ADP1611

Rev. 0 | Page 14 of 20

APPLICATION CIRCUITS

The circuit in Figure 27 shows the ADP1611 in a step-up

configuration. The ADP1611 is used here to generate a 15 V

regulator with the following specifications:

The output can be set to the desired voltage using Equation 2.

Use Equations 16 and 17 to change the compensation network.

IN

SD

SS

RT

SW

ON

FB

COMP

22nF

GND

L1

4.7

µH

D1

ADP1611

5

6

3

2

7

8

1

4

10

µF

150pF

220k

Ω

10

µF

R1

112k

Ω

R2

10k

Ω

5V

15V

Figure 27. 5 V to 15 V Step-Up Regulator

STEP-UP DC-TO-DC CONVERTER WITH TRUE

SHUTDOWN

Some battery-powered applications require very low standby

current. The ADP1611 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 ADP1611

to achieve output load disconnect at shutdown. To shut down

the ADP1611 and disconnect the output from the input, drive

the SD pin below 0.4 V.

IN

SHDN

SS

RT

SW

FB

COMP

22nF

GND

4.7

µH

ADP1611

5

6

3

2

7

8

1

4

10

µF

B

Q1

A

Q1

FDC6331

150pF

220k

Ω

10

µF

112k

Ω

ON

10k

Ω

10k

Ω

5V

15V

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

step-up , 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.

IN

SD

SS

RT

SW

ON

FB

COMP

22nF

GND

L1

4.7

µH

D1

D2

D3

BAV99

BAV99

BZT52C22

BZT52C5VIS

BAV99

ADP1611

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

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.