ALTAIR04-900 Datasheet, PDF (21/29 Pages) STMicroelectronics – Off-line all-primary-sensing switching regulator

ALTAIR04-900
Application information
5.10
Layout recommendations
A proper printed circuit board layout is essential for correct operation of any switch-mode
converter and this is true for the ALTAIR04-900 as well. Careful component placing, correct
traces routing, appropriate traces widths and compliance with isolation distances are the
major issues. In particular:
● The compensation network should be connected as close as possible to the COMP
pin, maintaining the trace for the GND as short as possible
● Signal Ground should be routed separately from power ground, as well from the sense
resistor trace.
Figure 19. Suggested routing for converter
OUT
AC IN
AC IN
GND
VDD
DRAIN
FB/ZCD _ALTAIR04-900
COMP
GND IREF
SOURCE
Doc ID 18211 Rev 2
21/29