ADP1611

Rev. 0 | Page 15 of 20

SEPIC POWER SUPPLY

The circuit in Figure 30 shows the ADP1611 in a single-ended

primary inductance converter (SEPIC) topology. This topology

is useful for an unregulated input voltage, such as a battery-

powered application in which the input voltage can vary

between 2.7 V to 5 V, and the regulated output voltage falls

within the input voltage range.

The input and the output are dc-isolated by a coupling capaci-

tor, C1. In steady state, the average voltage of C1 is the input

voltage. When the ADP1611 switch turns on and the diode

turns off, the input voltage provides energy to L1, and C1

provides energy to L2. When the ADP1611 switch turns off and

the diode turns on, the energy in L1 and L2 is released to charge

to supply current to the load.

2.5V–5.5V

3.3V

IN

SD

SS

RT

SW

ON

FB

COMP

22nF

GND

L1

4.7

µH

L2

4.7

µH

ADP1611

5

6

3

2

7

8

1

4

10

µF

1nF

60k

Ω

10

µF

C1

10

µF

R1

16.8k

Ω

R2

10k

Ω

Figure 30. 3.3 V DC-to-DC Converter