Rev. 1.7
12/2010
Page 1 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
vicorpower.com
BCM352F440T330A00
BCM352T440T330A00
(Formerly VIB0003TFJ)
FEATURES
•352 Vdc – 44 Vdc 325 W Bus Converter
•High efficiency (>95%) reduces system power
consumption
•High power density (>1000 W/in3)
reduces power system footprint by >40%
•“Full Chip” V•I Chip package enables surface mount,
low impedance interconnect to system board
•Contains built-in protection features: undervoltage,
overvoltage lockout, overcurrent protection, short
circuit protection, overtemperature protection.
•Provides enable/disable control, internal temperature
monitoring
•ZVS/ZCS Resonant Sine Amplitude Converter topology
•Can be paralleled to create multi-kW arrays
TYPICAL APPLICATIONS
•High End Computing Systems
•Automated Test Equipment
•Telecom Base Stations
•High Density Power Supplies
•Communications Systems
DESCRIPTION
The V•I ChipTM bus converter is a high efficiency (>95%) Sine
Amplitude ConverterTM (SACTM) operating from a 330 to 365
Vdc primary bus to deliver an isolated 41.25 – 45.63 V nominal,
unregulated secondary. The SAC offers a low AC impedance
beyond the bandwidth of most downstream regulators,
meaning that input capacitance normally located at the input
of a regulator can be located at the input to the SAC. Since the
K factor of the BCM352F440T330A00 is 1/8, that capacitance
value can be reduced by a factor of 64x, resulting in savings of
board area, materials and total system cost.
The BCM352F440T330A00 is provided in a V•I Chip package
compatible with standard pick-and-place and surface mount
assembly processes. The V•I Chip package provides flexible
thermal management through its low junction-to-case and
junction-to-board thermal resistance. With high conversion
efficiency the BCM352F440T330A00 increases overall system
efficiency and lowers operating costs compared to
conventional approaches.
SW1
enable / disable
switch
F1
VC1 1 µF
IN
PC
TM
-Out
+Out
-In
+In
BCM
PR
PC
VC
TM
IL
OS
SG
PRM
CD
-Out
+Out
-In
+In
VC
PC
TM
VTM
-Out
+Out
-In
+In
L
O
A
D
TYPICAL APPLICATION
BCMTM
Bus Converter
VIN = 330 – 365 V
VOUT = 41.25 – 45.63 V (NO LOAD)
POUT = 325 W(NOM)
K = 1/8
S
NRTL
CUS
PART NUMBER DESCRIPTION
BCM352F440T330A00 -40°C – 125°C TJ, J lead
Rev. 1.7
12/2010
Page 2 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
ABSOLUTE MAXIMUM RATINGS
+IN to –IN . . . . . . . . . . . . . . . . . . . . . . . . -1.0 Vdc – +400 Vdc
PC to –IN . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 Vdc – +20 Vdc
TM to –IN . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 Vdc – +7 Vdc
+IN/-IN to +OUT/-OUT . . . . . . . . . . . . . . . . . . . 4242 V (Hi Pot)
+IN/-IN to +OUT/-OUT. . . . . . . . . . . . . . . . . . . 500 V (working)
+OUT to –OUT . . . . . . . . . . . . . . . . . . . . . . -1.0 Vdc - +60 Vdc
Temperature during reflow . . . . . . . . . . . . . . . . 245°C (MSL 6)
PACKAGE ORDERING INFORMATION
CONTROL PIN SPECIFICATIONS
See section 5.0 for further application details and guidelines.
PC (V•I Chip BCM Primary Control)
The PC pin can enable and disable the BCM. When held below
VPC_DIS the BCM shall be disabled. When allowed to float with
an impedance to –IN of greater than 50 kΩthe module will
start. When connected to another BCM PC pin, the BCMs will
start simultaneously when enabled. The PC pin is capable of
being driven high by an either external logic signal or internal
pull up to 5 V (operating).
