ST1S14 STMicroelectronics, ST1S14 Datasheet - Page 27

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

ST1S14
Equation 34
The
Equation 35
considering T
Equation 36
where T
The voltage divider introduces a gain factor K between the V
effectiveness of the current protection. The worst case scenario is the minimum K, that is
the minimum output voltage, over the input voltage
over V
As a consequence the minimum feedback voltage to keep the inductor current limited over
the input voltage range can be expressed making
expressing V
Equation 37
Equation 37
voltage divider over the entire input voltage range. The
considering the minimum value of the peak current limit given in
characteristics on page
Δ
I
L TOFF
Equation 29
IN
SW
range).
=
=1/f
expresses the worst case scenario as it considers the minimum K gain of the
–
--------------------------------------------------------------------- - T
O_SET
ON
(
V
SW
D
that has been already reduced to its minimum.
and
+
and considering the nominal f
Δ
V
as given in
I
O_MIN
V
L TON
Equation 30
FB
6.
L
(
V
+
=
IN
DCR
V
)
V
---------------------------------------------------------------- T
O
Doc ID 17977 Rev 1
IN
=
Equation
=
–
1.22
L
(
in overcurrent conditions can be simplified to:
I ⋅
DCR
V
)
FB
(
–
⋅
⎛
⎝
SW
L
L
⎛
⎝
-----------------------------------
V
+
1:
1
1.22 T
IN
R
–
+
⋅
DSON
90ns
R
------ -
R
T
1
2
⋅
ON_MIN
⎞
⎠
SW
SW
=
) I ⋅
)
≅
Equation 35
V
.
(Chapter 5.2: Minimum output voltage
(
–
------------------------------------------------------------------------------------- - 1.18μs
FB
⎛
⎝
⋅
V
ON MIN
(
V
⋅
D
Figure 16
V
------------------ -
D
+
1.22
O_SET
+
V
(
)
FB
I
O_SET
≅
L
⋅
V
-------- - 90ns
⋅
equal to
DCR
L
V
------------------ -
IN
Table 6: Electrical
1.22
O_SET
plots the
(
L
Application information
and V
)
)
⎞
⎠
+
)
Equation 36
DCR
FB
Equation 37
that affect the
L
I ⋅
⎞
⎠
(
and
27/42
)