BCD384F120T300A00 Datasheet, PDF (14/21 Pages) Vicor Corporation – BCM® Bus Converter

Sine Amplitude Converter™ Point of Load Conversion
L_in = 5.7nH
+
R9R_{c.C2inmINΩ}
CC_II_NN
VVin_IN
0.0625µF
I^I_QQ
18mA
1/32 • I_out
–
I^I_Oo_Uut_T
108nH
V•I
++
480mΩ
1/32 • V_in
––
K
BCM384x120y300Azz
R_out
6_R.0_Om_UTΩ
C^C_Oo_Uu_Tt
31µF
L_out = 500pH
+
RR_CcoOutUT
570µΩ
V^V_Oo_Uu_Tt
–
Figure 17 — VI Chip^® module AC model
The Sine Amplitude Converter (SAC™) uses a high frequency
resonant tank to move energy from input to output. The resonant
LC tank, operated at high frequency, is amplitude modulated as
a function of input voltage and output current. A small amount
of capacitance embedded in the input and output stages of the
module is sufficient for full functionality and is key to achieving
power density.
The BCM384x120y300A00 SAC can be simplified into the
preceeding model.
R_OUT represents the impedance of the SAC, and is a function of the
R_DSON of the input and output MOSFETs and the winding resistance
of the power transformer. I_Q represents the quiescent current of
the SAC control, gate drive circuitry, and core losses.
The use of DC voltage transformation provides additional
interesting attributes. Assuming that R_OUT = 0Ω and I_Q = 0A, Eq. (3)
now becomes Eq. (1) and is essentially load independent, resistor R
is now placed in series with V_IN.
At no load:
V_OUT = V_IN • K
K represents the “turns ratio” of the SAC.
Rearranging Eq (1):
K = ^VOUT
V_IN
In the presence of load, V_OUT is represented by:
V_OUT = V_IN • K – I_OUT • R_OUT
and I_OUT is represented by:
I ^{OU T = IIN}
–
K
I_Q
R
(1)
V_Vinin
+
–
S_SA_AC_C™
K^K =⁼ 1¹/^/3³²2
VV_oo_uu_tt
Figure 18 — K = 1/32 Sine Amplitude Converter
(2)
with series input resistor
The relationship between V_IN and V_OUT becomes:
V_OUT = (V_IN – I_IN • R) • K
(5)
(3)
Substituting the simplified version of Eq. (4)
(I_Q is assumed = 0A) into Eq. (5) yields:
(4)
V_OUT = V_IN • K – I_OUT • R • K²
(6)
BCM^® Bus Converter
Page 14 of 21
Rev 1.5
08/2016
vicorpower.com
800 927.9474