MAX15569 Datasheet, PDF (37/41 Pages) Maxim Integrated Products – 2-Phase/1-Phase QuickTune-PWM Controller with Serial I2C Interface

MAX15569
2-Phase/1-Phase QuickTune-PWM Controller with
Serial I²C Interface
Table 12. Layout Procedures
COMPONENTS
DESCRIPTION
Capacitors
The general rule is that capacitors take priority over resistors since they provide a filtering function. The list
below is in order of priority:
1) V_BIAS Capacitors: Place these near the IC pins with wide traces and good connection to PGND.
2) CSP_ - CSN_ Differential Filter Capacitors: Place the capacitors and the step resistor near the IC pins.
These inputs are critical because they are used for regulation and load-line, as well as current limit and
current balance.
3) Common-Mode Capacitors: The capacitors to AGND take the next priority.
4) FB and GNDS Capacitors: The FB capacitor can be slightly farther away from the IC since the FB resistor
has priority to be closer to the IC.
FB and FBAC
The FB and FBAC resistors should be near the respective pins. Keep the trace short to reduce any inductance.
Current Sense
Thermistors
Catch Resistors
Remote Sense
I²C
AGND
Use Kelvin-sense connection to the sense element (inductor or sense resistor).
Route CSP_ traces near CSN_. Avoid any switching signals, especially LX when routing these current-sensing
signals.
The NTC for THERM sensing should be placed near the power components of the first phase.
Catch resistors should be placed near the point of load so that the output-voltage trace does not need to route
back to the IC. The ground catch resistor is less critical as it only requires a via to connect to the PGND plane.
Route together in a quiet layer, avoiding any switching signals, especially LX.
Pullups for I²C Interface and INT do not need to be too close to the IC and can be placed farther away to make
space for other more important components near the IC.
Place a small 0.1µF decoupling capacitor for the V_TT near the pullup resistors.
Keep the AGND polygon just large enough to cover AGND components. Do not make it any larger than
necessary. The AGND polygon should not run under any high-voltage switching traces since all AGND
connections should be on the other side of the IC, away from the driver pins.
AGND-PGND
Exposed Pad
Power
Components
AGND-PGND connection should be made away from the PGND pins so as not to be in the path of the
DRVPWM_ drive currents. A good location is near the BIAS pin.
Connect to AGND.
Place the power components close to keep the current loop small. Avoid large LX nodes. Use multiple vias to
keep the impedance low and to carry the high currents.
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