VTM48EF015T115A00

VTM Current Multiplier
VTM48EF015T115A00
®
S
US
C
C
NRTL
US
High Efficiency, Sine Amplitude Converter™
FEATURES
• 48 Vdc to 1.5 Vdc 115 A current multiplier
- Operating from standard 48 V or 24 V PRM™ regulators
• High efficiency (>94%) reduces system power
consumption
• High density (392 A/in3)
• “Full Chip” VI Chip® package enables surface mount,
low impedance interconnect to system board
• Contains built-in protection features against:
- Overvoltage
- Overcurrent
• Provides enable / disable control,
internal temperature monitoring
• ZVS / ZCS resonant Sine Amplitude Converter topology
• Less than 50 ºC temperature rise at full load
in typical applications
TYPICAL APPLICATIONS
• High End Computing Systems
• Automated Test Equipment
• High Density Power Supplies
• Communications Systems
TYPICAL APPLICATION
DESCRIPTION
The VI Chip® current multiplier is a high efficiency (>94%) Sine
Amplitude Converter™ (SAC™) operating from a 26 to 55 Vdc
primary bus to deliver an isolated output. The Sine Amplitude
Converter offers a low AC impedance beyond the bandwidth
of most downstream regulators; therefore capacitance normally
at the load can be located at the input to the Sine Amplitude
Converter. Since the K factor of the VTM48EF015T115A00 is
1/32, the capacitance value can be reduced by a factor of 1024,
resulting in savings of board area, materials and total system cost.
The VTM48EF015T115A00 is provided in a VI Chip® package
compatible with standard pick-and-place and surface mount
assembly processes. The co-molded VI Chip® package provides
enhanced thermal management due to a large thermal
interface area and superior thermal conductivity. The high
conversion efficiency of the VTM48EF015T115A00 increases
overall system efficiency and lowers operating costs compared
to conventional approaches.
The VTM48EF015T115A00 enables the utilization of Factorized
Power Architecture™ which provides efficiency and size
benefits by lowering conversion and distribution losses and
promoting high density point of load conversion.
VIN = 26 to 55 V
IOUT = 115 A (NOM)
VOUT = 0.8 to 1.7 V (NO LOAD)
K = 1/32
PART NUMBER
DESCRIPTION
VTM48EF015T115A00
-40°C to 125°C TJ
Voltage
Control
Feedback
Enable/
Disable
Voltage
Reference
PC
PR
+IN
TM
+OUT
PC
-IN
IF RE
+OUT1
+OUT2
+IN
VTM48EF015T115A00
PRMTM
Regulator
38 to 55
Vdc Input
Load
-IN
-OUT
SG VC
VC
Current
Sense
Constant
Vc
-OUT1
-OUT2
PC
+OUT1
+IN
+OUT2
VTM48EF015T115A00
-IN
VC
VTM® Current Multiplier
Rev 3.5
vicorpower.com
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09/2015
800 927.9474
-OUT1
-OUT2
VTM48EF015T115A00
1.0 ABSOLUTE MAXIMUM VOLTAGE RATINGS
The absolute maximum ratings below are stress ratings only. Operation at or beyond these maximum ratings can cause permanent
MIN
MAX
UNIT
MIN
MAX
UNIT
damage to the device.
+ IN to - IN . . . . . . . . . . . . . . . . . . . . . . . . . . .
PC to - IN . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TM to -IN . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VC to - IN . . . . . . . . . . . . . . . . . . . . . . . . . . . .
-1.0
-0.3
-0.3
-0.3
60
20
7
20
VDC
VDC
VDC
VDC
IM to - IN.........................................................
+ IN / - IN to + OUT / - OUT (hipot)................
+ IN / - IN to + OUT / - OUT (working)...........
+ OUT to - OUT...............................................
0
3.15
1500
60
5.5
-1.0
VDC
VDC
VDC
VDC
2.0 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 = 25 ºC unless otherwise noted.
ATTRIBUTE
Input voltage range
VIN slew rate
VIN UV turn off
SYMBOL
VIN
VIN_UV
PNL
Inrush current peak
IINRP
Output current (average)
Output current (peak)
Output power (average)
IIN_DC
K
VOUT
IOUT_AVG
IOUT_PK
POUT_AVG
Efficiency (ambient)
hAMB
Efficiency (hot)
Efficiency (over load range)
Output resistance (cold)
Output resistance (ambient)
Output resistance (hot)
Switching frequency
Output ripple frequency
hHOT
h20%
ROUT_COLD
ROUT_AMB
ROUT_HOT
FSW
FSW_RP
Output voltage ripple
VOUT_PP
Output inductance (parasitic)
LOUT_PAR
Output capacitance (internal)
COUT_INT
Output capacitance (external)
COUT
PROTECTION
Overvoltage lockout
Overvoltage lockout
response time constant
Output overcurrent trip
Short circuit protection trip current
Output overcurrent
response time constant
Short circuit protection response time
Thermal shutdown setpoint
Reverse inrush current protection
MIN
TYP
26
0
dVIN /dt
No Load power dissipation
DC input current
Transfer ratio
Output voltage
CONDITIONS / NOTES
No external VC applied
VC applied
Module latched shutdown,
No external VC applied, IOUT = 115A
VIN = 48 V
VIN = 26 V to 55 V
VIN = 48 V, TC = 25 ºC
VIN = 26 V to 55 V, TC = 25 ºC
VC enable, VIN = 48 V, COUT = 64400 µF,
RLOAD = 12 mΩ
K = VOUT / VIN, IOUT = 0 A
VOUT = VIN • K - IOUT • ROUT, Section 11
30°C < Tc < 100°C,
Iout_max = - (3/14) * Tc + 136.43
TC = 30 ºC
TPEAK < 10 ms, IOUT_AVG ≤ 115 A
IOUT_AVG ≤ 115 A
VIN = 48 V, IOUT = 115 A
VIN = 26 V to 55 V, IOUT = 115 A
VIN = 48 V, IOUT = 57.5 A
VIN = 48 V, IOUT = 130
A
VIN = 48 V, TC = 100°C, IOUT = 115 A
23 A < IOUT < 115 A
TC = -40°C, IOUT = 115 A
TC = 25°C, IOUT = 115 A
TC = 100°C, IOUT = 115 A
18
1.5
2.2
7.2
Module latched shutdown
TOVLO
Effective internal RC filter
IOCP
ISCP
TOCP
Effective internal RC filter (Integrative).
