ADP1610

Rev. 0 | Page 14 of 16

DC-DC STEP-UP SWITCHING CONVERTER WITH

TRUE SHUTDOWN

Some battery-powered applications require very low standby

current. The ADP1610 typically consumes 10 nA from the

input, which makes it suitable for these applications. However,

the output is connected to the input through the inductor and

the rectifying diode, allowing load current draw from the input

while shut down. The circuit in Figure 28 enables the ADP1610

to achieve output load disconnect at shutdown. To shut down

the ADP1610 and disconnect the output from the input, drive

the SD pin below 0.4 V.

IN

SD

SS

RT

SW

FB

COMP

22nF

GND

L

4.7

µH

D1

ADP1610

5

6

3

2

7

8

1

4

10

µF

B

Q1

A

Q1

FDC6331

150pF

220k

Ω

10

µF

R1

71.3k

Ω

OFF

R2

10k

Ω

R3

10k

Ω

3.3V

10V

Figure 28. Step-Up Regulator with True Shutdown

TFT LCD BIAS SUPPLY

Figure 29 shows a power supply circuit for TFT LCD module

applications. This circuit has +10 V, −5 V, and +22 V outputs.

The +10 V is generated in the step-up configuration. The −5 V

and +22 V are generated by the charge-pump circuit. During the

step-up operation, the SW node switches between 10 V and

ground (neglecting forward drop of the diode and on resistance

of the switch). When the SW node is high, C5 charges up to

10 V. C5 holds its charge and forward-biases D8 to charge C6

to −10 V. The Zener diode, D9, clamps and regulates the output

to −5 V.

The VGH output is generated in a similar manner by the

charge-pump capacitors, C1, C2, and C4. The output

voltage is tripled and regulated down to 22 V by the

Zener diode, D5.

IN

SD

SS

RT

SW

ON

FB

COMP

22nF

GND

L

4.7

µH

D1

D2

D3

BAV99

BAV99

BZT52C22

BZT52C5VIS

BAV99

ADP1610

5

6

3

2

7

8

1

4

C1

10nF

10

µF

150pF

220k

Ω

10

µF

C2

1

µF

C3

10

µF

R1

71.3k

Ω

R2

10k

Ω

D5

D9

3.3V

VGL

–5V

VGH

22V

10V

D5

D4

D8

D7

C4

10nF

R3

200

Ω

C5

10nF

C6

10

µF

R4

200

Ω

Figure 29. TFT LCD Bias Supply

SEPIC POWER SUPPLY

The circuit in Figure 30 shows the ADP1610 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 ADP1610 switch turns on and the diode

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

provides energy to L2. When the ADP1610 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

4.7

µH

L2

ADP1610

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-DC Converter