XRP7714 Datasheet, PDF (12/27 Pages) Exar Corporation – Quad Channel Digital PWM Step Down Controller

XRP7714
Quad Channel Digital PWM Step Down Controller
FUNCTIONAL DESCRIPTION AND OPERATION
The XRP7714 is a quad-output digital pulse width modulation (DPWM) controller with integrated
gate drivers for the use in synchronous buck switching regulators. Each output voltage can be
programmed from 0.9V to 5.1V without the need of an external voltage divider. The wide range of
the programmable DPWM switching frequency (from 300kHz to 1.5MHz) enables the user to
optimize for efficiency or component sizes. The digital regulation loop requires no external passive
components for network compensation. The loop performance does not need to be compromised
due to component tolerance, aging, and operating condition. Each digital controller provides a
number of safety features, such as over-current protection (OCP) and over-voltage protection
(OVP). The chip also provides over-temperature protection (OTP) and under-voltage lock-out
(UVLO) for two input voltage rails. The XRP7714 also has up to 6 GPIOs and a Standby Linear
Regulator to provide standby power. An I²C bus interface is provided to program the IC as well as
to communicate with the host for fault reporting and handling, power rail monitoring, channel
enable and disable, Standby LDO voltage reconfiguration, and Standby LDO enable and disable.
The XRP7714 offers a complete solution for soft-start and soft-stop. The delay and ramp of each
PWM regulator can be independently controlled. During soft-stop, the output voltage ramps down
with a programmable slope until it reaches a pre-set value. This pre-set value can be programmed
between within zero volts and the target voltage with the same set target voltage resolution.
REGISTER TYPES
There are two types of registers in the XRP7714: read/write registers and read-only registers. The
read/write registers are used for the control functions of the IC and can be programmed using
configuration non-volatile memory (NVM) or through an I²C command. The read-only registers are
for feedback functions such as error/warning flags and for reading the output voltage or current.
NON-VOLATILE CONFIGURATION MEMORY
The non-volatile memory (NVM) in XRP7714 stores the configuration data for the chip and all of the
power rails. This memory is normally configured during manufacturing time. Once a specific bit of
the NVM is programmed, that bit can never be reprogrammed again [i.e. one-time programmable].
During chip power up, the contents in the NVM are automatically transferred to the internal
registers of the chip. Programmed cells have been verified to be permanent for at least 10 years
and are highly reliable.
CHIP POWER-UP
The figure below shows the power-up sequence of XRP7714 during the normal operation. The
startup stage is divided into three phases. The first phase is the internal LDO power-up phase. The
second phase is the configuration transfer phase. The third phase is chip ready phase. The power
up sequence is less than 1ms.
© 2010 Exar Corporation
12/27
Rev. 1.1.3