BCM48BH120120B00 Datasheet, PDF (10/16 Pages) Vicor Corporation – Fixed Ratio DC-DC Converter

BCM48BH120T120B00
3.0 POWER, VOLTAGE, EFFICIENCY RELATIONSHIPS
Because of the high frequency, fully resonant SAC topology,
power dissipation and overall conversion efficiency of BCM^®
converters can be estimated as shown below.
Key relationships to be considered are the following:
INPUT
POWER
1. Transfer Function
a. No load condition
V_OUT = V_IN • K
Eq. 1
Where K (transformer turns ratio) is constant
for each part number
b. Loaded condition
V_OUT = Vin • K – I_OUT • R_OUT
Eq. 2
2. Dissipated Power
The two main terms of power losses in the
BCM module are:
- No load power dissipation (P_NL) defined as the power
used to power up the module with an enabled power
train at no load.
- Resistive loss (R_OUT) refers to the power loss across
the BCM module modeled as pure resistive impedance.
P_DISSIPATED ~~ P_NL + P_ROUT
Eq. 3
Therefore, with reference to the diagram shown in Figure 15
P_OUT = P_IN – P_DISSIPATED = P_IN – P_NL – P_ROUT Eq. 4
Notice that R_OUT is temperature and input voltage dependent
and P_NL is temperature dependent (See Figure 15).
P_NL
Figure 15 — Power transfer diagram
OUTPUT
POWER
P _{R OUT}
The above relations can be combined to calculate the overall module efficiency:
( ) ^{h = POUT = PIN – PNL – PROUT = VIN • IIN – PNL – (IOUT)2 • ROUT = 1 – PNL + (IOUT)2 • ROUT}
P_IN
P_IN
V_IN • I_IN
V_IN • I_IN
Eq. 5
BCM^® Bus Converter
Page 10 of 16
Rev 1.2
07/2015
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