Datasheet

LM2767
www.ti.com SNVS069C –FEBRUARY 2000–REVISED MAY 2013
Typical Performance Characteristics (continued)
(Circuit of Figure 4, V
IN
= 5V, T
A
= 25°C unless otherwise specified)
Switching Frequency vs Switching Frequency vs
Supply Voltage Temperature
Figure 11. Figure 12.
Output Ripple vs
Load Current
Figure 13.
CIRCUIT DESCRIPTION
The LM2767 contains four large CMOS switches which are switched in a sequence to double the input supply
voltage. Energy transfer and storage are provided by external capacitors. Figure 14 illustrates the voltage
conversion scheme. When S
2
and S
4
are closed, C
1
charges to the supply voltage V+. During this time interval,
switches S
1
and S
3
are open. In the next time interval, S
2
and S
4
are open; at the same time, S
1
and S
3
are
closed, the sum of the input voltage V+ and the voltage across C
1
gives the 2V+ output voltage when there is no
load. The output voltage drop when a load is added is determined by the parasitic resistance (R
ds(on)
of the
MOSFET switches and the ESR of the capacitors) and the charge transfer loss between capacitors. Details will
be discussed in the following application information section.
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