TM (V•I Chip BCM Temperature Monitor)
The TM pin monitors the internal temperature of the BCM
within an accuracy of +5/-5°C. It has a room temperature
setpoint of ~3.0 V and an approximate gain of 10 mV/°C. It
can source up to 100 µA and may also be used as a “Power
Good” flag to verify that the BCM is operating.
-In
PC
RSV
TM
+In
-Out
+Out
-Out
+Out
Bottom View
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
T
4 3 2 1
A
B
C
D
E
H
J
K
L
M
N
P
R
T
Signal
Name Designation
+In A1-E1, A2-E2
–In L1-T1, L2-T2
TM H1, H2
RSV J1, J2
PC K1, K2
+Out A3-D3, A4-D4,
J3-M3, J4-M4
–Out E3-H3, E4-H4,
N3-T3, N4-T4
Rev. 1.7
12/2010
Page 3 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
ATTRIBUTE SYMBOL CONDITIONS / NOTES MIN TYP MAX UNIT
Voltage range VIN 330 352 365 Vdc
dV/dt dVIN /dt 1V/µs
Quiescent power PQPC connected to -IN 395 410 mW
No load power dissipation PNL VIN = 352 V 6.5 9.5 W
VIN = 330 to 365 V 12
Inrush Current Peak IINR_PVIN = 365 V COUT = 100 µF, 24.5 A
POUT = 325 W
DC Input Current IIN_DC POUT = 325 W 1A
K Factor
(
VOUT
)
K 1/8
VIN
Output Power (Average) POUT VIN = 352 VDC; See Figure 14 325 W
VIN = 330 – 365 VDC; See Figure 14 305
Output Power (Peak) POUT_PVIN = 352 VDC 495 W
Average POUT < = 325 W, Tpeak < 5 ms
Output Voltage VOUT Section 3.0 No load 41.25 45.63 V
Output Current (Average) IOUT Pout < = 325 W 7.7 A
Efficiency (Ambient) ηVIN = 352 V, POUT = 325 W 94.4 95.7 %
VIN = 330 V to 365 V, POUT = 325 W 94.4
Efficiency (Hot) ηVIN = 352 V, TJ= 100° C,POUT = 325 W 94.3 95.3 %
Minimum Efficiency η 60 W < POUT < 325 W Max 90 %
(Over Load Range)
Output Resistance (Ambient) ROUT TJ= 25° C 100 140 180 mΩ
Output Resistance (Hot) ROUT TJ= 125° C 150 190 230 mΩ
Output Resistance (Cold) ROUT TJ= -40° C 60 115 180 mΩ
Load Capacitance COUT 100 uF
Switching Frequency FSW 1.56 1.65 1.73 MHz
Ripple Frequency FSW_RP 3.12 3.3 3.46 MHz
Output Voltage Ripple VOUT_PP COUT = 0 µF, POUT = 325 W, VIN = 352 V, 192 400 mV
Section 8.0
VIN to VOUT (Application of VIN)T
ON1VIN = 352 V, CPC = 0; See Figure 16 460 540 620 ms
PC
PC Voltage (Operating) VPC 4.7 55.3 V
PC Voltage (Enable) VPC_EN 22.5 3V
PC Voltage (Disable) VPC_DIS <2 V
PC Source Current (Startup) IPC_EN 50 100 300 uA
PC Source Current (Operating) IPC_OP 23.5 5mA
PC Internal Resistance RPC_SNK Internal pull down resistor 50 150 400 kΩ
PC Capacitance (Internal) CPC_INT Section 5.0 1000 pF
PC Capacitance (External) CPC_EXT External capacitance delays PC enable time 1000 pF
External PC Resistance RPC Connected to –VIN 50 kΩ
PC External Toggle Rate FPC_TOG 1Hz
PC to VOUT with PC Released Ton2 VIN = 352 V, Pre-applied 50 100 150 µs
CPC = 0, COUT = 0; See Figure 16
PC to VOUT, Disable PC TPC_DIS VIN = 352 V, Pre-applied 410 µs
CPC = 0, COUT = 0; See Figure 16
1.0 ELECTRICAL CHARACTERISTICS
Specifications apply over all line and load conditions unless otherwise noted; Boldface specifications apply over the
temperature range of -40°C < TJ< 125°C (T-Grade); All other specifications are at TJ= 25ºC unless otherwise noted
