PRM48BH480x250A00

PRM® Regulator
PRM48BH480x250A00
S
C
NRTL
US
High Efficiency Converter
Features
Product Ratings
• 48.0 V input (38.0 V to 55.0 V),
non-isolated ZVS buck-boost regulator
• 20.0 V to 55.0 V adjustable output range
VIN = 38.0 V to 55.0 V
POUT = 250 W
VOUT = 48.0 V
(20.0 V to 55.0 V Trim)
IOUT = 5.21 A
• 250 W output power in 0.57 in2 footprint
• 96.7% typical efficiency, at full load
• 1676 W/in3 (102 W/cm3) Power Density
• 5.29 MHrs MTBF (MIL-HDBK-217 Plus Parts Count)
• Pin selectable operating mode
Product Description
n Adaptive Loop
n Remote Sense / Slave
• Half VI
Chip®
The VI Chip® PRM® Regulator is high eﬃciency converter,
operating from a 38.0 to 55.0 Vdc input to generate a regulated
20.0 to 55.0 Vdc output. The ZVS buck-boost topology enables
high switching frequency (~1.03 MHz) operation with high
conversion eﬃciency. High switching frequency reduces the
size of reactive components enabling power density up to
1676 W/in3.
Package
n 22.0mm x 16.5mm x 6.73mm
Typical Applications
•
•
•
•
•
High Density Power Supply DC-DC rail outputs
High Density ATE system DC-DC power
Telecom NPU and ASIC core power
Communications Systems
Non-isolated and isolated power converters
The Half VI Chip® package is compatible with standard pickand-place and surface mount assembly processes with a planar
thermal interface area and superior thermal conductivity.
In a Factorized Power Architecture™ system, the PRM and
downstream VTM® current multiplier minimize distribution
and conversion losses in a high power solution, providing an
isolated, regulated output voltage.
The PRM48BH480x250A00 has two selectable modes of
regulation depending on the application requirements.
In Adaptive Loop Operation, the PRM48BH480x250A00 utilizes
a unique feed-forward scheme that enables precise regulation
of an isolated POL voltage without the need for remote sensing
and voltage feedback.
In Remote Sense Operation, the internal regulation circuitry is
disabled, and an external control loop and current sensor
maintain regulation. This aﬀords ﬂexibility in the design of both
voltage and current compensation loops to optimize
performance in the end application.
PRM® Regulator
Rev 1.4
vicorpower.com
Page 1 of 42
07/2014
800 927.9474
PRM48BH480x250A00
Typical Applications
PRM
ENABLE
VAUX
SGND
RTRIM
RAL
VTM
REF/
REF_EN
TRIM
ON/OFF
CONTROL
AL
VT
SHARE/
CONTROL NODE
VC
VOUT
Adaptive Loop Temperature Feedback
+OUT
TM
VTM Start Up Pulse
VC
IFB
PC
+OUT
+IN
COUT
SGND
Vin
+IN
VF: 20 V to 55 V
CIN
–IN
SGND
LF
CF
–OUT
–IN
–OUT
PRIMARY
GND
SECONDARY
SEC_GND
ISOLATION BOUNDRY
SGND
Typical Application: PRM48BH480x250A00 + VTM Adaptive Loop Configuration
VREF
SGND
ENABLE
VAUX
SGND
SGND
SGND
OUT
Voltage Sense and Error Amplifier
(Differential)
GND
VTM
REF/
REF_EN
TRIM
ON/OFF
CONTROL
REF 3312
IN
AL
VT
SHARE/
CONTROL NODE
VC
SGND
TM
Voltage Reference with Soft Start
IFB
Voltage Sense
PRM
VTM Start up Pulse
V+
+OUT
VC
PC
V–
VOUT
+IN
VIN
+IN
LF
External Current Sense
–IN
SGND
COUT
SGND
+OUT
CIN
[1]
–IN
+IN
CF
–IN
–OUT
GND
–OUT
PRIMARY
SECONDARY
ISOLATION BOUNDRY
SGND
Typical Application: PRM48BH480x250A00 + VTM, non-isolated Remote Sense Configuration
[1]
Non-Isolated Configuration: –Out connected to -IN
PRM® Regulator
Rev 1.4
vicorpower.com
Page 2 of 42
07/2014
800 927.9474
GND
[1]
LOAD
PRM48BH480x250A00
Pin Configuration
1
SHARE/
CONTROL NODE
A
TRIM
C
NC
E
TOP VIEW
2
B
ENABLE
D
NC
F
AL
3
VT
A
IFB
C
REF/REF_EN
E
4
B
VAUX
D
SGND
F
VC
+IN
G
G
+OUT
-IN
H
H
-OUT
Half VIC SMD
Pin Descriptions
Pin
Number
Signal Name
F4
SHARE
(Adaptive Loop / Slave Operation)
CONTROL NODE
(Remote Sense Operation)
VT
(Adaptive Loop Operation)
ENABLE
VAUX
TRIM
IFB
(Remote Sense Operation)
NC
SGND
NC
REF
(Adaptive Loop Operation)
REF_EN
(Remote Sense Operation)
AL
(Adaptive Loop Operation)
VC
G1,G2
+IN
G3,G4
+OUT
H1,H2
-IN
H3,H4
-OUT
A1
A3
B2
B4
C1
C3
D2
D4
E1
E3
F2
Type
BIDIR
INPUT
INPUT
BIDIR
OUTPUT
INPUT
INPUT
n/a
INPUT
n/a
Function
Parallel sharing control bus for master-slave configuration.
Modulator control node input. Driven by external error amplifier in Remote Sense
Operation.
VTM TM input for temperature compensation. Leave disconnected for Remote Sense
Operation.
Enables power supply when allowed to float high. 5 V during normal operation.
9 V auxiliary bias voltage.
Selects operating mode. Adjusts output voltage in Adaptive Loop Operation.
Current sense input for current limit and overcurrent protection in Remote Sense Operation.
Leave disconnected for Adaptive Loop Operation.
Do not connect this pin.
Signal ground, reference for analog controls. Kelvin connected internally to –IN and –OUT.
Do not connect this pin.
OUTPUT
Reference voltage for internal error amplifier in Adaptive Loop Operation.
OUTPUT
Powers and enables external control circuit voltage reference in Remote Sense Operation.
INPUT
OUTPUT
INPUT
POWER
OUTPUT
POWER
INPUT
POWER RETURN
OUTPUT
POWER RETURN
Adaptive loop gain control. Sets the magnitude of the Adaptive Loop load line in Adaptive
Loop Operation. Leave disconnected for Remote Sense Operation.
Bias voltage to power VTM module during start up
Positive input power terminal
Positive output power terminal
Negative input power terminal. Connected internally to -OUT.
Negative output power terminal. Connected internally to -IN.
PRM® Regulator
Rev 1.4
vicorpower.com
Page 3 of 42
07/2014
800 927.9474
PRM48BH480x250A00
Part Ordering Information
Device
Input Voltage
Range
Package Type
Output Voltage x 10
Temperature Grade
Output Power
Revision
Version
PRM
48B
H
480
T
250
A
00
PRM = PRM
48B = 38.0 V - 55.0 V
H = Half VIC
SMD
480 = 48.0 V
T = -40 to 125°C
M = -55 to 125°C
250 = 250 W
A
00 = AL / RS
Standard Models
Part Number
PRM48BH480T250A00
PRM48BH480M250A00
VIN
Package Type
VOUT
Temperature
38.0 V - 55.0 V
Half VIC
SMD
48.0 V
(20.0 V to 55.0 V)
-55 to 125°C
-40 to 125°C
Power
Version
250 W
AL / RS
(Pin Selectable)
Absolute Maximum Ratings
The ABSOLUTE MAXIMUM ratings below are stress ratings only. Operation at or beyond these maximum ratings can cause permanent damage to device.
Electrical specifications do not apply when operating beyond rated operating conditions. Operating beyond rated operating conditions for extended period of
time may affect device reliability. All voltages are specified relative to SGND unless otherwise noted. Positive pin current represents current flowing
out of the pin.
Parameter
Comments
Min
-0.3
SHARE / CONTROL NODE
-0.3
ENABLE
+IN to –IN
Continuous, non-operating
-1
100 ms, non-Operating
-0.5
VAUX
SGND
IFB
REF / REF _EN
Unit
10.5
V
+/-10
mA
5.5
V
+/-10
mA
80
V
100
V
10.5
V
+/-100
mA
+/-100
mA
-0.5
5.7
V
-0.3
3.6
V
10
mA
3.4
mA
3.6
V
Remote Sense Operation (REF _EN)
Adaptive Loop Operation (REF)
TRIM
Max
-0.3
AL
-0.3
3.6
V
VT
-0.3
4.8
V
-0.5
18
V
+/-1.8
A
VC to –OUT
+OUT to –OUT
-1
Output Current
Internal Operating
Temperature
Storage
Temperature
62
V
7.3
A
T Grade
-40
125
°C
M Grade
-55
125
°C
T Grade
-40
125
°C
M Grade
-65
125
°C
PRM® Regulator
Rev 1.4
vicorpower.com
Page 4 of 42
07/2014
800 927.9474
PRM48BH480x250A00
Electrical Specifications
Specifications apply over all line and load conditions, and trim from 20.0 V to 55.0 V, unless otherwise noted; Boldface specifications apply over the
temperature range of -40ºC < TINT < 125ºC; All Other specifications are at TINT = 25ºC unless otherwise noted.
Attribute
Symbol
Conditions / Notes
Min
Typ
Max
Unit
38.0
0.001
48.0
55.0
1000
V
V/ms
V
ms
W
mA
A
µF
mΩ
Power Input Specification
Input Voltage Range
VIN Slew Rate
Initialization Voltage
Initialization Delay
No Load Power Dissipation
Input Quiescent Current
Input Current
Input Capacitance (Internal)
Input Capacitance (Internal) ESR
VIN
dVIN /dt
VINIT
tINIT
PNL
IQC
IIN_DC
CIN_INT
RCIN
Continuous, operating
0 ≤ VIN ≤ 55.0 V
Internal micro controller initialization voltage
From VIN first crossing VINIT
ENABLE HIGH, VIN = 48.0 V
ENABLE LOW, VIN = 48.0 V
IOUT = 5.21 A, VIN = 48.0 V, VOUT = 48.0 V
Effective value, VIN = 48.0 V (see Fig. 13)
Effective value, VIN = 48.0 V
5.0
10
7.0
2.4
14.5
5.4
2
3.0
9.0
3.5
20.0
5.6
Power Output Specification
Rated Output Current
IOUT
Standalone and Master Operation, see Figure 1, SOA
5.21
A
Rated Output Power
POUT
250
W
1.07
MHz
Switching Frequency
FSW
Standalone and Master Operation, see Figure 1, SOA
VIN = 48.0 V VOUT = 48.0 V,
IOUT = 2.60 A, TINT = 25°C
Over line, load, trim and temperature,
exclusive of burst mode
From VIN first crossing VIN_UVLO+_SUPV
to ENABLE high; tINIT expired
1.07
MHz
Output Turn-ON Delay
tON
0.94
0.70
From ENABLE pin release to ENABLE high, VIN applied, tOFF expired
Start up Sequence Timeout
Efficiency Ambient
Efficiency Hot
Efficiency Over Temperature
Output Discharge current
tSTARTUP_SEQ From ENABLE high to start up sequence complete
ηAMB
ηHOT
η
IOD
µs
20
µs
17
ms
95.7
96.7
%
VIN = 48.0 V, VOUT = 48.0 V, IOUT = 2.60 A, TINT = 25°C
94.7
95.7
%
VIN = 38.0 V to 55.0 V,
VOUT = 48.0 V, IOUT = 5.21 A, TINT = 25°C
VIN = 38.0 V to 55.0 V,
IOUT = 5.21 A, TINT = 25°C, over trim
VIN = 48.0 V, VOUT = 48.0 V,
IOUT = 5.21 A, TINT = 100°C
VIN = 48.0 V, VOUT = 48.0 V,
IOUT = 2.60 A, TINT = 100°C
VIN = 38.0 V to 55.0 V , VOUT = 48.0 V,
IOUT = 5.21 A, TINT = 100°C
VIN = 38.0 V to 55.0 V , IOUT = 5.21 A,
TINT = 100°C, over trim
95.0
%
92.0
%
95.5
96.5
%
94.5
95.8
%
95.0
%
91.5
%
>50% load and VOUT = 48.0 V; over temperature
94.5
%
>50% load; over temperature and trim
89.0
%
Average Value
VIN = 48.0 V, VOUT = 48.0 V,
IOUT = 5.21 A, COUT_EXT = 0 F, 20 MHz BW
VOUT_PP
Output Inductance (Parasitic)
LOUT_PAR
Frequency @ 1.03 MHz, Simulated J-Lead model
Output Capacitance (Internal)
COUT_INT
Effective value, VOUT = 48.0 V (see Fig.13)
RCOUT
20
VIN = 48.0 V, VOUT = 48.0 V, IOUT = 5.21 A, TINT = 25°C
Output Voltage Ripple
Output Capacitance (Internal) ESR
1.03
Effective value, VOUT = 48.0 V
PRM® Regulator
Rev 1.4
vicorpower.com
Page 5 of 42
07/2014
800 927.9474
0.5
1000
2.5
mA
1500
mV
nH
2
µF
3.0
mΩ
PRM48BH480x250A00
Electrical Specifications (cont.)
Specifications apply over all line and load conditions, and trim from 20.0 V to 55.0 V, unless otherwise noted; Boldface specifications apply over the
temperature range of -40ºC < TINT < 125ºC; All Other specifications are at TINT = 25ºC unless otherwise noted.
