SLIM-ADC-16
Analog to Digital
Converter
Updated
4-30-08. Update page for name changes.
No pwb or schematic changes.
Updated
7-14-08. Parts list revised for incorrect
switch (SW1, SW2) part number.
SLIM-ADC-16,
AtoD Converter, 16 bit, size
A
Use your mouse's "right click" and "Save Link" to download:
a. SKSLIM-ADC-16,
Schematic, in ExpressPCB software.
b. PWB-ADC10,
Base
artwork for PWB, in ExpressPCB software.
Use this drawing to order the pwb from Express, or to locate
the parts on the SLIM-ADC-16.
c. PLSLIM-ADC-16 rev A,
Parts List in text format. Open with Exel or Lotus,
etc.
The SLIM-ADC-16 is a dual 16 bit converter that uses
the
AD7685. There is no manual adjustment resistor to set the A to D
range. It is not needed to obtain excellent resolution in the
MSA and VNA systems. Each AtoD will digitize its
input
of 0 to 5 volts to a bit value of 0 to 65536 bits. This
equates
to 76.3 uv per bit.
Both A/D's will
capture, and clock out their
data concurrently. The software commands both U2 and
U3 to
begin conversion with a single toggle of the signal, "CONVERT".
16 toggles of the signal, "SERCLOCK", causes the I.C. to
output a serial stream of
16 bits. The SDO outputs of the AtoD I.C.'s have
limited current
capability. Therefore, Q1 and Q2 provide current
sinking to
drive the "WAIT" and "ACK" lines to the LPT port of the Computer.
The Computer's LPT port
is nominally a TTL compatable input with a pull up resistor to
+5 volts.
The circuit is designed with thru hole pads, to
allow each input to be connected
to an external switch. The switch selects the amount of capacitance to
be placed in shunt with the
input. Each switch is a single pole, dual throw, with a
non-connecting center position. This allows a selection of
3
different integration times (Video Bandwidth). This module is
expected to be mounted very close to the front panel of the integrated
system so that the user can mount the switches on the front panel and
maintain very short leads from the switches to the bottom of the module.
The base PWB has the part number,
PWB-ADC10. The "10" signifies the use of a 10 pin MSOP
package. There are other A/D I.C.s with this package. More
A/D SLIMs could be created from this pwb design.
SKSLIM-ADC-16, Schematic of
SLIM-ADC-16