MCP3422A0-E/MF MICROCHIP [Microchip Technology], MCP3422A0-E/MF Datasheet - Page 33

• Manufacturer Part Number: MCP3422A0-E/MF
• Manufacturer: MICROCHIP [Microchip Technology]

6.2
The MCP3422/3/4 devices can be used for broad
ranges of sensor and data acquisition applications.
Figure 6-5
battery voltage and current using the MCP3422 device.
Channels 1 and 2 are measuring the voltage and the
current, respectively.
When the input voltage is greater than the internal ref-
erence voltage (V
divider circuit to prevent the output code from being
saturated. In the example, R
divider. The R
than the internal reference voltage (V
FIGURE 6-5:
© 2009 Microchip Technology Inc.
(Rechargeable)
Application Examples
shows a circuit example measuring both the
Battery
1
and R
REF
V
R
IN
1
2
Battery Voltage and Charging/Discharging Current Measurement.
and R
= 2.048V), it needs a voltage
are set to yield V
=
------------------
R
Discharging Current
1
R
2
1
+
Charging
Current
V
2
= Voltage Divider
and R
R
BAT
2
×
V
REF
2
BAT
form a voltage
= 2.048V).
IN
to be less
R
R
V
1
2
IN
10 µF
0.1 µF
For the current measurement, the device measure the
voltage across the current sensor, and converts it by
dividing the measured voltage by a known resistance
value. The voltage drops across the sensor is waste.
Therefore, the current measurement often prefers to
use a current sensor with smaller resistance value,
which, in turn, requires high resolution ADC device.
The device can measure the input voltage as low as
2 µV range (or current in ~ µA range) with 18 bit
resolution and PGA = 8 settings.
The MSB (= sign bit) of the output code determines the
direction of the current, which identifies the charging or
the discharging current.
1
2
3
4
SDA
Current Sensor
5 kΩ
V
CH1+
CH1-
MCP3422
SDA
DD
CH2+
CH2-
SCL
V
SS
8
7
6
5
MCP3422/3/4
SCL
5 kΩ
(MASTER)
To Battery
To MCU
V
DS22088C-page 33
DD
To Load