Attribute
Symbol
Conditions / Notes
Min
Typ
Max
Unit
47.00
20.0
1.7
48.00
49.00
55.0
1.9
0.2
0.2
0.2
V
V
ms
%
%
%
3
%
5
%
7.3
A
7.29
A
47
µF
25
µF
4.8
V
Power Output Specifications: Adaptive Loop Operation
Output Voltage Setpoint
Output Voltage Trim Range
Output Voltage Rise Time
Output Voltage Load Regulation
Output Voltage Line Regulation
Total Regulation Error
Total AL Regulation Error
Output Current Limit
VOUT_SET
VOUT
tRISE_VOUT
From soft start initiated to output voltage settled
VOUT_REG_LOAD Adaptive loop load line inactive
VOUT_REG_LINE Adaptive loop load line inactive
VOUT_REG_TOTAL PRM output voltage, Adaptive Loop load line inactive
VOUT_REG_AL
ILIMIT
Load Capacitance (Electrolytic)
CLOAD_ALEL
Load Capacitance (Ceramic)
CLOAD_CER
Load Transient Voltage Deviation
Load Transient Recovery Time
No load, trim Inactive, Adaptive Loop load line inactive
VTRANS
tTRANS
VTM output voltage, total Adaptive Loop regulation,
VOUT = 48.0 V, trim inactive
Rated Power Within an Array
Current Sharing Difference
(Master to Slave)
IOUT_ARRAY
POUT_ARRAY
IOUT_SHARE_MS
1
VTM output voltage, total Adaptive Loop regulation,
trim active, exclusive of external resistor tolerances
VIN = 48.0 V, VOUT = 48.0 V, TINT = 25°C, constant
current limit after supervisory limit detection time tLIM_SUPV
5.7
Over line, load, trim and temperature
5.2
0.1 Ω ≤ ESR ≤ 1 Ω, See Figure 32,
total capacitance (CLOAD_ALEL + CLOAD_CER) ≤ 47 µF
6.5
2 mΩ ≤ ESR ≤ 200 mΩ, See Figure 32
10% ↔ 100% load step, 10 A/µsec, 0 µF COUT,
deviation from initial setpoint
10% ↔ 100% load step, 10 A/µsec, 0 µF COUT,
Recovery to 90% of final value, Adaptive Loop
load line inactive
10% ↔ 100% load step, 10 A/µsec, 0 µF COUT,
Recovery to 90% of final value,
Adaptive Loop load line active, VAL = 0.96 V
Power Output Specifications: Slave Operation with AL Master
Slave Operation within an array, up to 5°C case
Rated Current Within an Array
1.8
0.02
0.02
temperature differential, master-slave configuration
Slave Operation within an array, up to 30°C case
temperature differential, master-slave configuration
Slave Operation within an array, up to 5°C case
temperature differential, master-slave configuration
Slave Operation within an array, up to 30°C case
temperature differential, master-slave configuration
Equal input, and output voltage at full load;
VIN = 48.0 V, VOUT = 48.0 V
Equal input and output voltage at full load;
Over line and trim, with 25°C ≤ TC ≤ 100°C and ≤ 5°C
part-part temp. mismatch
Equal input, and output voltage at full load;
Over line and trim, with 25°C ≤ TC ≤ 100°C
and ≤ 30°C part-part temp. mismatch
PRM® Regulator
Rev 1.4
vicorpower.com
Page 6 of 42
07/2014
800 927.9474
100
µs
500
µs
4.2
A
3.6
A
200
W
175
W
15
%
15
%
20
%
PRM48BH480x250A00
Electrical Specifications (cont.)
Specifications apply over all line and load conditions, and trim from 20.0 V to 55.0 V, unless otherwise noted; Boldface specifications apply over the
temperature range of -40ºC < TINT < 125ºC; All Other specifications are at TINT = 25ºC unless otherwise noted.
Attribute
Symbol
Conditions / Notes
Min
Power Output Specifications: Slave Operations (cont.)
Equal input, output, and SHARE voltage at full load;
Current Sharing Difference
(Slave to Slave)
Maximum Array Size
Output Voltage Range
Rated Current Within an Array
Rated Power Within an Array
Current Sharing Difference
Maximum Array Size
IOUT_SHARE_SS
NPRMS_PARALLEL
VIN = 48.0 V, VOUT = 48.0 V
Equal input, output and SHARE voltage at full load;
Over line and trim, with 25°C ≤ TC ≤ 100°C
and ≤ 5°C part-part temp. mismatch
Equal input, output, and SHARE voltage at full load;
Over line and trim, with 25°C ≤ TC ≤ 100°C
and ≤ 30°C part-part temp. mismatch
Maximum number of parallel devices,
master-slave configuration
Power Output Specifications: Remote Sense Operation
VOUT
Remote Sense Operation within an array,
up to 5°C case temperature differential
IOUT_ARRAY
Remote Sense Operation within an array,
up to 30°C case temperature differential
Remote Sense Operation within an array,
up to 5°C case temperature differential
POUT_ARRAY
Remote Sense Operation within an array,
up to 30°C case temperature differential
Equal input, output, and CONTROL NODE voltage
at full load; VIN = 48.0 V, VOUT = 48.0 V
Equal input, output and CONTROL NODE voltage at
full load; Over line and trim, with 25°C ≤ TC ≤ 100°C
IOUT_SHARE_RS and ≤ 5°C part-part temp. mismatch
Equal input, output, and CONTROL NODE voltage at
full load; Over line and trim,
with 25°C ≤ TC ≤ 100°C and ≤ 30°C
part-part temp. mismatch (worst case)
Maximum number of parallel devices, Remote Sense
NPRMS_PARALLEL
configuration, CONTROL NODE externally driven
PRM® Regulator
Rev 1.4
vicorpower.com
Page 7 of 42
07/2014
800 927.9474
20.0
Typ
Max
Unit
5
%
10
%
15
%
5
PRMs
55.0
V
4.7
A
4.2
A
225
W
202
W
5
%
10
%
15
%
10
PRMs
PRM48BH480x250A00
Electrical Specifications (cont.)
Specifications apply over all line and load conditions, and trim from 20.0 V to 55.0 V, unless otherwise noted; Boldface specifications apply over the
temperature range of -40ºC < TINT < 125ºC; All Other specifications are at TINT = 25ºC unless otherwise noted.
Attribute
Symbol
Conditions / Notes
Min
Typ
Max
Unit
24.5
22.7
2.2
62.6
63.6
1.0
57.9
26.0
8.8
9.5
7.2
V
V
V
V
V
V
V
V
ºC
W
V
V
V
6.9
V
5
ms
75
ms
Powertrain Protections
Input Undervoltage Turn-ON
Input Undervoltage Turn-OFF
Input Undervoltage Hysteresis
Input Overvoltage Turn-ON
Input Overvoltage Turn-OFF
Input Overvoltage Hysteresis
Output Overvoltage Threshold
Minimum Current Limited Vout
Overtemperature Shutdown Setpoint
Output Power Limit
Short Circuit VOUT Threshold
Short Circuit VOUT Recovery Threshold
Short Circuit CONTROL NODE Threshold
Short Circuit CONTROL NODE
Recovery Threshold
VIN_UVLO+
VIN_UVLOVUVLO_HYST
VIN_OVLOVIN_OVLO+
VOVLO_HYST
VOUT_OVP+
VOUT_UVP
TINT_OTP
PPROT
VSC_VOUT
VSC_VOUTR
VSC_VCN
Instantaneous powertrain shutdown, detected after tBLANK
(VIN_UVLO+) - (VIN_UVLO-)
Instantaneous powertrain shutdown, detected after tBLANK
(VIN_OVLO+) - (VIN_OVLO-)
Instantaneous shutdown, detected after tPROT
Instantaneous shutdown, detected after tPROT
22.0
1.8
56.0
0.7
56.0
tSC
Short Circuit Recovery Time
Overcurrent (IFB) and
Input Over/Undervoltage Blanking Time
Overtemperature, Output Overvoltage
and ENABLE Shutdown Response Time
(Hardware)
tSCR
Short circuit fault detected after VSC_VOUT
and VSC_VCN thresholds persist for this time
Excludes tOFF
tBLANK
67.3
1.4
60.0
12
125
250
VSC_VCNR
Short Circuit Timeout
2.5
50
tPROT
120
150
2
µs
µs
Powertrain Supervisory Limits
Input Undervoltage Turn-ON
(Supervisory)
Input Undervoltage Turn-OFF
(Supervisory)
Input Undervoltage Hysteresis
(Supervisory)
Input Overvoltage Turn-ON
(Supervisory)
Input Overvoltage Turn-OFF
(Supervisory)
Input Overvoltage Hysteresis
(Supervisory)
Undertemperature Shutdown Setpoint
(Supervisory)
Supervisory Limit Response Time
VIN_UVLO+_SUPV
VIN_UVLO-_SUPV
35.8
Powertrain shutdown, detected after tLIM_SUPV
VUVLO_HYST_SUPV (VIN_UVLO+_SUPV) - (VIN_UVLO-_SUPV)
VIN_OVLO-_SUPV
VIN_OVLO+_SUPV
33.6
1.9
2.2
56.0
57.7
Powertrain shutdown, detected after tLIM_SUPV
VOVLO_HYST_SUPV (VIN_UVLO+_SUPV) - (VIN_UVLO-_SUPV)
TINT_UTP
32.2
T Grade
M Grade
tLIM_SUPV
PRM® Regulator
Rev 1.4
vicorpower.com
Page 8 of 42
07/2014
800 927.9474
0.8
37.0
V
V
2.5
V
V
58.9
60.0
V
1.2
1.7
V
-40
-55
150
ºC
ºC
µs
PRM48BH480x250A00
Signal Specifications
Specifications apply over all line and load conditions, TINT = 25ºC and output voltage from 20.0 V to 55.0 V, unless otherwise noted.
Boldface specifications apply over the temperature range of -40ºC < TINT < 125ºC (T-grade).
ENABLE
• The ENABLE pin enables and disables the PRM
• In PRM array configurations, ENABLE pins should be connected in order to synchronize start up
• ENABLE is 5 V with 1.8 mA source capability during normal operation
Signal Type
Analog Output
Attribute
Symbol
Normal
State
ENABLE Voltage
VENABLE
Operation
ENABLE Current
IENABLE_OP
ENABLE Source Current
IENABLE_EN
Minimum Time to Start
tOFF
Start up
Start up
ENABLE
ENABLE
Standby
RENABLE_EXT
Resistance (External)
Fault
Typ
Max
Unit
4.7
5.0
5.3
V
1.8
mA
After tOFF
90
13.0
VENABLE_DIS
Disable Threshold
ENABLE
Digital Output
Min
VENABLE_EN
Enable Threshold
Digital Input / Output
Conditions / Notes
ENABLE
Sink Current to SGND
IENABLE_FAULT
0.97
µA
15.0
17.0
ms
2.5
3.2
V
2.40
Resistance to SGND required
V
235
Ω
4
mA
to disable the PRM
ENABLE voltage 1 V or above
VAUX: Auxillary Voltage Source
• Intended to power auxiliary circuits
• 9 V during normal operation with 5 mA source capability
Signal Type
State
Normal
Attribute
Symbol
VAUX Voltage
VVAUX
VAUX Current
IVAUX
Conditions / Notes
Min
Typ
Max
Unit
8.6
9.0
9.5
V
5
mA
400
mV
0.04
µF
IOUT = 0A, CVAUX_EXT = 0. Maximum
Operation
VAUX Voltage Ripple
VVAUX_PP
Analog Output
specification includes powertrain
100
operation in burst mode.
VAUX Capacitance
Transition
(External)
VAUX Fault Response
Time
CVAUX_EXT
tFR_VAUX
From fault recognition to
30
µs
VAUX = 1.5 V
VC: VTM Control
• Pulsed voltage source used to power and synchronize downstream VTM during start up
• 14 V, 10 ms typical voltage pulse
Signal Type
State
Attribute
VC Voltage
Analog Output
Start up
Symbol
VVC_START
VC Available Current
VC Duration
VC Slew Rate
IVC_START
Conditions / Notes
Connected to VTM VC or equivalent,
VC = 14 V, VIN > 20 V
Max
Unit
13
14
18
V
200
7
mA
10
16
ms
0.25
V/µs
Connected to VTM or equivalent,
IVC = 115 mA, CVC = 3.2 uF
ENABLE to VC Delay
Typ
IVC = 115 mA, CVC = 3.2 uF
tVC
dVC/dt
Min
tENABLE-VC
0.02
20
PRM® Regulator
Rev 1.4
vicorpower.com
Page 9 of 42
07/2014
800 927.9474
µs
PRM48BH480x250A00
Signal Specifications (cont.)
Specifications apply over all line and load conditions, TINT = 25ºC and output voltage from 20.0 V to 55.0 V, unless otherwise noted.
Boldface specifications apply over the temperature range of -40ºC < TINT < 125ºC (T-grade).
