PT3668 [TI]
30-A Dual Output Isolated DC/DC Converter; 30 -A双输出隔离式DC / DC转换器
| 型号： | PT3668 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 30-A Dual Output Isolated DC/DC Converter |
| 文件： | 总15页 (文件大小：309K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PT3660 Series
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
Features
• Dual Outputs
• Dual Logic On/Off Control
• Over-Temperature Shutdown
• Over-Voltage Protection
(Coordinated Shutdown)
• Under-Voltage Lockout
• Input Differential EMI Filter
• Solderable Copper Case
• Safety Approvals:
UL1950
(Independantly Regulated)
• Power-up/Down Sequencing
• Input Voltage Range:
36V to 75V
• 1500 VDC Isolation
• Temp Range: –40° to 100°C
• High Efficiency: 88%
• Fixed Frequency Operation
• Over-Current Protection
(Both Outputs)
CSA 22.2 950
Description
Ordering Information
protection, and an input under-
voltage lockout. In addition, both
output voltages are designed to meet
the power-up/power-down sequenc-
ing requirements of popular DSP
ICs.
The PT3660 series is housed in
space-saving solderable copper case.
The package does not require a
heatsink and is available in both
vertical and horizontal configura-
tions, including surface mount. The
‘N’ configuration occupies less than 2
in² of PCB area.
Pt. No.
Vo1/Vo2
The PT3660 Excalibur™ Series
is a 30-A rated, dual-output isolated
DC/DC converter that combines
state-of-the-art power conversion
technology with unparalleled flex-
ibility. These modules operate from
a standard telecom (–48V) central
office (CO) supply to produce two
independantly regulated outputs.
The PT3660 series is characterized
with high efficiencies and ultra-fast
transient response, and incorporates
many features to facilitate system
integration. These include a flexible
“On/Off” enable control, output
current limit, over-temperature
PT3661o
PT3662o
PT3663o
PT3665o
PT3666o
PT3667o
PT3668o
= 5.0/3.3 Volts
= 3.3/2.5 Volts
= 3.3/1.8 Volts
= 3.3/1.5 Volts
= 2.5/1.8 Volts
= 5.0/1.8 Volts
= 3.3/1.2 Volts
PT Series Suffix
(PT1234x)
Case/Pin
Order
Package
Configuration
Suffix
Code
Vertical
Horizontal
SMD
N
A
C
(EKD)
(EKA)
(EKC)
This product is pin-compatible
with the PT4660 series.
(Reference the applicable package code draw-
ing for the dimensions and PC board layout)
Typical Application
V1 Adjust
V2 Adjust
20
13
Vo 2 adj
Vo1 adj
Vo 1
Vo 2
+VIN
9–12
Vo1
1
3
+Vin
21–24
Vo2
PT3660
L
O
A
D
L
O
A
D
EN 1*
4
EN
2
–V IN
C O M
2
14–19
–Vin
COM
* Inverted logic
For technical support and more information, see inside back cover or visit www.ti.com
PT3660 Series
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
Pin-Out Information
Pin Function
On/Off Logic
Pin 3 Pin 4
Output Status
Pin
Function
Pin
Function
1
2
3
4
5
6
7
8
9
+V
-V
10
+Vo1
in
19
COM
1
0
×
×
1
0
Off
On
Off
11
12
13
14
15
16
17
18
+Vo1
in
20
21
22
23
24
25
26
Vo2 Adjust
+Vo2
EN 1
+Vo1
EN 2
Vo1 Adjust
COM
COM
COM
COM
COM
+Vo2
TEMP
+Vo2
Notes:
Logic 1 =Open collector
Logic 0 = –Vin (pin 2) potential
AUX
+Vo2
Do Not Connect
Do Not Connect
+Vo1
Do Not Connect
Do Not Connect
For positive Enable function, connect pin 3
to pin 2 and use pin 4.
