APPLICATION NOTE 906

The MAX1864 Generates 1.2V or Lower Output Voltage

Dec 27, 2001

Abstract: Article shows how a regulator can generate an output voltage that is less than the reference voltage. Circuit generates a 1.0V output voltage. The MAX1864 triple-output power supply is featured.

With most regulators, it is difficult to generate an output voltage that is less than the reference voltage. This note describes a way to use the MAX1864 to achieve an output voltage less than its 1.236V reference.

The MAX1864 includes a positive linear regulator gain block. With a few external resistors, it can achieve an output voltage below 1.236V. Figure 1 shows the schematic of the implementation. Since the voltage at the FB pin is the reference voltage, a lower output voltage, VOUT1, is obtained if a voltage (V2) higher than the reference voltage is generated. Due to the high input impedance at the FB pin, if R5 is chosen to be equal to R6, we have

V2 - VFB = VFB - VOUT1,

This yields V2 = 2VFB - VOUT1.

To generate a 1.0V output voltage with VFB = 1.236V, V2 should then be 1.472V. This can be achieved by properly choosing the resistance of R8 and R9:



If R8 = 10kΩ, then R9 will be 52.4kΩ. Therefore, a 1.0V output voltage is generated.

Figure 1. Schematic of 1.0V power supply with the MAX1864.
Figure 1. Schematic of 1.0V power supply with the MAX1864.

Related Parts
MAX1864 xDSL/Cable Modem Triple/Quintuple Output Power Supplies Free Samples  


Next Steps
EE-Mail Subscribe to EE-Mail and receive automatic notice of new documents in your areas of interest.
Download Download, PDF Format (62kB)  
Share
Other Channels  Email this page to an associate or friend. 



APP 906: Dec 27, 2001
APPLICATION NOTE 906, AN906, AN 906, APP906, Appnote906, Appnote 906

Share



More