XRP7720 Datasheet, PDF (19/28 Pages) Exar Corporation – Quad Output Universal Customizable PMIC with PFM

XRP7720
Quad Output Universal Customizable PMIC with PFM
 HW Power Good – the Power Good
hardware monitoring function. It can only
be forwarded to GPIO1. It is an output
voltage monitoring function that is a
hardware comparison of channel output
voltage against its user defined Power
Good threshold limits (Power Good
minimum and maximum levels). It has no
hysteresis. Multiple channel selections will
be combined using the AND logic function
of all channels selected.
 The Power Good minimum and maximum
levels are expressed as percentages of the
target voltage.
 “PGood Max” is the upper window and
“PGood Min” is the lower window. The
minimum and maximum for each of these
values can be calculated with the following
equation:
𝑁 ∗ 𝐿𝑆𝐵(𝑚𝑉) ∗ 10⁵
𝑃𝐺𝑂𝑂𝐷(%) = _{𝑉𝑡𝑎𝑟𝑔𝑒𝑡 (𝑉)}
 Where N =1 to 63 for the PGOOD Max
value and N=1 to 62 for the PGOOD Min
value. For example, with the target
voltage of 1.5V and set point resolution of
2.5mV (LSB), the Power Good min and
max values can range from 0.17% to
10.3% and 0.17% to 10.5% respectively.
A user can effectively double the range by
changing to the next higher output
voltage range setting, but at the expense
of reduced set point resolution.
FAULT HANDLING
There are seven different types of fault
handling:
 Under Voltage Lockout (UVLO)
monitors voltage supplied to the Vcc pin
and will cause the controller to shutdown
all channels if the supply drops to critical
levels.
 Over Temperature Protection (OTP)
monitors temperature of the chip and will
cause the controller to shutdown all
channels if temperature rises to critical
levels.
 Over Voltage Protection (OVP)
monitors regulated voltage of a channel
and will cause the controller to react in a
user specified way if the regulated voltage
surpasses threshold level.
 Over Current Protection (OCP)
monitors current of a channel and will
cause the controller to react in a user
specified way if the current level
surpasses threshold level.
 Start-up Time-out Fault monitors
whether a channel gets into regulation in
a user defined time period
 LDO5 Over Current Protection (LDO5
OCP) monitors current drawn from the
regulator and will cause the controller to
be reset if the current exceeds LDO5 limit
(155mA typical)
UVLO
Both UVLO warning and fault levels are user
programmable and set at 200mV increments
in PA 5.1.
When the warning level is reached the
controller will generate a flag if GPIO0 is so
configured (see the Digital I/O section).
When an under voltage fault condition occurs
the XRP7720 outputs are shut down. In
addition, the host can be informed by
forwarding the Low Vcc signal to any
GPIO/PSIO (see the Digital I/O section). This
signal transitions when the UVLO fault occurs.
Once the UVLO condition clears (Vcc voltage
rises above or to the user-defined UVLO
warning level) the Low Vcc signal will
transition and the controller will be reset.
Special attention needs to be paid in the case
when Vcc = LDO5 = 4.75V to 5.5V. Since the
input voltage ADC resolution is 200mV the
UVLO warning and fault set points are coarse
© 2014 Exar Corporation
19/28
Rev. 1.0.0