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TLV701xx

www.ti.com

SBVS161

– NOVEMBER 2011

APPLICATION INFORMATION

constant over the complete output load current and temperature range. The devices are ensured to operate over

a temperature range of

–40°C to +125°C.

INPUT AND OUTPUT CAPACITOR REQUIREMENTS

The TLV701 requires a 1-

µF or larger capacitor connected between OUT and GND for stability. Ceramic or

tantalum capacitors can be used. Larger value capacitors result in better transient and noise performance.

Although an input capacitor is not required for stability, when a 0.1-

µF or larger capacitor is placed between IN

and GND, it counteracts reactive input sources and improves transient and noise performance. Higher value

capacitors are necessary if large, fast rise time load transients are anticipated.

BOARD LAYOUT RECOMMENDATIONS

Input and output capacitors should be placed as close to the device pins as possible. To avoid interference of

the output capacitor should be connected directly to the device GND pin.

POWER DISSIPATION AND JUNCTION TEMPERATURE

To ensure reliable operation, worst-case junction temperature should not exceed +125

°C. This restriction limits

the power dissipation the regulator can handle in any given application. To ensure the junction temperature is

The maximum power dissipation limit is determined using Equation 1:

(1)

where:

The regulator dissipation is calculated using Equation 2:

(2)

Power dissipation that results from quiescent current is negligible.

REGULATOR PROTECTION

The TLV701xx series of LDO regulators use a PMOS-pass transistor that has a built-in back diode that conducts

reverse current when the input voltage drops below the output voltage (for example, during power-down). Current

is conducted from the output to the input and is not internally limited. If extended reverse voltage operation is

anticipated, external limiting might be appropriate.

The TLV701xx features internal current limiting. During normal operation, the TLV701xx limits output current to

approximately 250 mA. When current limiting engages, the output voltage scales back linearly until the

overcurrent condition ends. Take care not to exceed the rated maximum operating junction temperature of

+125

°C. Continuously running the device under conditions where the junction temperature exceeds +125°C

degrades device reliability.

The ability to remove heat from the die is different for each package type, presenting different considerations in

the printed circuit board (PCB) layout. The PCB area around the device that is free of other components moves

the heat from the device to the ambient air. Using heavier copper increases the effectiveness in removing heat

from the device. The addition of plated through-holes to heat-dissipating layers also improves heatsink

the product of the output current and the voltage drop across the output pass element, as shown in Equation 2.

Copyright

© 2011, Texas Instruments Incorporated

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