TPS54331 datasheet(21/36 Pages) TI1

21 / 36 page

TPS54331

www.ti.com

SLVS839F – JULY 2008 – REVISED OCTOBER 2014

The nominal on-resistance for the high-side FET in Equation 33 is assumed. Equation 33 accounts for the worst

case variation of operating-frequency set point. Any design operating near the operational limits of the device

should be carefully checked to ensure proper functionality.

9.2.2.10 Power Dissipation Estimate

The following formulas show how to estimate the device power dissipation under continuous-conduction mode

(CCM) operations. These formulas should not be used if the device is working in the discontinuous-conduction

mode (DCM) or pulse-skipping Eco-mode.

The device power dissipation includes:

1. Conduction loss:

Pcon = IOUT

2 × R

DS(on) × VOUT / VIN

where

•

IOUT s the output current (A)

•

RDS(on) is the on-resistance of the high-side MOSFET (Ω)

•

VOUT is the output voltage (V)

•

VIN is the input voltage (V)

2. Switching loss:

Psw = 0.5 × 10

-9 × V

2 × I

OUT × ƒSW

where

•

ƒSW is the switching frequency (Hz)

3. Gate charge loss:

Pgc = 22.8 × 10

-9 × ƒ

4. Quiescent current loss

Pq = 0.11 × 10

-3 × V

Therefore:

Ptot = Pcon + Psw + Pgc + Pq

where

•

Ptot is the total device power dissipation (W)

For given TA :

TJ = TA + Rth × Ptot

where

•

TJ is the junction temperature (°C)

•

TA is the ambient temperature (°C)

•

Rth is the thermal resistance of the package (°C/W)

For given TJMAX = 150°C:

TAMAX = TJMAX – Rth × Ptot

where

•

TJMAX is maximum junction temperature (°C)

•

TAMAX is maximum ambient temperature (°C)

Submit Documentation Feedback

Product Folder Links: TPS54331

TPS54331 Datasheet(PDF) 21 Page - Texas Instruments

TPS54331 Datasheet(HTML) 21 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

Datasheet Download

Link URL