For negative Enable function, leave pin 4
open and use pin 3.
Note: Shaded functions indicate signals that are
referenced to the input (-Vin) potential.
Pin Descriptions
+Vin: The positive input supply for the module with
respect to –Vin. When powering the module from a
–48V telecom central office supply, this input is
connected to the primary system ground.
voltage, and is independant of the enable logic status.
(Note: A load impedance of less than 1MΩ will adversly
affect the module’s over-temperature shutdown threshold.
Use a high-impedance input when monitoring this
signal.)
–Vin: The negative input supply for the module, and
the 0VDC reference for the EN 1, EN 2, TEMP, and
AUX signals. When the module is powered from a
+48V supply, this input is connected to the 48V–Return.
AUX: Produces a regulated output voltage of 11.6V
5%, which is referenced to –Vin. The current drawn
from the pin must be limited to 10mA. The voltage
may be used to indicate the output status of the
module to a primary referenced circuit, or power a
low-current amplifer.
EN 1: The negative logic input that enables the
module output. This pin is TTL compatible and
referenced to –Vin. A logic ‘0’ at this pin enables the
module’s outputs. A logic ‘1’ or high impedance
disables the module’s outputs. If not used, the pin
must be connected to –Vin.
Vo1: The higher regulated output voltage, which is
referenced to the COM node.
Vo2: The lower regulated output voltage, which is
EN 2: The positive logic input that enables the
module output. This pin is TTL compatible and
referenced to –Vin. A logic ‘1’ or high impedance
enables the module’s outputs. If not used, the pin
should be left open circuit.
referenced to the COM node.
COM: The secondary return reference for the module’s
two regulated output voltages. It is DC isolated from
the input supply pins.
Vo1 Adjust: Using a single resistor, this pin allows Vo1
to be adjusted higher or lower than the preset value.
If not used, this pin should be left open circuit.
TEMP: This is the output voltage produced by the
module’s internal temperature sensor. The voltage at
this pin is referenced to –Vin and rises approximately
10mV/°C from an intital value of 0.1VDC at –40°C
(Vtemp =0.5 + 0.01·Tsense). The signal is available
whenever the module is supplied with a valid input
Vo2 Adjust: Using a single resistor, this pin allows Vo2
to be adjusted higher or lower than the preset value.
If not used, this pin should be left open circuit.
For technical support and more information, see inside back cover or visit www.ti.com
PT3660 Series
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
Specifications (Unless otherwise stated, Ta =25°C, Vin =48V, & Io1=Io2=10A)
PT3660 SERIES
Typ
Characteristics
Symbols
Conditions
Min
Max
Units
Output Current
Io1, Io2
Vo1
Vo1 ≤3.3V
Vo1 =5.0V
All voltages
Vo1 ≤3.3V
Vo1 =5.0V
0
0
0
0
0
—
—
—
—
—
15
10
15
30
25
A
A
A
Vo2
Io1+Io2
Total (both outputs)
Input Voltage Range
Set Point Voltage Tolerance
Temperature Variation
Line Regulation
Vin
Votol
∆Regtemp
∆Regline
∆Regload
36
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
48
1
0.5
5
2
2
2
2
75
2
—
10
10
10
10
5
V
%Vo
%Vo
mV
–40 to +100°C Case, Io1 =Io2 =0A
Over Vin range with Io1=Io2=5A
1A ≤Io1 ≤Io1max, Io2 =1A
1A ≤Io2 ≤Io1max, Io1 =1A
1A ≤Io2 ≤Io1max, Io1 =1A
1A ≤Io1 ≤Io1max, Io2 =1A
Includes set-point, line load,
–40°C to +100°C case
Load Regulation
∆Vo1
∆Vo2
∆Vo1
∆Vo2
∆Vo1
∆Vo2
PT3661
PT3662
PT3663
PT3665
PT3666
PT3667
PT3668
