XRP7724 Datasheet, PDF (24/29 Pages) Exar Corporation – Quad Channel Digital PWM/PFM Programmable Power Management System

XRP7724
Quad Channel Digital PWM/PFM
Programmable Power Management System
be connected between the CPLL pin and
AGND.
In applications where this functionality is not
desired, the CPLL capacitor is not necessary
and can be omitted, and the pin shall be left
floating. In addition, the user needs to make
sure the function gets disabled through
register settings.
The external clock must be routed to GPIO0.
The GPIO0 setting must reflect the range of
the external clock applied to it: Sys_Clock/8
corresponds to the range of 10.9MHz to
14.7MHz while Sys_Clock/4 setting
corresponds to the range of 21.8Mhz to
29.6MHz.
The functionality is enabled in
PowerArchitect™ 5.0 by selecting External
Clock-in function under GPIO0.
For more on details how to monitor PLL lock
in-out, please contact Exar or your local Exar
representative.
CLOCK OUT
XRP7724 can supply clock out to be used by
another XRP7724 controller. The clock gets
routed out through GPIO1 and can be set to
system clock divided by 8 (Sys_Clock/8) or
system clock divided by 4 (Sys_Clock/4)
frequencies.
The functionality is enabled in PA5 by
selecting External Clock-Out function under
GPIO1.
CHANNEL CONTROL
Channels including LDO3.3 can be controlled
independently by any GPIO/PSIO or I2C
command. Channels will start-up or shut-
down following transitions of signals applied
to GPIO/PSIOs set to control the channels.
The control can always be overridden with an
I2C command.
Regardless whether the channels are
controlled independently or are in a group,
the ramp rates specified are followed (see the
Power Sequencing section).
Regulated voltages and voltage drops across
synchronous FET on each switching channel
can be read back using x I2C commands y.
The regulated voltage read back resolution is
15mV, 30mV and 60mV per LSB depending
on the target voltage range. The voltage drop
across synchronous FET read back resolution
is 1.25mV and 2.5mV per LSB depending on
the range.
Through an I2C command the host can check
the status of the channels; whether they are
in regulation or at fault.
Regulated voltages can be dynamically
changed on switching channels using I2C
commands with resolution of 2.5mV, 5mV
and 10mV depending on the target voltage
range (in PWM mode only).
For more information on I2C commands
please contact Exar or your local Exar
representative.
POWER SEQUENCING
All four channels and LDO3.3 can be grouped
together and as such start-up and shut-down
in a user defined sequence.
Selecting none means channel(s) will not be
assigned to any group and as such will be
controlled independently.
Group Selection
© 2012 Exar Corporation
There are three groups:
24/29
Rev. 1.0.1