XRP7725 Datasheet, PDF (24/34 Pages) Exar Corporation – Power Management System

XRP7725
Intel Node Manager Compatible Programmable
Power Management System
and perform auto-restart of the channel, or
restart the chip.
WARNING: Choosing the “Restart Chip”
option during development is NOT
recommended as it makes debug efforts
difficult.
The output current reported by the XRP7725
is processed through a seven sample median
filter in order to reduce noise. The OCP limit
is compared against unfiltered ADC output.
LDO5 OCP
When current is drawn from the LDO5 that
exceeds the LDO5 current limit the controller
will be reset.
LDO3.3 OCP
When current drawn from LDO3.3 exceeds
LDO3.3 current limit the regulator gets shut
down, a fault is generated, and the host will
be notified by the SUPPLY_FAULT_EVENT
interrupt generated by the controller. The
host then can through an I²C command check
which channel/regulator is at fault. Once the
fault condition is removed, the host needs to
turn the regulator on again.
For the case of Shutdown and Auto-restart
Channel, the user has an option to specify
startup timeout (the time in which the fault is
validated) and hiccup timeout (the period
after which the controller will try to restart
the channel) periods in 1 msec increments
with a maximum value of 255 msec.
Note: The Channel Fault Action response is
the same for an OVP or OCP event.
Start-up Time-out Fault
A channel will be at Startup Timeout Fault if it
does not come-up in the time period specified
in the “Startup Timeout” box. In addition, a
channel is at Startup Timeout Fault if its pre-
bias configuration voltage is within a defined
value too close to the target.
When the fault is generated, the host will be
notified by the SUPPLY_FAULT_EVENT
interrupt generated by the controller. The
host then can use an I²C command to check
which channel is at fault.
V5EXT SWITCHOVER
The V5EXT gives a user an opportunity to
supply an external 5 Volt rail to the controller
in order to reduce the controller’s power
dissipation. The 5 Volt rail can be an
independent power rail present in a system or
any of 7725 channels regulated to 5 Volts (in
the PFM mode in particular) and routed back
to the V5EXT pin. It is important to mention
that voltage to V_CC must be applied all the
time even after the switchover in which case
the current drawn from V_CC supply will be
minimal.
If the function not used, we recommend the
pin to be either grounded or left floating in
conjunction with making sure the function
gets disabled through register settings.
V5EXT switchover control
The function is enabled in PA 5.1. The
switchover thresholds are programmable in
50mV steps with a total range of 200mV.
Hysteresis to switch the external 5 Volt
supply in-out is 150mV. LDO5 automatically
turns off when the external voltage is
switched in and turns on when the external
voltage drops below the lower threshold.
© 2014 Exar Corporation
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Rev. 1.0.0