TSCP
From detection to cessation
of switching (Instantaneous)
TJ_OTP
VTM® Current Multiplier
Rev 3.5
vicorpower.com
Page 2 of 17
09/2015
800 927.9474
26
V
5.8
6.5
4.2
5.5
W
11
A
4.5
A
V/V
V
130
200
185
VDC
A
A
W
91.7
%
94.0
90.9
90.7
0.67
0.84
1.00
1.40
2.80
1.0
1.08
1.18
1.50
3.00
%
%
mΩ
mΩ
mΩ
MHz
MHz
150
200
mV
150
pH
420
µF
55.1
58.2
138
250
190
64400
µF
60
V
0.2
125
Reverse Inrush protection enabled for this product
V/µs
115
90.0
84.0
91.5
89.5
89.0
80
0.35
0.50
0.64
1.30
2.60
UNIT
55
55
1
1/32
COUT = 0 F, IOUT = 115 A, VIN = 48 V,
20 MHz BW, Section 11
Frequency up to 30 MHz,
Simulated J-lead model
Effective Value at 1.5 VOUT
VTM Standalone Operation.
VIN pre-applied, VC enable
VIN_OVLO+
MAX
µs
250
A
A
9.1
ms
1
µs
130
135
ºC
VTM48EF015T115A00
3.0 SIGNAL 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 = 25°C unless otherwise noted.
• Used to wake up powertrain circuit.
• A minimum of 11.5 V must be applied indefinitely for VIN < 26 V
to ensure normal operation.
• VC slew rate must be within range for a successful start.
SIGNAL TYPE
STATE
ATTRIBUTE
External VC voltage
VTM CONTROL : VC
• PRM™ module VC can be used as valid wake-up signal source.
• Internal Resistance used in “Adaptive Loop” compensation
• VC voltage may be continuously applied
SYMBOL
VVC_EXT
VC current draw
IVC
Steady
ANALOG
INPUT
VC internal diode rating
VC internal resistor
VC internal resistor
temperature coefficient
VC start up pulse
VC slew rate
VC inrush current
CONDITIONS / NOTES
Required for start up, and operation
below 26 V. See Section 7.
VC = 11.5 V, VIN = 0 V
VC = 11.5 V, VIN > 26 V
VC = 16.5 V, VIN > 26 V
Fault mode. VC > 11.5 V
MIN
TYP
11.5
16.5
115
0
0
60
100
N/A
DVC_INT
RVC-INT
MAX UNIT
TVC_COEFF
V
150
mA
V
kΩ
N/A ppm/°C
Tpeak <18 ms
20
V
Required for proper start up;
0.02
0.25 V/µs
VC = 16.5 V, dVC/dt = 0.25 V/µs
1
A
VIN pre-applied, PC floating,
VC to VOUT turn-on delay
TON
500
µs
VC enable, CPC = 0 µF
Transitional
VC
= 11.5 V to PC high, VIN = 0 V,
VC to PC delay
Tvc_pc
75
125
µs
dVC/dt = 0.25 V/µs
VC = 0 V
3.2
µF
Internal VC capacitance
CVC_INT
PRIMARY CONTROL : PC
• The PC pin enables and disables the VTM™ module.
• Module will shutdown when pulled low with an impedance
When held below 2 V, the VTM module will be disabled.
less than 400 Ω.
• PC pin outputs 5 V during normal operation. PC pin is equal to 2.5 V
• In an array of VTM modules, connect PC pin to synchronize start up.
during fault mode given VIN > 26 V or VC > 11.5 V.
• PC pin cannot sink current and will not disable other modules
• After successful start up and under no fault condition, PC can be used as
during fault mode.
a 5 V regulated voltage source with a 2 mA maximum current.
Start Up
SIGNAL TYPE
ANALOG
OUTPUT
STATE
Steady
Start Up
Enable
DIGITAL
INPUT / OUPUT
Disable
Transitional
ATTRIBUTE
PC voltage
PC source current
PC resistance (internal)
PC source current
PC capacitance (internal)
PC resistance (external)
PC voltage
PC voltage (disable)
PC pull down current
PC disable time
PC fault response time
VVC_SP
dVC/dt
IINR_VC
SYMBOL
IPC_OP
RPC_INT
Internal pull down resistor
IPC_EN
CPC_INT
Section 7
RPC_S
VPC_EN
VPC_DIS
IPC_PD
TPC_DIS_T
TFR_PC
From fault to PC = 2 V
CURRENT MONITOR : IM
• The IM pin voltage varies between 0.2 V and 0.61 V representing the
output current within ±25% under all operating line temperature
conditions between 50% and 100%.
