AS13986 datasheet(8/13 Pages) AMSCO

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AS13986

Datasheet - D e t a i l e d D e s c r i p t i o n

8 Detailed Description

Regulator On/Off Operation

The AS13986 outputs (VOUT1 and VOUT2) are enabled by pulling the corresponding ENx pin high (1.4V) and disabled

by pulling the ENx pin low (0V). For reliable operation, the signal source used to drive the ENx input must be capable

of swinging above and below the specified turn-on/off voltage thresholds listed in Table 3 on page 4 (Enable Input

Logic Low and Enable Input Logic High parameters).

Note: Reliable enable/disable operation of VOUT1 and VOUT2 is guaranteed by driving the ENx pins with tR and tF =

10ms.

Fast Turn-On Time

In normal operation, the AS13986 outputs are turned on when VREF reaches its regulated value (1.23V nominal). Turn-

on time is decreased by charging the capacitor at pin BYPASS with the internal 70µA current source. The current

source is turned off when the bandgap voltage reaches approximately 95% of its regulated value.

Turn-on time is determined by the time constant of the bypass capacitor; smaller capacitor values decrease turn-on

time, although noise reduction decreases as well. Therefore, turn-on time and noise reduction must be taken into con-

sideration when choosing the value of the bypass capacitor.

AS13986 Datasheet(PDF) 8 Page - ams AG