EVALA5970D STMicroelectronics, EVALA5970D Datasheet - Page 26

• Manufacturer Part Number: EVALA5970D
• Description: Power Management Modules & Development Tools EVAL BOARD A5970D Auto Grade
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of EVALA5970D

• 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: 1 A
• Dimensions: 23 mm x 20 mm
• For Use With/related Products: AN1330
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application ideas
6
6.1
6.2
26/31
Application ideas
Positive buck-boost regulator
The device can be used to implement a 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 duty cycle. The maximum output current is given by I
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 0.5 A. This is due to the fact that the
current flowing trough the internal power switch is delivered to the output only during the
OFF phase.
Figure 25. 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 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
V (the maximum operating input voltage).
Figure 26. Buck-boost regulator
Figure
VIN=5V
C1
10uF
25V
Ceramic
Vin=5V Vout=12V
Figure 25
26, the schematic circuit for a standard buck-boost topology is shown. The output
C2
220pF
below shows the schematic diagram of this topology for an output voltage
C3
22nF
R3
4.7k
Iout=0.3A
O
COMP
VCC
= - V
SYNC VREF
Efficiency=76%
8
4
IN
2
· D/(1-D). The maximum output current is equal to I
L5970
3.3V
6
U1
GND
7
3
1
5
INH
OUT
FB
D1
STPS2L25U
L1
33uH
IN
-V
O
M1
STN4NE03L
, that has to be lower than 36
D2
STPS2L25U
2.7k
24k
OUT
VOUT=12V/0.3A
C4
100uF
16V
=1× (1-D). The
O
OUT
=V
AN1330
IN
=1 · (1-
·