MCP6401R-ESLASHST datasheet(16/38 Pages) MICROCHIP

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MCP6401/1R/1U/2/4

DS22229B-page 16

4.7.2

BATTERY CURRENT SENSING

The MCP6401/1R/1U/2/4 op amps’ Common Mode

Input Range, which goes 0.3V beyond both supply

rails, supports their use in high-side and low-side

battery current sensing applications. The low quiescent

current (45 µA, typical) helps prolong battery life, and

the rail-to-rail output supports detection of low currents.

Figure 4-9 shows a high side battery current sensor

circuit. The 10

Ω resistor is sized to minimize power

losses. The battery current (IDD) through the 10Ω

resistor causes its top terminal to be more negative

than the bottom terminal. This keeps the Common

Mode input voltage of the op amp below VDD, which is

within its allowed range. The output of the op amp will

also be below VDD, which is within its Maximum Output

Voltage Swing specification.

FIGURE 4-9:

Supply Current Sensing.

4.7.3

INSTRUMENTATION AMPLIFIER

The MCP6401/1R/1U/2/4 op amps are well suited for

conditioning

sensor

signals

battery-powered

applications. Figure 4-10 shows a two op amp

instrumentation amplifier, using the MCP6402, that

works well for applications requiring rejection of

Common Mode noise at higher gains. The reference

voltage (VREF) is supplied by a low impedance source.

In single supply applications, VREF is typically VDD/2.

FIGURE 4-10:

Two Op Amp

Instrumentation Amplifier.

VDD

IDD

100 k

1.8V

VOUT

6.0V

OUT

–

10 V/V

() 10

()

⋅

------------------------------------------

To load

MCP6401

OUT

–

() 1

------

---------

⎝⎠

⎛⎞

REF

VREF R1

VOUT

1/2 MCP6402

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