VIN - VOUT (V)

0

0.5

1

1.5

2

2.5

3

3.5

4

50

100

150

200

250

300

350

D001

DSBGA

USON

LP5952

www.ti.com

SNVS469F – OCTOBER 2006 – REVISED DECEMBER 2015

This establishes the relationship between the power dissipation allowed due to thermal consideration, the voltage

drop across the device, and the continuous current capability of the device. Equation 1 and Equation 2 must be

used to determine the optimum operating conditions for the device in any application. As an example, to keep full

load current capability of 350 mA for a 1.5-V output voltage option at a high ambient temperature of 85°C, VIN

has to be kept

≤ 2.1 V (for DSBGA package):

VIN ≤ PD / IOUT + VOUT = 221 mW / 350 mA + 1.5 V = 2.1 V

(3)

Figure 11 shows the output current derating due to these considerations:

TA = 85°C

VOUT = 1.5 V

RθJA(DSBGA) = 181°C/W

RθJA(USON) = 181.6°C/W

Figure 11. Maximum Load Current vs VIN – VOUT

The typical contribution of the bias input voltage supply VBATT to the power dissipation can be neglected

(Equation 4):

PD_VBATT = VBATT × IQVBATT = 5.5 V × 50 µA = 0.275 mW typical

(4)

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