MCP3421EV Microchip Technology, MCP3421EV Datasheet - Page 11

• Manufacturer Part Number: MCP3421EV
• Description: BOARD EVAL FOR MCP3421 SOT23-6
• Manufacturer: Microchip Technology

Specifications of MCP3421EV

• Design Resources: MCP3421EV Gerber Files
• Number Of Adc's: 1
• Number Of Bits: 18
• Sampling Rate (per Second): 4
• Data Interface: Serial
• Inputs Per Adc: 1 Single Ended
• Input Range: ±2.5 V
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Utilized Ic / Part: MCP3421
• Silicon Manufacturer: Microchip
• Application Sub Type: ADC
• Kit Application Type: Data Converter
• Silicon Core Number: MCP3421
• Kit Contents: Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Not applicable / Not applicable

4.0
4.1
The MCP3421 is a low-power, 18-Bit Delta-Sigma A/D
converter with an I
contains an on-board voltage reference (2.048V),
programmable gain amplifier (PGA), and internal
oscillator. When the device powers up (POR is set), it
automatically resets the configuration bits to default
settings.
Device default settings are:
• Conversion bit resolution: 12 bits (240 sps)
• PGA gain setting: x1
• Continuous conversion
Once the device is powered-up, the user can
reprogram the configuration bits using I
interface any time. The configuration bits are stored in
volatile memory.
User selectable options are:
• Conversion bit resolution: 12, 14, 16, or 18 bits
• PGA Gain selection: x1, x2, x4, or x8
• Continuous or one-shot conversion
In the Continuous Conversion mode, the device
converts the inputs continuously. While in the One-Shot
Conversion mode, the device converts the input one
time and stays in the low-power standby mode until it
receives another command for a new conversion.
During the standby mode, the device consumes less
than 1 µA maximum.
4.2
The device contains an internal Power-On-Reset
(POR) circuit that monitors power supply voltage (V
during operation. This circuit ensures correct device
start-up at system power-up and power-down events.
The POR has built-in hysteresis and a timer to give a
high degree of immunity to potential ripples and noises
on the power supply. A 0.1 µF decoupling capacitor
should be mounted as close as possible to the V
for additional transient immunity.
The threshold voltage is set at 2.2V with a tolerance of
approximately ±5%. If the supply voltage falls below
this threshold, the device will be held in a reset
condition. The typical hysteresis value is approximately
200 mV.
© 2009 Microchip Technology Inc.
DESCRIPTION OF DEVICE
OPERATION
General Overview
Power-On-Reset (POR)
2
C serial interface. The device
2
C serial
DD
DD
pin
)
The POR circuit is shut-down during the low-power
standby mode. Once a power-up event has occurred,
the
(approximately 300 µs) before a conversion can take
place. During this time, all internal analog circuitries are
settled before the first conversion occurs.
illustrates the conditions for power-up and power-down
events under typical start-up conditions.
When the device powers up, it automatically resets
and sets the configuration bits to default settings. The
default configuration bit conditions are a PGA gain of
1 V/V and a conversion speed of 240 SPS in
Continuous Conversion mode. When the device
receives an I
performs an internal reset similar to a Power-On-Reset
event.
FIGURE 4-1:
4.3
The device contains an on-board 2.048V voltage
reference. This reference voltage is for internal use
only and not directly measurable. The specifications of
the reference voltage are part of the device’s gain and
drift specifications. Therefore, there is no separate
specification for the on-board reference.
4.4
The differential analog input channel has a switched
capacitor structure. The internal sampling capacitor
(3.2 pF for PGA = 1) is charged and discharged to
process a conversion. The charging and discharging of
the input sampling capacitor creates dynamic input
currents at each input pin. The current is a function of
the
proportional to the internal sampling capacitance,
sampling frequency, and PGA setting.
V
2.2V
2.0V
DD
differential
device
Reset Start-up
Internal Voltage Reference
Analog Input Channel
300 µS
2
C General Call Reset command, it
requires
input
Normal Operation
POR Operation.
voltages,
additional
MCP3421
DS22003E-page 11
and
Reset
delay
Figure 4-1
inversely
Time
time