ADPL12005/ADPL12006

20V, 5A/6A Fully Integrated Synchronous Buck

Converters

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Analog Devices | 12

Applications Information

Setting the Output Voltage

To program the output voltage, connect a resistor-divider from the output (OUT) to GND (See Figure 2). Select RFB2

(FB to GND resistor) less than or equal to 50kΩ. Calculate RFB1 (OUT to FB resistor) with the following equation:

Equation 1:

RFB1 = RFB2 × (

VOUT

VFB

– 1)

Where, VFB is the feedback regulation voltage. See the Electrical Characteristics table for more details.

ADPL12005

ADPL12006

FB

RFB1

VOUT

RFB2

Figure 2. Output Voltage Setting using External Resistor-Divider

Table 1 provides component selection recommendations for each output range for the adjustable-output configuration.

Recommendations can be further optimized for specific applications. The CFF values listed in Table 1 are recommended

based on RFB1 = 50kΩ. The CFF recommendation changes with the RFB1 selection.

Table 1. Recommended Components

SWITCHING

FREQUENCY (kHz)

VOUT (V)

INDUCTOR (µH)

EFFECTIVE COUT (µF)

CFF (pF)

400

0.8V–1.8V

1.5

440

100

1.8V–3V

3.3

440

100

3V–5V

3.3

150

47

5V–10V

4.7

90

100

10V–12V

6.8

90

100

1500

0.8V–1.8V

0.47

240

10

1.8V–3V

0.56

100

33

3V–5V

1.2

66

33

5V–10V

2.2

44

82

Inductor Selection

Inductor design is a compromise between the size, efficiency, control-loop bandwidth, and stability of the converter.

Insufficient inductance value would increase the inductor current ripple, causing higher conduction losses and higher

output voltage ripple. Since the slope compensation is fixed internally for the ADPL12005/ADPL12006, it might also cause

current-mode-control instability to appear. A large inductor reduces the ripple, but increases the size and cost of the

solution and slows the response. The nominal standard value selected should be within ±30% of the specified inductance.

See Table 1 for recommended inductor values.