MCP6294IPWR datasheet(21/45 Pages) TI1

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0.2

0.4

0.6

0.8

LOAD (A)

C219

Gain

OUT

MAX

OUT

MIN

MAX

MIN

Gain

SHUNT

MAX

SHUNT

LOAD

MAX

100mV

100m

OUT

LOAD

SHUNT

Gain

MCP6291, MCP6292, MCP6294

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SBOS879D – JULY 2017 – REVISED OCTOBER 2019

Product Folder Links: MCP6291 MCP6292 MCP6294

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Typical Application (continued)

9.2.2 Detailed Design Procedure

The transfer function of the circuit in Figure 33 is shown in Equation 1.

(1)

The load current (ILOAD) produces a voltage drop across the shunt resistor (RSHUNT). The load current is set from

0 A to 1 A. To keep the shunt voltage below 100 mV at maximum load current, the largest shunt resistor is

defined using Equation 2.

(2)

Using Equation 2, RSHUNT is 100 mΩ. The voltage drop produced by ILOAD and RSHUNT is amplified by the

MCP629x to produce an output voltage of roughly 0 V to 4.95 V. The gain needed by the MCP629x to produce

the necessary output voltage is calculated using Equation 3:

(3)

Using Equation 3, the required gain is calculated to be 49.5 V/V, which is set with resistors RF and RG.

Equation 4 is used to size the resistors, RF and RG, to set the gain of the MCP629x to 49.5 V/V.

(4)

Choosing RF as 165 kΩ and RG as 3.4 kΩ provides a combination that equals roughly 49.5 V/V. Figure 34 shows

the measured transfer function of the circuit shown in Figure 33.

9.2.3 Application Curve

Figure 34. Low-Side, Current-Sense Transfer Function

MCP6294IPWR Datasheet(PDF) 21 Page - Texas Instruments

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