mV
mV
Cross Regulation
Total Output Variation
Efficiency
∆Regcross
∆Votol
η
2
2
3
3
%Vo
88
87
86
86
85
88
86
—
—
—
—
—
—
—
%
Vo Ripple (pk-pk)
V
r
Io1=Io2=5A, 20MHz bandwidth
Vo=5V
Vo<5V
—
—
—
—
75
50
mVpp
Transient Response
ttr
1A/µs load step from 50% to 100% Iomax
(either output)
—
—
25
100
—
µSec
%Vo
6.0
Current Limit
Output Rise Time
Output Over-Voltage Protection
Switching Frequency
Under-Voltage-Lockout
ILIM
ton
OVP
fs
Each output with other unloaded
At turn-on to within 90% of Vo
Either output; shutdown and latch off
15.5
—
—
280
—
30
18
5
125
—
34
32
—
10
—
320
36
—
A
mSec
%Vo
kHz
(1)
UVLO
Rising
Falling
V
Internal Input Capacitance
Cin
—
2
—
µF
On/Off Control
Input High Voltage
Input Low Voltage
Input Low Current
Referenced to –Vin
VIH
VIL
IIL
3.5
0
—
—
—
0.8
V
(2)
—
—
0
0.5
3
—
5
mA
mA
µF
Standby Current
Iin standby
Cout
Viso
C iso
Riso
Pins 2, 3, & 4 connected
Per each output
External Output Capacitance
Primary/Secondary Isolation
—
5,000
1500
—
—
—
—
—
V
1500
pF
MΩ
10
—
(3)
(3)
Temperature Sense
Vtemp
Output voltage at temperatures:-
–40°C
100°C
—
—
0.1
1.5
—
—
V
(4)
Operating Temperature Range
Over-Temperature Protection
Solder Reflow Temperature
Storage Temperature
Mechanical Shock
Mechanical Vibration
T
OTP
Treflow
Over Vin range
Case temperature (auto restart)
Surface temperature of module pins or case
—
–40
100
—
–40
—
—
—
—
—
500
85
—
°C
°C
°C
°C
G’s
a
(5)
215
125
—
T
s
—
—
Per Mil-STD-883D, Method 2002.3
Per Mil-STD-883D, Method 2007.2, Suffix N
(6)
(6)
—
—
10
—
—
G’s
20–2,000Hz
Suffixes A, C
20
Weight
Flammability
—
—
—
—
90
—
grams
Materials meet UL 94V-0
Notes: (1) This is a fixed parameter. Adjusting Vo1 or Vo2 higher will increase the module’s sensitivity to over-voltage detection. For more information, see the
application note on output voltage adjustment.
(2) The EN1 and EN2 control inputs (pins 3 & 4) have internal pull-ups and may be controlled with an open-collector (or open-drain) transistor. Both
inputs are diode protected and can be connected to +Vin. The maximum open-circuit voltage is 5.4V.
(3) Voltage output at “TEMP” pin is defined by the equation:- VTEMP = 0.5 + 0.01·T, where T is in °C. See pin descriptions for more information.
(4) See SOA curves or consult the factory for the appropriate derating.
(5) During solder reflow of SMD package version do not elevate the module case, pins, or internal component temperatures above a peak of 215°C. For
further guidance refer to the application note, “Reflow Soldering Requirements for Plug-in Power Surface Mount Products,” (SLTA051).
(6) The case pins on the through-holed package types (suffixes N & 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
Typical Characteristics
PT3661
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
PT3661 (V1/V2 =5.0V/3.3V); Vin =48V (See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
Power Dissipation vs (Io1 + Io2)
20
16
12
8
100
90
I
2 out
80
70
60
50
6
3
1
4
0
0
6
12
18
24
30
0
3
6
9
12
15
Io1 + Io2 (A)
I1 out (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs I1out; I2out @9A, 12A, and 15A
90
80
70
60
50
40
30
20
100
90
80
70
60
50
Airflow
I2 out
9
300LFM
200LFM
100LFM
Nat conv
12
15
0
5
10
15
20
25
30
0
3
6
9
12
15
Io1 + Io2 (A)
I1 out (A)
Cross Regulation: V1out vs I2out @I1out =1A
5.05
5.025
5
4.975
4.95
0
3
6
9
12
15
I2 out (A)
Cross Regulation: V2out vs I1out @I2out =1A
3.32
3.31
3.3
3.29
3.28
0
3
6
9
12
15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the converter.
Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
Typical Characteristics
PT3662—48V
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
PT3662 (V1/V2 =3.3V/2.5V); Vin =48V (See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
Power Dissipation vs (Io1 + Io2)
90
20
16
12
8
85
I2 out
6
3
1
80
75
70
4
0
0
3
6
9
12
15
0
6
12
18
24
30
I1 out (A)
Io1 + Io2 (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs I1out; I2out @9A, 12A, and 15A
90
85
80
75
70
90
80
70
60
50
40
30
20
Airflow
I2 out
300LFM
200LFM
100LFM
Nat conv
9
12
15
0
3
6
9
12
15
0
5
10
15
20
25
30
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: V1out vs I2out @I1out =1A
3.36
3.33
3.30
3.27
3.24
0
3
6
9
12
15
I2 out (A)
Cross Regulation: V2out vs I1out @I2out =1A
2.530
2.515
2.500
2.485
2.470
0
3
6
9
12
15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the converter.
Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
Typical Characteristics
PT3663—48V
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
PT3663 (V1/V2 =3.3V/1.8V); Vin =48V (See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
Power Dissipation vs (Io1 + Io2)
90
20
16
12
8
85
I2 out
6
80
75
70
3
1
4
0
0
3
6
9
12
15
0
6
12
18
24
30
I1 out (A)
Io1 + Io2 (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs I1out; I2out @9A, 12A, and 15A
90
85
80
75
70
90
80
70
60
50
40
30
20
Airflow
I2 out
300LFM
200LFM
100LFM
Nat Conv
9
12
15
0
5
10
15
20
25
30
0
3
6
9
12
15
Io1 + Io2 (A)
Iout (A)
Cross Regulation: V1out vs I2out @I1out =1A
3.36
3.34
3.32
3.3
3.28
3.26
3.24
0
3
6
9
12
15
I2 out (A)
Cross Regulation: V2out vs I1out @I2out =1A
1.82
1.81
1.8
1.79
1.78
0
3
6
9
12
15
I2 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the converter.
Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
Typical Characteristics
PT3665—48V
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
PT3665 (V1/V2 =3.3V/1.5V); Vin =48V (See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
Power Dissipation vs (Io1 + Io2)
100
20
16
12
8
90
I2 out
80
6
3
1
70
60
50
4
0
0
3
6
9
12
15
0
6
12
18
24
30
I1 out (A)
Io1 + Io2 (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs I1out; I2out @9A, 12A, and 15A
100
90
80
70
60
50
90
80
70
60
50
40
30
20
Airflow
I2 out
9
300LFM
200LFM
100LFM
Nat Conv
12
15
0
3
6
9
12
15
0
5
10
15
20
25
30
I2 out (A)
Io1 + Io2 (A)
Cross Regulation: V1out vs I2out @I1out =1A
3.32
3.31
3.3
3.29
3.28
0
3
6
9
12
15
I2 out (A)
Cross Regulation: V2out vs I1out @I2out =1A
1.51
1.505
1.5
1.495
1.49
0
3
6
9
12
15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the converter.
Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
Typical Characteristics
PT3666—48V
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
PT3666 (V1/V2 =2.5V/1.8V); Vin =48V (See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
Power Dissipation vs I1out and I2out
100
10
8
90
I2 out
80
6
6
3
1
70
4
60
50
2
0
0
3
6
9
12
15
0
3
6
9
12
15
I1 out (A)
Io1 + Io2 (A)
Efficiency vs I1out; I2out @9A, 12A, and 15A
Safe Operating Area: (Io1 + Io2)
100
90
80
70
60
50
90
80
70
60
50
40
30
20
Airflow
I2 out
300LFM
200LFM
100LFM
Nat Conv
9
12
15
0
3
6
9
12
15
0
5
10
15
20
25
30
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: V1out vs I2out @I1out =1A
2.52
2.51
2.5
2.49
2.48
0
3
6
9
12
15
I2 out (A)
Cross Regulation: V2out vs I1out @I2out =1A
1.81
1.805
1.8
1.795
1.79
0
3
6
9
12
15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the converter.
Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
Typical Characteristics
PT3667—48V
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
PT3667 (V1/V2 =5V/1.8V); Vin =48V (See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
Power Dissipation vs (Io1 + Io2)
100
20
16
12
8
90
I2 out
80
6
3
1
70
60
50
4
0
0
3
6
9
12
15
0
6
12
18
24
30
I1 out (A)
Io1 + Io2 (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs I1out; I2out @9A, 12A, and 15A
90
80
70
60
50
40
30
20
100
90
80
70
60
50
Airflow
I2 out
9
300LFM
200LFM
100LFM
Nat conv
12
15
0
3
6
9
12
15
0
5
10
15
20
25
30
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: V1out vs I2out @I1out =1A
5.02
5.01
5
4.99
4.98
0
3
6
9
12
15
I2 out (A)
Cross Regulation: V2out vs I1out @I2out =1A
1.81
1.805
1.8
1.795
1.79
0
3
6
9
12
15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the converter.
Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com
Typical Characteristics
PT3668—48V
30-A Dual Output Isolated
DC/DC Converter
SLTS181 OCTOBER 2002
PT3668 (V1/V2 =3.3V/1.2V); Vin =48V (See Notes A & B)
Efficiency vs I1out; I2out @1A, 3A, and 6A
Power Dissipation vs (Io1 + Io2)
100
20
16
12
8
90
I
2 out
80
70
60
50
6
3
1
4
0
0
6
12
18
24
30
0
3
6
9
12
15
Io1 + Io2 (A)
I1 out (A)
Efficiency vs I1out; I2out @9A, 12A, and 15A
Safe Operating Area: (Io1 + Io2)
90
80
70
60
50
40
30
20
100
90
80
70
60
50
Airflow
I2 out
300LFM
200LFM
100LFM
Nat Conv
9
12
15
0
5
10
15
20
25
30
0
3
6
9
12
15
Io1 + Io2 (A)
I1 out (A)
Cross Regulation: V1out vs I2out @I1out =1A
3.32
3.31
3.3
3.29
3.28
0
3
6
9
12
15
I2 out (A)
Cross Regulation: V2out vs I1out @I2out =1A
1.21
1.205
1.2
1.195
1.19
0
3
6
9
12
15
I1 out (A)
Note A: All Characteristic data in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the converter.
Note B: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
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Application Notes
PT3660, PT4660 & PT4680 Series
Operating Features & System Considerations for the
PT3660/4660/4680 Dual-Output Converters
Under-Voltage Lock-Out
Over-Current Protection
The dual-outputs of the PT3660, PT4660, and PT4680
series of DC/DC converters have independent output
voltage regulation and current limit control. Applying a
load current in excess of the current limit threshold at
either output will cause the respective output voltage to
drop. However, the voltage at Vo2 is derived from Vo1.
Therefore a current limit fault on Vo1 will also cause Vo2
to drop. Conversely, a current limit fault applied to Vo2
will only cause Vo2 voltage to drop, and Vo1 will remain
in regulation.
The Under-Voltage Lock-Out (UVLO) circuit prevents
operation of the converter whenever the input voltage to
the module is insufficient to maintain output regulation.