Rev. 1.7
12/2010
Page 4 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
vicorpower.com
PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
1.0 ELECTRICAL CHARACTERISTICS (CONT.)
Specifications apply over all line and load conditions unless otherwise noted; Boldface specifications apply over the
temperature range of -40°C < TJ< 125°C (T-Grade); All other specifications are at TJ= 25ºC unless otherwise noted
ATTRIBUTE SYMBOL CONDITIONS / NOTES MIN TYP MAX UNIT
TM
TM accuracy ACTM -5 +5 ºC
TM Gain ATM 10 mV/°C
TM Source Current ITM 100 uA
TM Internal Resistance RTM_SNK 25 40 50 kΩ
External TM Capacitance CTM 50 pF
TM Voltage Ripple VTM_PP CTM = 0µF, VIN = 365 V, POUT = 325 W 200 400 500 mV
PROTECTION
Negative going OVLO VIN_OVLO-365 380 390 V
Positive going OVLO VIN_OVLO+380 385 400 V
Negative going UVLO VIN_UVLO-270 285 304 V
Positive going UVLO VIN_UVLO+285 300 325 V
Output Overcurrent Trip IOCP VIN = 352 V, 25°C 10 12 15 A
Short Circuit Protection ISCP 15 A
Trip Current
Short Circuit Protection TSCP 1.2 us
Response Time
Thermal Shutdown TJ_OTP 125 130 135 °C
Junction setpoint
GENERAL SPECIFICATION
Isolation Voltage (Hi-Pot) VHIPOT 4242 V
Working Voltage (IN – OUT) VWORKING 500 V
Isolation Capacitance CIN_OUT Unpowered unit 500 660 800 pF
Isolation Resistance RIN_OUT 10 MΩ
MTBF MIL HDBK 217F, 25° C, GB 4.2 Mhrs
cTUVus
Agency Approvals/Standards CE Mark
ROHS 6 of 6
Rev. 1.7
12/2010
Page 5 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
1.1 APPLICATION CHARACTERISTICS
All specifications are at TJ= 25ºC unless otherwise noted. See associated figures for general trend data.
ATTRIBUTE SYMBOL CONDITIONS / NOTES TYP UNIT
No Load Power PNL VIN = 352 V, PC enabled; See Figure 1 6.5 W
Inrush Current Peak INR_PCOUT = 100 µF, POUT = 325 W 2 A
Efficiency (Ambient) ηVIN = 352 V, POUT = 325 W 95.7 %
Efficiency (Hot – 100°C) ηVIN = 352 V, POUT = 325 W 95.3 %
Output Resistance (-40°C) ROUT VIN = 352 V 115 mΩ
Output Resistance (25°C) ROUT VIN = 352 V 140 mΩ
Output Resistance (100°C) ROUT VIN = 352 V 190 mΩ
Output Voltage Ripple VOUT_PP COUT = 0 uF, POUT = 325 W @ VIN = 352, 192 mV
VIN = 352 V
VOUT Transient (Positive) VOUT_TRAN+IOUT_STEP = 0 TO 7.7 A,3.2 mV
ISLEW >10 A/us; See Figure 11
VOUT Transient (Negative) VOUT_TRAN-IOUT_STEP = 7.7 A to 0 A, 2.8 mV
ISLEW > 10 A/us; See Figure 12
Undervoltage Lockout TUVLO 150 µs
Response Time Constant
Output Overcurrent TOCP 10 < IOCP < 15 A 7.5 ms
Response Time Constant
Overvoltage Lockout TOVLO 120 µs
Response Time Constant
TM Voltage (Ambient) VTM_AMB TJ≅27°C 3 V
Rev. 1.7
12/2010
Page 6 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
No Load Power Dissipation vs Line
0
2
4
6
8
10
12
325 330 335 340 345 350 355 360 365 370
Input Voltage (V)
No Load Power Dissipation (W)
-40°C 25°C 100°C
T :
CASE
94
94.5
95
95.5
96
96.5
97
-60 -40 -20 0 20 40 60 80 100 120
Case Temperature (C)
