AS1370 datasheet(20/28 Pages) AMSCO

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[v2-00] 2016-Jun-01

AS1370 − Application Information

This shows why it is convenient to increase the output capacitor

value for a better support for fast load changes. Of course the

formula holds for t < “propagation time”, so that a faster LDO

needs a smaller cap at the load to achieve a similar transient

response. For instance, 50mA load current step produces 50mV

output drop if the LDO response is 1μs and the load cap is 1μF.

There is also a steady state error caused by the finite output

impedance of the regulator. This is derived from the load

regulation specification discussed above.

Turn On Time

This specification defines the time taken for the LDO to awake

from shutdown. The time is measured from the release of the

shutdown pin to the time that the output voltage is within 5%

of the final value. It assumes that the voltage at VIN is stable and

within the regulator min and max limits. Shutdown reduces the

quiescent current to very low, mostly leakage values (<1μA

typ.).

Thermal Protection

To prevent operation under extreme fault conditions, such as a

permanent short circuit at the output, thermal protection is

built into the device. Die temperature is measured, and when a

170°C threshold is reached, the device enters shutdown. When

the die cools sufficiently, the device will restart (assuming input

voltage exists and the device is enabled). Hysteresis of 15°C

prevents low frequency oscillation between start-up and

shutdown around the temperature threshold.

AS1370 データシート(PDF) 20 Page - ams AG