Vicor VI-J00 Family DC-DC Converters and Configurable Power Supplies - Manual (Page 30)

Design Guide & Applications Manual
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies
VI-200 and VI-J00 Family Design Guide Rev 3.5 vicorpower.com
Page 29 of 98
Apps. Eng. 800 927.9474 800 735.6200
OVERVIEW
The LC filter design below is a comparatively simple solution
for reducing ripple on the outputs of Vicor’s VI-200 and
VI-J00 Family converter modules. These components are
small and provide significant peak-to-peak noise attenuation.
Since an output filter capacitor is already present in the
DC-DC converter, adding an inductor and capacitor to the
output creates a pi filter. It is important that the inductor
wire be of a size sufficient to carry the load current,
including a safety factor, and that the core does not
saturate. LC filters are generally needed only where very
accurate analog signals are involved.
The RAM /MI-RAM (Ripple Attenuator Module) should be
used if greater attenuation of output ripple is required, or
where additional AC power line ripple frequency rejection
is required.
All standard outputs will function with either remote sense
or local sense, with the recommended capacitance. Lower
ESR is achieved with capacitors in parallel. Ripple data
measured at 20 MHz bandwidth limit.
Adding excessive amounts of external filtering may
compromise the stability of the converter and result in
oscillation.
FILTER COMPONENTS FOR 5 V OUTPUT
• L1 — Vicor P/N 30268 or Micrometals #T38-26/90 core
with 2T #14 wire (200 nH)
• C1, C2 — Vicor P/N 30800, 270 µF / 10 V,
solid tantalum, ESR 90 m Ω typical
• Typical data at high line input:
With full load, ripple ~ 11 mV p-p
With 50% load, ripple ~ 8 mV p-p
FILTER COMPONENTS FOR 12 V AND 15 V OUTPUTS
• L1 — Vicor P/N 30268 or Micrometals #T38-26/90 core
with 2T #14 wire (200 nH)
• C1, C2 — Vicor P/N 30506, 120 µF / 20 V,
solid tantalum, ESR 90 m Ω typical
• Typical data at high line input:
With full load, ripple ~ 5 mV p-p
With 10% load, ripple ~ 15 mV p-p
FILTER COMPONENTS FOR 24 V AND 28 V OUTPUTS
• L1 — Vicor P/N 30268 or Micrometals #T38-26/90 core
with 2T #14 wire (200 nH)
• C1, C2 — Vicor P/N 30507, 68 µF / 30 V,
solid tantalum, ESR 160 m Ω typical
• Typical data at high line input:
With full load, ripple ~ 6 mV p-p
With 10% load, ripple ~ 18 mV p-p
–OUT
–S
+S
+OUT +IN
GATE
IN
GATE
OUT
–IN
TRIM
L1
C1 C2
10. Optional Output Filters
Figure 10 –1 — Recommended LC output filter