a5975d STMicroelectronics, a5975d Datasheet - Page 39

• Manufacturer Part Number: a5975d
• Description: Up To 3 A Step-down Switching Regulator For Automotive Applications
• Manufacturer: STMicroelectronics

A5975D
8.9
Equation 40
Equation 41
An important point to take into account is that the ground pin of the device is connected to
the negative output voltage. Therefore, the device is subjected to a voltage equal to V
which must be lower than 36 V (the maximum operating input voltage).
Figure 27. Negative buck-boost regulator
Floating boost current generator
The A5975D does not support a nominal boost conversion as this topology requires a low
side switch, however, a floating boost can be useful in applications where the load can be
floating. A typical example is a current generator for LED driving, as the LED does not
require a connection to the ground.
Figure 28. Floating boost topology
10V
4.7
6.8
A5975D
Doc ID 018760 Rev 1
I
SW
=
D
I
-------------- -
1 D
LOAD
–
=
--------------- -
5
+
=
5
12
----------------------- -
1 0.706
–
=
0.5
0.706
=
1.7A
Application information
ESR>35m
470
AM09693v1
IN
Ω
39/50
-V
6
O
,