Efficiency (%)
Full Load Efficiency vs. Case Temperature
360 V 352 V 365 V
V :
IN
Efficiency & Power Dissipation -40°C Case
60
65
70
75
80
85
90
95
0123456789
Output Load (A)
Efficiency (%)
8
10
12
14
16
18
20
22
Power Dissipation (W)
330 V 352 V 365 V
V :
IN 330 V 352 V 365 V
η
PD
80
82
84
86
88
90
92
94
96
98
0123456789
5
7
9
11
13
15
17
Efficiency & Power Dissipation 25°C Case
Output Current (A)
Efficiency (%)
Power Dissipation (W)
330 V 352 V 365 V
V :
IN 330 V 352 V 365 V
η
PD
80
82
84
86
88
90
92
94
96
98
0123456789
4
6
8
10
12
14
16
18
20
Efficiency & Power Disspiation 100°C Case
Output Current (A)
Efficiency (%)
330 V 352 V 365 V
V :
IN 330 V 352 V 365 V
Power Dissipation (W)
η
PD
100
110
120
130
140
150
160
170
180
190
200
-60 -40 -20 0 20 40 60 80 100 120
ROUT vs. Case Temperature
Case Temperature (°C)
Rout (mΩ)
I :
OUT 0.7 A 7.7 A
Figure 1 – No load power dissipation vs. VIN; TCASE Figure 2 – Full load efficiency vs. temperature; VIN
Figure 3 – Efficiency and power dissipation at -40°C (case); VIN Figure 4 – Efficiency and power dissipation at 25°C (case); VIN
Figure 5 – Efficiency and power dissipation at 100°C (case); VIN Figure 6 – ROUT vs. temperature vs. IOUT
Rev. 1.7
12/2010
Page 7 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
0
50
100
150
200
250
02468
Ripple vs. Load
Load Current (A)
Ripple (mV pk-pk)
Vpk-pk (mV)
Figure 7 – Vripple vs. IOUT ; 352 Vin, no external capacitance Figure 8 – PC to VOUT startup waveform
Figure 9 – VIN to VOUT startup waveform Figure 10 – Output voltage and input current ripple, 352 Vin,
325 W no COUT
Figure 11 – Positive load transient (0 – 7.7 A) Figure 12 – Negative load transient (7.7 A – 0 A)
Rev. 1.7
12/2010
Page 8 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
vicorpower.com
PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
ATTRIBUTE SYMBOL CONDITIONS / NOTES MIN TYP MAX UNIT
Length L 32.4 / 1.27 32.5 / 1.28 32.6 / 1.29 mm/in
Width W 21.7 / 0.85 22.0 / 0.87 22.3 / 0.89 mm/in
Height H 6.48 / 0.255 6.73 / 0.265 6.98 / 0.275 mm/in
Volume Vol No Heatsink 4.81 / 0.295 cm3/in3
Footprint F No Heatsink 7.3 / 1.1 cm2/in2
Power Density PDNo Heatsink 1100 W/in3
68 W/cm3
Weight W 0.5/14 oz/g
Lead Finish
Nickel (0.51-2.03 µm)
Palladium (0.02-0.15 µm) µm
Gold (0.003-0.05 µm)
Operating Temperature TJ-40 125 °C
Storage Temperature TST -40 125 °C
Thermal Capacity 9 Ws/°C
Peak Compressive Force No J-lead support 5 6 lbs
Applied to Case (Z-axis)
ESD Rating ESDHBM Human Body Model[a] 1500 VDC
ESDMM Machine Model[b] 400
Peak Temperature During Reflow MSL 5 225 °C
MSL 6 245 °C
Peak Time Above 183°C 150 s
Peak Heating Rate During Reflow 1.5 3 °C/s
Peak Cooling Rate Post Reflow 1.5 6 °C/s
Thermal Impedance ØJC Min Board Heatsinking 1.1 1.5 °CW
2.0 PACKAGE/MECHANICAL SPECIFICATIONS
All specifications are at TJ= 25ºC unless otherwise noted. See associated figures for general trend data.