The UVLO has approximately 2V of hysterisis. This is
to prevent oscillation with a slowly changing input volt-
age. Below the UVLO threshold the module is off and
the enable control inputs, EN1 and EN2 are inoperative.
Primary-Secondary Isolation
The PT4460/80 and PT3660 series of DC/DC converters
incorporate electrical isolation between the input termi-
nals (primary) and the output terminals (secondary). All
converters are production tested to a withstand voltage
of 1500VDC. The isolation complies with UL60950 and
EN60950, and the requirements for operational isolation.
This allows the converter to be configured for either a
positive or negative input voltage source.
The current limit circuitry incorporates a limited amount
of foldback. The fault current flowing into an absolute
short circuit is therefore slightly less than the current
limit threshold. Recovery from a current limit fault is
automatic and the converter will not be damaged by a
continuous short circuit at either output.
Output Over-Voltage Protection
The regulation control circuitry for these modules is
located on the secondary (output) side of the isolation
barrier. Control signals are passed between the primary
and secondary sides of the converter via a proprietory
magnetic coupling scheme. This eliminates the use of
opto-couplers. The data sheet ‘Pin Descriptions’ and
‘Pin-Out Information’ provides guidance as to which
reference (primary or secondary) that must be used for
each of the external control signals.
Each output is monitored for over voltage (OV). For fail
safe operation and redundancy, the OV fault detection
circuitry uses a separate reference to the voltage regula-
tion circuits. The OV threshold is fixed, and set nominally
25% higher than the set-point output voltage. If either
output exceeds the threshold, the converter is shutdown
and must be actively reset. The OV protection circuit
can be reset by momentarily turning the converter off.
This is accomplished by either cycling one of the output
enable control pins (EN1 or EN2), or by removing the
input power to the converter. Note: If Vo1 or Vo2 is adjusted
to a higher voltage, the margin between the respective steady-
state output voltage and its OV threshold is reduced. This can
make the module sensitive to OV fault detection, that may
result from random noise and load transients.
Fuse Requirements
To comply with safety agency requirements, these con-
verters must be operated with an external input fuse.
A fast-acting 250-V fuse is required. Table 1-1 gives
the recommended current rating for the product series
being used.
Over-Temperature Protection
Table 1-1; Recommended Fuse Rating
The converter has an internal temperature sensor. At a
case temperature of approximately 115°C the converter
will shut down, and will automatically restart when the
temperature returns to about 100°C. The analog voltage
generated by the sensor is also made available at the
‘TEMP’ output (pin 5), and can be monitored by the
host system for diagnostic purposes. Consult the ‘Pin
Descriptions’ section of the data sheet for further infor-
mation on this feature.
Product
Series
Input
Bus
Total
Iout
Fuse
Rating
PT4660
PT4680
PT3660
48V
24V
48V
20A
20A
30A
7A
10A
7A
For technical support and more information, see inside back cover or visit www.ti.com
Application Notes
PT3660, PT4660 & PT4680 Series
the outputs of the converter. An example of this configu-
ration is detailed in Figure 2-2. Note: The converter will
only produce and output voltage if a valid input voltage is
applied to Vin.
Using the On/Off Enable Controls on the PT3660/
4660/4680 Series of Dual-Output Converters
The PT3660/4660 (48V input) and PT4680 (24V input)
series of dual-output DC/DC converters incorporate
both positive and negative logic Output Enable controls.
EN1 (pin 3) is the positive enable input, and EN2 (pin 4)
is the negative enable input. Both inputs are TTL logic
compatible, and are electrically referenced to -Vin (pin 2)
on the primary (input) side of the converter. A pull-up
resistor is not required, but may be added if desired.
Adding a pull-up resistor from either input, up to +Vin,
will not damage the converter.
