For technical support and more information, see inside back cover or visit www.ti.com
Standard Application
Features
36V to 75V Input Voltage Range
Programmable Output Voltage
Range: 1.3V to 3.5V
-40 to +85C Ambient
1500 VDC Isolation
89% Efficiency
On/Off Inhibit
Differential Remote Sense
N+1 Current Sharing
SLTS024C
(Revised 6/20/2002)
Description
The PT4481 ExcaliburTM DC/DC
converter module combines state-of-the-
art power conversion technology with
un-paralleled flexibility. Incorporating
high efficiency and ultra-fast transient
response, these modules provide up to
30A of output current over the program-
mable voltage range of 1.3V to 3.5V.
This represents a full 100W output at
3.3V.
The modules include a number of
inbuilt features to facilitate system
integration. These include a foldback
output current limit, over-temperature
protection, and an inhibit on/off control.
A differential remote sense is also provided
to compensate for voltage drop between
the converter and load.
For applications requiring power
supply redundancy, multiple PT4481
modules may connected for operation in
an `N+1' configuration. Each PT4481
connected will share the load current with
other active PT4481 modules.
Over-Current Protection
Over-Temperature Protection
Over-Voltage Protection
Space-Saving Package
Solderable Copper Case
Safety Approvals:
UL 60950
CSA 22.2 950
VDE EN60950 Pending
L
O
A
D
PT4481
+ V
sns
+ V
out
- V
out
- V
sns
7
8 - 1 3
1 4 - 1 9
2 0
2 5
2 2
2 4
2 3
VID0 - VID4
+ V
in
V
in
1
2
3
Inhibit
C
1
+
P R O G R A M M I N G P I N S
+ V
O U T
+ V
IN
V
IN
V
O U T
C
o
+
2 1
C
2
C
o
= Optional 330F electrolytic capacitor
C
1
= Optional 33F, 100V electrolytic capacitor
C
2
= Optional 1F, 100V ceramic capacitor
Programming pins, VID0VID4, are shown
configured for Vo =3.3V
For normal operation, pin 3 (Inhibit) must be
connected to Vin.
For details on additional N+1 components
consult the related application note.
Ordering Information
PT4481
o = 1.3 to 3.5 Volts
PT Series Suffix
(PT1234
x
)
Case/Pin
Order
Package
Configuration
Suffix
Code *
Vertical
N
(EKD)
Horizontal
A
(EKA)
SMD
C
(EKC)
* Previously known as package styles 1200,
1210, and 1215.
(Reference the applicable package code draw-
ing for the dimensions and PC board layout)
Pin-Out Information
Pin
Function
1
+V
in
2
V
in
3
Inhibit
4
Do not connect
5
Do not connect
6
Sync
7
(+)Remote Sense
8+V
out
9
+V
out
10 +V
out
11 +V
out
12 +V
out
13 +V
out
Pin
Function
14
V
out
15
V
out
16
V
out
17
V
out
18V
out
19
V
out
20
()Remote Sense
21
VID0
22
VID1
23
VID2
24
VID3
25
VID4
26
Share
PT4481--48V
100-W 30-A Programmable
Isolated DC/DC Converter
Pins 6 & 26 are used for N+1 configuration (see
related application note). For stand-alone
operation, leave open circuit.
Shaded functions indicate those pins that are
referenced to primary-side potential.
