TLV1117LV Series

SBVS160A

– MAY 2011 – REVISED SEPTEMBER 2011

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APPLICATION INFORMATION

The TLV1117LV is a low quiescent current linear regulator designed for high current applications. Unlike typical

high current linear regulators, the TLV1117LV series consume significantly less quiescent current. These devices

deliver excellent line and load transient performance. The device is low noise, and exhibits a very good

power-supply rejection ratio (PSRR). As a result, it is ideal for high current applications that require very sensitive

power-supply rails.

This family of regulators offers both current limit and thermal protection. The operating junction temperature

range of the device is

–40°C to +125°C.

Input and Output Capacitor Requirements

For stability, 1.0-

μF ceramic capacitors are required at the output. Higher-valued capacitors improve transient

performance. X5R- and X7R-type ceramic capacitors are recommended because these capacitors have minimal

variation in value and equivalent series resistance (ESR) over temperature. Unlike traditional linear regulators

that need a minimum ESR for stability, the TLV1117LV series are ensured to be stable with no ESR. Therefore,

cost-effective ceramic capacitors can be used with these devices. Effective output capacitance that takes bias,

temperature, and aging effects into consideration must be greater than 0.5

μF to ensure stability of the device.

Although an input capacitor is not required for stability, it is good analog design practice to connect a 0.1-

μF to

1.0-

μF, low-ESR capacitor across the IN pin and GND pin of the regulator. This capacitor counteracts reactive

input sources and improves transient response, noise rejection, and ripple rejection. A higher-value capacitor

may be necessary if large, fast rise-time load transients are anticipated, or if the device is not located physically

close to the power source. If source impedance is greater than 2

Ω, a 0.1-μF input capacitor may also be

necessary to ensure stability.

Board Layout Recommendations to Improve PSRR and Noise Performance

Input and output capacitors should be placed as close to the device pins as possible. To improve characteristic

ac performance such as PSRR, output noise, and transient response, it is recommended that the board be

the device. In addition, the ground connection for the output capacitor should be connected directly to the GND

pin of the device. Higher value ESR capacitors may degrade PSRR performance.

Internal Current Limit

The TLV1117LV internal current limit helps to protect the regulator during fault conditions. During current limit,

the output sources a fixed amount of current that is largely independent of the output voltage. In such a case, the

device cools down, it is turned on by the internal thermal shutdown circuit. If the fault condition continues, the

device cycles between current limit and thermal shutdown. See the Thermal Information section for more details

The PMOS pass element in the TLV1117LV device has a built-in body diode that conducts current when the

voltage at OUT exceeds the voltage at IN. This current is not limited; if extended reverse voltage operation is

anticipated, external limiting to 5% of the rated output current is recommended.

Dropout Voltage

PMOS device behaves as a resistor in dropout.

Transient Response

As with any regulator, increasing the size of the output capacitor reduces over-/undershoot magnitude.

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© 2011, Texas Instruments Incorporated