ADC12L030CIWM National Semiconductor, ADC12L030CIWM Datasheet - Page 32

• Manufacturer Part Number: ADC12L030CIWM
• Description: 3.3V Self-Calibrating 12-Bit Plus Sign Serial I/O A/D Converters with MUX and Sample/Hold
• Manufacturer: National Semiconductor

www.national.com
Application Hints
Note: V
caps. The DS14C335 has an internal DC-DC converter that generates the necessary TIA/EIA-232-E output levels from a 3.3V supply. There are four 0.47 µF
capacitors required for the DC-DC converter that are not shown in the above schematic.
The assignment of the RS232 port is shown below
A sample program, written in Microsoft
shown on the next page. The program prompts for data
mode select instruction to be sent to the A/D. This can be
found from the Mode Programming table shown earlier. The
data should be entered in “1”s and “0”s as shown in the table
with DI0 first. Next the program prompts for the number of
SCLKs required for the programmed mode select instruction.
For instance, to send all “0”s to the A/D, selects CH0 as the
+input, CH1 as the −input, 12-bit conversion, and 13-bit MSB
first data output format (if the sign bit was not turned off by a
previous instruction). This would require 13 SCLK periods
since the output data format is 13 bits. The part powers up
with No Auto Cal, No Auto Zero, 10 CCLK Acquisition Time,
12-bit conversion, data out with sign, 12- or 13-bit MSB First,
power up, and user mode. Auto Cal, Auto Zero, Power UP
and Power Down instructions do not change these default
settings. The following power up sequence should be fol-
lowed:
1. Run the program
2. Prior to responding to the prompt apply the power to the
3. Respond to the program prompts
It is recommended that the first instruction issued to the
ADC12L038 be Auto Cal (see Section 1.1).
ADC12L038
A
+
, V
D
+
, and V
REF
COM1
+
on the ADC12L038 each have 0.01 µF and 0.1 µF chip caps, and 10 µF tantalum caps. All logic devices are bypassed with 0.1 µF
Input Address
Output Address
(Continued)
™
QuickBasic, is
3FE
3FC
B7
X
X
B6
32
X
X
B5
X
X
CTS
B4
0
B3
X
X
B2
X
X
RTS
B1
X
DTR
DS011830-45
B0
X