MAX17019 - High-Input-Voltage Quad-Output Controller

The MAX17019 standard application circuit provides a 5V/5AP-P main stage, a 1.8V/3AP-P VDDQ
and 0.9A/2A VTT outputs for DDR, and a 1.05V/5AP-P chipset supply.
The MAX17019 supports four power outputs—one highvoltage
step-down controller, two internal MOSFET step-down switching regulators, and one high-current
source/sink linear regulator.
The step-down switching regulators use a current-mode fixed-frequency architecture compensated by the output capacitance. An internal 50mA 5V linear regulator provides the bias supply
and driver supplies, allowing the controller to power up from input supplies greater than 5.5V.

The MAX17019 uses a light-load pulse-skipping operating mode for all switching regulators. The switching regulators turn off the low-side MOSFETs when the current sense detects zero inductor current. This keeps the inductor from discharging the output capacitors and forces the switching regulator to skip pulses under light-load conditions to avoid overcharging the output.

Pcb Layout Guidelines
Careful PCB layout is critical to achieving low switching losses and clean, stable operation. The switching power stage requires particular attention. If possible, mount all the power components on the top side of the board,with their ground terminals flush against one another.
Follow the MAX17019 evaluation kit layout and use the following guidelines for good PCB layout:

• Keep the high-current paths short, especially at the ground terminals. This practice is essential for stable, jitter-free operation.

• Keep the power traces and load connections short. This practice is essential for high efficiency. Using thick copper PCBs (2oz vs. 1oz) can enhance fullload efficiency by 1% or more. Correctly routing PCB traces is a difficult task that must be approached in terms of fractions of centimeters, where a single milliohm of excess trace resistance causes a measurable
efficiency penalty.

• Minimize current-sensing errors by connecting CSPA and CSNA directly across the current-sense
resistor (RSENSE_).

• When trade-offs in trace lengths must be made, it is preferable to allow the inductor charging path to be made longer than the discharge path. For example, it is better to allow some extra distance between the input capacitors and the high-side MOSFET than to allow distance between the inductor and the lowside MOSFET or between the inductor and the output
filter capacitor.

• Route high-speed switching nodes (BST_, LX_,
DHA, and DLA) away from sensitive analog areas
(REF, REFIND, FB_, CSPA, CSNA).

PDF Link: http://datasheets.maxim-ic.com/en/ds/MAX17019.pdf