DRV593_15 Datasheet, PDF (18/27 Pages) Texas Instruments – 3−A HIGH−EFFICIENCY PWM POWER DRIVER

DRV593
DRV594
SLOS401C – OCTOBER 2002 – REVISED JULY 2010
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PRINTED-CIRCUIT BOARD (PCB) LAYOUT CONSIDERATIONS
Since the DRV593 and DRV594 are high-current switching devices, a few guidelines for the layout of the
printed-circuit board (PCB) must be considered:
1. Grounding. Analog ground (AGND) and power ground (PGND) must be kept separated, ideally back to
where the power supply physically connects to the PCB, minimally back to the bulk decoupling capacitor (10
µF ceramic minimum). Furthermore, the PowerPAD ground connection should be made to AGND, not
PGND. Ground planes are not recommended for AGND or PGND, traces should be used to route the
currents. Wide traces (100 mils) should be used for PGND while narrow traces (15 mils) should be used for
AGND.
2. Power supply decoupling. A small 0.1 mF to 1 mF ceramic capacitor should be placed as close to each set
of PVDD pins as possible, connecting from PVDD to PGND. A 0.1 mF to 1 mF ceramic capacitor should also
be placed close to the AVDD pin, connecting from AVDD to AGND. A bulk decoupling capacitor of at least
10 mF, preferably ceramic, should be placed close to the DRV593 or DRV594, from PVDD to PGND. If power
supply lines are long, additional decoupling may be required.
3. Power and output traces. The power and output traces should be sized to handle the desired maximum
output current. The output traces should be kept as short as possible to reduce EMI, i.e., the output filter
should be placed as close to the DRV593 or DRV594 outputs as possible.
4. PowerPAD. The DRV593 and DRV594 in the Quad Flatpack package use TI's PowerPAD technology to
enhance the thermal performance. The PowerPAD is physically connected to the substrate of the DRV593
and DRV594 silicon, which is connected to AGND. The PowerPAD ground connection should therefore be
kept separate from PGND as described above. The pad underneath the AGND pin may be connected
underneath the device to the PowerPAD ground connection for ease of routing. For additional information on
PowerPAD PCB layout, refer to the PowerPAD Thermally Enhanced Package application note, (SLMA002).
5. Thermal performance. For proper thermal performance, the PowerPAD must be soldered down to a thermal
land, as described in the PowerPAD Thermally Enhanced Package application note, (SLMA002). In addition,
at high current levels (greater than 2 A) or high ambient temperatures (greater than 25°C), an internal plane
may be used for heat sinking. The vias under the PowerPAD should make a solid connection, and the plane
should not be tied to ground except through the PowerPAD connection, as described above.
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