ZHCSGP0A July 2017 – September 2017 TPS7A39
PRODUCTION DATA.
Layout is a critical part of good power-supply design. There are several signal paths that conduct fast-changing currents or voltages that can interact with stray inductance or parasitic capacitance to generate noise or degrade the power-supply performance. To help eliminate these problems, bypass the IN pin to ground with capacitors.
Tie the GND pin directly to the thermal pad under the device. The thermal pad must be connected to any internal PCB ground planes using multiple vias directly under the device.
Every capacitor must be placed as close as possible to the device and on the same side of the PCB as the regulator itself.
Do not place any of the capacitors on the opposite side of the PCB from where the regulator is installed. The use of vias and long traces is strongly discouraged because these circuits can impact system performance negatively, and even cause instability.
To improve ac performance (such as PSRR, output noise, and transient response), TI recommends that the board be designed with separate ground planes for VIN and VOUT, with each ground plane star connected only at the GND pin of the device. In addition, the ground connection for the bypass capacitor must connect directly to the GND pin of the device.
Solder pad footprint recommendations for the TPS7A39 are available at the end of this document and at www.ti.com.