For technical support and more information, see inside back cover or visit www.ti.com
PT4480 Series Comparison
Output Voltage
Configuration for
Functionality
Program Range
Current Sharing
PT4481
Regulator
1.3V 3.5V
N+1 with other PT4481s
PT4482
Regulator
1.3V 3.5V
With PT4499 boosters
PT4499
PT4482 Booster
N/A
Used only with PT4482
PT4483
Regulator
4.6V5.7V
N+1 with other PT4483s
PT4484
Regulator
4.6V5.7V
With PT4498 boosters
PT4498
PT4484 Booster
N/A
Used only with PT4484
PT4485
Regulator
6.5V 17.5V
N+1 with other PT4485s
PT4486
Regulator
6.5V17.5V
With PT4497 boosters
PT4497
PT4486 Booster
N/A
Used only with PT4486
PT4481--48V
100-W 30-A Programmable
Isolated DC/DC Converter
Programming Information
VID4=1 VID4=0
VID3 VID2 VID1 VID0
Vout
Vout
1
1
1
1
2.0V
1.30V
1
1
1
0
2.1V
1.35V
1
1
0
1
2.2V
1.40V
1
1
0
0
2.3V
1.45V
1
0
1
1
2.4V
1.50V
1
0
1
0
2.5V
1.55V
1
0
0
1
2.6V
1.60V
1
0
0
0
2.7V
1.65V
0
1
1
1
2.8V
1.70V
0
1
1
0
2.9V
1.75V
0
1
0
1
3.0V
1.80V
0
1
0
0
3.1V
1.85V
0
0
1
1
3.2V
1.90V
0
0
1
0
3.3V
1.95V
0
0
0
1
3.4V
2.00V
0
0
0
0
3.5V
2.05V
Logic 0 = Connect to ()Remote Sense, pin 20
Logic 1 = Open circuit (no pull-up resistors)
VID3 & VID4 must not be changed while unit is operating
# This specification covers only the PT4481 regulator.
Specifications
(Unless otherwise stated, T
a
=25C, V
in
=48V, V
o
=3.3V, C
o
=0F, and I
o
=I
o
max)
PT4481
Characteristic
Symbol
Conditions
Min
Typ
Max
Units
Output Current
I
o
Over V
in
range
0
--
30
A
Input Voltage Range
V
in
Over I
o
Range
36
4875
VDC
Set Point Voltage Tolerance
V
o
tol
--
1
1.5
%V
o
Temperature Variation
Reg
temp
40
T
case
+100C, I
o
=0
--
0.5
--
%V
o
Line Regulation
Reg
line
Over V
in
range
--
0.1
1
%V
o
Load Regulation
Reg
load
Over I
o
range
--
0.2
1
%V
o
Total Output Voltage Variation
V
o
tot
Includes set-point, line, load,
--
2
3
%V
o
40
T
case
+100C
Efficiency
I
o
=15A
V
o
=3.3V
--
89
--
V
o
=2.5V
--
87
--
%
V
o
=1.5V
--
81
--
V
o
Ripple (pk-pk)
V
r
20MHz bandwidth
V
o
>
2V
--
60
75
mV
pp
V
o
2V
--
45
55
Transient Response
t
tr
0.1A/s load step, 50% to 75% I
o
max
--
N/A
--
s
V
tr
V
o
over/undershoot
--
1
--
%V
o
1A/s load step, 50% to 100% I
o
max
--
75
--
s
V
o
over/undershoot
--
5
--
%V
o
Current Limit
I
lim
V
in
=36V,
V
o
= 1%
--
35
--
A
foldback continuous limit
Current Share Tolerance
I
shr
tol
With other PT4481 modules in N+1
--
10
--
%
Over-Voltage Protection
OVP
Shutdown and latch off
--
125
--
%V
o
Switching Frequency
s
Over V
in
range
270
300
350
kHz
Under-Voltage Lockout
UVLO
--
34.5
--
V
Inhibit (Pin 3)
Referenced to V
in
(pin 2)
Input High Voltage
V
IH
2.5
--
Open
(1)
V
Input Low Voltage
V
IL
0.5
--
+0.8
Input Low Current
I
IL
--
0.2
--
mA
Standby Input Current
I
in
standby
pins 3 & 2 connected
--
4
10
mA
Internal Input Capacitance
C
in
--
3
--
F
External Output Capacitance
C
out
Between +V
o
and V
o
0
--
10,000
F
Isolation Voltage
Inputoutput/inputcase
1500
--
--
V
Capacitance
Input to output
--
1100
--
pF
Resistance
Input to output
10
--
--
M
Operating Temperature Range
T
c
Case temperature, over V
in
range
-40
--
+115
(2)
C
Over-Temperature Shutdown
OTP
Case temperature, auto reset
--
120
--
C
Storage Temperature
T
s
--
-40
--
+125
C
Reliability
MTBF
Per Bellcore TR-332
1.4
--
--
10
6
Hrs
50% stress, T
a
=40C, ground benign
Mechanical Shock
--
Per Mil-Std-883D, method 2002.3,
--
500
--
G's
1mS, half-sine, mounted to a fixture
Mechanical Vibration
--
Mil-Std-883D, Method 2007.2
Suffixes A, C
--
20
(3)
--
G's
20-2000Hz, pcb mounted
Weight
--
--
--
90
--
grams
Flammability
--
Materials meet UL 94V-0
Notes:
(1) The Inhibit (pin 3) has an internal pull-up, which if left open circuit allows the converter to operate when input power is applied. The open-circuit is
limited to 6.5V. Refer to the application notes for interface considerations.