SGND: Signal Ground
• All control signals must be referenced to this pin, with the exception of VC
• SGND is internally connected to -IN and -OUT
Signal Type
Analog Input / Output
State
Any
Attribute
Maximum Allowable
Current
Symbol
Conditions / Notes
ISGND
Min
Typ
-100
Max
Unit
100
mA
TRIM
• TRIM is used to select operating mode and trim the output voltage in Adaptive Loop Operation
• Internal pullup to VCC_INT through 10 kΩ resistor
• When pulled below 0.45 V during power up, Remote Sense / Slave Operation is selected
• When allowed to pull up above 0.55 V during power up, Adaptive Loop Operation is selected
• Operating mode is detected during power up and cannot be changed unless input power is cycled
Signal Type
State
Attribute
Internally Generated
Normal
Operation
VCC
Internal Pullup
Resistance to VCC_INT
Analog Input
Mode Detection
Delay
Mode
Remote Sense
Detect
Enable Threshold
Remote Sense
Disable Threshold
Symbol
Conditions / Notes
VCC_INT
RTRIM_INT
tMODE_DETECT
0.5% tolerance resistor
From ENABLE high to mode detected,
after VIN first applied
Min
Typ
Max
Unit
3.20
3.28
3.36
V
9.83
10.00
10.18
kΩ
100
140
200
µs
Pull below this value during first
VRS_MODE_EN
start up after application of power to
0.45
V
enable Remote Sense / Slave Operation
Pull above this value during first
VRS_MODE_DIS
start up after application of power to
enable Adaptive Loop Operation
PRM® Regulator
Rev 1.4
vicorpower.com
Page 10 of 42
07/2014
800 927.9474
0.55
V
PRM48BH480x250A00
Signal Specifications (cont.)
Specifications apply over all line and load conditions, TINT = 25ºC and output voltage from 20.0 V to 55.0 V, unless otherwise noted.
Boldface specifications apply over the temperature range of -40ºC < TINT < 125ºC (T-grade).
TRIM (Adaptive Loop Operation Only)
• Provides dynamic trim control over the PRM output voltage in Adaptive Loop Operation
• Sampled prior to every start up to detect if trim is active or inactive
• Output voltage is equal to 20 times the voltage at the TRIM pin when applied TRIM voltage is within the active range
• Trim state is detected during normal operation and cannot be changed until start up is initiated
Signal Type
State
Attribute
Symbol
Conditions / Notes
Min
Start up
Trim Enable Threshold
VTRIM_EN
Trim Disable Threshold
VTRIM_DIS
Minimum Trim Disable
Resistance
Trim Capacitance
(External)
Trim Sample Delay
Analog Input
TRIM Pin
Analog Range
TRIM Gain
RTRIM_DIS_MIN
3.20
start up to disable trim control
to disable trim
10
From ENABLE high to TRIM sampled
100
VTRIM_RANGE
See Figure 26
1.00
%ACC_TRIM
VOUT Referred
Trim Resolution
VOUT_RES
Trim Latency
tTRIM_LAT
Trim Bandwidth
BWTRIM
VOUT / VTRIM,
Vout accuracy, exclusive of
140
0.5
external resistor tolerance
100
pF
200
µs
2.75
V
V/V
2.0
200
60
-3dB point
PRM® Regulator
Rev 1.4
vicorpower.com
Page 11 of 42
07/2014
800 927.9474
V
MΩ
20
VTRIM applied within active range
Unit
V
Pull above this value during
Minimum TRIM resistance required
Max
3.10
tENABLE_TRIM
GTRIM
Trim Accuracy
start up to enable trim control
Typ
CTRIM_EXT
Normal
Operation
Pull below this value during
120
1.2
%
mV
240
µs
kHz
PRM48BH480x250A00
Signal Specifications (cont.)
Specifications apply over all line and load conditions, TINT = 25ºC and output voltage from 20.0 V to 55.0 V, unless otherwise noted.
Boldface specifications apply over the temperature range of -40ºC < TINT < 125ºC (T-grade).
AL: Adaptive Loop (Adaptive Loop Operation Only)
• Provides Adaptive Loop load line programming in Adaptive Loop Operation
• Internal pullup to VCC_INT through 10 kΩ resistor
• Sampled prior to every start up to detect if Adaptive Loop load line is active or inactive
• Leave open to disable Adaptive Loop load line
• Not used in Remote Sense Operation
Signal Type
State
Attribute
Symbol
Conditions / Notes
Start up
AL Enable Threshold
VAL_EN
AL Disable Threshold
VAL_DIS
Minimum AL Disable
Resistance
AL Capacitance
(External)
AL Sample Delay
Internally generated
Analog Input
VCC
Internal Pullup
Resistance to VCC_INT
Normal
Operation
AL Pin Analog Range
AL Gain
RAL_DIS_MIN
tENABLE_AL
Referred Compensation
Typ
to disable AL load line
From ENABLE high to AL sampled
RAL_INT
0.5% tolerance resistor
VAL_RANGE
3.20
10
AL Latency
tAL_LAT
AL Bandwidth
BWAL
MΩ
100
pF
140
200
µs
3.20
3.28
3.36
V
9.83
10.00
10.18
kΩ
0
Positive correction slope, VT inactive
3.10
1.0
Full load slope accuracy exclusive
0.5
of external resistor tolerance
2.0
3
Maximum increase from no
load setpoint, VOUT ≤ 55.0 V
60
-3dB point
PRM® Regulator
Rev 1.4
vicorpower.com
Page 12 of 42
07/2014
800 927.9474
V
100
LLAL_RES
VOUT_AL_MAX
Unit
V
to disable AL load line
Minimum AL resistance required
Max
3.10
Pull above this value during start up
VCC_INT
AL Load Line Accuracy %ACC_LL_AL
Maximum Output
to enable AL load line
Min
CAL_EXT
GAL
AL Load Line Resolution
Pull below this value during start up
120
1.2
V
Ω/V
%
mΩ
5
V
240
µs
kHz
PRM48BH480x250A00
Signal Specifications (cont.)
Specifications apply over all line and load conditions, TINT = 25ºC and output voltage from 20.0 V to 55.0 V, unless otherwise noted.
Boldface specifications apply over the temperature range of -40ºC < TINT < 125ºC (T-grade).
VT: VTM Temperature (Adaptive Loop Operation Only)
• VTM temperature compensation for Adaptive Loop regulation
• Adjusts the slope of the Adaptive Loop load line to account for changes in VTM output resistance over temperature
• Connect to TM pin of compatible downstream VTM to enable temperature compensation
• Leave disconnected to disable temperature compensation
Signal Type
State
Attribute
Symbol
Conditions / Notes
Min
Internal Resistance
to SGND
VT Enable Threshold
VT Disable Threshold
VT Disable Default
Analog Input
Normal
Operation
Temperature
VT Analog Range
VT Temperature
Coefficient
RVT_INT
VVT_DIS
TVT_DIS
temperature compensation
TCVT_RES
VT Latency
tVT_LAT
Bandwidth
BWVT
2.18
VT within active range, referenced
to 2.98 V
VTM TM voltage applied, .01V/°K,
referenced to 25°C
VTM TM voltage applied, .01V/°K
REF Voltage
VREF
Normal
Operation
Analog Output
GREF_VOUT
Scale Factor
REF Resistance
(External)
REF Capacitance
(External)
REF Voltage Ripple
-3dB point
ENABLE to REF Delay
Transition
VAUX to REF Delay
3.98
30
%/V
0.3
%/C
120
Typ
tVAUX_REF
µs
kHz
Max
Unit
2.4
V
VOUT / VREF
20
V/V
10
MΩ
CREF_EXT
tENABLE_REF
°C
240
1.5
Min
V
VOUT = 48.0 V, trim inactive
RREF_EXT
VREF_PP
°C
0.4
60
V
V
25
when VT disabled
REF: Reference (Adaptive Loop Operation Only)
• Functions as REF pin in Adaptive Loop Operation
• REF represents the internal voltage reference for the voltage control circuit
• VOUT approximately equal to 20 times REF voltage
Signal Type
State
Attribute
Symbol
Conditions / Notes
REF to VOUT
1.9
Default AL temperature setting
Unit
kΩ
2.1
Pull below this value to disable VT
VVT_OP
TCVT
Max
80.4
VVT_EN
TCVT
VT Resolution
Typ
200
pF
Includes burst mode, 20 MHz BW
25
mV
ENABLE low to REF low
120
µs
1
ms
VAUX = 8.1 V to REF soft start
ramp initiated
PRM® Regulator
Rev 1.4
vicorpower.com
Page 13 of 42
07/2014
800 927.9474
PRM48BH480x250A00
Signal Specifications (cont.)
Specifications apply over all line and load conditions, TINT = 25ºC and output voltage from 20.0 V to 55.0 V, unless otherwise noted.
Boldface specifications apply over the temperature range of -40ºC < TINT < 125ºC (T-grade).
REF_EN: Reference Enable (Remote Sense and Slave Operation Only)
• Functions as REF_EN pin in Remote Sense and Slave Operation
• REF_EN signals successful start up and powertrain ready to operate
• Intended to power and enable the external feedback circuit reference in Remote Sense Operation
• 3.25 V, 4 mA regulated voltage source
Signal Type
State
Attribute
Symbol
Conditions / Notes
Min
REF_EN Voltage
REF_EN Source
Normal
Operation
Analog Output
Impedance
REF_EN Current
REF_EN Capacitance
(External)
REF_EN Voltage Ripple
ENABLE to REF_EN
Transition
Delay
VAUX to REF_EN
Delay
Typ
Max
Unit
3.25
3.37
V
50
100
Ω
IREF_EN
4
mA
CREF_EN_EXT
0.1
µF
VREF_EN
REF_EN unloaded
ROUT_REF_EN
VREF_EN_PP
Includes burst mode, 20 MHz BW
25
mV
tENABLE_REF_EN
ENABLE low to REF_EN low
120
µs
tVAUX_REF_EN
VAUX = 8.1 V to REF_EN high
1
ms
Share (Adaptive Loop and Slave Operation Only)
• Functions as SHARE pin in master slave array configuration
• Current share bus for array operation (master/slave scheme)
• Sources current and provides SHARE signal in master operation
• Sinks constant current when externally driven in active range (Slave Operation)
Signal Type
State
Attribute
Symbol
Conditions / Notes
SHARE Voltage
Standalone/
Analog Output
Master
Operation
Active Range
SHARE Available
Current
SHARE Resistance
to SGND
Analog Input
Slave
Operation
SHARE Sink Current
2.72
VSHARE
ISHARE
Min
0.79
VSHARE > 0.79 V
Max
Unit
7.40
V
2.5
RSHARE
ISHARE_SINK
Typ
mA
93.3
VSHARE > 0.79 V
PRM® Regulator
Rev 1.4
vicorpower.com
Page 14 of 42
07/2014
800 927.9474
0.25
0.50
kΩ
0.75
mA
PRM48BH480x250A00
Signal Specifications (cont.)
Specifications apply over all line and load conditions, TINT = 25ºC and output voltage from 20.0 V to 55.0 V, unless otherwise noted.
Boldface specifications apply over the temperature range of -40ºC < TINT < 125ºC (T-grade).
Control Node (Remote Sense Operation Only)
• Functions as CONTROL NODE pin in Remote Sense Operation
• Modulator control node voltage sets power train timing
• Driven by external error amplifier in Remote Sense Operation
• Sinks constant current when externally driven in active range
• Sources current, and clamps voltage to 0.79 V when pulled below active range
Signal Type
State
Attribute
Symbol
Conditions / Notes
CONTROL NODE
Voltage Active Range
CONTROL NODE
Analog Input
Normal
Operation
Source Current
CONTROL NODE
Sink Current
CONTROL NODE
Resistance to SGND
VCN
Min
Typ
0.79
ICN_LOW
VCN < 0.79 V
ICN_SINK
VCN > 0.79 V
0.25
RCN
0.50
Max
Unit
7.40
V
2.5
mA
0.75
mA
93.3
kΩ
IFB: Current Feedback (Remote Sense Operation Only)
• Functions as IFB pin in Remote Sense Operation
• A voltage proportional to the PRM output current must be supplied externally to the IFB pin in order for the device to properly protect overcurrent events
and to enable output current limit (clamp)
• Overcurrent protection trip will cause instantaneous powertrain disable, detected after tBLANK
• Not used for Adaptive Loop Operation
Signal Type
State
Attribute
Symbol
Conditions / Notes
Min
Typ
Max
Unit
Current Limit (Clamp)
Threshold
Analog Input
Normal
Operation
VIN = 48.0 V; VOUT = 48.0 V
VIFB_IL
TINT = 25°C
Over line, trim, and temperature
Not production tested; guaranteed
Overcurrent
Protection
VIFB_OC
Threshold
by design; TINT = 25°C
1.90
2.00
1.85
2.58
2.69
2.10
V
2.15
V
2.80
V
2.82
V
2.17
kΩ
Not production tested; guaranteed
by design; over line, trim,
2.56
and temperature
IFB Input Impedance
RIFB
Current Limit
Bandwidth
BWIL
2.09
2.13
2.0
NC: No Connect
• Reserved for factory use only
• No connections should be made to these pins
PRM® Regulator
Rev 1.4
vicorpower.com
Page 15 of 42
07/2014
800 927.9474
kHz
PRM48BH480x250A00
Functional Block Diagram
+IN
+OUT
Q3
Q1
COUT
CIN
L
-IN
-OUT
Q2
Q4
PGND
Internal
VCC
Regulator
30.1 kΩ
VCC
Modulator
2.5 mA Min
Error Amplifier
3.3 V
Linear
Regulator
0.5 mA
Voltage Reference
3.3 V
SHARE/
CONTROL NODE
1.58 kΩ
OTP
Enable
10
kΩ
VT
10
kΩ
2.1 kΩ
ENABLE
10 kΩ
20 kΩ
TRIM
0.01 uF
NC
Control and Monitoring
1000 pF
NC
Overvoltage
Lockout
Undervoltage
Lockout
10 kΩ
0.01 uF
Current
Limit
1000 pF
Output
Short
Circuit
35.7 kΩ
IN
Adaptive
Loop
SGND
SGND
PGND
PRM® Regulator
Rev 1.4
vicorpower.com
Page 16 of 42
07/2014
800 927.9474
SGND
REF/
REF_EN
60.4
kΩ
10
kΩ
6800
pF
OUT
IFB
30.1 W
0.01 uF
Output
Overvoltage
Protection
AL
57.6 kΩ
VAUX
VC
2200
pF
PRM48BH480x250A00
High Level Functional State Diagram
Conditions that cause state transitions are shown along arrows. Sub-sequence activities listed inside the state bubbles.
