DRV8818_15 Datasheet, PDF (20/31 Pages) Texas Instruments – DRV8818 Stepper Motor Controller IC

DRV8818
SLVSAX9D – SEPTEMBER 2011 – REVISED JANUARY 2015
11 Layout
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11.1 Layout Guidelines
The VMA and VMB pins should be bypassed to GND using low-ESR ceramic bypass capacitors with a
recommended value of 0.1μF rated for VM. This capacitor should be placed as close to the VMA and VMB pins
as possible with a thick trace or ground plane connection to the device GND pin.
The VMA and VMB pins must be bypassed to ground using an appropriate bulk capacitor. This component may
be an electrolytic and should be located close to the DRV8818.
A low-ESR ceramic capacitor must be placed in between the CP1 and CP2 pins. TI recommends a value of 0.22-
μF rated for VM. Place this component as close to the pins as possible.
A low-ESR ceramic capacitor must be placed in between the VM and VCP pins. TI recommends a value of 0.22-
μF rated for 16 V. Place this component as close to the pins as possible.
Ensure proper connection of the DRV8818 PowerPAD to the PCB. The PowerPAD should be connected to a
copper plane that is connected to GND. The copper plane should have a large area to allow for thermal
dissipation from the DRV8818.
11.1.1 Heatsinking
The PowerPAD™ package uses an exposed pad to remove heat from the device. For proper operation, this pad
must be thermally connected to copper on the PCB to dissipate heat. On a multi-layer PCB with a ground plane,
this can be accomplished by adding a number of vias to connect the thermal pad to the ground plane. On PCBs
without internal planes, copper area can be added on either side of the PCB to dissipate heat. If the copper area
is on the opposite side of the PCB from the device, thermal vias are used to transfer the heat between top and
bottom layers.
For details about how to design the PCB, refer to TI Application Report SLMA002, PowerPAD™ Thermally
Enhanced Package and TI Application Brief SLMA004, PowerPAD™ Made Easy, available at www.ti.com.
In general, the more copper area that can be provided, the more power can be dissipated.
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