SIGNAL TYPE
ANALOG
OUTPUT
STATE
Steady
ATTRIBUTE
IM Voltage (No Load)
IM Voltage (50%)
IM Voltage (Full Load)
IM Gain
IM Resistance (External)
CONDITIONS / NOTES
VPC
SYMBOL
VIM_NL
VIM_50%
VIM_FL
A IM
RIM_EXT
MIN
TYP
4.7
5
50
50
150
100
60
2
2.5
MAX UNIT
5.3
2
400
300
1000
3
2
5.1
5
100
V
mA
kΩ
µA
pF
kΩ
V
V
mA
µs
µs
• The IM pin provides a DC analog voltage proportional to
the output current of the VTM module.
CONDITIONS / NOTES
TJ = 25 ºC, VIN = 48 V, IOUT = 0 A
TJ = 25 ºC, VIN = 48 V, IOUT = 57.5 A
TJ = 25 ºC, VIN = 48 V, IOUT = 115 A
TJ = 25 ºC, VIN = 48 V, IOUT > 57.5 A
MIN
TYP
MAX
UNIT
0.2
0.07
0.28
0.61
6
0.3
V
V
V
mV/A
MΩ
2.5
VTM® Current Multiplier
Rev 3.5
vicorpower.com
Page 3 of 17
09/2015
800 927.9474
VTM48EF015T115A00
TEMPERATURE MONITOR : TM
• The TM pin monitors the internal temperature of the VTM controller IC
• The TM pin has a room temperature setpoint of 3 V
within an accuracy of ±5°C.
and approximate gain of 10 mV/°C.
• Can be used as a "Power Good" flag to verify that
• Output drives Temperature Shutdown comparator
the VTM module is operating.
SIGNAL TYPE
STATE
ANALOG
OUTPUT
ATTRIBUTE
TM voltage
TM source current
TM gain
Steady
Disable
DIGITAL OUTPUT
(FAULT FLAG)
Transitional
SYMBOL
VTM_AMB
ITM
ATM
TM voltage ripple
VTM_PP
TM voltage
TM resistance (internal)
TM capacitance (external)
TM fault response time
VTM_DIS
RTM_INT
CTM_EXT
TFR_TM
CONDITIONS / NOTES
TJ controller = 27°C
MIN
TYP
MAX UNIT
2.95
3.00
3.05
100
V
µA
mV/°C
200
mV
50
50
V
kΩ
pF
µs
10
CTM = 0 F, VIN = 48 V,
IOUT = 115 A
120
Internal pull down resistor
25
From fault to TM = 1.5 V
0
40
10
4.0 TIMING DIAGRAM
ISEC
6
7
ISEC
ISEC
1
2 3
VC
4
8
d
5
b
VVC-EXT
a
VOVLO
VPRI
NL
≥ 26 V
c
e
f
VSEC
TM
VTM-AMB
PC
g
5V
3V
a: VC slew rate (dVC/dt)
b: Minimum VC pulse rate
c: TOVLO_PIN
d: TOCP_SEC
e: Secondary turn on delay (TON)
f: PC disable time (TPC_DIS_T)
g: VC to PC delay (TVC_PC)
1. Initiated VC pulse
2. Controller start
3. VPRI ramp up
4. VPRI = VOVLO
5. VPRI ramp down no VC pulse
6. Overcurrent, Secondary
7. Start up on short circuit
8. PC driven low
Notes:
– Timing and voltage is not to scale
– Error pulse width is load dependent
VTM® Current Multiplier
Rev 3.5
vicorpower.com
Page 4 of 17
09/2015
800 927.9474
VTM48EF015T115A00
5.0 APPLICATION CHARACTERISTICS
The following values, typical of an application environment, are collected at TC = 25 ºC unless otherwise noted. See associated
figures for general trend data.
