AN2559 datasheet(30/35 Pages) STMICROELECTRONICS

Part #	AN2559

Description	System power supply board for digital solutions

PDF	35 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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30 / 35 page

Measurements

AN2559

30/35

Figure 29.

Efficiency of analog output, by input voltage level

6.2.2

Output voltage ripple

The output voltage ripple of the switching parts of the Analog and VSYS outputs are shown in

Figure 30 and Figure 31. The measurements were made for different input voltages,

because the current ripple influence on the output voltage ripple depends on the input

voltage level. The output voltage ripple on the 3.3 V Analog output and the VAUX output are

displayed in Figure 32 and Figure 33. As these outputs are generated by LDOs, the output

voltage ripple is the same (independent) for all input voltages, and is very low. Therefore,

only one output voltage ripple image is shown in the figures 32 and 33. All of the

measurements were taken at full output load.

Figure 30.

Analog 5 V - output voltage ripple

AI14500

Vin (V)

Efficency (%)

90.0

80.0

70.0

60.0

50.0

40.0

30.0

20.0

10.0

0.0

100.0

AN2559 Datasheet(PDF) 30 Page - STMicroelectronics