Datasheet

( )
-
= ´ ´
´
IN OUT
OUT
LOAD(LL)
X IN SW
V V
V
1
I
2 L V f
´
³
´
OUT
SW X
V ESR
20mV
f L
V
VDDQSNS
V
REFIN
(1)
(2)
t
ON
t
OFF
Slope (2)
Jitter
20 mV
Slope (1)
Jitter
UDG-10139
V
REFIN
+Noise
TPS51216
SLUSAB9A –NOVEMBER 2010–REVISED APRIL 2013 www.ti.com
Figure 31. Ripple Voltage Slope and Jitter Performance
For a good jitter performance, use the recommended down slope of approximately 20 mV per switching period as
shown in Figure 31 and Equation 2.
where
• V
OUT
is the VDDQ output voltage
• L
X
is the inductance (2)
Light-Load Operation
In auto-skip mode, the TPS51216 SMPS control logic automatically reduces its switching frequency to improve
light-load efficiency. To achieve this intelligence, a zero cross detection comparator is used to prevent negative
inductor current by turning off the low-side MOSFET. Equation 3 shows the boundary load condition of this skip
mode and continuous conduction operation.
(3)
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