VOUT =

1

RSET (k )

0.508 *

(

)

+1

(V)

1

RSET =

0.508

±1

(k )

VOUT

11

TPSM84A21

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SLVSDF7A – DECEMBER 2016 – REVISED JULY 2017

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7.3 Feature Description

7.3.1 Adjusting the Output Voltage (VADJ)

The VADJ pin programs the output voltage of the TPSM84A21. The output voltage adjustment range is from

0.508 V to 1.35 V. The adjustment method requires the addition of RSET connected between VADJ and AGND. If

an RSET resistor is not populated, the module will default to 0.508 V. The VS+ pin (pin 14) must be connected to

VOUT. TI recommends to make the VS+ connection at the load for the best load regulation performance. The

RSET resistor must be connected directly between the VADJ pin (pin 15) and AGND (pin 16).

Equation 1 can be used to calculate the ideal RSET resistor value for a given output voltage, VOUT. Use

Equation 2 to calculate the actual VOUT for a given RSET resistor. Table 1 lists the ideal RSET resistor values for a

number of common voltages. Table 1 also lists the closest E96 standard resistor values to the ideal RSET values

along with the actual output voltage and the set-point error when using the E96 resistor value. For the most

accurate output voltage set-point it is best to use the ideal resistor value. The ideal resistor value may not be a

standard value and may require two standard value resistors in series or parallel to obtain the desired output

voltage.

(1)

(2)

Table 1. RSET Resistor Values

Closest E96 Resistor Value

VOUT (V)

Ideal RSET (kΩ)

RSET (kΩ)

Actual VOUT (V)

%

0.508

Open

Open

0.508

–

0.55

12.095

12.1

0.549

–0.003

0.60

5.522

5.49

0.601

0.088

0.65

3.578

3.57

0.65

0.046

0.70

2.646

2.67

0.698

–0.248

0.75

2.099

2.10

0.749

–0.013

0.80

1.739

1.74

0.799

–0.006

0.85

1.485

1.50

0.847

–0.392

0.9

1.296

1.30

0.899

–0.137

0.95

1.149

1.15

0.949

–0.027

1.00

1.033

1.02

1.006

0.603

1.05

0.937

0.931

1.053

0.348

1.10

0.858

0.866

1.095

–0.490

1.15

0.791

0.787

1.153

0.303

1.20

0.734

0.732

1.202

0.166

1.25

0.685

0.681

1.254

0.317

1.30

0.641

0.649

1.291

–0.712

1.35

0.603

0.604

1.349

–0.070