EP5352QI Datasheet, PDF (11/18 Pages) Altera Corporation – 500/600/800mA PowerSoC Synchronous Buck Regulators With Integrated Inductor

EP5382QI/EP5362QI/EP5352Q I
Recommendation 3: Multiple small vias (0.25mm after copper plating) should be used to connect
ground terminals of the Input capacitor and the output capacitor to the system ground plane. This
provides a low inductance path for the high-frequency AC currents, thereby reducing ripple and
suppressing EMI (see Fig. 5, Fig. 6, and Fig. 7).
Recommendation 4: The large thermal pad underneath the component must be connected to the
system ground plane through as many thermal vias as possible. The vias should use 0.33mm drill
size with minimum one ounce copper plating (0.035mm plating thickness). This provides the path for
heat dissipation from the converter.
Recommendation 5: The system ground plane referred to in recommendations 3 and 4 should be
the first layer immediately below the surface layer (PCB layer 2). This ground plane should be
continuous and un-interrupted below the converter and the input and output capacitors that carry
large AC currents. If it is not possible to make PCB layer 2 a continuous ground plane, an
uninterrupted ground “island” should be created on PCB layer 2 immediately underneath the
EP53x2QI and its input and output capacitors. The vias that connect the input and output capacitor
grounds, and the thermal pad to the ground island, should continue through to the PCB GND layer as
well.
Recommendation 6: As with any switch-mode DC/DC converter, do not run sensitive signal or
control lines underneath the converter package.
Figure 6 shows an example schematic for the EP53x2QI using the internal voltage select. In this
example, the device is set to a V_OUT of 1.2V (VS2=0, VS1=1, VS0=1).
VS2
17
VS1 ¹⁸
VS0
19
ENABLE ²⁰
10 NC
9 NC
8 NC
7 _VOUT
V_IN
4.7uF/2.2uF
(see layout recommendation 3)
10µF
V_OUT
Figure 6. Example application, Vout=1.2V.
Figure 7 shows an example schematic using an external voltage divider. VS0=VS1=VS2= “1”. The
resistor values are chosen to give an output voltage of 2.6V.
03132
11
October 11, 2013
www.altera.com/enpirion
Rev H