Datasheet

L6738A Application details
Doc ID 18134 Rev 2 25/32
Connect output bulk capacitors (C
OUT
) as near as possible to the load, minimizing parasitic
inductance and resistance associated to the copper trace, also adding extra decoupling
capacitors along the way to the load when this results in being far from the bulk capacitors
bank.
Remote Sense Connection must be routed as parallel nets from the FBG/VSEN pins to the
load in order to avoid the pick-up of any common mode noise. Connecting these pins in
points far from the load causes a non-optimum load regulation, increasing output tolerance.
Locate current reading components close to the device. The PCB traces connecting the
reading point must use dedicated nets, routed as parallel traces in order to avoid the pick-up
of any common mode noise. It's also important, to avoid any offset in the measurement and,
to get a better precision, to connect the traces as close as possible to the sensing elements.
A small filtering capacitor can be added, near the controller, between VOUT and GND, on
the CSN line to allow higher layout flexibility.
Figure 11. Power connections (heavy lines)
Gate traces and phase trace must be sized according to the driver RMS current delivered to
the power MOSFET. The device robustness allows the managing of applications with the
power section far from the controller without losing performance. However, when possible, it
is recommended to minimize the distance between the controller and power section.
Small signal components and connections to critical nodes of the application, as well as
bypass capacitors for the device supply, are also important. Locate the bypass capacitor
(VCC and bootstrap capacitor) and feedback compensation components as close to the
device as practical.
Figure 12. Drivers turn-on and turn-off paths
L
C
IN
V
IN
UGATE
PHASE
LGATE
GND
LOAD
L6738
C
OUT
RGATE RINT
CGD
CGS CDS
VCCDR
LS DRIVER LS MOSFET
GND
LGATE
RGATE RINT
CGD
CGS CDS
BOOT
HS DRIVER HS MOSFET
PHASE
UGATE