TLV9151 datasheet(27/60 Pages) TI1

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7.2.1.2 Detailed Design Procedure

The transfer function of the circuit in Figure 7-1 is given in Equation 1.

VOUT = ILOAD × RSHUNT × Gain

(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.

RSHUNT = VSHUNT_MAX

ILOAD_MAX = 100 mV1 A = 100 mΩ

(2)

Using Equation 2, RSHUNT is calculated to be 100 mΩ. The voltage drop produced by ILOAD and RSHUNT is

amplified by the TLV9151-Q1 to produce an output voltage of 0 V to 4.9 V. The gain needed by the TLV9151-Q1

to produce the necessary output voltage is calculated using Equation 3.

Gain = VOUT_MAX − VOUT_MIN

VIN_MAX− VIN_MIN

(3)

Using Equation 3, the required gain is calculated to be 49 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 TLV9151-Q1 to 49 V/V.

Gain = 1 + RFRG

(4)

Choosing RF as 360 kΩ, RG is calculated to be 7.5 kΩ. RF and RG were chosen as 360 kΩ and 7.5 kΩ because

they are standard value resistors that create a 49:1 ratio. Other resistors that create a 49:1 ratio can also be

used. Figure 7-2 shows the measured transfer function of the circuit shown in Figure 7-1.

7.2.1.3 Application Curves

ILOAD (A)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Figure 7-2. Low-Side, Current-Sense, Transfer Function

7.3 Power Supply Recommendations

The TLV915x-Q1 is specified for operation from 2.7 V to 16 V (±1.35 V to ±8 V); many specifications apply from

–40°C to 125°C. Parameters that can exhibit significant variance with regard to operating voltage or temperature

are presented in Section 5.8.

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TLV9151-Q1, TLV9152-Q1, TLV9154-Q1

SBOSA23G – MAY 2020 – REVISED MARCH 2024

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