Application of
Vin
VIN > UVLO+
STARTUP SEQUENCE
STANDBY SEQUENCE
tON expired
ENABLE: 1.8mA to HIGH
VC Pulse
REF_EN active
ENABLE rising edge
ENABLE: 10uA to LOW
tOFF expired
ENABLE: 90uA to HIGH
Adaptive loop and trim modes latched
RS mode latched at first ENABLE
after Vin applied only
Powertrain Stopped
ENABLE falling edge,
Output OVP,
or OTP detected
Powertrain Active
tSTARTUP_SEQ
expired
Input OVLO or UVLO,
Output UVP,
or UTP detected
Fault
Autorecovery
ENABLE falling edge,
Output OVP or
OTP detected
FAULT SEQUENCE
Input OVLO or UVLO,
Output UVP,
or UTP detected
ENABLE pulsed: 25mA to
LOW
Powertrain Stopped
SUSTAINED
OPERATION
ENABLE: 1.8mA to HIGH
Powertrain Active
Short Circuit detected
PRM® Regulator
Rev 1.4
vicorpower.com
Page 17 of 42
07/2014
800 927.9474
PRM® Regulator
Rev 1.4
vicorpower.com
Page 18 of 42
07/2014
800 927.9474
AL
TRIM
2.4V
20V
48V
55V
tAUX_REF
TRIM Ignored
2
TRIM
INACTIVE
TRIM and AL pins
sampled
Soft Start
tVC
tENABLE_VC
tOFF tON
Micro controller
initialized
1V
0V
1.0V
3.3V
2.75V
VAUX
VAUX
VREF
VOUT_MIN
OUT_NOM
VOUTV
VOUT_OVP+
VOUT_MAX
VC
VVC_START
VENABLE_EN
ENABLE
OUTPUT
INPUT
ILIMIT
VENABLE
Iout
VSHARE_MIN
SHARE
REF
INPUT
VINIT
VSHARE_MAX
+IN
VIN_UVLO
VIN_OVLO
OUTPUT
OUTPUT
OUTPUT
BIDIR
BIDIR
BIDIR
INPUT
1
INPUT POWER ON
AND UV TURN ON
AL = 1V
3
AL
ACTIVE
FirstEnb: TR not low = not RS mode
TR high = trim inactive for this enabled period
AL not high = AL active for this enabled period
Vout increases by
VAL * GAL * IOUT
tBLANK
tBLANK
tBLANK
4
INPUT
OV
tOFF
Soft Start
5
INPUT OV
RECOVERY
TR high = trim inactive for this enabled period
AL not high = AL active for this enabled period
tPROT
tPROT
8
9
FULL LOAD OUTPUT
APPLIED
OV
Current sense activated, and output
increase due to AL after tSTARTUP_SEQ
expires
AL = 1V
tSTARTUP_SEQ
tON
6
7
ENABLE ENABLE
DISABLE RELEASE
TR high = trim inactive for this enabled period
AL not high = AL active for this enabled period
PRM48BH480x250A00
Timing Diagrams (Adaptive Loop Operation)
Module Inputs are shown in blue; Module Outputs are shown in brown.
PRM® Regulator
Rev 1.4
vicorpower.com
Page 19 of 42
07/2014
800 927.9474
ILIMIT
VOUT
INPUT
1V
3.3V
1V
1V
2.4V
2.75V
20V
48V
55V
tBLANK
AL pin Ignored
VOUT = VTRIM * 20
Micro controller
Opera ng Mode
ini alized Trim and AL state detected
AL
TRIM 2.75V
2.4V
INPUT
3.3V
VAUX
OUTPUT
VAUX
REF
VOUT_MIN
VOUT_NOM
VOUT_MAX
VC
VVC_START
VENABLE_EN
ENABLE
VENABLE
Iout
VSHARE_MIN
SHARE
VSHARE_MAX
VINIT
VIN_UVLO
+IN
VIN_OVLO
OUTPUT
OUTPUT
OUTPUT
BIDIR
BIDIR
BIDIR
INPUT
tSC
tSCR+tOFF
FirstEnb: TR not low = not RS mode
TR not high = trim ac ve for this enabled period
AL high = AL inac ve for this enabled period
10
11
12
INPUT POWER ON
AL
OUTPUT
AND UV TURN ON
INACTIVE AND SHORT
TRIM
CIRCUIT
ACTIVE
tOFF
14
OT SHUTDOWN
AND RECOVERY
AL ac ve
Vout increase due to Iout and AL
a!er tSTARTUP_SEQ expires
VOUT clamped to 55V
for VTRIM > 2.75V
tSTARTUP_SEQ
13
ENABLE
TOGGLING
15
OUTPUT
POWER LIMIT
PROTECTION
tLIM_SUPV
16
CURRENT
LIMIT
EVENT
tBLANK
17
INPUT POWER OFF
AND
UV TURN OFF
TR high = trim inac ve for this enabled period
AL not high = AL ac ve for this enabled period
TR high = trim inac ve for this enabled period
AL not high = AL ac ve for this enabled period
TR not high = trim ac ve for this enabled period
AL high = AL inac ve for this enabled period
PRM48BH480x250A00
Timing Diagrams (Adaptive Loop Operation) (cont.)
Module Inputs are shown in blue; Module Outputs are shown in brown.
VINIT
VIN_UVLO
VENABLE
VIFB_IL
PRM® Regulator
Rev 1.4
vicorpower.com
Page 20 of 42
07/2014
800 927.9474
TRIM
VAUX
tVC
tAUX_REF_EN
tOFF tON
Micro controller
ini alized
VAUX
VREF_EN
REF_EN
VOUT
VOUT_OVP+
VC
VVC_START
VENABLE_EN
ENABLE
IFB
VIFB_OC
VCN_MIN
CONTROL
NODE
VCN_MAX
+IN
VIN_OVLO
1
INPUT POWER ON AND UV
TURN ON
tBLANK
tENABLE_REF_EN
tBLANK
4
INPUT OV
RECOVERY
tENABLE_REF_EN
tPROT
5
ENABLE
DISABLE
6
ENABLE
RELEASE
tON
TRIM ignored for all subsequent
start up events un l VIN is removed
This blue shaded region is where trim voltage is a don’t care.
RS opera ng mode is latched. TRIM is ignored un l Vin is
removed.
t < tBLANK
tBLANK
2
3
QUICK OC INPUT OV
(t<tBLNK)
First Enable:
Trim Low = RS mode
RS mode detected and latched
tENABLE_REF_EN
tPROT
7
8
FULL LOAD LOAD RELEASE AND
APPLIED OUTPUT OV (SLOW F/B)
PRM48BH480x250A00
Timing Diagrams (Remote Sense Operation)
Module Inputs are shown in blue; Module Outputs are shown in brown.
VENABLE
VIFB_IL
VIFB_OC
PRM® Regulator
Rev 1.4
vicorpower.com
Page 21 of 42
07/2014
800 927.9474
tOFF
Micro controller
ini alized
TRIM
VAUX
VAUX
VREF_EN
REF_EN
VOUT
VOUT_OVP+
VC
VVC_START
VENABLE_EN
ENABLE
IFB
VCN_MIN
CONTROL
NODE
VCN_MAX
VINIT
VIN_UVLO
+IN
VIN_OVLO
9
START UP WITH
MINIMUM < dVIN/dt < 1.2V/ms
<tBLANK
tSC
10
OUTPUT
SHORT
CIRCUIT
First Enable:
Trim Low = RS mode
RS mode detected and latched
12
CURRENT
LIMIT EVENT
This blue shaded region is where trim voltage is a don’t care.
RS opera ng mode is latched. TRIM is ignored un l Vin is
removed.
tSCR+tOFF
11
OUTPUT POWER
LIMIT
PROTECTION
TRIM ignored for all subsequent
start up events un l VIN is removed
tBLANK
13
INPUT UV
PRM48BH480x250A00
Timing Diagrams (Remote Sense Operation) (cont.)
Module Inputs are shown in blue; Module Outputs are shown in brown.
PRM48BH480x250A00
Typical Performance Characteristics
The following figures present typical performance at TC = 25ºC, unless otherwise noted. See associated figures for general trend data.
!"#$#
6.0
300
200
Power
3.0
150
2.0
100
1.0
50
0.0
0
30
35
40
45
50
55
%!"&'
%!&##'
Figure 3 — No Load Power Dissipation vs. VIN, module disabled Enable = Low
!"#$#
Figure 5 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 20.0 V, TCASE = 25°C
Figure 2 — No Load Power Dissipation vs. VIN, module enabled
!"#$#
Figure 4 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 20.0 V, TCASE = -40°C
Power
! "#$
Figure 1 — DC Safe Operating Area (SOA)
60
Output Voltage (V)
Current
25
Figure 6 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 20.0 V, TCASE = 100°C
PRM® Regulator
Rev 1.4
vicorpower.com
Page 22 of 42
07/2014
800 927.9474
20
4.0
250
Output Power (W)
Output Current (A)
Current
5.0
%!&'#(
DC Safe Operating Area
PRM48BH480x250A00
Typical Performance Characteristics (cont.)
The following figures present typical performance at TC = 25ºC, unless otherwise noted. See associated figures for general trend data.
&!'()
&!'%%(
%!&$$'
!""#$
Figure 11 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 55.0 V, TCASE = 25°C
%!&"'
!"#$%
Figure 8 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 48.0 V, TCASE = 25°C
!""#$
!"#$%
Figure 10 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 55.0 V, TCASE = -40°C
Figure 7 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 48.0 V, TCASE = -40°C
%!&'$(
Figure 9 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 48.0 V, TCASE = 100°C
Figure 12 — Total efficiency and power dissipation vs. VIN and IOUT
VOUT = 55.0 V, TCASE = 100°C
PRM® Regulator
Rev 1.4
vicorpower.com
Page 23 of 42
07/2014
800 927.9474
!""#$
&!'"%(
!"#$%
PRM48BH480x250A00
Typical Performance Characteristics (cont.)
The following figures present typical performance at TC = 25ºC, unless otherwise noted. See associated figures for general trend data.
Effective Internal Input and Output Capacitance
vs. Applied Voltage
4.5
INPUT AND OUTPUT
CAPACITANCE
4.0
Effective Capacitance (µF)
5.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
5
10
15
20
25
30
35
40
45
50
55
Applied Voltage (V)
Input and Output Capacitance (µF)
Power Train Switching Frequency and
Periodic Input Charge vs. Input Voltage - Full Load
1025
14
975
10
950
8
Fsw (kHz)
12
925
Input Charge
(µC)
900
6
4
875
2
850
0
44
46
48
50
52
54
VOUT: 48 V
56
Input Voltage (V)
VOUT: 20 V
VOUT: 55 V
Fsw (kHz)
16
14
1000
12
975
10
8
950
925
Output Charge
(µC)
6
900
4
875
2
850
0
40
42
44
46
48
50
52
54
56
Input Voltage (V)
VOUT: 20 V
VOUT: 48 V
Figure 17 — Typical SHARE / CONTROL NODE Voltage vs. TCASE and IOUT;
VIN = 48.0 V, VOUT = 48.0 V
Total Output Charge per
Switching Cycle (µC)
Switching
Frequency
(kHz)
1025
Power Train Switching Frequency and
Periodic Output Charge vs. Input Voltage - Full Load
1050
Figure 14 — Typical Power Train Switching Frequency and Periodic Input
Charge vs. VIN, VOUT; IOUT = 5.21 A
38
16
1000
42
Figure 16 — Output Power vs. SHARE / CONTROL NODE Voltage;
VIN = 48.0 V, VOUT = 48.0 V, TCASE = 25°C
Switching
Frequency
(kHz)
Total Input Charge per
Switching Cycle (µC)
1050
40
Figure 13 — Effective Internal Input and Output Capacitance vs. Voltage –
Ceramic Type
38
VOUT: 55 V
Figure 15 — Typical Power Train Switching Frequency and Periodic Output
Charge vs. VIN, VOUT; IOUT = 5.21 A
PRM® Regulator
Rev 1.4
vicorpower.com
Page 24 of 42
07/2014
800 927.9474
PRM48BH480x250A00
Typical Performance Characteristics (cont.)
The following figures present typical performance at TC = 25ºC, unless otherwise noted. See associated figures for general trend data.
