12V PWM Controller with Hot-Swap
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Startup Sequencing (DCENI, THRESH)
The DCENI input must be above V
THRESH
for the PWM
controller to start. By connecting the DCENI inputs of
multiple devices together and having different start
thresholds (V
THRESH_
), the startup of the PWM con-
trollers can be staggered to provide power sequencing.
Connect a resistive divider from REG to THRESH to
AGND to set the start thresholds of each device
between 0.6V and 2.5V. Connect THRESH to AGND to
produce a default 1.220V threshold for DCENI.
Connecting THRESH to REG disables the converter.
See Figure 1 and the Typical Operating Circuit.
PGI
DCENO
DCENI1
PGOOD1
STARTUP1
THRESH1
DCENI2
PGOOD2
STARTUP2
THRESH2
DCENI3
PGOOD3
STARTUP3
THRESH3
TRACKING
PGI
DCENO
DCENI1
PGOOD1
STARTUP1
THRESH1
DCENI2
PGOOD2
STARTUP2
THRESH2
DCENI3
PGOOD3
STARTUP3
C
START
REG2
STARTUP
SEQUENCING
PGI
DCEN0
DCENI1
PGOOD1
DCENI2
PGOOD2
DCENI3
PGOOD3
PGOOD
SEQUENCING
THRESH2
THRESH3
THRESH3
REG3
THRESH1
REG1
STARTUP1
STARTUP2
STARTUP3
Figure 1. Tracking, STARTUP Sequencing, and PGOOD Sequencing Configurations