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http://www.union-ic.com Rev.02 Dec.2014

11/18

UM1650 UM1750

Typical Application Circuit

VIN

VOUT

GND

1μF

1μF

Figure 1. UM1650S-xx Typical Application Circuit

VIN

VOUT

SHDN

GND

1

μF

Chip Enable

1

μF

VIN

VOUT

SHDN

GND

FB

1

μF

Chip Enable

1

μF

R1

R2

UM1750S-00/UM1750Y-00/UM1750DA-00 Output Voltage Setting

The output voltage of the UM1750 adjustable regulator is programmed using an external resistor

divider as shown in Figure 3. The output voltage is calculated using:











 



2

1

1

R

R

V

V

FB

O

Resistors R1 and R2 should be chosen for approximately 3-5μA divider current. Lower value

resistors can be used but offer no inherent advantage and waste more power. Higher values should

be avoided, as leakage currents at FB increase the output voltage error. The recommended design

procedure is to choose R2 = 200kΩ to set the divider current at 5μA and then calculate R1 using:

2

1

1

R

V

V

R

FB

O

















