MCP3901EV-MCU16 Microchip Technology, MCP3901EV-MCU16 Datasheet - Page 29

• Manufacturer Part Number: MCP3901EV-MCU16
• Description: BOARD EVAL FOR 2CH ADC MCP3901
• Manufacturer: Microchip Technology

Specifications of MCP3901EV-MCU16

• Number Of Adc's: 2
• Number Of Bits: 24
• Data Interface: SPI™
• Inputs Per Adc: 1 Differential
• Input Range: ±1 V
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: MCP3901
• Silicon Manufacturer: Microchip
• Application Sub Type: ADC
• Kit Application Type: Data Converter
• Silicon Core Number: MCP3901, PIC24F, PIC24H, DsPIC33, PIC18F86J55
• Kit Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TABLE 5-6:
TABLE 5-7:
5.7
5.7.1
The MCP3901 contains an internal voltage reference
source, specially designed to minimize drift over
temperature. In order to enable the internal voltage
reference, the VREFEXT bit in the Configuration
register must be set to ‘0’ (Default mode). This internal
V
typical value of this voltage reference is 2.37V ±2%.
The internal reference has a very low typical
temperature coefficient of ±12 ppm/°C, allowing the
output codes to have minimal variation with respect to
temperature, since they are proportional to (1/V
The noise of the internal voltage reference is low
enough not to significantly degrade the SNR of the
ADC if compared to a precision, external low noise
voltage reference.
The output pin for the internal voltage reference is
REFIN+/OUT.
When the internal voltage reference is enabled, the
REFIN- pin should always be connected to AGND.
For optimal ADC accuracy, appropriate bypass
capacitors should be placed between REFIN+/OUT
and AGND. Decoupling at the sampling frequency,
around 1 MHz, is important for any noise around this
frequency will be aliased back into the conversion data
(0.1 µF ceramic and 10 µF tantalum capacitors are
recommended).
© 2010 Microchip Technology Inc.
0 1 1 1
0 1 1 1
0 0 0 0
1 1 1 1
1 0 0 0
1 0 0 0
0 1 1 1
0 1 1 1
0 0 0 0
1 1 1 1
1 0 0 0
1 0 0 0
REF
supplies reference voltage to both channels. The
Voltage Reference
INTERNAL VOLTAGE REFERENCE
1 1 1 1
1 1 1 1
0 0 0 0
1 1 1 1
0 0 0 0
0 0 0 0
1 1 1 1
1 1 1 1
0 0 0 0
1 1 1 1
0 0 0 0
0 0 0 0
OSR = 64 OUTPUT CODE EXAMPLES
OSR = 32 OUTPUT CODE EXAMPLES
ADC Output code (MSB First)
ADC Output code (MSB First)
1 1 1 1
1 1 1 1
0 0 0 0
1 1 1 1
0 0 0 0
0 0 0 0
1 1 1 1
1 1 1 1
0 0 0 0
1 1 1 1
0 0 0 0
0 0 0 0
1 1 1 1
1 1 1 1
0 0 0 0
1 1 1 1
0 0 0 0
0 0 0 0
1 1 1 1
1 1 1 1
0 0 0 0
1 1 1 1
0 0 0 0
0 0 0 0
REF
).
1 1 1 1
1 1 1 0
0 0 0 0
1 1 1 1
0 0 0 1
0 0 0 0
1 0 0 0
0 0 0 0
0 0 0 0
1 0 0 0
1 0 0 0
0 0 0 0
These bypass capacitors are not mandatory for correct
ADC operation, but removing these capacitors may
degrade the accuracy of the ADC. The bypass capaci-
tors also help the applications where the voltage
reference output is connected to other circuits. In this
case, additional buffering may be needed as the output
drive capability of this output is low.
5.7.2
When the VREFEXT bit is high, the two reference pins
(REFIN+/OUT, REFIN-) become a differential voltage
reference input. The voltage at the REFIN+/OUT pin is
noted as V
noted as V
given by the following equation:
EQUATION 5-4:
The specified V
REFIN- pin voltage (V
Typically, for single-ended reference applications, the
REFIN- pin should be directly connected to AGND.
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
REF
REF
DIFFERENTIAL EXTERNAL
VOLTAGE INPUTS
Hexadecimal
-. The differential voltage input value is
+ and the voltage at the REFIN- pin is
Hexadecimal
0x7FFFE0
0xFFFFF0
0x7FFFF0
0x800010
0x800000
REF
V
0x000000
0x7FFF80
0x7FFF00
0xFFFF80
0x800080
0x800000
0x000000
REF
range is from 2.2V to 2.6V. The
= V
REF
REF
-) should be limited to ±0.3V.
+ – V
MCP3901
20-Bit Resolution
17-Bit Resolution
REF
DS22192C-page 29
+ 524, 287
+ 524, 286
-
- 524, 288
- 524,287
+ 65, 535
+ 65, 534
Decimal
- 65, 536
Decimal
- 65,535
-1
-1
0
0