User's Manual

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Note d’étude / Technical document : URDx– OTL 5635.1– 007 / 70 230 Edition 03
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3.5 EXAMPLE OF POWER SUPPLY
3.5.1 Example 1
It the following application note from Linear Technology LTC3440, this schematic is an example of a DC/DC
power supply able to power 3.6V under 2.1A. This can be use with a AC/DC 5V unit or an USB or PCMCIA bus
as input power source.
Figure 9: Example of power supply based on a DC/DC step down converter
3.5.2 Example 2
If the whole power consumption is not an issue, this example of a voltage regulator used with an AC/DC 5V
converter, can be used as a DC power supply.
Figure 10: Example of power supply based on regulator
The voltage output is given by:
VOUT = 1.235V × [1 + (R1 / R2)]
To have 3.7V out R1=560K & R2=271.8K
(270K+1.8K)