ST1S14 STMicroelectronics, ST1S14 Datasheet - Page 24

• Manufacturer Part Number: ST1S14
• Description: Up to 3 A step down switching regulator
• Manufacturer: STMicroelectronics

Application information
7.3
24/42
Thermal considerations
The dissipated power of the device is tied to three different sources:
●
Equation 24
Where D is the duty cycle of the application. Note that the duty cycle is theoretically given by
the ratio between V
compensate for the losses in the overall application. For this reason, the conduction losses
related to the R
●
Equation 25
Where T
switching losses when driving an inductive load (see
switching time.
Figure 15. Switching losses
●
Equation 26
Conduction losses due to the not insignificant R
Switching losses due to turning ON and OFF. These are derived using the following
equation:
Quiescent current losses.
RISE
P
and T
SW
DSON
=
FALL
OUT
V
increase compared to an ideal case.
IN
and V
⋅
represent the switching times of the power element that cause the
I
OUT
⋅
IN
Doc ID 17977 Rev 1
(
---------------------------------------- - F
, but in practice it is substantially higher than this value to
T
P
RISE
ON
=
+
2
P
T
R
Q
FALL
DSON
=
V
)
⋅
IN
⋅
(
⋅
SW
I
OUT
I
Q
=
)
DSON
V
2
Figure
IN
⋅
D
⋅
I
, which are equal to:
OUT
15). T
⋅
T
SW_EQ
SW
is the equivalent
⋅
F
SW
ST1S14