TPS54821

www.ti.com

SLVSB14

– OCTOBER 2011

THERMAL INFORMATION

TPS54821

QFN

UNITS

14 PINS

Junction-to-ambient thermal resistance

47.2

32

Junction-to-case (top) thermal resistance

64.8

Junction-to-board thermal resistance

14.4

°C/W

Junction-to-top characterization parameter

0.5

Junction-to-board characterization parameter

14.7

Junction-to-case (bottom) thermal resistance

3.2

(1)

For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

(2)

distortion starts to substantially increase. Thermal management of the PCB should strive to keep the junction temperature at or below

125

°C for best performance and long-term reliability. See power dissipation estimate in application section of this data sheet for more

information.

(3)

Test board conditions:

(a) 2.5 inches

× 2.5 inches, 4 layers, thickness: 0.062 inch

(b) 2 oz. copper traces located on the top of the PCB

(c) 2 oz. copper ground planes on the 2 internal layers and bottom layer

(d) 4 0.010 inch thermal vias located under the device package

ELECTRICAL CHARACTERISTICS

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

SUPPLY VOLTAGE (VIN AND PVIN PINS)

PVIN operating input voltage

1.6

17

V

VIN operating input voltage

4.5

17

V

VIN internal UVLO threshold

VIN rising

4.0

4.5

V

VIN internal UVLO hysteresis

150

mV

VIN shutdown supply Current

EN = 0 V

2

5

μA

VIN operating

– non switching supply current

VSENSE = 610 mV

600

800

μA

ENABLE AND UVLO (EN PIN)

Enable threshold

Rising

1.21

1.26

V

Enable threshold

Falling

1.10

1.17

Input current

EN = 1.1 V

1.15

μA

Hysteresis current

EN = 1.3 V

3.3

μA

VOLTAGE REFERENCE

Voltage reference

0 A

0.594

0.6

0.606

V

MOSFET

High-side switch resistance

BOOT-PH = 3 V

32

60

m

Ω

BOOT-PH = 6 V

26

40

m

Ω

VIN = 12 V

19

30

m

Ω

ERROR AMPLIFIER

Error amplifier Transconductance (gm)

1300

μMhos

Error amplifier dc gain

VSENSE = 0.6 V

1000

4000

V/V

Error amplifier source/sink

±110

μA

overdrive

Start switching threshold

0.25

V

COMP to Iswitch gm

21

A/V

CURRENT LIMIT

(1)

Measured at pins

Copyright

© 2011, Texas Instruments Incorporated

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