Figure 2-2; Negative Enable Configuration
3
EN 1*
4
EN
2
PT4660
1
=Outputs On
BSS138
– VIN
Automatic (UVLO) Power-Up
2
–Vin
Connecting EN1 (pin 3) to -Vin (pin 2) and leaving EN2
(pin 4) open-circuit configures the converter for automatic
power up. (See data sheet “Typical Application”). The
converter control circuitry incorporates an “Under Voltage
Lockout” (UVLO) function, which disables the output
until the minimum specified input voltage is present at
Vin. (See data sheet Specifications). The UVLO circuitry
ensures a clean transition during power-up and power-
down, allowing the converter to tolerate a slow-rising
input voltage. For most applications EN1 and EN2, can
be configured for automatic power-up.
On/Off Output Voltage Sequencing
The output voltages from these dual-output DC/DC
converters are independantly regulated, and are inter-
nally sequenced to meet the power-up requirements of
popular microprocessor and DSP chipsets. Figure 2-3
shows the waveforms from a PT4661 after the converter
is enabled at t=0s. During power-up, the Vo1 and Vo2
voltage waveforms typically track within 0.4V prior to
Vo2 reaching regulation. The waveforms were measured
with a 5-Adc resistive load at each output, and with a
48-VDC input source applied. The converter typically
produces a fully regulated output within 25ms. The
actual turn-on time will vary slightly with input voltage,
but the power-up sequence is independent of the load at
either output.
Positive Output Enable (Negative Inhibit)
To configure the converter for a positive enable function,
connect EN1 (pin 3) to -Vin (pin 2), and apply the system
On/Off control signal to EN2 (pin 4). In this configura-
tion, a logic ‘0’ (-Vin potential) applied to pin 4 disables
the converter outputs. An example of this configuration
is detailed in Figure 2-1.
Figure 2-1; Positive Enable Configuration
Figure 2-3; Vo1, Vo2 Power-Up Sequence
Vo1 (2V/Div)
Vo2 (2V/Div)
3
EN 1*
4
EN
2
PT4660
IIN (0.5A/Div)
1
=Outputs Off
– VIN
BSS138
2
–Vin
0
5
10
15
20
25
30
35
t (milliseconds)
During turn-off, both outputs drop rapidly due to the
discharging effect of actively switched rectifiers. The
voltage at Vo1 remains higher than Vo2 during this
period. The discharge time is typically 100µs, but will
vary with the amount of external load capacitance.
Negative Output Enable (Positive Inhibit)
To configure the converter for a negative enable function,
EN2 (pin 4) is left open circuit, and the system On/Off
control signal is applied to EN1 (pin 3). A logic ‘0’ (-Vin
potential) must then be applied to pin 3 in order to enable
For technical support and more information, see inside back cover or visit www.ti.com
Application Notes
PT3660, PT4660 & PT4680 Series
Adjusting the Output Voltage of the PT3660,
PT4660, and PT4680 Dual-Output Converters
3.Vo must always be at least 0.3V lower than Vo1.
2
4. The over-voltage protection threshold is fixed, and is set
nominally 25% above the set-point output voltage.
Adjusting Vo1 or Vo2 higher will reduce the voltage
margin between the respective steady-state output
voltage and its over-voltage (OV) protection threshold.
This could make the module sensitive to OV fault
detection, as a result of random noise and load tran-
sients.
The dual output voltages from the PT3660/PT4660
(48V Bus), and PT4680 (24V Bus) series of DC/DC
converters can be independently adjusted by up to 10%,
higher or lower than the factory trimmed pre-set voltage.
The adjustment requires the addition of a single external
1
resistor . Table 3-1 gives the adjustment range of Vo1
and Vo2 for each model in the series as Va(min) and
Va(max).
Note: An OV fault is a latched condition that shuts down
both outputs of the converter. The fault can only be cleared
by cycling one of the Enable control pins (EN1* / EN2), or
by momentarily removing the input power to the module.
Vo1 Adjust Down: Add a resistor (R1), between pin 13
2
(V1 Adj) and pin 12 (Vo1) .