Figure 13 – PC disable waveform, 352 VIN, 100 µF COUT full load
Safe Operating Area
0
100
200
300
400
500
600
40.00 41.00 42.00 43.00 44.00 45.00 46.00
Output Voltage (V)
Output Power (W)
Steady State 5 mS 325 W Ave
Figure 14 – Safe Operating Area vs. VOUT
[a] JEDEC JESD 22-A114C.01
[b] JEDED JESD 22-A115-A
Rev. 1.7
12/2010
Page 9 of 17
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
TOP VIEW ( COMPONENT SIDE ) BOTTOM VIEW
2.1 MECHANICAL DRAWING & RECOMMENDED LAND PATTERN
RECOMMENDED LAND PATTERN
( COMPONENT SIDE SHOWN )
inch
mm
NOTES:
.
DIMENSIONS ARE .
2.
UNLESS OTHERWISE SPECIFIED, TOLERANCES ARE:
.X / [.XX] = +/-0.25 / [.01]; .XX / [.XXX] = +/-0.13 / [.005]
3.
PRODUCT MARKING ON TOP SURFACE
DXF and PDF files are available on vicorpower.com
4
Rev. 1.7
12/2010
Page 10 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
RECOMMENDED LAND PATTERN
(NO GROUNDING CLIPS)
TOP SIDE SHOWN
RECOMMENDED LAND PATTERN
(With GROUNDING CLIPS)
TOP SIDE SHOWN
NOTES: 1. MAINTAIN 3.50 [0.138] DIA. KEEP-OUT ZONE
FREE OF COPPER, ALL PCB LAYERS.
2. (A) MINIMUM RECOMMENDED PITCH IS 39.50 [1.555],
THIS PROVIDES 7.00 [0.275] COMPONENT
EDGE-TO-EDGE SPACING, AND 0.50 [0.020]
CLEARANCE BETWEEN VICOR HEAT SINKS.
(B) MINIMUM RECOMMENDED PITCH IS 41.00 [1.614],
THIS PROVIDES 8.50 [0.334] COMPONENT
EDGE-TO-EDGE SPACING, AND 2.00 [0.079]
CLEARANCE BETWEEN VICOR HEAT SINKS.
3. V•I CHIP LAND PATTERN SHOWN FOR REFERENCE ONLY;
ACTUAL LAND PATTERN MAY DIFFER.
DIMENSIONS FROM EDGES OF LAND PATTERN
TO PUSH-PIN HOLES WILL BE THE SAME FOR
ALL FULL SIZE V•ICHIP PRODUCTS.
4. RoHS COMPLIANT PER CST-0001 LATEST REVISION.
5. UNLESS OTHERWISE SPECIFIED:
DIMENSIONS ARE MM [INCH].
TOLERANCES ARE:
X.X [X.XX] = ±0.3 [0.01]
X.XX [X.XXX] = ±0.13 [0.005]
6. PLATED THROUGH HOLES FOR GROUNDING CLIPS (33855)
SHOWN FOR REFERENCE. HEATSINK ORIENTATION AND
DEVICE PITCH WILL DICTATE FINAL GROUNDING SOLUTION.
2.3 RECOMMENDED LAND PATTERN FOR PUSH PIN HEAT SINK
Rev. 1.7
12/2010
Page 11 of 17
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
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
VOUT = VIN • K Eq. 1
Where K (transformer turns ratio) is constant
for each part number
b. Loaded condition
VOUT = Vin • K – IOUT • ROUT Eq. 2
2. Dissipated Power
The two main terms of power losses in the
BCM module are:
-No load power dissipation (PNL) defined as the power
used to power up the module with an enabled power
train at no load.
-Resistive loss (ROUT) refers to the power loss across
the BCM modeled as pure resistive impedance.
PDISSIPATED ~PNL + PROUT Eq. 3
~
Therefore, with reference to the diagram shown in Figure 15
POUT = PIN –P
DISSIPATED = PIN –P
NL –P
ROUT Eq. 4
Notice that ROUT is temperature and input voltage dependent
and PNL is temperature dependent (See Figure 15).
