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ams Datasheet

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[v1-04] 2015-Jun-19

AS1382 − Detailed Description

The step-down converter is a high efficiency fixed frequency

current mode regulator. By using low resistance internal PMOS

and NMOS switches efficiency up to 96% can be achieved. The

fast switching frequency allows using small inductors, without

increasing the current ripple. The unique feedback and

regulation circuit guarantees optimum load and line regulation

over the whole output voltage range, up to an output current

of 1A with an output capacitor of only 10

µF. The implemented

current limitation protects the DCDC and the coil during

overload condition.

Mode Settings

Low-Ripple, Low-Noise Operation

MODE pin = high

In this mode there is no minimum coil current necessary before

switching OFF the PMOS. As result, the ON time of the PMOS

will be reduced down to tmin_on at no or light load conditions,

even if the coil current is very small or the coil current is

inverted. This results in a very low ripple and noise, but

decreased efficiency, at light loads, especially at low input to

output voltage differences. Because of the inverted coil current

in that case the regulator will not operate in pulse skip mode.

Figure 10:

AS1382 Low Noise Mode

DC/DC Buck Burst Mode: Shows the DC/DC switching waveforms for low noise operation

Detailed Description

VOUT (50mV/div)

LX (2V/div)

coil current (200mA/div)

time (5us/div)