ADP5072ACBZ-R7 datasheet(16/24 Pages) AD

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ADP5072

Data Sheet

Rev. 0 | Page 16 of 24

APPLICATIONS INFORMATION

COMPONENT SELECTION

Feedback Resistors

The ADP5072 provides an adjustable output voltage for both boost

and inverting regulators. An external resistor divider sets the output

voltage where the divider output must equal the appropriate

feedback reference voltage, VFB1 or VFB2. To limit the output voltage

accuracy degradation due to feedback bias current, ensure that the

current through the divider is at least 10 times IFB1 or IFB2.

Set the positive output for the boost regulator by

FT1

POS

FB1



×+





where:

VPOS is the positive output voltage.

VFB1 is the FB1 reference voltage.

RFT1 is the feedback resistor from VPOS to FB1.

RFB1 is the feedback resistor from FB1 to AGND.

Set the negative output for the inverting regulator by

(

)

FT2

NEG

FB2

REF

FB2

−−

where:

VNEG is the negative output voltage.

VFB2 is the FB2 reference voltage.

RFT2 is the feedback resistor from VNEG to FB2.

RFB2 is the feedback resistor from FB2 to VREF.

VREF is the VREF pin reference voltage.

Table 8. Recommended Feedback Resistor Values

Desired Output

Voltage (V)

Boost Regulator

Inverting Regulator

RFT1 (MΩ)

RFB1 (kΩ)

Calculated

Output Voltage (V)

RFT2 (MΩ)

RFB2 (kΩ)

Calculated

Output Voltage (V)

±4.2

0.432

102

4.188

0.715

115

−4.174

±5

0.604

115

5.002

1.15

158

−5.023

±9

1.24

121

8.998

1.62

133

−8.944

±12

1.4

100

12.000

1.15

71.5

−12.067

±13

2.1

137

13.063

2.8

162

−13.027

±15

2.43

137

14.990

2.32

118

−14.929

±18

2.15

100

18.000

2.67

113

−18.103

±20

2.55

107

19.865

2.94

113

−20.014

±24

3.09

107

23.903

3.16

102

−23.984

±30

3.65

100

30.000

4.12

107

−30.004

ADP5072ACBZ-R7 Datasheet(PDF) 16 Page - Analog Devices

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