BQ25606 Datasheet, PDF (34/43 Pages) Texas Instruments – Standalone 3.0-A, Single Cell Battery Charger With 40V Over Voltage Protection Controller

bq25606
SLUSCK6 – MAY 2017
11 Layout
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11.1 Layout Guidelines
The switching node rise and fall times should be minimized for minimum switching loss. Proper layout of the
components to minimize high frequency current path loop (see Figure 38) is important to prevent electrical and
magnetic field radiation and high frequency resonant problems. Follow this specific order carefully to achieve the
proper layout.
1. Place input capacitor as close as possible to PMID pin and GND pin connections and use shortest copper
trace connection or GND plane.
2. Place inductor input pin to SW pin as close as possible. Minimize the copper area of this trace to lower
electrical and magnetic field radiation but make the trace wide enough to carry the charging current. Do not
use multiple layers in parallel for this connection. Minimize parasitic capacitance from this area to any other
trace or plane.
3. Put output capacitor near to the inductor and the device. Ground connections need to be tied to the IC
ground with a short copper trace connection or GND plane.
4. Route analog ground separately from power ground. Connect analog ground and connect power ground
separately. Connect analog ground and power ground together using thermal pad as the single ground
connection point. Or using a 0-Ω resistor to tie analog ground to power ground.
5. Use single ground connection to tie charger power ground to charger analog ground. Just beneath the
device. Use ground copper pour but avoid power pins to reduce inductive and capacitive noise coupling.
6. Place decoupling capacitors next to the IC pins and make trace connection as short as possible.
7. It is critical that the exposed thermal pad on the backside of the device package be soldered to the PCB
ground. Ensure that there are sufficient thermal vias directly under the IC, connecting to the ground plane on
the other layers.
8. Ensure that the number and sizes of vias allow enough copper for a given current path.
See the EVM user's guide SLUUBL3 for the recommended component placement with trace and via locations.
For the VQFN information, refer to SCBA017 and SLUA271.
11.2 Layout Example
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Figure 38. High Frequency Current Path
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