ATTRIBUTE
SYMBOL
No load power dissipation
Efficiency (ambient)
Efficiency (hot)
Output resistance (cold)
Output resistance (ambient)
Output resistance (hot)
PNL
hAMB
hHOT
ROUT_COLD
ROUT_AMB
ROUT_HOT
Output voltage ripple
VOUT_PP
VOUT transient (positive)
VOUT_TRAN+
VOUT transient (negative)
VOUT_TRAN-
CONDITIONS / NOTES
TYP
UNIT
VIN = 48 V, PC enabled
VIN = 48 V, IOUT = 115 A
VIN = 48 V, IOUT = 115 A, TC = 100 ºC
VIN = 48 V, IOUT = 115 A, TC = -40 ºC
VIN = 48 V, IOUT = 115 A
VIN = 48 V, IOUT = 115 A, TC = 100 ºC
COUT = 0 F, IOUT = 115 A, VIN = 48 V,
20 MHz BW, Section 12
IOUT_STEP = 0 A TO 115A, VIN = 48 V,
ISLEW = 36 A /us
IOUT_STEP = 115 A to 0 A, VIN = 48 V
ISLEW = 23 A /us
2.1
91.8
90.3
0.7
0.9
1.0
W
%
%
mΩ
mΩ
mΩ
116
mV
40
mV
60
mV
No Load Power Dissipation vs. Line Voltage
Full Load Efficiency (%)
3.5
3.0
2.5
2.0
1.5
92
90
88
86
84
82
80
1.0
26
29
32
35
38
41
43
46
49
52
-40
55
-20
0
-40 °C
TCASE:
25 °C
VIN :
100 °C
84
PD
76
72
26
39
52
65
78
91
26 V
48 V
55 V
100
48 V
55 V
104
117
48
44
40
36
32
28
24
20
16
12
8
4
0
η
88
84
80
PD
76
72
130
0
13
26
39
52
65
78
91
104
117
130
Load Current (A)
Load Current (A)
VIN:
26 V
92
Efficiency (%)
88
13
80
96
Power Dissipation (W)
Efficiency (%)
48
44
40
36
32
28
24
20
16
12
8
4
0
η
0
60
Efficiency & Power Dissipation 25 °C Case
Efficiency & Power Dissipation -40 °C Case
96
80
40
Figure 2 — Full load efficiency vs. temperature
Figure 1 — No load power dissipation vs. VIN
92
20
Case Temperature (°C)
Input Voltage (V)
Power Dissipation (W)
Power Dissipation (W)
Full Load Efficiency vs. TCASE
94
4.0
26 V
48 V
55 V
VIN:
26 V
48 V
55 V
26 V
48 V
Figure 3 — Efficiency and power dissipation at –40°C
Figure 4 — Efficiency and power dissipation at 25°C
VTM® Current Multiplier
Rev 3.5
vicorpower.com
Page 5 of 17
09/2015
800 927.9474
55 V
VTM48EF015T115A00
Efficiency & Power Dissipation 100 °C Case
84
PD
76
72
0
12
23
26 V
VIN:
35
46 58 69 81
Load Current (A)
48 V
55 V
92
1.5
ROUT (mΩ)
88
2.0
Power Dissipation (W)
Efficiency (%)
92
80
ROUT vs. TCASE at VIN = 48 V
48
44
40
36
32
28
24
20
16
12
8
4
0
96
1.0
0.5
0.0
-40
104 115
-20
26 V
48 V
55 V
I OUT :
Output Voltage Ripple vs. Load
Output Current (A)
VRIPPLE (mV PK-PK)
150
125
100
75
50
25
0
35
46
58
69
81
92
104
115
Load Current (A)
VIN:
26 V
48 V
60
80
100
115 A
57.5 A
Safe Operating Area
175
23
40
Figure 6 — ROUT vs. temperature
200
12
20
Case Temperature (ºC)
Figure 5 — Efficiency and power dissipation at 100°C
0
0
220
200
180
160
140
120
100
80
60
40
20
0
Limited by Power
< 10 ms, 200 A Maximum Current
< 30°C TCASE, 130 A Maximum Current
Limited by ROUT
115 A Maximum Current Region
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Output Voltage (V)
55 V
Figure 7 — VRIPPLE vs. IOUT ; No external COUT. Board mounted
module, scope setting: 20 MHz analog BW
Figure 8 — Safe operating area
Figure 9 — Full load ripple, 100 µF CIN; No external COUT. Board
mounted module, scope setting : 20 MHz analog BW
Figure 10 — Start up from application of VIN ;
VC pre-applied COUT = 64400 µF
VTM® Current Multiplier
Rev 3.5
vicorpower.com
Page 6 of 17
09/2015
800 927.9474
1.6
1.8
2.0
2.2
VTM48EF015T115A00
Figure 11 — Start up from application of VC;
VIN pre-applied COUT = 64400 µF
Figure 12 — 0 A – 115 A transient response:
C IN = 100 µF, no external COUT
IM Voltage vs. Load at VIN = 48 V
0.6
0.5
IM (V)
0.4
0.3
0.2
0.1
0
12
23
35
46
58
69
81
92
104
115
Load Current (A)
-40 °C
TCASE :
Figure 13 — 115 A – 0 A transient response:
C IN = 100 µF, no external COUT
25 °C
100 °C
Figure 14 — IM voltage vs. load
IM Voltage vs. Load at 25 °C Case
IM Voltage at 115 A Load vs. TCASE
0.6
0.6
0.5
0.5
IM (V)
IM (V)
0.4
0.3
0.4
0.2
0.3
0.1
0.0
0.2
12
23
35
46
58
69
81
92
104
115
-40
-20
Load Current (A)
VIN :
26 V
48 V
20
40
60
80
TCASE (°C)
55 V
Figure 15 — IM voltage vs. load
0
VIN :
26 V
48 V
Figure 16 — Full load IM voltage vs. TCASE
VTM® Current Multiplier
Rev 3.5
vicorpower.com
Page 7 of 17
09/2015
800 927.9474
55 V
100
VTM48EF015T115A00
6.0 GENERAL CHARACTERISTICS
Specifications apply over all line and load conditions unless otherwise noted; Boldface specifications apply over the temperature
range of -40 ºC < TJ < 125 ºC (T-Grade); All Other specifications are at TJ = 25°C unless otherwise noted.
