The Primarion? PX3520 is a high performance power
stage for the highest power density server and workstation
buck regulation solutions. The PX3520 combined with the
Primarion? PX3535 or PX3538 Digital Multiphase
Controllers offers a complete high current, small form factor
solution with superior accuracy, transient response, and
protection features.
The PX3520 integrates a low RDSon high-side P-Channel
MOSFET together with both high-side and low-side
MOSFET drivers. The integration of the high-side power
FET with high- and low-side drivers minimizes switching
losses while providing industry leading power density. At
an upper limit duty cycle of 20%, PX3520 can support a
maximum average output current of 30A per phase in an
area less than 16 mm2, smaller than most discrete power
MOSFETs. The PX3520 low-side driver supply (VDRIVE)
may be biased separately from the VCC supply from 5V to
12V to optimize system efficiency.
The PX3520 has a patent pending lossless current sensor
which accurately senses the current in the high-side FET
independent of VID, inductor value, supply, temperature,
and switching frequencies. This integrated current sense
method provides the accuracy of precision resistor based
sensing with no efficiency loss.
The PX3520 has an integrated high-side FET short detector
which reacts rapidly on startup to protect the processor
before the controller is powered up. The output high-side
short pins from each phase can drive a single external
crowbar circuitry for rapid protection from a high-side short
on any phase of a multiphase solution. The high-side short
pin also acts as an input, detecting alert signals from every
PX3520 power stage in the system and protecting each
power stage internally.
The PX3520 also has an integrated junction temperature
sensor which provides an on-die measurement of the highside
FET temperature. When used with the Primarion
controllers, this feature provides accurate, programmable
over-temperature protection.
The PX3520 uses CSP packaging to provide the lowest
thermal resistance and smallest footprint. A relaxed 0.65
mm ball pitch allows for easy assembly.