INPUT
POWER
OUTPUT
POWER
PNL
PROUT
Figure 15 – Power transfer diagram
The above relations can be combined to calculate the overall module efficiency:
η=POUT =PIN –P
NL –P
ROUT =
PIN PIN
VIN • IIN –P
NL –(I
OUT)2• ROUT =1 –
(
PNL + (IOUT)2• ROUT
)
VIN • IIN VIN • IIN
Eq. 5
Rev. 1.7
12/2010
Page 12 of 17
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
4.0 OPERATING
12
3456
VUVLO+
PC
5 V
3 V
LL • K
A: TON1
B: TOVLO*
C: Max recovery time
D:TUVLO
E: TON2
F: TOCP
G: TPC–DIS
H: TSSP**
1: Controller start
2: Controller turn o
3: PC release
4: PC pulled low
5: PC released on output SC
6: SC removed
Vout
TM
3 V @ 27°C
0.4 V
VIN
3 V 5 V
2.5 V
500mS
before retrial
VUVLO–
A
B
E
H
ISSP
IOUT
IOCP
G
F
D
C
VOVLO+
VOVLO–
VOVLO+
NL
Notes:
– Timing and voltage is not to scale
– Error pulse width is load dependent
*Min value switching o
**From detection of error to power train shutdown
C
Figure 16 – Timing diagram
Rev. 1.7
12/2010
Page 13 of 17
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
5.0 USING THE CONTROL SIGNALS TM AND PC
The PC control pin can be used to accomplish the following
functions:
•Delayed start: At start-up, PC pin will source a constant
100 uA current to the internal RC network. Adding an
external capacitor will allow further delay in reaching the
2.5 V threshold for module start.
•Synchronized start up: In a parallel module array, PC pins
shall be connected in order to ensure synchronous start of all
the units. While every controller has a calibrated 2.5 V
reference on PC comparator, many factors might cause
different timing in turning on the 100 uA current source on
each module, i.e.:
– Different VIN slew rate
– Statistical component value distribution
By connecting all PC pins, the charging transient will be
shared and all the modules will be enabled synchronously.
•Auxiliary voltage source: Once enabled in regular
operational conditions (no fault), each BCM PC provides a
regulated 5 V, 2 mA voltage source.
•Output Disable: PC pin can be actively pulled down in order
to disable module operations. Pull down impedance shall be
lower than 400 Ωand toggle rate lower than 1 Hz.
•Fault detection flag: The PC 5 V voltage source is internally
turned off as soon as a fault is detected. After a minimum
disable time, the module tries to re-start, and PC voltage is
re-enabled. For system monitoring purposes (microcontroller
interface) faults are detected on falling edges of PC signal.
It is important to notice that PC doesn’t have current sink
capability (only 150 kΩtypical pull down is present),
therefore, in an array, PC line will not be capable of disabling
all the modules if a fault occurs on one of them.
The temperature monitor (TM) pin provides a voltage propor-
tional to the absolute temperature of the converter control IC.
It can be used to accomplish the following functions:
•Monitor the control IC temperature: The temperature in
Kelvin is equal to the voltage on the TM pin scaled
by x100. (i.e. 3.0 V = 300 K = 27ºC). It is important to
remember that V•I chips are multi-chip modules, whose
temperature distribution greatly vary for each part number as
well with input/output conditions, thermal management and
environmental conditions. Therefore, TM cannot be used to
thermally protect the system.
•Fault detection flag: The TM voltage source is internally
turned off as soon as a fault is detected. After a minimum
disable time, the module tries to re-start, and TM voltage is
re-enabled.
6.0 FUSE SELECTION
V•I Chips are not internally fused in order to provide flexibility
in configuring power systems. Input line fusing of V•I Chips is
recommended at system level, in order to provide thermal
protection in case of catastrophic failure.