ATTRIBUTE
MECHANICAL
Length
Width
Height
Volume
Weight
SYMBOL
L
W
H
Vol
W
CONDITIONS / NOTES
MIN
32.25 / [1.270]
21.75 / [0.856]
6.48 / [0.255]
No heat sink
Nickel
Palladium
Gold
Lead finish
TYP
32.5 / [1.280]
22.0 / [0.866]
6.73 / [0.265]
4.81 / [0.294]
14.5 / [0.512]
MAX
UNIT
32.75 / [1.289]
22.25 / [0.876]
6.98 / [0.275]
mm/[in]
mm/[in]
mm/[in]
cm3/[in3]
g/[oz]
0.51
0.02
0.003
2.03
0.15
0.051
µm
-40
N/A
125
N/A
°C
°C
THERMAL
Operating temperature
Thermal resistance
VTM48EF015T115A00 (T-Grade)
VTM48EF015M115A00 (M-Grade)
Isothermal heatsink and
isothermal internal PCB
TJ
fJC
Thermal capacity
ASSEMBLY
Peak compressive force
applied to case (Z-axis)
Storage temperature
TST
ESDHBM
ESDCDM
SOLDERING
Peak temperature during reflow
Peak time above 245°C
Peak heating rate during reflow
Peak cooling rate post reflow
MTBF
Agency approvals / standards
°C/W
9
Ws/°C
6
5.41
125
N/A
Supported by J-lead only
ESD withstand
SAFETY
Working voltage (IN – OUT)
Isolation voltage (hipot)
Isolation capacitance
Isolation resistance
1
VTM48EF015T115A00 (T-Grade)
VTM48EF015M115A00 (M-Grade)
Human Body Model,
"JEDEC JESD 22-A114C.01"
Charge Device Model,
"JEDEC JESD 22-C101-C"
-40
N/A
TBD
VDC
TBD
MSL 4 (Datecode 1528 and later)
60
1.5
1.5
VIN_OUT
VHIPOT
CIN_OUT
RIN_OUT
1500
1800
10
Unpowered unit
lbs
lbs / in2
°C
°C
2000
MIL-HDBK-217 Plus Parts Count;
25ºC Ground Benign, Stationary,
TBD
Indoors / Computer Profile
Telcordia Issue 2 - Method I Case III;
TBD
Ground Benign, Controlled
cTUVus
cURus
CE Marked for Low Voltage Directive and RoHS Recast Directive, as applicable
VTM® Current Multiplier
Rev 3.5
vicorpower.com
Page 8 of 17
09/2015
800 927.9474
245
90
3
6
°C
s
°C/s
°C/s
60
VDC
VDC
pF
MΩ
2200
MHrs
MHrs
VTM48EF015T115A00
7.0 USING THE CONTROL SIGNALS VC, PC, TM, IM
The VTM Control (VC) pin is an input pin which powers the
internal VCC circuitry when within the specified voltage range
of 11.5 V to 16.5 V. This voltage is required for VTM™ current
multiplier start up and must be applied as long as the input is
below 26 V. In order to ensure a proper start, the slew rate of
the applied voltage must be within the specified range.
Some additional notes on the using the VC pin:
• In most applications, the VTM module will be powered
by an upstream PRM™ regulator which provides a 10 ms
VC pulse during start up. In these applications the VC pins
of the PRM module and VTM module should be tied together.
• The VC voltage can be applied indefinitely allowing for
continuous operation down to 0 VIN.
• The fault response of the VTM module is latching.
A positive edge on VC is required in order to restart the unit.
If VC is continuously applied the PC pin may be toggled to
restart the VTM module.
Primary Control (PC) pin can be used to accomplish the
following functions:
• Delayed start: Upon the application of VC, the PC pin will
source a constant 100 µA current to the internal RC
network. Adding an external capacitor will allow further
delay in reaching the 2.5 V threshold for module start.
• Auxiliary voltage source: Once enabled in regular
operational conditions (no fault), each VTM PC provides a
regulated 5 V, 2 mA voltage source.
• Output disable: PC pin can be actively pulled down in order
to disable the module. Pull down impedance shall be lower
than 400 Ω.
• Fault detection flag: The PC 5 V voltage source is internally
turned off as soon as a fault is detected. It is important to
notice that PC doesn’t have current sink capability. Therefore,
in an array, PC line will not be capable of disabling
neighboring modules if a fault is detected.
• Fault reset: PC may be toggled to restart the unit if VC
is continuously applied.
Temperature Monitor (TM) pin provides a voltage
proportional 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 100. (i.e. 3.0 V = 300 K = 27 ºC). If a heat sink is applied,
TM can 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. For system
monitoring purposes (microcontroller interface) faults are
detected on falling edges of TM signal.
Current Monitor (IM) pin provides a voltage proportional to
the output current of the VTM module. The nominal voltage
will vary between 0.07 V and 0.61 V over the output current
range of the VTM module (See Figures 14 –16). The accuracy of
the IM pin will be within 25% under all line and temperature
conditions between 50% and 100% load.
8.0 START UP BEHAVIOR
Depending on the sequencing of the VC with respect to the
input voltage, the behavior during start up will vary as follows:
• Normal operation (VC applied prior to VIN ): In this case the
controller is active prior to ramping the input. When the
input voltage is applied, the VTM module output voltage
will track the input (See Figure 10). The inrush current is
determined by the input voltage rate of rise and output
capacitance. If the VC voltage is removed prior to the input
reaching 26 V, the VTM may shut down.
