TPS54232

www.ti.com

SLVS876D – NOVEMBER 2008 – REVISED NOVEMBER 2014

9.2.2.9 Power Dissipation Estimate

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

operations. They 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 x R

DS(on) x VOUT/VIN

2. Switching loss: Psw = 0.5 x 10-9 x VIN2 x IOUT x Fsw

3. Gate charge loss: Pgc. = 22.8 x 10-9 x Fsw

4. Quiescent current loss: Pq = 0.085 x 10-3 x VIN

Where:

IOUT is 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).

Fsw is the switching frequency (Hz).

So:

Ptot = Pcon + Psw + Pgc + Pq

For given TA , TJ = TA + Rth x Ptot.

For given TJMAX = 150°C, TAMAX = TJMAX– Rth x Ptot.

Where:

Ptot is the total device power dissipation (W).

TA is the ambient temperature (°C).

TJ is the junction temperature (°C) .

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

TJMAX is maximum junction temperature (°C).

TAMAX is maximum ambient temperature (°C).

Copyright © 2008–2014, Texas Instruments Incorporated

Submit Documentation Feedback

21

Product Folder Links: TPS54232