(2) See Safe Operating Area curves or contact the factory for the appropriate derating.
(3) The case pins on through-hole pin configuration (suffix A) must be soldered. For more information see the applicable package outline drawing.
#
For technical support and more information, see inside back cover or visit www.ti.com
Note A:
Characteristic data has been developed from actual products tested at 25C. This data is considered typical data for the Converter.
Note B:
SOA curves represent the conditions at which internal components are at or below the manufacturer's maximum operating temperatures
Efficiency vs Output Current
Ripple vs Output Current
Power Dissipation vs Output Current
Typical Characteristics
PT4481--48V
100-W 30-A Programmable
Isolated DC/DC Converter
Stand Alone, No Heatsink
Safe Operating Area, V
in
=48V
(See Note B)
Performance Characteristics, V
o
=3.3V
(See Note A)
20
30
40
50
60
70
80
90
0
5
10
15
20
25
30
Iout (A)
Ambient Temperature (C
)
500LFM
400LFM
300LFM
200LFM
100LFM
Nat conv
Airflow
50
60
70
80
90
100
0
5
10
15
20
25
30
Iout (A)
Efficiency - %
48.0V
75.0V
36.0V
V
IN
0
20
40
60
80
100
0
5
10
15
20
25
30
Iout (A)
Ripple - mV
75.0V
48.0V
36.0V
V
IN
0
4
8
12
16
20
0
5
10
15
20
25
30
Iout (A)
Pd - Watts
36.0V
75.0V
48.0V
V
IN
For technical support and more information, see inside back cover or visit www.ti.com
Application Notes
PT4481
Configuring PT4481 DC/DC Converters
for N+1 Operation
`N+1' vs OR'ing
The PT4481 DC/DC converter modules may be
operated with other PT4481 modules in `N+1'
configurations. A simple OR'ing connection allows
a number of converters to share the load current. An
`N+1' configuration adds redundancy by employing
at least one more converter than is necessary to
supply the load. This ensures that upon the loss of
one converter, sufficient capacity remains to supply
the load without interruption. As an example, a 45-A
load configured for `N+1' would require no less than
three PT4481 converters. Two are needed to meet
the load demand, plus one additional converter to
ensure redundancy. Figure 1-1 shows the schematic
for operating two PT4481 converters in an `N+1'
configuration for a 25-A load application.
Blocking Diodes
A true `N+1' redundant system must also protect the
output bus against fault current back-feeding a con-
verter. Without a blocking diode, a converter will sink
current as a result of a fault at its output, or due to the
loss of its input source. The blocking diodes
4
, (D
1
PT4481
PT4481
1
2
813
20
7
REMOTE SENSE (+)
REMOTE SENSE ()
PROGRAMMING PINS
3
C
OUT
, 330F
(Required)
+
1
813
1419
25
24
23
22
21
1419
2
6
26
20
6
26
7
REMOTE SENSE (+)
21
22
23
24
25
3
PROGRAMMING PINS
D
2
, OR'ing Diode
(Required)
V
IN
+V
IN
25-A
LOAD
Inhibit
V
OUT
+V
OUT
+V
IN
V
IN
+V
OUT
V
OUT
VID4 VID0
+Sns
Sns
Share
Sync
Inhibit
Sns
Share
Sync
Inhibit
+Sns
+V
IN
V
IN
+V
OUT
V
OUT
VID4 VID0
C
IN
+
C
IN
+
D
1
, OR'ing Diode
(Required)
F1
F2
C
OUT
, 330F
(Required)
+
Figure 1-1; Connection Schematic for Operation in Parallel/N+1 Configuration
& D
2
in Figure 1-1), protect against reverse current
flow under such conditions.
Notes
1. For `N+1' redundancy, always use one more
converter than is required to supply the load.
2. The VID pins for all converter modules must be
independently set to the same voltage program code.