• Stand-alone operation (VC applied after VIN ): In this case the
VTM module output will begin to rise upon the application
of the VC voltage (See Figure 11). The Adaptive Soft Start
Circuit (See Section 11) may vary the ouput rate of rise in
order to limit the inrush current to its maximum level. When
starting into high capacitance, or a short, the output current
will be limited for a maximum of 120 µ/sec. After this period,
the Adaptive Soft Start Circuit will time out and the VTM
module may shut down. No restart will be attempted until
VC is re-applied or PC is toggled. The maximum output
capacitance is limited to 64400 µF in this mode of operation
to ensure a sucessful start.
9.0 THERMAL CONSIDERATIONS
VI Chip® products are multi-chip modules whose temperature
distribution varies greatly for each part number as well as with
the input / output conditions, thermal management and
environmental conditions. Maintaining the top of the
VTM48EF015T115A00 case to less than 100 ºC will keep all
junctions within the VI Chip® module below 125 ºC for most
applications.
The percent of total heat dissipated through the top surface
versus through the J-lead is entirely dependent on the
particular mechanical and thermal environment. The heat
dissipated through the top surface is typically 60%. The heat
dissipated through the J-lead onto the PCB board surface is
typically 40%. Use 100% top surface dissipation when
designing for a conservative cooling solution.
It is not recommended to use a VI Chip® module for an extended
period of time at full load without proper heat sinking.
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DVC_INT
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CIN
1000 pF
3.1 V
PC Pull-Up
& Source
-VIN
RVC_INT
VC
+VIN
100 A
18 V
150 K
5V
2 mA
2.5 V
Enable
10.5 V
VDD
Regulator
Supply
Enable
OVLO
UVLO
VIN
Adaptive
Soft Start
Enable
Modulator
Enable
Fault Logic
Gate Drive
Supply
Primary
Gate
Drive
Cr
VREF
(127°C)
Over
Temperature
Protection
VREF
Lr
Primary Stage &
Resonant Tank
Single Ended
Primary
Current Sensing
Q2
Q1
Secondary
Gate Drive
Power
Transformer
Temperature
Dependent
Voltage Source
C2
C1
Q3
40 K
1K
Q4
102
0.01 F
3 VMAX
240 AMAX
Synchronous
Rectification
TM
IM
Right
J-lead
-VOUT
COUT
+VOUT
+VOUT
COUT
-VOUT
Left
J-lead
VTM48EF015T115A00
10.0 VTM MODULE BLOCK DIAGRAM
VTM48EF015T115A00
11.0 SINE AMPLITUDE CONVERTERTM POINT OF LOAD CONVERSION
90 pH
IOUT
IOUT
LIN = 3.7 nH
0.84 mΩ
+
VIN
V
IN
OUT
RROUT
R
RCIN
CIN
6.3 mΩ
CCININ
0.98 Ω
V•I
1/32 • IOUT
900 nF
IIQQ
46 mA
+
+
–
–
LOUT = 150 pH
RRCOUT
COUT
+
50 µΩ
1/32 • VIN
COUT
COUT
420 µF
VOUT
V
OUT
K
–
–
Figure 17 — VI Chip® product AC model
The Sine Amplitude Converter (SAC™) uses a high frequency
resonant tank to move energy from input to output. (The
resonant tank is formed by Cr and leakage inductance Lr in the
power transformer windings as shown in the VTM™ Module
Block Diagram. See Section 10). 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 VTM48EF015T115A00 SAC can be simplified into the
following model:
At no load:
ROUT represents the impedance of the SAC, and is a function of
the RDSON of the input and output MOSFETs and the winding
resistance of the power transformer. IQ represents the
quiescent current of the SAC control and gate drive circuitry.
The use of DC voltage transformation provides additional
interesting attributes. Assuming that ROUT = 0 Ω and IQ = 0 A,
Eq. (3) now becomes Eq. (1) and is essentially load
independent, resistor R is now placed in series with VIN as
shown in Figure 18.
RR
VOUT = VIN • K
(1)
VIN
Vin
+
–
SAC™
K SAC
= 1/32
K = 1/32
VOUT
Vout
K represents the “turns ratio” of the SAC.
Rearranging Eq (1):
K=
VOUT
VIN
(2)
Figure 18 – K = 1/32 Sine Amplitude Converter with series
input resistor
The relationship between VIN and VOUT becomes:
In the presence of load, VOUT is represented by:
VOUT = (VIN – IIN • R) • K
VOUT = VIN • K – IOUT • ROUT
(3)
Substituting the simplified version of Eq. (4)
(IQ is assumed = 0 A) into Eq. (5) yields:
and IOUT is represented by:
IOUT =
(5)
IIN – IQ
K
(4)
VOUT = VIN • K – IOUT • R • K2
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VTM48EF015T115A00
This is similar in form to Eq. (3), where ROUT is used to
represent the characteristic impedance of the SAC™. However,
in this case a real R on the input side of the SAC is effectively
scaled by K2 with respect to the output.
Assuming that R = 1 Ω, the effective R as seen from the secondary
side is 1 mΩ, with K = 1/32 as shown in Figure 18.
A similar exercise should be performed with the addition of a
capacitor or shunt impedance at the input to the SAC.
A switch in series with VIN is added to the circuit. This is
depicted in Figure 19.
