Datasheet

Device description PM8903A
12/33 Doc ID 024147 Rev 1
5 Device description
The PM8903A is a high efficiency synchronous step-down monolithic switching regulator
capable of delivering up to 3 A continuous output current.
The power input voltage (V
IN
) can range from 2.8 V to 6 V, the signal input voltage (V
CC
) can
range from 2.9 V to 5.5 V.
Thanks to the 0.6 V internal reference and 0-100% duty cycle capability, the PM8903A can
precisely regulate output voltages ranging from 0.6 V to almost V
IN
(limited only by minimum
T
OFF
time). The output voltage accuracy is better than ±1% over line, load and temperature.
The PM8903A embeds low R
DS(on)
(35 mΩ) N-channel MOSFETs for both HS (high-side)
and LS (low-side) and implements the proprietary pulse-skipping technology, therefore, the
PM8903A guarantees high efficiency over all the load range.
The voltage mode control loop with high bandwidth error amplifier and external
compensation enables a wide range of output filter configurations (including all MLCC
solutions) and fast response to load transient. The high-switching frequency (typically 1.1
MHz) and the small VFQFPN16 3x3 mm package allow very compact VR solutions.
The PM8903A features a full set of protections and output voltage monitoring:
● Precise and accurate dual level overcurrent protection (internally compensated against
temperature variations)
● Over and undervoltage protection
● Overtemperature protection
● Undervoltage lockout on both signal and power supply
● Power Good open drain output easily provides real-time information about the output
voltage.
By simply connecting two PM8903As through the SYNCH pin, they can synchronize each
other with 180° phase shift switching interleaving, reducing RMS current absorption from the
input filter and preventing ‘beating frequency’ noise, therefore allowing the size and cost of
the input filter to be reduced.
A simple resistor connected from the PSKIP/MS pin to ground enables/disables pulse-
skipping technology and assigns master or slave status to the IC.
The dedicated ENABLE pin (EN) offers easy control on the power sequencing or to reset the
latched protection. Forcing the EN low, the device enters shutdown state and absorbs a total
quiescent current from V
CC
and V
IN
less than 15 µA.
5.1 Power section
The PM8903A integrates two low R
DS(on)
(35 mΩ) N-channel MOSFETs as low-side and
high-side switches, optimized for fast switching transition and high efficiency over all the load
range. The power stage is designed to deliver a continuous output current up to 3 A.
The HS MOSFET drain is connected to the VIN pins (power input), the LS MOSFET source
is connected to the PGND pins (power ground), and HS MOSFET source and LS MOSFET
drain are connected together and to the PHASE pins (see
Figure 2 ). The driving section is
supplied from the V
IN
pins through an internal voltage regulator (V
DRIVE
) that assures the
proper driving voltage over all the VIN range.