Delta Electronics DNL Series manual Vref, PS1=5V

For Ratio-Metric applications that need the outputs of PS1 and PS2 achieve the regulation set point at same time, use equation 1 to calculate R1, set △V=Voset,PS1–Voset,PS2and △V will be negative. The waveforms of power up and down are showed in Figures 7 and 8.

R1 =	[(Voset ,PS 2	+ ∆V ) − Vref ]	* 20K Ω ------------------------------------------------------	(1)
		Vref

Note:

1.Vref =0.4×Voset,PS2 , please refer to Table 5 for Vref set value.

2.△V is the maximum difference of voltage between PS1 and PS2 supply voltage.

For example, the PS1 Voset,PS1=5V, the PS2 Voset,PS2=3.3V, R1 is calculated as follows:

R1 =	[(3.3 + 1.7) − 1.32]	* 20K = 55.75K Ω
	1.32

PS1=5V

+△V=1.7V PS2=3.3V

PS1

PS2

Figure 7. Ratio–metric tracking Power up

Figure 8. Ratio–metric tracking Power down

For Ratio-Metric applications that need the PS2 supply voltage rises first at power up and falls second at power down. To calculate R1, use the following equation (2) and set △ V ≦

0.4×Voset,PS2, △V will be negative. The waveforms of power up and down are showed in Figures 9 and 10.

R1 =	[(Voset , ps 2	− ∆V ) − Vref ]	* 20K -----------------------------------------------------------------	(2)
		Vref

Note:

1.Vref =0.4×Voset,PS2 , please refer to Table 5 for Vref set value.

2.△V is defined as the voltage difference between VoPS1 and VoPS2 when VoPS2 reaches its rated voltage.

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