SS
VVin
IN
+
–
C
C
SACTM
SAC
K = 1/32
K = 1/32
VVout
OUT
Figure 19 — Sine Amplitude Converter™ with input capacitor
A change in VIN with the switch closed would result in a
change in capacitor current according to the following
equation:
IC(t) = C
dVIN
dt
Low impedance is a key requirement for powering a highcurrent, low voltage load efficiently. A switching regulation
stage should have minimal impedance while simultaneously
providing appropriate filtering for any switched current. The
use of a SAC between the regulation stage and the point of
load provides a dual benefit of scaling down series impedance
leading back to the source and scaling up shunt capacitance or
energy storage as a function of its K factor squared. However,
the benefits are not useful if the series impedance of the SAC
is too high. The impedance of the SAC must be low, i.e. well
beyond the crossover frequency of the system.
A solution for keeping the impedance of the SAC low involves
switching at a high frequency. This enables small magnetic
components because magnetizing currents remain low. Small
magnetics mean small path lengths for turns. Use of low loss
core material at high frequencies also reduces core losses.
The two main terms of power loss in the VTMTM module are:
- No load power dissipation (PNL): defined as the power
used to power up the module with an enabled powertrain
at no load.
- Resistive loss (ROUT): refers to the power loss across
the VTMTM current multiplier modeled as pure resistive
impedance.
PDISSIPATED = PNL + PROUT
(7)
(10)
Therefore,
POUT = PIN – PDISSIPATED = PIN – PNL – PROUT
Assume that with the capacitor charged to VIN, the switch is
opened and the capacitor is discharged through the idealized
SAC. In this case,
IC = IOUT • K
The above relations can be combined to calculate the overall
module efficiency:
(8)
h =
(9)
=
POUT = PIN – PNL – PROUT
PIN
PIN
Substituting Eq. (1) and (8) into Eq. (7) reveals:
IOUT =
C
K2
•
dVOUT
dt
The equation in terms of the output has yielded a K2 scaling
factor for C, specified in the denominator of the equation.
A K factor less than unity, results in an effectively larger
capacitance on the output when expressed in terms of the
input. With a K= 1/32 as shown in Figure 19, C = 1 µF would
appear as C=1024 µF when viewed
from the output.
(11)
VIN • IIN – PNL – (IOUT)2 • ROUT
VIN • IIN
= 1–
(
)
PNL + (IOUT)2 • ROUT
VIN • IIN
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12.0 INPUT AND OUTPUT FILTER DESIGN
A major advantage of a SAC™ system versus a conventional
PWM converter is that the former does 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 achieving
high 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 VTM™ current multiplier
dynamic response, the impedance presented to its input
terminals must be low from DC to approximately 5 MHz.
Input capacitance may be added to improve transient
performance or compensate for high source impedance.
2.Further reduce input and/or output voltage ripple without
sacrificing dynamic response.
Given the wide bandwidth of the VTM module, 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 VTM module multiplied by
its K factor.
3.Protect the module from overvoltage transients imposed
by the system that would exceed maximum ratings and
cause failures.
The VI Chip® module input/output voltage ranges must
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.
13.0 CAPACITIVE FILTERING CONSIDERATIONS
FOR A SINE AMPLITUDE CONVERTERTM
It is important to consider the impact of adding input and
output capacitance to a Sine Amplitude Converter on the
system as a whole. Both the capacitance value and the
effective impedance of the capacitor must be considered.
A Sine Amplitude Converter has a DC ROUT value which has
already been discussed in section 11. The AC ROUT of the
SAC contains several terms:
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• Resonant tank impedance
• Input lead inductance and internal capacitance
• Output lead inductance and internal capacitance
The values of these terms are shown in the behavioral model in
section 11. It is important to note on which side of the
transformer these impedances appear and how they reflect
across the transformer given the K factor.
The overall AC impedance varies from model to model. For
most models it is dominated by DC ROUT value from DC to
beyond 500 KHz. The behavioral model in section 11 should be
used to approximate the AC impedance of the specific model.
Any capacitors placed at the output of the VTM reflect back to
the input of the VTM module by the square of the K factor (Eq.
9) with the impedance of the VTM module appearing in series.
It is very important to keep this in mind when using a PRM™
regulator to power the VTM module. Most PRM modules have
a limit on the maximum amount of capacitance that can be
applied to the output. This capacitance includes both the PRM
output capacitance and the VTM module output capacitance
reflected back to the input. In PRM remote sense applications,
it is important to consider the reflected value of VTM module
output capacitance when designing and compensating the
PRM control loop.
Capacitance placed at the input of the VTM module appear to
the load reflected by the K factor with the impedance of the
VTM module in series. In step-down ratios, the effective
capacitance is increased by the K factor. The effective ESR of
the capacitor is decreased by the square of the K factor, but
the impedance of the module appears in series. Still, in most
step-down VTM modules an electrolytic capacitor placed at the
input of the module will have a lower effective impedance
compared to an electrolytic capacitor placed at the output. This
is important to consider when placing capacitors at the output
of the module. Even though the capacitor may be placed at
the output, the majority of the AC current will be sourced from
the lower impedance, which in most cases will be the module.
This should be studied carefully in any system design using a
module. In most cases, it should be clear that electrolytic
output capacitors are not necessary to design a stable,
well-bypassed system.
VTM48EF015T115A00
14.0 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 current multiplier 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 the same K factor, the VTM
module will inherently share the load current (typically 5%)
with parallel units according to the equivalent impedance
divider that the system implements from the power source to
the point of load.
