EVALA5970AD STMicroelectronics, EVALA5970AD Datasheet - Page 32

• Manufacturer Part Number: EVALA5970AD
• Description: BOARD EVAL FOR A5970AD REG
• Manufacturer: STMicroelectronics

Specifications of EVALA5970AD

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.235 ~ 35V
• Current - Output: 1A
• Voltage - Input: 4 ~ 36V
• Regulator Topology: Buck
• Frequency - Switching: 500kHz
• Board Type: Fully Populated
• Utilized Ic / Part: A5970AD
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Application information
8.7
32/42
Figure 22. Positive buck-boost regulator
Negative buck-boost regulator
In
voltage is:
Equation 37
where the ideal duty cycle D for the buck boost converter is:
Equation 38
The considerations given in
Also the
So, as an example, considering the conversion V
Equation 39
Equation 40
An important thing 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
Equation 34
23, the schematic circuit for a standard buck-boost topology is shown. The output
till
Equation 36
A5970AD
Section 8.7
Doc ID 14661 Rev 4
I
SW
=
V
D
can be used to calculate the maximum output current.
I
-------------- -
OUT
1 D
D
LOAD
=
–
for the real duty cycle are still valid here.
=
--------------- -
5
=
+
----------------------------- -
V
5
=
IN
12
–
–
V
V
----------------------- -
1 0.706
–
IN
OUT
=
–
V
IN
0.5
⋅
OUT
0.706
------------ -
1 D
= 12 V to V
D
–
=
1A
OUT
= -5 V, I
LOAD
= 0.3 A:
A5970AD
IN
-V
O
,