supply
terminals, not to the other switch terminal. This is why
both sides of a given switch can show leakage currents
of either the same or opposite polarity.
VCC and GND power the internal logic and logic-level
translators, and set the input logic limits. The logic-level
translators convert the logic levels into switched VCC
and VEE signals to drive the gates of the analog switch.
This drive signal is the only connection between the
logic supplies and logic signals and the analog supplies."

[jodev]

Hello,
I plan to make megadrum32/32 inputs,
but I find the pcb too small (iréalisable by method do-it-yourself)
I would like to know if it is possible to have the schematic of circuit all In One 32 inputs with 74HC4851 ?
in order to remake the pcb a little larger.
thank you.

jodev

[dmitri]

Great! So we can get rid of all Schottky diodes? Where would you buy it? I don't see it on Farnell.

[Synthex]

Does anyone know any better autorouter PCB layout software than DipTrace ?
After an hour of calculation, he gave me this design !!!

PCB_NIMP_001.GIF

[Synthex]

Great! So we can get rid of all Schottky diodes?

Like with the 74HC4851.

Where would you buy it? I don't see it on Farnell.

You can find it directly on the Maxim web site.

[dmitri]

Does anyone know any better autorouter PCB layout software than DipTrace ?
After an hour of calculation, he gave me this design !!!

Never used autorouting nor autoplacing - neither produce acceptable results.

[Synthex]

neither produce acceptable results.

I agree with you, but motherboard PCB for computers are not done by hand anyway !