DC Modulator Gain and Powertrain Equivalent
Resistance vs. Output Current - VOUT = 20 V
10
125
100
5
100
80
2.5
75
0
50
40
25
20
GCN (dB)
7.5
-2.5
Req
(Ω)
-5
0
0.75
1.5
2.25
3
3.75
rIN (Ω )
120
Req (Ω )
150
GCN
(dB)
60
0
0
5.25
4.5
Powertrain Equivalent Input
Resistance vs. Output Current - VOUT = 20 V
0
0.75
1.5
Load Current (A)
VIN: 38 V
VIN: 48 V
VIN: 38 V
VIN: 55 V
Figure 18 — Powertrain Characteristics vs. IOUT, VIN
Resistive Load, VOUT = 20.0 V
GCN (dB)
5
250
0
200
-5
150
-10
100
Req
(Ω)
-15
-20
50
300
2.25
3
3.75
VIN: 48 V
4.5
20
0
0
0.75
1.5
VIN: 48 V
VIN: 38 V
VIN: 55 V
GCN (dB)
5
300
250
0
200
-5
150
-10
100
Req
(Ω)
-15
50
0
-20
3
3.75
4.5
50
VIN: 48 V
4.5
5.25
5.25
VIN: 48 V
VIN: 55 V
Powertrain Equivalent Input
Resistance vs. Output Current - VOUT = 55 V
30
20
10
0
0
0.75
Load Current (A)
VIN: 38 V
3.75
40
rIN (Ω )
GCN
(dB)
2.25
3
Figure 22 — Magnitude of powertrain dynamic input impedance vs. IOUT;
VIN; VOUT = 48.0 V
Req (Ω )
10
1.5
2.25
Load Current (A)
DC Modulator Gain and Powertrain Equivalent
Resistance vs. Output Current - VOUT = 55 V
0.75
VIN: 55 V
30
5.25
Figure 19 — Powertrain Characteristics vs. IOUT, VIN Resistive Load,
VOUT = 48.0 V
0
5.25
Powertrain Equivalent Input
Resistance vs. Output Current - VOUT = 48 V
Load Current (A)
VIN: 38 V
4.5
10
50
0
1.5
3.75
40
rIN (Ω )
GCN
(dB)
dB)
Req (Ω )
10
0.75
3
Figure 21 — Magnitude of powertrain dynamic input impedance vs. IOUT;
VIN; VOUT = 20.0 V
DC Modulator Gain and Powertrain Equivalent
Resistance vs. Output Current - VOUT = 48 V
0
2.25
Load Current (A)
1.5
2.25
3
3.75
4.5
5.25
Load Current (A)
VIN: 55 V
Figure 20 — Powertrain Characteristics vs. IOUT, VIN Resistive Load,
VOUT = 55.0 V
VIN: 38 V
VIN: 48 V
VIN: 55 V
Figure 23 — Magnitude of powertrain dynamic input impedance vs. IOUT;
VIN; VOUT = 55.0 V
PRM® Regulator
Rev 1.4
vicorpower.com
Page 25 of 42
07/2014
800 927.9474
PRM48BH480x250A00
General Characteristics
Specifications apply over all line and load conditions, TINT = 25ºC and output voltage from 20.0 V to 55.0 V, unless otherwise noted.
Boldface specifications apply over the temperature range of -40ºC < TINT < 125ºC (T-grade).
Attribute
Symbol
Conditions / Notes
Min
Typ
Max
Unit
21.8
22.0
22.3
mm
(0.86)
(0.87)
(0.88)
in
16.3
16.5
16.8
mm
(0.64)
(0.65)
(0.66)
in
6.48
6.73
6.98
mm
(0.255)
(0.265)
(0.275)
Mechanical
Length
Width
Height
Volume
Weight
L
W
H
No Heatsink
Vol
W
Lead Finish
in
2.44
cm3
(0.15)
in3
7
g
Nickel
0.51
2.03
Palladium
0.02
0.15
Gold
0.003
0.050
-40
-55
125
125
µm
Thermal
Operating Internal Temperature
Thermal Impedance
TINT
θINT-CASE
θINT-LEAD
T Grade
M Grade
2
9
5
Thermal Capacity
ºC
ºC
ºC/W
ºC/W
Ws / ºC
Assembly
Peak Compressive Force
Applied to Case (Z-axis)
Storage Temperature
TST
Moisture Sensitivity Level
MSL
ESD Rating
HBM
CDM
Peak Temperature During Reflow
-40
-65
T Grade
M Grade
MSL 6, 245°C Reflow
MSL 5, 225°C Reflow
Method per Human Body Model Test
ESDA/JEDEC JDS-001-2012
Charged Device Model JESD22-C101E
Agency Approvals / Standards
CLASS 1C
V
Under MSL 5 conditions above
60
1.5
2.5
Reliability and General Agency Approvals
Telcordia Issue 2 - Method I Case 1; Ground Benign,
Controlled
MIL-HDBK-217 Plus Parts Count - 25C Ground Benign,
Stationary, Indoors / Computer Profile
CTUVUS
245
ºC
225
90
2.0
3.0
ºC
s
ºC / s
ºC / s
5.28
MHrs
5.29
MHrs
CE Marked for Low Voltage Directive and RoHS Recast Directive, as applicable
PRM® Regulator
Rev 1.4
vicorpower.com
Page 26 of 42
07/2014
800 927.9474
lbs
lbs / in2
ºC
ºC
CLASS 2
Soldering
Under MSL 6 conditions above
Maximum Time Above 217 ºC
Peak Heating Rate During Reflow
Peak Cooling Rate Post Reflow
MTBF
3
5.3
125
125
Supported by J-Lead only
PRM48BH480x250A00
Pin Functions
If TRIM is permitted to pull up to 3.20 V or higher during start
up, trim is disabled, and the output is set to the nominal of 48.0 V.
+IN, -IN
Input power pins
If TRIM is held between 1.00 V to 2.75 V during start up, trim
is enabled, and the output is scaled by a factor of 20 resulting
in an output voltage range of 20.0 V to 55.0 V.
+OUT, -OUT
Output power pins. Module cannot sink current.
This selection persists until the PRM is restarted with the
ENABLE pin, or due to fault auto-recovery.
ENABLE
This pin turns the supply on and off. The pin is both an input and an
output and can provide the following features:
AL: Adaptive Loop (Adaptive Loop Operation)
This input pin allows you to set the Adaptive Loop load line.
Every volt on this pin represents 1.0 Ω of positive output slope.
There is an internal 10 kΩ pullup resistor to VCC_INT. If AL is
permitted to pull up to 3.20 V or higher during start up, the
Adaptive Loop load line is disabled.
n
n
Delayed Start: upon application of voltage (>UVLO) to the
module power input and after toff, the ENABLE pin will source a
constant 90 μA current.
Output enable: When ENABLE is allowed to pull up above the
enable threshold, the ENABLE pin will pull up to 5 V with
1.8 mA source capability, and the module will be enabled.
This selection persists until the PRM is restarted with the
ENABLE pin, or due to fault auto-recovery.
Output disable: ENABLE may be pulled down externally in order
to disable the module. Pull down resistance should be less than
235 Ω to SGND.
ENABLE control should be implemented using an open collector
configuration. It is not recommended to drive this pin externally.
VT: VTM Temperature (Adaptive Loop Operation)
This pin is used in the Adaptive Loop compensation algorithm to
account for the VTM output resistance variation as a function of
temperature. The VTM TM pin provides this voltage, scaled as the
temperature in K (Kelvin) divided by 100, so 25°C is 2.98 V. Leave
disconnected or pull below 1.9 V to disable. The adjustment is fixed
at 0.3%/°C relative to the value at 25°C
VAUX: Auxiliary Voltage Source
Use this pin to power external devices with a non-isolated 9 V
supply, with up to 5 mA load capability, switched with ENABLE
input. Do not place a capacitor over 0.04 µF on this pin.
REF: Reference (Adaptive Loop Operation)
This output pin allows you to monitor the internal reference voltage
in Adaptive Loop Operation. During normal operation it represents
the output voltage scaled by a factor of 20.
n
n
Fault detection flag: The ENABLE 5 V voltage source is
internally turned off when a fault condition is detected.
SGND: Signal Ground
This is a low current pin which provides a Kelvin connection to the
PRMs internal signal ground. Use this pin as the ground reference for
external circuitry and signals to avoid voltage drops caused by high
currents on power returns. In array configurations, SGND pins
should be star connected at a single point. A series resistor (~1Ω) to
the star location is recommended to decouple return currents.
VC: VTM Control
This output pin is used to temporarily provide VCC voltage to
connected VTMs during start up. The pulse is nominally 14 V, 10 ms
wide. A VTM can self-power once its input voltage reaches its
minimum specified input voltage. The PRM output must be checked
to make sure it reaches this threshold voltage before the VC pulse
expires.
TRIM
The TRIM pin is used to select the operating mode and to trim
the PRM output when Adaptive Loop operating mode is
selected. The TRIM pin has an internal pull-up to VCC_INT
through a 10 kΩ resistor.
Operating Mode Select:
If TRIM is pulled below 0.45 V during the first startup after VIN
is applied, Remote Sense / Slave operation is selected.
Otherwise, Adaptive Loop operation is selected.
This selection persists until VIN is removed from the part, and is
not changed by fault or disable events.
Output Voltage Trim:
Sets the output voltage of the PRM in Adaptive Loop operation.
In Adaptive Loop Operation this pin is for monitoring purposes only
and should not be driven or loaded externally.
REF_EN: Reference Enable (Remote Sense Operation)
In Remote Sense Operation this pin outputs a regulated 3.25 V, 4 mA
voltage source. It is enabled only after successful start up of the PRM
powertrain. REF_EN is intended to power the output current
transducer and also the voltage reference for the external control
loop. Powering the reference generator with REF_EN helps provide a
controlled start up, since the output voltage of the system is able to
track the reference level as it comes up.
SHARE (Adaptive Loop and Slave Operation)
This bus sets the output current level for all the PRM modules when
operating in an array (master-slave configuration). Connect them
together among the modules in the shared bus. One PRM should be
configured as a master by connecting TRIM for Adaptive Loop
Operation. All other PRMs should be configured as slaves by pulling
their respective TRIM pins low. This pin can be used to monitor the
error voltage externally. 0 to 100% load is represented by a voltage
between 0.79 V and 7.40 V.
CONTROL NODE (Remote Sense Operation)
In Remote Sense Operation, this is the input to the modulator which
determines the powertrain timing and ultimately the module output
power. An internal 0.5 mA current sink is always active. The bidirectional buffer between CONTROL NODE and the modulator has
two states. In normal operation, CONTROL NODE will be above the
0.79 V switching threshold, and will drive the modulator through the
buffer. An internal 7.40 V clamp determines the maximum output
power that can be requested of the modulator.
PRM® Regulator
Rev 1.4
vicorpower.com
Page 27 of 42
07/2014
800 927.9474
PRM48BH480x250A00
When CONTROL NODE falls below 0.79 V, the converter will stop
switching. An internal circuit clamps the modulator input to 7.40 V,
and a buffer will source up to 2.5 mA out of the pin at that clamp
level. For this reason, the output impedance of the amplifier driving
CONTROL NODE must be taken into account. A rail-to-rail
operational amplifier with low output impedance is always
recommended.
rEQ_IN
CIN_INT
CONTROL NODE
+
+
rEQ_OUT
RCN
ICN_LOW
Output
VCN · GCN
VCN
The PRM48BH480x250A00 regulator is specifically designed to
provide a controlled Factorized Bus distribution voltage for powering
downstream VTM Transformer — fast, efficient, isolated, low noise
Point-of-Load (POL) converters.
The PRM48BH480x250A00 can be configured for two operating
modes depending on the type of regulation required.
In Adaptive Loop Operation the regulation circuitry is enabled
within the device and regulates the voltage at the output terminals.
The PRM48BH480x250A00 has a programmable Adaptive Loop load
line which can be used to compensate for downstream VTM output
resistance allowing for precise point of load regulation without the
need for remote sensing.
+
VIN
Design Guidelines
COUT_INT
-
-
In Remote Sense Operation, the internal regulation circuitry is
disabled and the voltage regulation circuitry is provided externally
allowing for remote sensing directly at the point of load. In certain
applications Remote Sense Operation can improve regulation
accuracy, and allow for operating with high amounts of load
capacitance and optimizing load transient response.
Figure 24 — PRM48BH480x250A00 AC small signal model
The powertrain small signal (plant) response consists of a single pole
determined by the load resistance, the powertrain equivalent output
resistance, and the total output capacitance (internal and external to
the module). Both the modulator gain and the equivalent output
resistance vary as a function of line, load and output voltage. As the
load increases, the powertrain pole moves to higher frequency. As a
result, the closed loop crossover frequency will be the highest at full
load and lowest at minimum load. Figure 24 shows a reference AC
small-signal model.
IFB: Current Feedback (Remote Sense Operation)
In Remote Sense Operation, IFB is the input for the module output
overcurrent protection and current limit features. A voltage
proportional to the powertrain output current must be applied to IFB
in order for overcurrent protection to operate properly.
If the IFB voltage exceeds the IFB pin’s overcurrent protection
threshold, the powertrain will stop switching. If the IFB voltage falls
below the overcurrent protection threshold within tBLANK time, then
the powertrain will immediately resume switching. Otherwise a fault
is detected.
The current limit threshold for the IFB pin is set lower than the
protection threshold. When the IFB pin average voltage exceeds the
current limit threshold, an internal integrator will activate a clamp
amplifier which overrides the modulator input maximum level. This
causes the powertrain to maintain a constant output current.
The bandwidth of this current limit integrator is significantly slower
than that of the CONTROL NODE input. Therefore this current limit
cannot be used in lieu of properly compensating the (external)
control loop to avoid exceeding maximum current or power ratings
for the device.
Operating Mode Selection
The operating mode is selected through use of the TRIM pin.
When the part is first enabled after VIN is applied, the TRIM voltage is
sampled. The TRIM pin has an internal pull up resistor to VCC_INT, so
unless external circuitry pulls the pin voltage lower,
it will float up to VCC_INT.
If TRIM is pulled lower than 0.45 V during the first startup after
VIN is applied, the part will be configured for Remote Sense / Slave
Operation, where the internal voltage regulation circuitry is disabled.
In this case, for all subsequent operation the part will output a
voltage dependent on the SHARE / CONTROL NODE voltage
provided externally (either from an external regulation circuit or
master PRM).
To configure the part for Remote Sense or Slave Operation, connect
the TRIM pin to SGND. It is recommended to make this connection
through a 0 Ω jumper for troubleshooting purposes.
