BCM6123E60E15A3T00 Datasheet, PDF (22/28 Pages) Vicor Corporation – BCM® Bus Converter

Sine Amplitude Converter™ Point of Load Conversion
L_{PRI_IN_LEADS} ^{= 6.7 nH}
+
VV_PRINI
C_{PRI_INT_ESR}
0.75 mΩ
C_{PRI_INT}
11.2 µF
C_IN
RC_IN
I ^IPRI__QQ
270 mA
–
1/4 • I_SEC
I_O^IS_UEC_T
0.53 nH
V•I
++
10 mΩ
1/4 • V_PRI
––
K
BCM6123x60E15A3yzz
R_SEC
1_R.9_O6_UTmΩ
C_OUT
L_{SEC_OUT_LEADS} ^{= 0.64 nH}
RCC_{SEOC_UINTT_ESR}
60.4 µΩ
C_{SEC_INT}
140 µF
+
V^V_O^SE_U^C_T
–
Figure 16 — BCM module AC model
The Sine Amplitude Converter (SAC™) uses a high frequency
resonant tank to move energy from Primary to secondary and
vice versa. The resonant LC tank, operated at high frequency,
is amplitude modulated as a function of primary voltage and
secondary current. A small amount of capacitance embedded in
the primary and secondary stages of the module is sufficient for full
functionality and is key to achieving high power density.
The BCM6123x60E15A3yzz SAC can be simplified into the
preceeding model.
At no load:
interesting attributes. Assuming that R_SEC = 0Ω and I_{PRI_Q} = 0A,
Eq. (3) now becomes Eq. (1) and is essentially load independent,
resistor R is now placed in series with P_RI.
R^R
+
V^V_Pⁱ_Rⁿ_{I –}
S^SA^AC^C™
K^K=⁼1¹/3^/42
V_So_Eu_C t
V_SEC = V_PRI • K
(1)
K represents the “turns ratio” of the SAC.
Rearranging Eq (1):
K = ^VSEC
VPRI
In the presence of load, V_SEC is represented by:
V_SEC = V_PRI • K – I_SEC • R_SEC
and Iout is represented by:
Figure 17 — K = 1/4 Sine Amplitude Converter
with series primary resistor
(2)
The relationship between V_PRI and V_SEC becomes:
V_SEC = (V_PRI – I_PRI ^• R) ^• K
(5)
Substituting the simplified version of Eq. (4)
(I_{PRI_Q} is assumed = 0A) into Eq. (5) yields:
(3)
V_SEC = V_PRI ^• K – I_SEC ^• R ^• K²
(6)
^{I SEC = IPRIK– IPRI_Q}
(4)
R_SEC represents the impedance of the SAC, and is a function
of the R_DSON of the primary and secondary MOSFETs and the
winding resistance of the power transformer. PRI_Q represents the
quiescent current of the SAC control, gate drive circuitry,
and core losses.
The use of DC voltage transformation provides additional
This is similar in form to Eq. (3), where R_SEC is used to represent the
characteristic impedance of the SAC™. However, in this case a real
R on the primary side of the SAC is effectively scaled by K² with
respect to the secondary.
Assuming that R = 1Ω, the effective R as seen from the secondary
side is 62.5mΩ, with K = 1/4 .
BCM^® Bus Converter
Page 22 of 28
Rev 1.2
07/2016
vicorpower.com
800 927.9474