(

)

J(MAX)

A

(MAX)

JA

T

T

PD

-

=

q

TPS27081A

SLVSBE9A – APRIL 2012 – REVISED JULY 2012

www.ti.com

Table 1. Component Values for VOUT Rise Time (continued)

Rise Time (sec)

VIN (V)

R2 (

Ω)

C1 (µF)

1.00m

5.0

61.9k

0.01

10.0µ

12.0m

5.0

61.9k

0.12

470µ

21.0m

1.5

61.9k

0.12

470µ

600m

3.0

333k

1.00

10.0µ

Low Voltage ON/OFF Interface

reliable operation apply ON/OFF logic that has the following VIH and VIL limits:

and thus allowing a 1.2V GPIO interface.

In applications where ON/OFF signal is not available connect ON/OFF pin to VIN. The TPS27081A will turn

ON/OFF in sync with the input supply connected to VIN.

Note: Connect a pull down resistor between ON/OFF pin to GND when ON/OFF is driven by a high-impedance

(tri-state) driver.

On-Chip Power Dissipation

Q2(ON)

Note: MOS switches can get extremely hot when operated in saturation region. As a general guideline, to avoid

transistors Q1 and Q2 going into saturation region set VGS > VT +VDS. E.g. VGS > 1.5V and VDS < 200mV

ensures switching region.

Thermal Reliability

For higher reliability it is recommended to limit TPS27081A IC’s die junction temperature to less than 125°C. The

IC junction temperature is directly proportional to the on-chip power dissipation. Use the following equation to

calculate maximum on-chip power dissipation to achieve the maximum die junction temperature target:

Where:

(4)

Improving Package Thermal Performance

The package

value depends on the PC board layout. An external heat sink and/or a cooling mechanism, like a cold air fan, can

help reduce

www.ti.com/thermal for a general guidance on improving device thermal performance.

6

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Product Folder Link(s): TPS27081A