The fuse shall be selected by closely matching system
requirements with the following characteristics:
• Current rating (usually greater than maximum BCM current)
• Maximum voltage rating (usually greater than the maximum
possible input voltage)
• Ambient temperature
• Nominal melting I2t
• Recommended fuse: ≤2.5 A Bussmann PC-Tron or
SOC type 36CFA.
Rev. 1.7
12/2010
Page 14 of 17
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
7.0 CURRENT SHARING
The SAC topology bases its performance on efficient transfer
of energy through a transformer, without the need of closed
loop control. For this reason, the transfer characteristic can be
approximated by an ideal transformer with some resistive drop
and positive temperature coefficient.
This type of characteristic is close to the impedance characteristic
of a DC power distribution system, both in behavior
(AC dynamic) and absolute value (DC dynamic).
When connected in an array (with same K factor), the BCM
module will inherently share the load current with parallel
units, according to the equivalent impedance divider that the
system implements from the power source to the point of load.
It is important to notice that, when successfully started, BCMs
are capable of bidirectional operations (reverse power transfer
is enabled if the BCM input falls within its operating range and
the BCM is otherwise enabled). In parallel arrays, because of
the resistive behavior, circulating currents are never experienced
(energy conservation law).
General recommendations to achieve matched array impedances
are (see also AN016 for further details):
• to dedicate common copper planes within the PCB to
deliver and return the current to the modules
• to make the PCB layout as symmetric as possible
• to apply same input/output filters (if present) to each unit
Figure 17 – BCM Array
Rev. 1.7
12/2010
Page 15 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
vicorpower.com
PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
8.0 INPUT AND OUTPUT FILTER DESIGN
A major advantage of SAC systems versus conventional PWM
converters is that the transformers do not require large
functional filters. The resonant LC tank, operated at extreme
high frequency, is amplitude modulated as a function of input
voltage and output current, and efficiently transfers charge
through the isolation transformer. A small amount of
capacitance, embedded in the input and output stages of the
module, is sufficient for full functionality and is key to achieve
power density.
This paradigm shift requires system design to carefully evaluate
external filters in order to:
1.Guarantee low source impedance:
To take full advantage of the BCM dynamic response, the
impedance presented to its input terminals must be low
from DC to approximately 5 MHz. The connection of the
V•I Chip to its power source should be implemented with
minimal distribution inductance. If the interconnect
inductance exceeds 100 nH, the input should be bypassed
with a RC damper to retain low source impedance and
stable operation. With an interconnect inductance of
200 nH, the RC damper may be as high as 1 µF in series
with 0.3 Ω. A single electrolytic or equivalent low-Q
capacitor may be used in place of the series RC bypass.
2.Further reduce input and/or output voltage ripple without
sacrificing dynamic response:
Given the wide bandwidth of the BCM, the source
response is generally the limiting factor in the overall
system response. Anomalies in the response of the source
will appear at the output of the BCM multiplied by its
K factor. This is illustrated in Figures 11 and 12.
3.Protect the module from overvoltage transients imposed
by the system that would exceed maximum ratings and
cause failures:
The V•I Chip input/output voltage ranges shall not be
exceeded. An internal overvoltage lockout function
prevents operation outside of the normal operating input
range. Even during this condition, the powertrain is exposed
to the applied voltage and power MOSFETs must withstand
it. A criterion for protection is the maximum amount of
energy that the input or output switches can tolerate if
avalanched.
Total load capacitance at the output of the BCM shall not
exceed the specified maximum. Owing to the wide bandwidth
and low output impedance of the BCM, low frequency bypass
capacitance and significant energy storage may be more
densely and efficiently provided by adding capacitance at the
input of the BCM. At frequencies <500 kHz the BCM appears
as an impedance of ROUT between the source and load.
Within this frequency range capacitance at the input appears
as effective capacitance on the output per the relationship
defined in Eq. 5.
COUT =CIN Eq. 6
K2
This enables a reduction in the size and number of capacitors
used in a typical system.
