DCM4623xD2K31E0y7z
Vicor provides a suite of online tools, including a simulator and
thermal estimator which greatly simplify the task of determining
whether or not a DCM thermal configuration is sufficient for a given
condition. These tools can be found at:
www.vicorpower.com/powerbench.
DCMs in current limit will operate with higher output current or
power than the rated levels. Therefore the Figure 20 Thermal Safe
Operating Area plot should be used for loads that drive the DCM in
to current limit for sustained operation.
Standalone Operation
The following Figure 21 shows the configuration of the Enhanced
VOUT DCM. An input filter is required to attenuate noise coming from
the input source. In case of the excessive line inductance, a properly
sized decoupling capacitor CDECOUPLE is required as shown
in the following figure.
DCM
R5
TR
+
+
EN
C2
FB1
FT
VTR
R1
L1
R2
R3
VEN
F1
+IN
-IN
+OUT
-OUT
+IN
+OUT
-OUT
L2
R4
1
COUT-EXT
CDECOUPLE
C5
C4
D1
_
_
-IN
Figure 21 — Enhanced VOUT DCM configuration circuit
If signal pins (TR, EN, FT) are not used, they can be left floating, and
DCM will work in the nominal output condition.
When common mode noise in the input side is not a concern, TR and
EN can be driven and FT received using -IN as a reference.
L1: 1 µH, minimized DCR;
R1: 1.0 Ω;
C1: Ceramic capacitors in parallel, C1 = 2 µF;
L2: L2 ≥ 0.15 µH;
R2: 1 Ω;
C
OUT-EXT: electrolytic or tantalum capacitor, 200 µF ≤ C3 ≤2000 µF;
C4, C5: additional ceramic /electrolytic capacitors, if needed for
output ripple filtering;
In order to help sensitive signal circuits reject potential noise,
additional components are recommended:
R5: 301 Ω, facilitate noise attenuation for TR pin;
FB1, C2: FB1 is a ferrite bead with an impedance of at least 10 Ω at
100MHz. C2 can be a ceramic capacitor of 0.1µF. Facilitate noise
attenuation for EN pin.
Note: Use an RCR filter network as suggested in the application note
AN:030 to reduce the noise on the signal pins.
DCM™ DC-DC Converter
Rev 1.0
Page 20 of 23
07/2017
VICOR [ VICOR CORPORATION ]
