Filter
Top Products
Design Guide & Applications Manual
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies
vicorpower.com 800-735-6200 Applications Engineering 1-800-927-9474 Rev. 2.1
Page 25 of 88
9. EMC Considerations
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
3 Amp Load 15 Amp Load 30 Amp Load
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.
+IN
–IN
+OUT
–OUT
C2
a
C1
C3
a
C2
b
C3
b
GATE
OUT
GATE
IN
+S
TRIM
–S
C1 = 100 µF
C2
a
–
C2
b
= 4,700 pF (Vicor Part # 01000)
C3
a
–
C3
b
= 0.01 µF (Vicor Part # 04872)
Conditions
Light Load = 3 A
Nominal Load = 15 A
Full Load = 30 A
Figure 9–10 — Output noise, no additional output filtering
Output Ripple vs. Load
Differential Output Filtering
Typical Vicor Module (VI-230-CV) 48 V Input, 5 V Output
5 V Outputs 12 – 15 V Outputs 24 – 48 V Outputs