Some general recommendations to achieve matched array
impedances:
• Dedicate common copper planes within the PCB
to deliver and return the current to the modules.
• Provide the PCB layout as symmetric as possible.
• Apply same input / output filters (if present) to each unit.
For further details see AN:016 Using BCM® Bus Converters
in High Power Arrays.
VIN
ZIN_EQ1
VTM™1
ZOUT_EQ1
16.0 REVERSE INRUSH CURRENT PROTECTION
The VTM48EF015T115A00 provides reverse inrush protection
which prevents reverse current flow until the input voltage is
high enough to first establish current flow in the forward
direction. In the event that there is a DC voltage present on the
output before the VTM module is powered up, this feature
protects sensitive loads from excessive dV/dT during power up
as shown in Figure 21.
If a voltage is present at the output of the VTM module which
satisfies the condition VOUT > VIN • K after a successful power
up the energy will be transferred from secondary to primary.
The input to output ratio of the VTM module will be
maintained. The VTM module will continue to operate in
reverse as long as the input and output voltages are within the
specified range. The VTM48EF015T115A00 has not been
qualified for continuous reverse operation.
Current Multiplier
TM
VC
PC
IM
R
R
VTM
VIN
®
+In
+Out
-In
-Out
+
_
A
VOUT
B
CD
E
F
G
H
RO_1
VC
ZIN_EQ2
VTM™2
ZOUT_EQ2
VIN
RO_2
+
–
DC
Load
Supply
VIN
ZIN_EQn
VTM™n
ZOUT_EQn
VOUT
RO_n
VOUT
Supply
Figure 20 — VTM current multiplier array
TM
15.0 FUSE SELECTION
In order to provide flexibility in configuring power systems
VI Chip® products are not internally fused. Input line fusing
of VI Chip® products is recommended at system level 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 current
of VTM module)
• Maximum voltage rating (usually greater than the maximum
possible input voltage)
• Ambient temperature
• Nominal melting I2t
Figure 21 — Reverse inrush protection
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PC
A: VOUT supply > 0 V
B: VC to -IN > 11.5 V controller wakes-up, PC & TM pulled
high, reverse inrush protection blocks VOUT supplying VIN
C: VIN supply ramps up
D: VIN > VOUT /K, powertrain starts in normal mode
E: VIN supply ramps down
F: VIN > VOUT /K, powertrain transfers reverse energy
G: VOUT ramps down, VIN follows
H: VC turns off
Supply
VTM48EF015T115A00
17.0 LAYOUT CONSIDERATIONS
The VTM48EF015T115A00 requires equal current density along
the output J-leads to achieve rated efficiency and output power
level. The negative output J-leads are not connected internally
and must be connected on the board as close to the VTMT™
current multiplier as possible. The layout must also prevent the
high output current of the VTM48EF015T115A00 from
interfering with the input-referenced signals.
To achieve these requirements, the following layout guidelines
are recommended:
• The total current path length from any point on the V+OUT
J-leads to the corresponding point on the V-OUT J-leads should
be equal (see Figure 22) .
Figure 22 — Equal current path
• Use vias along the negative output J-leads to connect the
negative output to a common power plane.
• Use sufficient copper weight and number of layers to carry
the output current to the load or to the output connectors.
• Be sure to include enough vias along both the positive and
negative J leads to distribute the current among the layers
of the PCB.
• Do not run input-referenced signal traces (VC, PC, TM
and IM) between the layers of the secondary outputs.
• Run the input-referenced signal traces (VC, PC, TM and IM)
such that V-IN shields the signals. See AN:005 FPA Printed
Circuit Board Layout Guidelines for more details.
Figure 23 — Symmetric layout
Equalizing the current paths is most easily accomplished by
centering the VTM module output J-leads between the output
connections of the PCB and by designing the board such that
the layout is symmetric from both sides of the output and from
the front and back ends of the output as shown in Figures 23
and 24.
Figure 24 — Symmetric layout
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VTM48EF015T115A00
17.1 MECHANICAL DRAWING
NOTES:
mm
1. DIMENSIONS ARE inch .
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
17.2 RECOMMENDED LAND PATTERN
4
3
2
A
B
C
D
E
F
G
H
J
K
L
M
N
Bottom View
Signal
Name
+In
–In
IM
TM
VC
PC
+Out
–Out
NOTES:
mm
1. DIMENSIONS ARE inch .
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
VTM® Current Multiplier
Rev 3.5
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Designation
M2, M1
M4, M3
N3
N4
N2
N1
A3-L3, A2-L2
A4-L4, A1-L1
1
VTM48EF015T115A00
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 makes no
representations or warranties with respect to the accuracy or completeness of the contents of this publication. Vicor reserves the right to make changes
to any products, specifications, and product descriptions at any time without notice. Information published by Vicor has been checked and is believed to
be accurate at the time it was printed; however, Vicor assumes no responsibility for inaccuracies. Testing and other quality controls are used to the extent
Vicor deems necessary to support Vicor’s product warranty. Except where mandated by government requirements, testing of all parameters of each
product is not necessarily performed.
Specifications are subject to change without notice.
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Product Warranty
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Vicor will repair or replace defective products in accordance with its own best judgment. For service under this warranty, the buyer must contact Vicor to
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email
Customer Service: [email protected]
Technical Support: [email protected]
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