XRP7724 Datasheet, PDF (25/29 Pages) Exar Corporation – Quad Channel Digital PWM/PFM Programmable Power Management System

XRP7724
Quad Channel Digital PWM/PFM
Programmable Power Management System
 Group 0 – is controlled by the chip
ENABLE or I2C command. Channels
assigned to this group will come up with
the ENABLE signal being high, and will go
down with the ENABLE signal being low.
The control can always be overridden with
an I2C command.
 Since it is recommended to leave the
ENABLE pin floating in the applications
when Vcc = LDO5 = 4.75V to 5.5V, please
contact Exar for how to configure the
channels to come up at the power up in
this scenario.
 Group 1 – can be controlled by any
GPIO/PSIO or I2C command. Channels
assigned to this group will start-up or
shut-down following transitions of a signal
applied to the GPIO/PSIO set to control
the group. The control can always be
overridden with an I2C command.
 Group 2 – can be controlled by any
GPIO/PSIO or I2C command. Channels
assigned to this group will start-up or
shut-down following transitions of a signal
applied to the GPIO/PSIO set to control
the group. The control can always be
overridden with an I2C command.
Start-up
milliseconds with a range of 0msec to
255msec.
Shut-down
For each channel within a group a user can
specify
the
following
shut-down
characteristics:
 Ramp Rate – expressed in milliseconds
per Volt. It does not apply to LDO3.3.
 Order – order position of a channel to
come-down within the group
 Wait Stop Thresh? – selecting this
option for a channel means the next
channel in the order cannot start ramping-
down until this channel reaches the Stop
Threshold level. The stop threshold level is
fixed at 600mV.
 Delay – additional time delay a user can
specify to postpone a channel shut-down
with respect to the previous channel in the
order. The delay is expressed in
milliseconds with a range of 0msec to
255msec.
For each channel within a group a user can
specify the following start-up characteristics:
 Ramp Rate – expressed in milliseconds
per Volt. It does not apply to LDO3.3.
 Order – order position of a channel to
come-up within the group
 Wait PGOOD? – selecting this option for
a channel means the next channel in the
order cannot start ramping-up until this
channel reaches the target level and its
Power Good flag gets asserted.
 Delay – an additional time delay a user
can specify to postpone a channel start-up
with respect to the previous channel in the
order. The delay is expressed in
MONITORING VCC AND TEMPERATURE
Through I2C commands, the host can read
back voltage applied to the Vcc pin and the
die temperature respectively. The Vcc read
back resolution is 200mV per LSB; the die
temperature read back resolution is 5C° per
LSB. For more on I2C commands please refer
to ANP-38 “XRP7724 Command Set and
Programming Guide”.
PROGRAMMING XRP7724
XRP7724 is a FLASH based device which
means its configuration can be programmed
into FLASH NVM and re-programmed a
number of times.
Programming of FLASH NVM is done through
PA5.
© 2012 Exar Corporation
25/29
Rev. 1.0.1