MCP3423-E/UN Microchip Technology, MCP3423-E/UN Datasheet - Page 15

• Manufacturer Part Number: MCP3423-E/UN
• Description: IC ADC 18BIT 3.75SPS 2CH 10-MSOP
• Manufacturer: Microchip Technology

Specifications of MCP3423-E/UN

• Data Interface: I²C, Serial
• Number Of Bits: 18
• Sampling Rate (per Second): 3.75
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 10-TFSOP (0.118", 3.00mm Width)
• Resolution (bits): 18bit
• Sampling Rate: 3.75SPS
• Input Channel Type: Differential
• Supply Voltage Range - Analog: 2.7V To 5.5V
• Supply Current: 145µA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: MCP3423EV - BOARD EVAL 18BIT 2CH ADC MCP3423
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

4.9
4.9.1
The digital output code is proportional to the input
voltage and PGA settings. The output data format is a
binary two’s complement. With this code scheme, the
MSB can be considered a sign indicator. When the
MSB is a logic ‘0’, the input is positive. When the MSB
is a logic ‘1’, the input is negative. The following is an
example of the output code:
a.
b.
c.
The MSB (sign bit) is always transmitted first through
the I
conversion is 18, 16, 14, or 12 bits depending on the
conversion rate selection bit settings by the user.
The output codes will not roll-over even if the input
voltage exceeds the maximum input range. In this
case, the code will be locked at 0111...11 for all
voltages greater than (V
1000...00 for voltages less than -V
Table 4-2
input levels for 18 bit conversion mode.
shows an example of minimum and maximum output
codes for each conversion rate option.
The number of output code is given by:
EQUATION 4-2:
The LSB of the data conversion is given by:
EQUATION 4-3:
© 2009 Microchip Technology Inc.
Number of Output Code =
Where:
Where:
=
for a negative full scale input voltage: 100...000
for a zero differential input voltage: 000...000
for a positive full scale input voltage: 011...111
Example: (CHn+ - CHn-)
Example: (CHn+ - CHn-)
Example: (CHn+ - CHn-) = 0
2
See
C serial data line. The resolution for each
N
(
Maximum Code
Digital Output Codes and
Conversion to Real Values
shows an example of output codes of various
Table 4-3
DIGITAL OUTPUT CODE FROM
DEVICE
LSB
=
Resolution, which is programmed in
the Configuration Register.
=
2 V
--------------------- -
for Maximum Code
×
2
+
N
REF
1
) PGA
REF
×
=
•
•
PGA = -2.048V
PGA = 2.048V
2 2.048V
--------------------------
- 1 LSB)/PGA and
×
×
2
(
---------------------------------------- -
N
CHn+ CHn-
2.048V
–
REF
Table 4-3
/PGA.
)
Table 4-1
setting. The measured unknown input voltage is
obtained by multiplying the output codes with LSB. See
the following section for the input voltage calculation
using the output codes.
TABLE 4-1:
TABLE 4-2: EXAMPLE OF OUTPUT CODE
TABLE 4-3:
Note 1:
Resolution
Note:
[CHn+ - CHn-] • PGA
Setting
Resolution Setting
12
14
16
18
Input Voltage:
2:
V
REF
shows the LSB size of each conversion rate
< -V
-1 LSB
-2 LSB
≥
- V
2 LSB
1 LSB
MSB is a sign indicator:
0: Positive input (CHn+ > CHn-)
1: Negative input (CHn+ < CHn-)
Output data format is binary two’s
complement.
Maximum n-bit code = 2
Minimum n-bit code = -1 x 2
V
12 bits
14 bits
16 bits
18 bits
- 1 LSB
0
REF
REF
REF
FOR 18 BITS (NOTE 1, NOTE 2)
Data Rate
3.75 SPS
240 SPS
60 SPS
15 SPS
RESOLUTION SETTINGS VS.
LSB
MINIMUM AND MAXIMUM
OUTPUT CODES (NOTE)
MCP3422/3/4
011111111111111111
011111111111111111
000000000000000010
000000000000000001
000000000000000000
111111111111111111
111111111111111110
100000000000000000
100000000000000000
Minimum
-131072
-32768
Digital Output Code
-2048
-8192
Code
N-1
DS22088C-page 15
15.625 µV
62.5 µV
250 µV
- 1
N-1
1 mV
LSB
Maximum
131071
32767
Code
2047
8191