If the sampled TRIM voltage is higher than 0.55 V during the first
startup after VIN is applied, then the part will be configured for
Adaptive Loop Operation, and the internal voltage regulation
circuitry is enabled. The PRM will output a voltage dependent on the
TRIM voltage, and will remain in this mode for as long as
VIN is applied.
To configure the part for Adaptive Loop Operation, leave the TRIM
pin disconnected, or apply a voltage/resistance within the specified
range.
The operating mode is detected during the first start up after VIN is
applied. This selection persists until VIN is removed from the part,
and is not changed by fault or disable events. Changing the operating
mode can only be done by removing VIN.
PRM® Regulator
Rev 1.4
vicorpower.com
Page 28 of 42
07/2014
800 927.9474
PRM48BH480x250A00
Design Guidelines (Adaptive Loop Operation)
The TRIM pin is pulled up internally to VCC_INT thorough a 10 kΩ
resistor. VTRIM can be actively set with a DAC that is ground
referenced to SGND. VTRIM can be passively set by connecting a
resistor, RTRIM, from TRIM to SGND such that the voltage divider
made with VCC_INT and the 10 kΩ pull up yields the desired VTRIM.
The formula for calculating this resistor is provided in Equation (1a).
In Adaptive Loop Operation, the internal voltage control circuitry is
enabled and the voltage at the output terminals is regulated. The
part is nominally set to provide a fixed 48.0 V output, and the TRIM
pin can be used to adjust the output over the range of 20.0 V
to 55.0 V.
When used with a VTM, the AL pin provides ability to program an
Adaptive Loop load line to compensate for the output resistance
(ROUT) of a downstream VTM, while the VT pin provides temperature
compensation to account for changes in the VTM ROUT over
temperature.
VOUT = VTRIM • 20
R TRIM =
(1)
10 kuVTRIM
10 kuVOUT_SET
=
VCC <VTRIM 20 uVCC <VOUT_SET
INT
Trim Mode and Output Trim Control (Adaptive Loop Operation)
In Adaptive Loop Operation, during any start up and after ENABLE
transitions high, the TRIM pin voltage is sampled to determine if
trim is active or inactive. If the sampled TRIM voltage is higher than
3.20 V then the PRM will disable trim. In this case, for all subsequent
operation the output voltage will be programmed to the nominal
output of 48.0 V and the TRIM pin will be ignored during normal
operation.
(1a)
INT
For 1.00 V≤ VTRIM ≤ 2.75 V where VOUT_SET is the desired output
voltage.
The output voltage transfer function saturates for applied TRIM
voltages above approximately 2.75 V as illustrated in Figure 26 to
prevent the output from being driven above its rated output voltage.
When TRIM is set lower than 1.00 V the output voltage is not
specified and stable operation is not guaranteed.
If the sampled TRIM voltage is between 1.00 V and 2.75 V then the
PRM will activate trim mode and it will remain in this mode as long
as the PRM is operating.
PRM VOUT vs. VTRIM
This selection persists until the PRM is restarted with the ENABLE
pin, or due to fault auto-recovery.
Output Voltage (V)
Recommended Range
VCCINT
10 KΩ
50
50
40
40
30
30
20
20
10
TRIM
VTRIM
0
Micro
Controller
10
Unspecified
Operaon
TRIM Pin Resistor (KΩ)
60
60
0
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25
TRIM Pin Voltage (V)
SGND
Output Voltage (V)
RTRIM
TRIM Pin Resistor (KΩ)
Figure 26 — PRM VOUT vs. VTRIM
SGND
SGND
When trim is enabled the voltage at this pin is sampled at 120 µs
intervals to determine the trim level. The output can be dynamically
trimmed during normal operation, however it is not recommended
to use this pin in an external analog feedback loop.
Figure 25 — TRIM Connection
The output as a function of VTRIM is defined by equation (1) for
1.00 V ≤ VTRIM ≤ 2.75 V, and allows for an output voltage ranging from
20.0 V to 55.0 V.
Refer to Table 1 for a summary of the TRIM pin functionality and the
recommended voltage/resistance that should be applied to this pin.
Trim Pin Function Summary
Operating State
VTRIM
RTRIM
Remote Sense / Slave Operation
<0.45 V
<1 kΩ
Adaptive Loop Operation
>0.55 V [2]
>3 kΩ [2]
1.00 V to 2.75 V
4.32 kΩ to 49.9 kΩ
Adaptive Loop Operation
Trim Active
VOUT = 20* VTRIM
Trim Mode
Trim Inactive
VOUT = 48.0 V
>3.20 V
>10 MΩ
Table 1 — TRIM Pin Function Summary
[2]
It is not recommended to configure TRIM with a voltage less than 1.00 V in Adaptive Loop Operation
PRM® Regulator
Rev 1.4
vicorpower.com
Page 29 of 42
07/2014
800 927.9474
Detected and Latched
At application of VIN
when ENABLE first transitions high
At application of VIN
when ENABLE first transitions high
At every start up when
ENABLE transitions high
PRM48BH480x250A00
Adaptive Loop Compensation (Adaptive Loop Operation)
A factorized power system naturally has a DC load line associated
with it since the regulator stage (PRM) is positioned before the
isolation and voltage transformation stage (VTM) Consider for a
moment a factorized power system that has the following
parameters:
PRM and VTM Output Voltage
Adaptive Loop Comensation Example
Output Voltage
%Difference From Nominal (%)
3
n VF = 40 V
n KVTM=1/4
n ROUT_VTM =10 mohm @ 25°C
At no load the output voltage at the load will be equal to 10 V
(VF • KVTM). With increasing load current, the output voltage at the
load will drop at a rate proportional to the VTMs ROUT. It should be
noted that the ROUT has a positive temperature coefficient and so the
DC load line changes with temperature.
Compensated VTM Output
0
Unc
Decre omensa
ted V
as e s
TM
with
Load Output
due
to R
-1
Adaptive Loop
compensation brings
output into regulation
OUT
0
20
40
60
80
VTM VOUT (Uncompensated)
PRM VOUT
VTM VOUT (Regulated)
Figure 27 — Adaptive Loop Compensation Illustration
For our hypothetical VTM from above (with KVTM = 1/4 and
ROUT_VTM = 10 mΩ) the output resistance reflected over to the input
would be equal to 160 mΩ. For this example, RLL_AL should be set
to -160 mΩ to approximately cancel at 25°C the inherent load line
from the VTM.
RLL_AL is set by the voltage difference between the AL pin and SGND
pin, VAL, per the following formula:
RLL_AL = VAL • (-1.0) Ω/V
(3)
VAL ≤ 3.10 V
Where VAL is the voltage on the AL pin
VAL is sampled by a 10-bit ADC, whose input is connected to VCC_INT
through a 10 kΩ pull up resistor. This pull up disables the AL engine
when the AL pin is left open. VAL can be actively set with a DAC that
is ground referenced to SGND. VAL can be passively set by connecting
a resistor, RAL, from AL to SGND such that the voltage divider made
with VCC_INT and the 10 kΩ pull up yields the desired VAL. The
formula for calculating this resistor is provided in Equation (4).
(2)
VTM
Where
ROUT_VTM is the VTM output resistance at 25°C
KVTM is the VTM transformer ratio VIN/VOUT
RAL =
10 kΩ ∙VAL
(4)
VCC_INT – VAL
PRM
ENABLE
VAUX
ON/OFF
CONTROL
SGND
RTRIM
RAL
VTM
REF/
REF_EN
TRIM
AL
VT
SHARE/
CONTROL NODE
VC
Adaptive Loop Temperature Feedback
VTM Start Up Pulse
VOUT
+OUT
TM
VC
PC
IFB
COUT
SGND
Vin
+IN
+OUT
–IN
–OUT
VF: 20 V to 55 V
CIN
SGND
100
Load Current (%)
Setting the Adaptive Loop Load Line (Adaptive Loop Operation)
To determine an appropriate value for the compensation slope
(RLL_AL) it helps to reflect the VTM’s output resistance to the input
side of the VTM. A resistance on the output side of the VTM is scaled
by the VTMs transformer ratio (KVTM) squared as defined
by equation (2):
2
ith
s es w
-3
If the presence of this load line is undesirable, the load line can be
eliminated by way of the PRMs Adaptive Loop (AL) engine. The AL
engine measures the output current of the PRM and accordingly
increases the output voltage of the PRM in order to regulate the
PRMs output resistance to a fixed negative resistance, RLL_AL, settable
by way of the AL pin. RLL_AL should be sized to exactly cancel the
ROUT of the VTM at 25°C. The AL engine is also able to account for
the positive temperature coefficient of ROUT by way of its VT pin
which will be explained shortly.
(K 1 )
a
Incre
1
R OUT
ut
r VTM
Outp
ate fo
PRM ompens
c
to
d
Loa
-2
If the presence of this load line is acceptable for your application,
then the PRM can be configured by way of the TRIM pin alone.
Please refer to the Trimming the Output Voltage section for details.
In this case both the AL and VT pins should be left open.
RLLAL = ROUT_REFL =ROUT_VTM_25C •
2
LF
+IN
CF
–OUT
–IN
PRIMARY
GND
SECONDARY
ISOLATION BOUNDRY
SGND
Figure 28 — PRM-VTM Adaptive Loop Example
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SEC_GND
PRM48BH480x250A00
VCCINT
VCCINT
10 KΩ
20 KΩ
AL
VT
2.18 V to 3.98 V
(-55°C to 125°C)
VTM TM
Micro
Controller
VAL
60.4k
Micro
Controller
SGND
SGND
RAL
SGND
SGND
SGND
Figure 29 — AL Connections
Figure 30 — VT Connections
This selection persists until the PRM is restarted with the ENABLE
pin, or due to fault auto-recovery. When AL is enabled, the voltage at
this pin is sampled at 120 µs intervals to determine the load line. The
load line can be adjusted during normal operation, however it is not
recommended to use this pin in an external analog feedback loop.
PRM and VTM Output Voltage
Adaptive Loop With Temperature Compensation
3
Output Voltage
%Difference From Nominal (%)
Similar to TRIM, AL is sampled during every start up to determine if
the Adaptive Loop load line is enabled or disabled. If the AL pin is
allowed to pull up to 3.20 V or higher during start up, then the PRM
will disable the Adaptive Loop load line as long as the PRM remains
operating. In this case, for all subsequent operation the output
voltage will be remain at the set voltage, and the AL pin will be
ignored.
2
PRM
NT
OT
MBIE
ut H
ut A
Outp
Outp
PR M
COLD
utput
PRM O
Compensation slope
increases with
temperature based
on VT feedback
1
Compensated VTM Output
0
VTM ROUT increases
with temperature
-1
-2
-3
0
20
40
60
80
100
Load Current (%)
Adaptive Loop Temperature Compensation
(Adaptive Loop Operation)
By connecting the VT pin of the PRM to the VTM’s TM pin, the PRM is
able to monitor the internal temperature of the VTM. Knowing the
VTM’s internal temperature and the temperature coefficient of the
VTM’s ROUT, which is preprogrammed into the PRMs microcontroller,
the AL engine is able to scale the nominal value of RLL_AL (set by the
AL pin) to track the VTM’s ROUT over temperature. In this way the
output resistance of the PRM can be tuned to cancel the output
resistance of the VTM with the addition of a single resistor across the
AL pin and a connection of the VTM’s TM pin to the PRMs VT pin.
VTM VOUT: -55°C (Uncompensated)
VTM VOUT: 25°C (Uncompensated)
VTM VOUT: 100°C (Uncompensated)
PRM VOUT: -55°C (VT = 2.18 V)
PRM VOUT: 25°C (VT = 2.98 V)
PRM VOUT: 100°C (VT = 3.73V)
VTM VOUT (Regulated)
Figure 31 — Adaptive Loop Temperature Compensation Illustration
The discussion thus far only considered the case where the AL
engine is used to compensate for the ROUT of the VTM. The AL engine
can be more generally used to account for distribution resistances in
both the factorized bus and the VTM’s output distribution bus. For
more information on how to apply the AL engine towards this end
please contact Vicor’s Applications Engineering department.
The VTM TM voltage is equal to the VTM internal sensed temperature
in Kelvin divided by 100. For a temperature range of -55°C to 125°C
the TM voltage will range from 2.18 V to 3.98 V. The Adaptive Loop
temperature compensation is pre-programed into the internal
microcontroller and is 0.3%/°C assuming the VT pin is connected to
the TM pin of a compatible VTM.
Stability Considerations and External Capacitance
(Adaptive Loop Operation)
In Adaptive Loop Operation, the internal voltage regulation is
enabled which has a pre-determined, fixed compensation network.
The compensation is designed to be stable over a fixed set of
operating and load conditions including load capacitance.
The TM pin has an internal pull down to SGND, and temperature
compensation is disabled for VT voltages less than 1.9 V. To disable
temperature compensation, leave the VT pin unconnected and open
circuit. When disabled, the temperature defaults 25°C.
Besides internal output capacitors, external output capacitors also
contribute to the closed loop frequency response, thus should be
identified and understood, in order to maintain the control loop
stability. This includes capacitance placed directly on the PRM
output, as well as capacitance on the output of any downstream VTM
(if used) reflected to its input.
Figure 32 illustrates the requirements for external capacitors for both
the capacitance and ESR value. As shown in Figure 32 (a), the
maximum capacitance value of ceramic capacitor is 25 µF, and the
capacitance of a combination of ceramic and electrotype capacitors
needs to be less than 47 µF. As shown in Figure 32 (b) and (c), the
ESR value of electrotype capacitors needs to be between
0.1 Ω and 1 Ω; the ESR value of ceramic capacitors needs to be
between 2 mΩ and 200 mΩ.
