EVALA5972D STMicroelectronics, EVALA5972D Datasheet - Page 24

• Manufacturer Part Number: EVALA5972D
• Description: Power Management Modules & Development Tools EVAL BOARD A5972 Auto Grade
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of EVALA5972D

• Input Voltage: 4.4 V to 36 V
• Output Voltage: 1.235 V to 35 V
• Board Size: 23 mm x 20 mm
• Product: Power Management Modules
• Supply Current: 2 A
• Dimensions: 23 mm x 20 mm
• For Use With/related Products: AN1517
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application ideas
6
6.1
7
24/29
Application ideas
Positive buck-boost regulator
The device can be used to implement an step-up/down converter with a positive output
voltage.
of 12 V.
The input voltage can range from 5 V and 35 V. The output voltage is given by V
D/(1-D), where D is the duty cycle. The maximum output current is given by I
The current capability is reduced by the term (1-D) and so, for example, with a duty cycle of
0.5, the maximum output current deliverable to the load is 0.75 A. This is due to the fact that
the current flowing through the internal power switch is delivered to the output only during
the OFF phase.
Figure 24. Positive buck-boost regulator
Buck-boost regulator
In
voltage is given by V
D), for the same reason as that of the up-down converter. An important thing to take in
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
36 V (the maximum operating input voltage).
Figure 25. Buck-boost regulator
Figure
VIN=5V
C1
10uF
10V
Ceramic
C1
10uF
10V
Ceramic
VIN=5V
Figure 24
25, the schematic circuit for a standard buck-boost topology is shown. The output
C2
220pF
10uF
25V
Ceramic
C2
C3
22nF
R3
4.7k
Vcc
COMP
below shows the schematic diagram of this topology for an output voltage
C3
220pF
O
= -V
8
4
C4
22nF
R3
4.7k
2
IN
Vcc
COMP
L5972D
· D/(1-D). The maximum output current is equal to I
6
GND
8
4
7
2
3
L5972D
1
5
6
OUT
FB
GND
7
D1
STPS2L25U
3
1
5
OUT
FB
L1
33uH
24k
2.7k
AM00135v1
IN
AM00136v1
-V
O
, which has to be lower than
D1
STPS2L25U
M1
STN4NE03L
C5
100uF
16V
L1
33uH
D2
STPS2L25U
2.7k
24k
VOUT=-12V/0.45A
OUT
VOUT=12V/0.45A
C4
100uF
16V
OUT
O
=1× (1-D).
=V
AN1517
=1 · (1-
IN
·