EMC VI-200, VI-J00 specifications Outputs 12 15 V Outputs 24 48 V Outputs, Output Ripple vs. Load

Design Guide & Applications Manual	9. EMC Considerations
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies

High Frequency Switching Noise. Peak-to-peak output voltage ripple is typically 2% or less (1% for 12 V outputs and above). Hence additional output filtering is generally not required. Digital systems rarely need additional filtering. However some analog systems, such as ultrasound systems, will probably require additional output filtering. See additional output filter choices in Table 9–1.

Line Related Output Noise. Line related output noise can be determined from the converter specification — Input Ripple Rejection. As an example, a VI-260-CV

(300 Vin to 5 Vout) has a rejection specification at 120 Hz of 30 + 20 Log (Vin / Vout). Vin = 300 and Vout = 5, hence its rejection is 30 + 35.56 = 65.56 dB, which provides an attenuation factor of 1.89 k. Therefore, if the input to the converter has 30 V p-p of ripple, the output p-p ripple would be 15.8 mV. It is not practical to attenuate this component further with passive filtering due to its low frequency, hence active filtering is required. The RAM contains both a passive filter for high frequency noise and an active filter for low frequency noise.

	5 V Outputs	12 – 15 V Outputs	24 – 48 V Outputs
No Additional Filter	2% p-p (Typical)	1% p-p (Typical)	0.2% p-p (Typical)
Low ESR Output Cap.	1% p-p (Typical)	0.5% p-p (Typical)	0.1% p-p (Typical)
LC Output Filter	0.4% p-p (Typical)	0.2% p-p (Typical)	0.05% p-p (Typical)
RAM Filter (VI-200)	<3 mV p-p (Maximum)	<3 mV p-p (Maximum)	<3 mV p-p (Maximum)
RAM Filter (VI-J00)	<10 mV (Maximum)	<10 mV (Maximum)	<10 mV (Maximum)

Table 9–1— Output filter options and output voltage and ripple

Differential Output Filtering

Typical Vicor Module (VI-230-CV) 48 V Input, 5 V Output

C2a			C3a
	+IN	+OUT				Conditions
	GATE	+S
			C1 = 100 µF			Light Load = 3 A
C1	OUT	TRIM
	GATE		C2a – C2b	= 4,700 pF	(Vicor Part # 01000)	Nominal Load = 15 A
		–S
	IN		C3a – C3b	= 0.01 µF	(Vicor Part # 04872)	Full Load = 30 A
	–IN	–OUT
C2b			C3b
		Output Ripple vs. Load
3 Amp Load			15 Amp Load			30 Amp Load

Figure 9–10— Output noise, no additional output filtering

vicorpower.com 800-735-6200 Applications Engineering 1-800-927-9474 Rev. 2.1

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