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CCER (uF)
25
CCER
25
22
ESR
(Ohm)
1
CCER + CEL < 47
47
0.1 ESR
1
200
2
0.1
ESREL
CEL(uF)
Maxium Capacitance limits
ESR
(Ohm)
(b) ESREL requirements
2
ESR
200
ESRCER
(c) ESRCER requirements
Figure 32 — Output Capacitance Limits
Current Limit (Adaptive Loop Operation)
In Adaptive Loop Operation, the current limit is controlled by the
internal microcontroller. The current limit approximates a “brickwall” limit where the output current is prevented from crossing the
current limit threshold by reducing the output voltage. The current
limit threshold is pre-programmed into the internal microcontroller
and cannot be changed externally.
When the internal sensed current crosses the current limit threshold,
the current limit will be activated after the detection time tLIM_SUPV.
Once activated, the microcontroller will reduce the error amplifier
reference voltage(represented by REF) in order to maintain the
output current at the limit value. Current limit is able to reduce the
output down to VOUT_UVP, below which the device will shut down do
to output under voltage protection.
Soft Start Timing and Start up (Adaptive Loop Operation)
In Adaptive Loop Operation, the PRM has an internal soft start
sequence which is initiated at every start up. This allows the PRM to
start into fully discharged load capacitance. The soft start sequence
ramps the output by modulating the error amplifier reference
voltage (REF). The result is that the PRM output will rise at a
controlled rate until the final voltage setpoint is reached. The total
ramp time is typically 1.8 ms independent of the output trim level.
This soft start ramp time is preprogrammed into the microcontroller
and cannot be changed externally.
Figure 34 — PRM Example 100% to 10% Load Transient Response,
Adaptive Loop Load Line Disabled
When the Adaptive Loop load line is enabled, the voltage will
recover to the value determined by the set point and Adaptive Loop
load line settings as illustrated in Figure 35.
Load Transient Response (Adaptive Loop Operation)
In Adaptive Loop Operation, response time is dependent on the
internal compensation. When the Adaptive Loop load line is
disabled, the PRM output voltage will recover to the initial set value
as illustrated in Figure 33 and Figure 34.
Figure 35 — PRM Example 10% to 100% Load Transient Response,
Adaptive Loop Load Line Enabled, VAL = 0.96 V
Actual response times are model dependent and will change based
on the load step magnitude, load capacitance and operating
conditions.
Figure 33 — PRM Example 10% to 100% Load Transient Response,
Adaptive Loop Load Line Disabled
Because the compensation is fixed internally the load transient
response cannot be altered for Adaptive Loop Operation.
In order to improve the load transient response performance, the
part can be configured for Remote Sense Operation with an external
voltage control loop optimized for the specific intended operating
conditions. Remote Sense Operation is described in the next section.
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n SHARE pins must be connected together to enable sharing. The
Arrays (Adaptive Loop Operation)
In Adaptive Loop operation a master-slave configuration is used for
arrays. Up to 5 PRMs of the same type may be placed in parallel to
expand the power capacity of the system.
bandwidth requirements of SHARE are low enough that the bus
can be considered a lumped element, rather than a transmission
line, and so star connections to the master PRM with stubs, as well
as daisy chain connections are permitted.
One PRM is designated as the master and contains the active control
loop which considers control pin inputs and drives SHARE. The other
PRMs listen to SHARE and act as slave powertrains only. The
following high-level guidelines must be followed in order for the
resultant system to start up and operate properly, and to avoid
overstress or exceeding any absolute maximum ratings.
n The resistances between slave unit SHARE pins and the master’s
should be well matched, to avoid introducing additional sharing
mismatches. The SHARE bus should not be routed under any
PRM. SHARE bus parasitic capacitance to +IN or +OUT
should be minimized.
n One PRM must be designated as a master through configuring the
n SGND of the master PRM is the reference for all control loop
TRIM pin voltage within the recommended range.
n All other PRMs must be designated as slave PRMs by tying TRIM
pins to SGND. It is recommended to make this connection
through a 0 Ω jumper for troubleshooting purposes.
functions. The SGND pins of each slave PRMs should be
connected to the SGND reference node on the board through
a 1 Ω resistor.
n When operating within an array, the master PRM is rated for full
n All PRMs in the array must be powered from a common power
power while the slave PRMs are de-rated to the array rated power
and current values provided for Slave Operation
(POUT_ARRAY,IOUT_ARRAY). The number of PRMs required to
achieve a given array capacity must consider these de-ratings to
avoid overstressing any PRM in the array.
source so that the input voltage to each PRM is the same. The IN
pins of all PRMs must be connected together.
n An independent fuse for each PRM +IN connection is required to
maintain safety certifications (see Fusing section).
n An independent inductor for each PRM +IN connection is
n Adaptive Loop design procedures above will hold for an array, in
recommended when used in an array, to control circulating
currents among the PRM inputs and reduce the impact of
beat frequencies.
general, although some parameters must be scaled against the
number of PRMs in the system.
Arrays of more than 5 PRMs may be possible through use of external
circuitry. Please contact Vicor Applications for assistance with array
sizing above 5 units.
n Mismatches in both inductance, and resistance from the common
power source to each PRM should be minimized.
n ENABLE pins must be connected together for start up
synchronization and proper fault response of the array.
PRM 1 MASTER
ENABLE
VAUX
VTM 1
REF/
REF_EN
TRIM
VOUT
VTM Start Up Pulse
AL
RTRIM
Adaptive Loop Temperature Feedback
SHARE/
CONTROL NODE
RAL
+OUT
VC
VC
VT
TM
PC
IFB
COUT
SGND 1
VIN
F1
+IN
LIN 1
+OUT
+IN
LF 1
CF 1
VF: 20 V to 55 V
–IN
CIN
SGND
–OUT
–IN
–OUT
GND
PRIMARY
SECONDARY
SEC_GND
GND
SHARE Bus
ENABLE Bus
ISOLATION BOUNDRY
SGND 1
PRM 2 SLAVE
ENABLE
VAUX
SGND 2
VTM 2
REF/
REF_EN
TRIM
AL
VC
SHARE/
CONTROL NODE
VT
VTM Start Up Pulse
TM
PC
IFB
F2
+IN
LIN 2
+OUT
+OUT
VC
+IN
LF 2
CF 2
–IN
SGND
–OUT
–OUT
–IN
PRIMARY
GND
SECONDARY
ISOLATION BOUNDRY
1Ω
SEC_GND
SGND 2
SGND 1
Figure 36 — Adaptive Loop Array Example
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Design Guidelines (Remote Sense Operation)
It is important to apply proper slew rate to the reference voltage rise
when the control loop is initially enabled. The recommended range
for reference rise time is 1 ms to 9 ms. The lower rise time limit will
ensure optimized modulator timing performance during start up,
and to allow the current limit feature (through IFB pin) to fully
protect the device during power-up. The upper rise time limit is
needed to guarantee a sufficient factorized bus voltage is provided to
any downstream VTM input before the end of the VC pulse.
In Remote Sense Operation, the PRM48BH480x250A00 is an
intelligent powertrain module designed to fully exploit external
output voltage feedback and current sensing sub-circuits. These two
external circuits are illustrated in Figure 36, which shows an
example of the PRM in a standalone application with local voltage
feedback and high side current sensing.
In general, these circuits include a precision voltage reference, an
operational amplifier which provides closed loop feedback
compensation, and a high side current sense circuit which includes a
shunt and current sense IC.
Setting the Output Current Limit and Overcurrent Protection Level
(Remote Sense Operation)
In Remote Sense Operation, the internal current sensing is disabled,
and an external current sense amplifier must be implemented to
provide feedback to the IFB pin.
The following design procedures refer to the circuit shown
in Figure 36.
The current limit and overcurrent protection set points are linked,
and scale together against the current sense shunt, and the gain of
the current sense amplifier. The output of the current sense IC
provides the IFB voltage which has VIFB_IL and VIFB_OC thresholds for
the two functions respectively. The set points are therefore defined
by:
Setting the Output Voltage Level (Remote Sense Operation)
The output voltage setpoint is a function of the voltage reference and
the output voltage sense ratio. With reference to Figure 36, R1 and R2
form the output voltage sensing divider which provides the scaled
output voltage to the negative input of the error amplifier; a
dedicated reference IC provides the reference voltage to the positive
input of the error amplifier. Under normal operation, the error
amplifier will keep the voltages at the inverting and non-inverting
inputs equal, and therefore the output voltage is defined by:
R1 R 2
R2
VOUT VREF u
VIFB _ IL
I IL (6)
RS u GCS
and
(5)
I OC Note that the component R1 will also factor into the compensation as
described in a later section.
VIFB _ OC
(7)
RS u GCS
where GCS is the gain of the current sense amplifier.
Voltage Sense and Error Amplifier
(Single Ended)
C2
C1
RSS
REF 3312
PRM
ENABLE
SGND
SGND
OUT
10 k
GND
REF/
REF_EN
AL
VT
SHARE/
CONTROL NODE
VC
SGND
CSS
SGND
V–
VOUT
SGND
+IN
+IN
+OUT
CIN
–IN
RS
External Current Sense
and Feedback
–IN
R2
Voltage Reference with Soft Start
V+
IFB
VIN
VREF
VREF
VAUX
TRIM
ON/OFF
CONTROL
IN
R3
SGND
–OUT
GND
SGND
Figure 37 — Remote Sense Example
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VOUT
COUT
R1
PRM48BH480x250A00
Control Loop Compensation Requirements
(Remote Sense Operation)
In order to properly compensate the control loop, all components
which contribute to the closed loop frequency response should be
identified and understood. Figure 24 shows the AC small signal
model for the module. Modulator DC gain GCN and powertrain
equivalent resistance rEQ_OUT are shown. These modeling parameters
will support a design cut-off frequency up to 50kHz.
Standard Bode analysis should be used for calculating the error
amplifier compensation and analyzing the closed loop stability. The
recommended stability criteria are as follows:
The system poles and zeros of the closed loop can then be defined as
follows:
n
RCOUT _ EXT n
3) Gain Slope = -20dB/decade : The closed loop gain should have a
slope of -20dB/decade at the crossover frequency.
The compensation characteristics must be selected to meet these
stability criteria. Refer to Figure 37 for a local sense, voltage-mode
control example based on the configuration in Figure 36. In this
example, it is assumed that the maximum crossover frequency
(FCMAX) has been selected to occur between B and C. Type-2
compensation (Curve IJKL) is sufficient in this case.
1
2 ʌu
n
n Powertrain equivalent resistance rEQ: See Figures 18, 19, 20
n Internal output capacitance: see Figure 13
In the case of ceramic capacitors, the ESR can be considered low
enough to push the associated zero well above the frequency of
interest. Applications with high ESR capacitor may require a
different type of compensation, or cascade control.
rEQ _ OUT RLOAD
G MB 20 log
n
FZ1 n
u COUT _ INT COUT _ EXT R3
R1
(8)
Compensation Zero:
1
2 ʌu R 3 u C1
(9)
Compensation Pole:
FP 2 n External output capacitance value
rEQ _ OUT u RLOAD
Compensation Mid-Band Gain:
The following data must be gathered in order to proceed:
n Modulator Gain GCN: See Figures 18, 19, 20
rEQ _ OUT u RLOAD
rEQ _ OUT RLOAD
Main pole frequency:
FP 5
1) Phase Margin > 45º: for the closed loop response, the phase
should be greater than 45º where the gain crosses 0 dB.
2) Gain Margin > 10dB : The closed loop gain should be lower than 10dB where the phase crosses 0º.
Powertrain pole, assuming the external capacitor ESR can be
neglected:
1
R3 u C1 u C2
2 ʌu
C1 C2
and for FP2>>FZ1 (C1 + C2 ≈ C1):
FP 2 5
1
2/ u R3 u C2
(10)
Open Loop Gain vs. Frequency
80
Gain (dB)
60
40
20
I
Application's op-amp
· G-
B
Compensation Gain
F
E
PRM Open Loop Min Load
B
A
PRM Open Loop Max Load
J
K
FCMIN
0
FCMAX
L
-20
C
G
-40
Frequency, Log scale
(y-intercept is application specific)
Figure 38 — Reference asymptotic Bode plot for the considered system
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Midband Gain Design: R1, R3 (Remote Sense Operation)
With reference to Figure 37: curve ABC is the:
n minimum output voltage in the application
n maximum input voltage expected in the application
n maximum load
PRM open loop response, and is where the maximum crossover
frequency occurs. In order for the maximum crossover frequency to
occur at the design choice FCMAX, the compensation gain must be
equal and opposite of the powertrain gain at this frequency. For
stability purposes, the compensation should be in the Mid-band
(J-K) at the crossover. Using Equation (8), the mid-band gain can be
selected appropriately.
Compensation Zero Design :C1 (Remote Sense Operation)
With reference to Figure 37: curve EFG is the:
n maximum output voltage in the application
n minimum input voltage expected in the application
n minimum load in the application
PRM open loop response, and is where the minimum crossover
frequency FCMIN occurs. Based on stability criteria, the compensation
must be in the mid-band at the minimum crossover frequency,
therefore FCMIN will occur where EFG is equal and opposite of GMB.
C1 can be selected using Equation (9) so that FZ1 occurs prior to FCMIN.
High Frequency Pole Design: C2 (Remote Sense Operation):
Using Equation (10), C2 should be selected so that FP2 is at least one
decade above FCMAX and prior to the gain bandwidth product of the
operational amplifier (10MHz for this example). For applications
with a higher desired crossover frequency the use of a high gain
bandwidth product amplifier may be necessary to ensure that the
real pole can be set at least one decade above the maximum
crossover frequency.
