ncp1521b ON Semiconductor, ncp1521b Datasheet - Page 12

• Manufacturer Part Number: ncp1521b
• Description: 1.5 Mhz, 600 Ma Stepdown Dcdc Converter
• Manufacturer: ON Semiconductor

Output Capacitor Selection
desired output ripple voltage. Ceramic capacitors with low
ESR values will have the lowest output ripple voltage and
are strongly recommended. The output capacitor requires
either an X7R or X5R dielectric.
regulated by pulse frequency modulation. The output
voltage ripple is independent of the output capacitor value.
It is set by the threshold of PFM comparator.
Table 3. LIST OF INDUCTOR
Selecting the proper output capacitor is based on the
The output ripple voltage in PWM mode is given by:
In PFM mode (at light load), the output voltage is
DV OUT + DI L
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f SW
1
VLF3010AT Series
MIPW3226 Series
DO1605-T Series
C OUT
LQ CBL2012
LPO3010
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(eq. 6)
NCP1521B
12
Feed-Forward Capacitor Selection
response and is critical to obtain good loop stability.
18 pF or higher ceramic capacitor is needed. Choose a
small ceramic capacitor X7R or X5R or COG dielectric.
Table 4. LIST OF OUTPUT CAPACITOR
The feed-forward capacitor sets the feedback loop
Given that the compensation is internally fixed, a fixed
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GRM21BR60J106ME19L
GRM188R60OJ106ME
GRM188R60J475KE
C2012X5ROJ475KB
C2012X5ROJ226M
C2012X5ROJ106K
JMK212BY475MG
JMK212BJ106MG
4.7 mF
4.7 mF
4.7 mF
10 mF
10 mF
10 mF
22 mF
10 mF