BCM48BH120M120A00 Datasheet, PDF (10/16 Pages) Vicor Corporation – Bus Converter

PRELIMINBACRMY4D8BAHTA12S0HTE1E20TA00 - BCM48BH120M120A00
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:
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 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).
INPUT
POWER
P_NL
Figure 15 – Power transfer diagram
OUTPUT
POWER
P _{R OUT}
The above relations can be combined to calculate the overall module efficiency:
( ) ^{η = 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
v i c o r p o w e r. c o m
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
Rev. 2.0
12/10
Page 10 of 16