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Arrays (Remote Sense Operation)
In Remote Sense Operation up to 10 PRMs of the same type may be
placed in parallel to expand the power capacity of the system. All
PRMs within the array are configured for Remote Sense Operation
and are driven by an external control circuit which considers the
control inputs and drives the CONTROL NODE bus. The following
high-level guidelines must be followed in order for the resultant
system to start up and operate properly, and to avoid overstress or
exceeding any absolute maximum ratings.
n
n
n All PRMs must be configured for Remote Sense Operation by
n
n
n
n
n
n
n
n
tying TRIM pins to SGND. It is recommended to make this
connection through a 0 Ω jumper for troubleshooting purposes.
All PRMs in the array must be powered from a common power
source so that the input voltage to each PRM is the same.
An independent fuse for each PRM +IN connection is required to
maintain safety certifications (see Fusing section).
An independent inductor for each PRM +IN connection is
recommended when used in an array, to control circulating
currents among the PRM inputs and reduce the impact of beat
frequencies.
Mismatches in both inductance, and resistance from the common
power source to each PRM should be minimized.
ENABLE pins must be connected together for start up
synchronization and proper fault response of the array.
Reference supply to the control loop voltage reference and
current sense circuitry must be enabled when all modules’ REF_EN
pins have reached their operational voltage levels.
A single external control circuit must be implemented as
n
n
n
n
described in the Remote Sense Operation design guidelines. The
control circuit should drive the CONTROL NODE bus.
CONTROL NODE pins must be connected together to enable
sharing. The bandwidth requirements of CONTROL NODE are low
enough that the bus can be considered a lumped element, rather
than a transmission line, and so star connections as well as daisy
chain connections are permitted.
Each PRM must have its own local current shunt and current
sense circuitry to drive its IFB pin.
The resistances between CONTROL NODE pins should be well
matched, to avoid introducing additional sharing mismatches.
The CONTROL NODE bus should not be routed under any PRM.
Parasitic capacitance to +IN or +OUT should be minimized.
One PRM should be designated to provide the SGND reference,
VAUX, and REF_EN voltages for the external circuitry.
The SGND pins of each PRM should be connected to the SGND
reference node on the board through a 1 Ω resistor.
When operating within an array, the PRMs are de-rated to the
array rated power and current values provided for Remote Sense
Operation (POUT_ARRAY, IOUT_ARRAY). The number of PRMs required
to achieve a given array capacity must consider these de-ratings
to avoid overstressing any PRM in the array.
When using VAUX to power external circuitry, total current draw
including CONTROL NODE sink currents must be taken into
account to ensure the maximum VAUX current is not exceeded.
Arrays of more than 5 PRMs may require additional circuitry to
provide the required source current. Contact Vicor Applications
Engineering for more information.
VREF
SGND 1
SGND 1
RSS
PRM 1
ENABLE
IN
OUT
GND
10 k
CSS
VAUX
REF/
REF_EN
TRIM
VTM 1
SGND 1
SGND 1
VC
VC
SHARE/
CONTROL NODE
VT
TM
V+
IFB
F1
+IN
LIN 1
+OUT
COUT
PC
V–
VOUT
+IN
VIN
Voltage Sense
VTM Start Up Pulse
AL
–IN
SGND
+OUT
+IN
LF 1
GND
CF 1
–IN
CIN
SGND
–OUT
–IN
–OUT
PRIMARY
GND
SECONDARY
GND
ENABLE Bus
CONTROL NODE Bus
ISOLATION BOUNDRY
SGND 1
PRM 2
ENABLE
VAUX
VTM 2
REF/
REF_EN
TRIM
SGND 2
LOAD
AL
VC
SHARE/
CONTROL NODE
VT
IFB
VTM Start Up Pulse
TM
V+
+IN
LIN 2
+OUT
PC
V–
VOUT
+IN
F2
+OUT
VC
–IN
SGND
+IN
LF 2
CF 2
–IN
SGND
–OUT
–OUT
–IN
GND
PRIMARY
SECONDARY
ISOLATION BOUNDRY
1Ω
SGND 2
SGND 1
Figure 39 — Non-Isolated Remote Sense Array Example
[1]
Non-Isolated Configuration: –Out connected to -IN
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GND
PRM48BH480x250A00
DESIGN GUIDELINES (General Operation)
2
The following guidelines are general guidelines that apply to any
mode of operation.
FPA System Considerations
There are a few system level design considerations that should be
carefully considered when using a PRM and VTM to implement a
Factorized Power Architecture (FPA) system
The VC pin of the PRM should be directly connected to the VC
pin of the VTM. The PRM and VTM coordinate the so start sequence
of the FPA system through this connection. If the VC pins are not
connected the VTM will not start up. When the PRM is ready to start
up, it applies a voltage on VC, which enables and powers the VTM’s
powertrain. The PRM then proceeds to ramp up its output voltage.
Aer approximately 10 ms, VC returns to 0 V and the VTM can then
derive power directly from the factorized bus provided that the
factorized bus voltage is above the minimum speciﬁed VTM
operating input voltage when the VC pulse expires.
£ k¥
² ln ´
¤ d¦
\ m 5 100
2
£ k¥
2
² ln ´ /
¤ d¦
(11)
Burst Mode Operation
At light loads, the PRM will operate in a burst mode due to minimum
timing constraints. An example burst operation waveform is
illustrated in Figure 39.
For very light loads, and also for higher input voltages, the minimum
time power switching cycle from the powertrain will exceed the
power required by the load. In this case the error ampliﬁer will
periodically drive SHARE/CONROL NODE below the switching
threshold in order to maintain regulation. Switching will cease
momentarily until the error ampliﬁer once again drives
SHARE/CONTROL NODE voltage above the threshold.
All VTM faults latch the VTM powertrain oﬀ. Input power to the
system as a whole must be recycled or the PRM should be disabled
and enabled by way of its ENABLE pin in order to restart the system.
It is recommended that the voltage on the factorized bus return to
zero before the PRM is re-enabled. Otherwise the so start of the
system may be compromised.
A RL ﬁlter should be placed between the PRM and VTM to locally
isolate switching ripple currents that can interfere with module
operation. It is important that the inductance have an impedance
that is much greater than that of the PRM output capacitance and
VTM input capacitance at the switching frequencies of the devices. A
resistor should be placed in shunt to this inductor to dampen the
resultant LC tank. For most cases 100 nH in parallel with 1 Ω is
suﬃcient to isolate the switching ripple currents.
Verifying Stability
A load step transient response can be used in order to estimate
stability.
Figure 41 — Light load burst mode of operation
Figure 38 illustrates an example of a load step response. Equation
(11) can be used to predict the phase margin based on the ratio of
the “kick” to “droop” (as deﬁned in Fig. 38).
Vout
Vout
d
time
Iout
d
time
Iout
time
time
(a) without adaptive loop
In burst mode, the gain of the SHARE/CONTROL NODE input to the
plant which is modeled in the previous sections is time varying.
Therefore the small signal analysis cannot be directly applied to
burst mode operation.
k
k
Note that during the bursts of switching, the powertrain frequency is
constant, but the number of pulses as well as the time between
bursts is variable. The variability depends on many factors including
input voltage, output voltages, load impedance, and error ampliﬁer
output impedance.
(b) with adaptive loop
Figure 40 — Load step response example and “droop” vs. “kick”
(a) without Adaptive Loop; (b) with Adaptive Loop.
Input and Output filter design
Figures 14 and 15 provide the total input and output charge per
cycle, as well as switching frequency, of the PRM at full load under
various input and output voltages conditions.
Figure 13 provides the eﬀective internal capacitance of the module.
A conservative estimate of input and output peak-peak voltage
ripple at nominal line and trim is provided by equation (12):
I FL u 0.4
f SW
CEXT
QTOT <
6V CINT
(12)
QTOT is the total input (Fig. 14) or output (Fig. 15) charge per
switching cycle at full load, while CINT is the module internal
eﬀective capacitance at the considered voltage (Fig. 13) and CEXT is
the external eﬀective capacitance at the considered voltage.
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Input Filter Stability
The PRM can provide very high dynamic transients. It is therefore
very important to verify that the voltage supply source as well as the
interconnecting lines are stable and do not oscillate. For this purpose,
the converter dynamic input impedance magnitude rEQ _ IN is
provided in Figures 21, 22, 23. It is recommended to provide
adequate design margin with respect to the stability conditions
illustrated in the previous sections.
Inductive source and local, external input decoupling capacitance
with negligible ESR (i.e.: ceramic type)
The voltage source impedance can be modeled as a series RLINE LLINE
circuit. The high performance ceramic decoupling capacitors will not
significantly damp the network because of their low ESR; therefore
in order to guarantee stability the following conditions must be
verified:
Rline Lline
(C IN _ INT C IN _ EXT ) u rEQ _ IN
Rline rEQ _ IN
(13)
(14)
Input Fuse Recommendations
A fuse should be incorporated at the input to each PRM, in series
with the +IN pin. A 10 A or smaller input fuse (Littelfuse® NANO2®
451/453 Series) is required to safety agency conditions of
acceptability. Always ascertain and observe the safety, regulatory, or
other agency specifications that apply to your specific application.
Thermal Considerations
VIChip 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 PRM48BH480x250A00 case to
less than 100ºC will keep all junctions within the VI Chip module
below 125ºC 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.
It is critical that the line source impedance be at least an octave
lower than the converter’s dynamic input resistance, 14. However,
RLINE cannot be made arbitrarily low otherwise equation 13 is
violated and the system will show instability, due to under-damped
RLC input network.
Inductive source and local, external input decoupling capacitance
with significant RCIN_EXT ESR (i.e.: electrolytic type)
In order to simplify the analysis in this case, the voltage source
impedance can be modeled as a simple inductor Lline. Notice that the
high performance ceramic capacitors CIN_INT within the PRM, should
be included in the external electrolytic capacitance value for this
purpose. The stability criteria will be:
rEQ _ IN RCIN _ EXT
(15)
Lline
rEQ _ IN
C IN _ EXT u RC IN _ EXT
(16)
Equation 16 shows that if the aggregate ESR is too small – for
example by using very high quality input capacitors (CIN_EXT) – the
system will be under-damped and may even become destabilized.
Again, an octave of design margin in satisfying 15 should be
considered the minimum.
Layout Considerations
Application Note AN:005 details board layout recommendations
using VI Chip® components, with details on good power connections,
reducing EMI, and shielding of control signals and techniques to
reference them to SGND.
Avoid routing control signals (ENABLE, TRIM, AL etc.) directly
underneath the PRM. It is critical that all control signals (aside from
VC and VT) are referenced to SGND, both for routing and for pulldown and bypassing purposes. VC and VT provide control and
feedback from a VTM, and must be referenced to –OUT of the PRM
(-IN of the VTM).
SGND is connected to –IN internally to the PRM. SGND should not be
tied to any other ground in the system.
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Product Outline Drawing and Recommended Land Pattern
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Rev 1.4
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Revision History
Revision
Date
Description
1.1
11/12/12
Final approved data sheet for intital release
n/a
1.2
02/15/13
Updated format throughout
all
Updated Maximum Time Abover 217°C
26
1.3
07/25/13
Added Array Diagrams
1.4
07/03/14
Page Number(s)
33 & 37
Updated Figure 1
22
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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.
Vicor’s Standard Terms and Conditions
All sales are subject to Vicor’s Standard Terms and Conditions of Sale, which are available on Vicor’s webpage or upon request.
Product Warranty
In Vicor’s standard terms and conditions of sale, Vicor warrants that its products are free from non-conformity to its Standard Specifications (the
“Express Limited Warranty”). This warranty is extended only to the original Buyer for the period expiring two (2) years after the date of shipment
and is not transferable.
UNLESS OTHERWISE EXPRESSLY STATED IN A WRITTEN SALES AGREEMENT SIGNED BY A DULY AUTHORIZED VICOR SIGNATORY, VICOR DISCLAIMS
ALL REPRESENTATIONS, LIABILITIES, AND WARRANTIES OF ANY KIND (WHETHER ARISING BY IMPLICATION OR BY OPERATION OF LAW) WITH
RESPECT TO THE PRODUCTS, INCLUDING, WITHOUT LIMITATION, ANY WARRANTIES OR REPRESENTATIONS AS TO MERCHANTABILITY, FITNESS FOR
PARTICULAR PURPOSE, INFRINGEMENT OF ANY PATENT, COPYRIGHT, OR OTHER INTELLECTUAL PROPERTY RIGHT, OR ANY OTHER MATTER.
This warranty does not extend to products subjected to misuse, accident, or improper application, maintenance, or storage. Vicor shall not be liable
for collateral or consequential damage. Vicor disclaims any and all liability arising out of the application or use of any product or circuit and assumes
no liability for applications assistance or buyer product design. Buyers are responsible for their products and applications using Vicor products and
components. Prior to using or distributing any products that include Vicor components, buyers should provide adequate design, testing and
operating safeguards.
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 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 returning the product to the factory. Vicor will pay all reshipment charges if the
product was defective within the terms of this warranty.
Life Support Policy
VICOR’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS
PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL COUNSEL OF VICOR CORPORATION. As used herein, life support
devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform
when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the
user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the
failure of the life support device or system or to affect its safety or effectiveness. Per Vicor Terms and Conditions of Sale, the user of Vicor products
and components in life support applications assumes all risks of such use and indemnifies Vicor against all liability and damages.
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. No license, whether express, implied, or arising by estoppel or otherwise, to any intellectual property rights is
granted by this document. Interested parties should contact Vicor's Intellectual 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; 6,788,033; 6,940,013; 6,969,909; 7,038,917; 7,154,250; 7,166,898; 7,187,263; 7,202,646; 7,361,844;
7,368,957; RE40,072; D496,906; 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: [email protected]
Technical Support: [email protected]
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