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TPS54821

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SLVSB14B – OCTOBER 2011 – REVISED FEBRUARY 2016

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Copyright © 2011–2016, Texas Instruments Incorporated

(1)

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

(2)

Power rating at a specific ambient temperature TA should be determined with a junction temperature of 125°C. This is the point where

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

6.4 Thermal Information

THERMAL METRIC(1)(2)

TPS54821

UNITS

RHL (14 PINS)

RθJA

Junction-to-ambient thermal resistance

47.2

°C/W

RθJA

Junction-to-ambient thermal resistance(3)

32

RθJCtop

Junction-to-case (top) thermal resistance

64.8

RθJB

Junction-to-board thermal resistance

14.4

ψJT

Junction-to-top characterization parameter

0.5

ψJB

Junction-to-board characterization parameter

14.7

RθJCbot

Junction-to-case (bottom) thermal resistance

3.2

(1)

Measured at pins

6.5 Electrical Characteristics

TJ = –40°C to 125°C, VIN = 4.5V to 17V, PVIN = 1.6V to 17V (unless otherwise noted)

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

≤ IOUT ≤ 8A

0.594

0.6

0.606

V

MOSFET

High-side switch resistance

BOOT-PH = 3 V

32

60

m

Ω

High-side switch resistance(1)

BOOT-PH = 6 V

26

40

m

Ω

Low-side Switch Resistance(1)

VIN = 12 V

19

30

m

Ω

ERROR AMPLIFIER

Error amplifier Transconductance (gm)

–2

μA < ICOMP < 2 μA, V(COMP) = 1 V

1300

μMhos

Error amplifier dc gain

VSENSE = 0.6 V

1000

4000

V/V

Error amplifier source/sink

V(COMP) = 1 V, 100 mV input overdrive

±110

μA

Start switching threshold

0.25

V

COMP to Iswitch gm

21

A/V