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MAX15112 Datasheet, PDF (16/23 Pages) Maxim Integrated Products – High-Efficiency, 12A, Current-Mode Synchronous Step-Down Regulator with Integrated Switches | |||
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MAX15112
High-Efficiency, 12A, Current-Mode Synchronous
Step-Down Regulator with Integrated Switches
Skip Mode Frequency and Output Ripple
Enable skip mode in battery-powered systems for high
efficiency at light loads. In skip mode the switching fre-
quency (fSKIP), as illustrated in Figure 1, is calc ulated as
follows:
fSKIP
=
t ON
+
1
t OFF1
+
t OFF2
where:
t ON
=
VIN
L
â VOUT
à ISKIP_LIMIT
t
OFF1
=
L
Ã
ISKIP_LIMIT
VOUT
and:
t OFF2
=
âQ OUT
ILOAD
t OFF2
=
L
à ISKIP_LIMIT
Ã


ï£
VIN
1
+1
- VOUT VOUT
ILOAD



Ã
ISKIP_LIMIT

ï£
2

â ILOAD 

Output ripple in skip mode is:
VOUT_RIPPLE
=
 L à ISKIP_LIMIT
COUT à (VIN - VOUT)
+

R ESR_COUT 

( ) Ã ISKIP_LIMIT - ILOAD
IL
VOUT
ISKIP-LIMIT
tON
tOFF1
tOFF2 = n à tCK
ILOAD
VOUT_RIPPLE
Figure 1. Skip Mode Waveform
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