EVALA5972D STMicroelectronics, EVALA5972D Datasheet - Page 26

• 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

Compensation network with MLCC (multiple layer ceramic capacitor) at the output
8
8.1
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Compensation network with MLCC (multiple layer
ceramic capacitor) at the output
MLCCs with values in the range of 10 µF-22 µF and rated voltages in the range of 10 V-25 V
are available today at relatively low cost from many manufacturers.
These capacitors have very low ESR values (a few mΩ) and thus are occasionally used for
the output filter in order to reduce the voltage ripple and the overall size of the application.
However, a very low ESR value affects the compensation of the loop (see
the
may be required.
system with ceramic capacitors at the output (the optimum component value depends on
the application).
Figure 27. MLCC compensation network example
External soft-start network
At the start-up, the device can quickly increase the current up to the current limit in order to
charge the output capacitor. If a soft ramp-up of the output voltage is required, an external
soft-start network can be implemented as shown in
up to an external reference (through R), and the B
This clamps the duty cycle, limiting the slew rate of the output voltage.
loop) and in order to keep the system stable, a more complicated compensation network
C1
C1
MLCC
MLCC
10uF
10uF
VIN=5V
VIN=5V
R2=4K7
R2=4K7
Figure 27
C3=220pF
C3=220pF
R1=3.3K
R1=3.3K
C4=4.7nF
C4=4.7nF
shows an example of compensation network that stabilizes the
COMP
COMP
Vcc
Vcc
R3=2.2K
R3=2.2K
R4=470
R4=470
C5=2.7nF
C5=2.7nF
8
8
4
4
2
2
L5972D
L5972D
6
6
7
7
3
3
1
1
5
5
GND
GND
JT
Figure
OUT
OUT
FB
FB
clamps the COMP pin.
D1
D1
28. The capacitor C is charged
STPS2L25U
STPS2L25U
AM00138v1
Coilcraft
Coilcraft
4.7uH
4.7uH
L1
L1
Section 4: Closing
VOUT=2.1V
VOUT=2.1V
C2
C2
MLCC
MLCC
6.3V
6.3V
22uF
22uF
AN1517