Rev. 1.7
12/2010
Page 16 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
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PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
Modulator
+VIN
PC
Enable
-VIN
2.5 V
100 µA
5 V
2 mA
150 K
1000 pF
18.5 V
Gate
Drive
Supply
2.5 V
Primary
Current Sensing
Start up &
Fault Logic
One shot
delay
320/540 ms
Wake-Up Power
and Logic
PC Pull-Up
& Source
Primary Stage &
Resonant Tank
1.5 k
Adaptive
Soft
Start
Fast
current
limit
Slow
current
limit
Vref Over-Current
Protection
Vref
(125ºC)
TM
Over
Temperature
Protection
UVLO
OVLO
VIN
Temperature
dependent voltage
source
Q1
Q2
Q3
Q4
Lp1
Lp2
Power
Transformer
Cr
Lr
Cr Lr
C1
C2
C3
C4
Primary
Gate Drive
2.50 V
CS2
40 K
Q5 Q6
+VOUT
-VOUT
Synchronous
Rectification
COUT
Ls1
Ls2
Secondary
Gate Drive
Figure 18 – BCM block diagram
Rev. 1.7
12/2010
Page 17 of 17
V•I CHIP INC. (A VICOR COMPANY) 25 FRONTAGE RD. ANDOVER, MA 01810 800-735-6200
vicorpower.com
PRELIMINARY DATASHEET
BCM352F440T330A00 - BCM352T440T330A00
Vicor’s comprehensive line of power solutions includes high density AC-DC
and DC-DC modules and accessory components, fully configurable AC-DC
and DC-DC power supplies, and complete custom power systems.
Information furnished by Vicor is believed to be accurate and reliable. However, no responsibility is assumed by Vicor for
its use. Vicor components are not designed to be used in applications, such as life support systems, wherein a failure or
malfunction could result in injury or death. All sales are subject to Vicor’s Terms and Conditions of Sale, which are
available upon request.
Specifications are subject to change without notice.
Intellectual Property Notice
Vicor and its subsidiaries own Intellectual Property (including issued U.S. and Foreign Patents and pending patent
applications) relating to the products described in this data sheet. Interested parties should contact Vicor's Intel-
lectual Property Department.
The products described on this data sheet are protected by the following U.S. Patents Numbers:
5,945,130; 6,403,009; 6,710,257; 6,911,848; 6,930,893; 6,934,166; 6,940,013; 6,969,909; 7,038,917;
7,166,898; 7,187,263; 7,361,844; D496,906; D505,114; D506,438; D509,472; and for use under 6,975,098
and 6,984,965
Vicor Corporation
25 Frontage Road
Andover, MA, USA 01810
Tel: 800-735-6200
Fax: 978-475-6715
email
Customer Service: custserv@vicorpower.com
Technical Support: apps@vicorpower.com
Warranty
Vicor products are guaranteed for two years from date of shipment against defects in material or workmanship when in
normal use and service. This warranty does not extend to products subjected to misuse, accident, or improper applica-
tion or maintenance. Vicor shall not be liable for collateral or consequential damage. This warranty is extended to the
original purchaser only.
EXCEPT FOR THE FOREGOING EXPRESS WARRANTY, VICOR MAKES NO WARRANTY, EXPRESS OR IMPLIED, INCLUDING,
BUT NOT LIMITED TO, THE WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Vicor will repair or replace defective products in accordance with its own best judgement. For service under this war-
ranty, the buyer must contact Vicor to obtain a Return Material Authorization (RMA) number and shipping instructions.
Products returned without prior authorization will be returned to the buyer. The buyer will pay all charges incurred in re-
turning the product to the factory. Vicor will pay all reshipment charges if the product was defective within the terms of
this warranty.
Information published by Vicor has been carefully checked and is believed to be accurate; however, no responsibility is
assumed for inaccuracies. Vicor reserves the right to make changes to any products without further notice to improve
reliability, function, or design. Vicor does not assume any liability arising out of the application or use of any product or
circuit; neither does it convey any license under its patent rights nor the rights of others. Vicor general policy does not
recommend the use of its components in life support applications wherein a failure or malfunction may directly threaten
life or injury. Per Vicor Terms and Conditions of Sale, the user of Vicor components in life support applications assumes
all risks of such use and indemnifies Vicor against all damages.