3. All converters connected for `N+1' operation
must be located on the same printed circuit
board. A similar footprint and trace layout for
each converter will facilitate current sharing.
4 A number of high-current rectifier diodes are
available with a low forward voltage drop. They
are specifically designed for OR'ing applications
in `N+1' systems. Eg. The 82CNQ030, and
MBRB2515.
5. As a result of excess capacity and the losses in the
blocking diodes, system efficiency is reduced.
6. The interconnection of pin 6 (Sync), and pin 26
(Share) between all modules are required for load
current sharing and operation at a common
frequency.
Application Notes
For technical support and more information, see inside back cover or visit www.ti.com
Operating Features of the PT4470 and PT4480
Series of Isolated DC/DC Converters
Under-Voltage Lockout
An Under-Voltage Lock-Out (UVLO) inhibits the
operation of the converter until the input voltage is
above the UVLO threshold (see the applicable data
sheet specification). Below this voltage, the module's
output is held off, irrespective of the state of the Inhibit
control (pin 3). If the Inhibit control is connected to V
in
(pin 2), the module will automatically power up when
the input voltage rises above the UVLO threshold. The
UVLO allows the module to produce a clean transition
during both power-up and power-down, even when the
input voltage is rising or falling slowly. It also reduces
the high start-up current during normal power-up of
the converter, and minimizes the current drain from the
input source during low-input voltage conditions. The
UVLO threshold includes about 2V of hysteresis. Once
operational, the converter will conform to its operating
specifications when the minimum specified input voltage
is reached.
Over-Current Protection
To protect against load faults, the PT4470/80 series of
DC/DC converters incorporate an output current limit.
Once the load current drawn from the module reaches
the current limit threshold, any attempt by the load to
draw additional current will result in a significant drop
in the module's regulated output voltage. The current
limit circuitry incorporates a limited amount of foldback.
This has the effect of slightly reducing the output current
from the module when supplying an absolute short circuit.
Upon removal of the load fault, the output voltage from
the converter will automatically recover to its programmed
regulation voltage.
Output Over-Voltage Protection
The PT4470/80 series of DC/DC converters incorporate
circuitry that continually senses the output for an over-
voltage (OV) condition. The OV threshold automatically
tracks the VID output voltage program setting to a level
25% higher than that programmed at the control pins,
VID0 through VID4. If the converter output voltage
exceeds the OV threshold, the converter is immediately
shut down and remains in a latched-off state. To resume
normal operation the converter must be actively reset.
This is accomplished by either cycling the status of the
Inhibit control (pin 3) from "On" to "Off" and then back
"On" again, or by momentarily removing the input power
to the converter. For failsafe operation and redundancy,
the OV protection uses circuitry that is independent of
the converter's internal feedback loop.
Over-Temperature Protection
Over-temperature protection is provided by an internal
temperature sensor, which closely monitors the tempera-
ture of the converter's metal case. If the case temperature
exceeds the specified limit (see applicable data sheet),
the converter will shut down. The converter will then
automatically restart when the sensed temperature drops
by about 10C. When operated outside its recommended
thermal derating envelope (see data sheet SOA curves),
the converter will typcially cycle on and off at intervals
from a few seconds to one or two minutes. This is to ensure
that the internal components are not permanently damaged
from excessive thermal stress.
Primary-Secondary Isolation
Electrical isolation is provided between the input terminals
(primary) and the output terminals (secondary). All con-
verters are production tested to a primary-secondary
withstand voltage of 1500VDC. This specification com-
plies with UL60950 and EN60950 and the requirements
for operational isolation. Operational isolation allows
these converters to be configured for either a positive or
negative input voltage source. The data sheet `Pin-Out
Information' uses shading to indicate which pins are
associated with the primary. They include pins 1 through
5, inclusive.
Fuse Recommendations
If desired, an input fuse may be added to protect against
the application of a reverse input voltage.
Thermal Considerations
Airflow may be necessary to ensure that the module can
supply the desired load current in environments with
elevated ambient temperatures. The required airflow
rate may be determined from the Safe Operating Area
(SOA) thermal derating chart (see converter specifica-
tions). The recommended direction for airflow is into
the longest side of the module's metal case. See Figure 1.
Recommended direction for airflow is
into (perpendicular to) the longest side.
Figure 1
PT4470, PT4480 Series
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