Layout Recommendations

Typically, there are two sources of noise emission in a

switching power supply: high di/dt loops and high dv/dt

surfaces. For example, traces that carry the drain cur-

rent often form high di/dt loops. Similarly, the heatsink

of the MOSFET presents a dv/dt source; therefore, mini-

mize the surface area of the heatsink as much as possi-

ble. Keep all PC board traces carrying switching

currents as short as possible to minimize current loops.

Use a ground plane for best results. The pins of the

µMAX package are positioned to allow easy interfacing

to the external MOSFET.

For universal AC input design, follow all applicable

safety regulations. Offline power supplies may require

UL, VDE, and other similar agency approvals. To avoid

noise coupling of signals from RT to NDRV, route traces

from RT away from NDRV.

Current-Mode PWM Controllers with

Programmable Switching Frequency

______________________________________________________________________________________

15

COMP

FB

GND

CS

NDRV

UVLO/EN

0V

12V

R2

R3

R1

C1

RT

UFLG

C6

R15

R12

C4

IN

MAX15001

C2

C3

R5

R6

15V

D1

Q1

L1

Figure 8. 12V to 15V Output Boost Regulator