TPS62870 datasheet(46/66 Pages) TI2

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operation. TI recommends low-ESR multilayer ceramic capacitors for best performance. In practice, the total

input capacitance is typically comprised of a combination of different capacitors, in which larger capacitors

provide the decoupling at lower frequencies and smaller capacitors provide the decoupling at higher frequencies.

The TPS6287x devices feature a butterfly layout with two pairs of VIN and GND pins on opposite sides of the

package. This allows the input capacitors to be placed symmetrically on the PCB so that the electromagnetic

fields generated cancel each other out, thereby reducing EMI.

The duty cycle of the converter is given by:

D= VOUTη×VIN

(9)

where

• VIN is the input voltage.

• VOUT is the output voltage.

• η is the efficiency.

D= 0.750.9×3.3=0.253

(10)

The value of input capacitance needed to meet the input voltage ripple requirements is given by:

CIN=D× 1−D ×IOUT

VINPP ×fsw

(11)

where

• D is the duty cycle.

• fsw is the switching frequency.

• L is the inductance.

• IOUT is the output current. Use the maximum value of 11.3A as given for ΔIOUT in Table 9-1

100mV is used as the input voltage ripple target.

CIN=0.253× 1−0.253 ×11.3

0.1×2.25×106 =9.5μF

(12)

The value of CIN calculated with Equation 11 is the effective capacitance after all derating, tolerance, and aging

effects have been considered. 5µF effective capacitance per input pin is required. TI recommends multilayer

ceramic capacitors with an X7R dielectric (or similar) for CIN, and these capacitors must be placed as close to

the VIN and GND pins as possible to minimize the loop area.

Table 9-3 lists a number of capacitors that are an excellent choice for this application. This list is not exhaustive

and other capacitors from other manufacturers can also be an excellent choice.

Table 9-3. List of Recommended Input Capacitors

CAPACITANCE

DIMENSIONS

VOLTAGE RATING

MANUFACTURER, PART NUMBER(1)

MM (INCH)

470nF ±10%

1005 (0402)

10V

Murata, GCM155C71A474KE36D

470nF ±10%

1005 (0402)

10V

TDK, CGA2B3X7S1A474K050BB

10μF ±10%

2012 (0805)

10V

Murata, GCM21BR71A106KE22L

10μF ±10%

2012 (0805)

10V

TDK, CGA4J3X7S1A106K125AB

22μF ±10%

3216 (1206)

10V

Murata, GCM31CR71A226KE02L

22μF ±20%

3216 (1206)

10V

TDK, CGA5L1X7S1A226M160AC

(1)

See Section 10.1.1.

TPS62870, TPS62871, TPS62872, TPS62873

SLVSGC5E – JANUARY 2023 – REVISED OCTOBER 2025

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