Datasheet

L6738A High Current embedded drivers
Doc ID 18134 Rev 2 21/32
Two main terms contribute in the device power dissipation: bias power and drivers' power.
● Device Power (P
DC
) depends on the static consumption of the device through the
supply pins and it is simply quantifiable as follows:
● Drivers' power is the power needed by the driver to continuously switch ON and OFF
the external MOSFETs; it is a function of the switching frequency and total gate charge
of the selected MOSFETs. It can be quantified considering that the total power P
SW
,
dissipated to switch the MOSFETs, is dissipated by three main factors: external gate
resistance (when present), intrinsic MOSFET resistance and intrinsic driver resistance.
This last term is the important one to be determined to calculate the device power
dissipation.
The total power dissipated to switch the MOSFETs for each phase featuring embedded
driver results:
where Q
GHS
is the total gate charge of the HS MOSFETs and Q
GLS
is the total gate
charge of the LS MOSFETs.
P
DC
V
CC
I
CC
V
VCCDR
I
VCCDR
⋅+⋅=
P
SW
F
SW
Q
GHS
VCCDR⋅ Q
GLS
VCCDR⋅+()⋅=