5.Never connect capacitors to either theAdVjoust or
1
Vo1 Adjust Up: To increase the output, add a resistor R2
Vo2 Adjust pins. Any capacitance added to these control
pins will affect the stability of the respective regulated
output.
2, 4
between pin 13 (V1 Adj) and pin 14 (COM)
.
Vo2 Adjust Down: Add a resistor (R3) between pin 20
2
(V2 Adj) and pin 21 (Vo2) .
The adjust up and adjust down resistor values can also be
calculated using the following formulas. Be sure to select
the correct formula parameter from Table 3-1 for the
output and model being adjusted.
Vo2 Adjust Up: Add a resistor R4 between pin 20
(V2 Adj) and pins 19 (COM)
2, 4
.
Ko (Va – Vr )
Vr (Vo – Va)
Refer to Figure 3-1 and Table 3-2 for both the placement and
value of the required resistor.
(R1) or (R3)
R2 or R4
=
=
– Rs
– Rs
kΩ
kΩ
Ko
Va – Vo
Notes:
1.Adjust resistors are not required ifanVdoVo2 are to
1
remain at their respective nominal set-point voltage.
In this case, V1 Adj (pin 13) and V2 Adj (pin 20) are
left open-circuit
Where: Vo = Original output voltage, (Vo1 or Vo2)
Va = Adjusted output voltage
Vr = The reference voltage from Table 3-1
Ko = The multiplier constant in Table 3-1
Rs = The series resistance from Table 3-1
2.Use only
a single 1% resistor in eith(eRr1) tohreR2
location to adjust Vo1, and in the (R3) or R4 location
to adjust Vo2. Place the resistor as close to the converter
as possible.
Figure 3-1; Placement of Output Adjust Resistors
Vo1
Vo2
9–12
Vo 1
Vo 2
+ VIN
1
+Vin
21–24
(R1)
(R3)
PT4660
13
20
Vo 1 adj
Vo 2 adj
L
O
A
D
L
O
A
D
3
EN 1*
4
EN
2
– VIN
2
–Vin
R 2
R 4
C O M
14–19
COM
*
Inverted logic
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Application Notes continued
PT3660, PT4660 & PT4680 Series
Table 3-1; ADJUSTMENT RANGE AND FORMULA PARAMETERS
Vo1 Bus
Vo2 Bus (2)
PT4681
PT4661
(R3)/R4
24V Bus Pt.# PT4681/7
48V Bus Pt.# PT4661/7
PT4682/3/5
PT4662/3/5
(R1)/R2
PT4688
PT4668
(R1)/R2
PT4686
PT4666
(R1)/R2
PT4682
PT4662
(R3)/R4
PT4683/6/7
PT4663/6/7
(R3)/R4
PT4685
PT4665
(R3)/R4
PT4688
PT4668
(R3)/R4
Adj. Resistor
(R1)/R2
Vo(nom)
Va(min)
Va(max)
Vr
Ko (V·kΩ)
Rs (kΩ)
5.0V
4.5V
5.5V
2.5V
1.248
20.0
3.3V
2.97V
3.63V
1.65V
8.234
20.0
3.3V
2.97V
3.63V
2.5V
10.96
4.99
2.5V
2.25V
2.75V
1.25
6.24
20.0
3.3V
2.97V
3.63V
1.5V
1.8
2.5V
2.25V
2.75V
1.5V
2.0
1.8V
1.62V
1.98V
1.5V
1.9
1.5V
1.35
1.65
TBD
TBD
TBD
1.2V
1.08
1.32
0.6V
0.726
4.22
4.99
3.32
3.32
Table 3-2a; ADJUSTMENT RESISTOR VALUES, Vo1
24V Bus Pt.# PT4681/7
48V Bus Pt.# PT4661/7
PT4682/3/5
PT4662/3/5
(R1)/R2
PT4688
PT4668
(R1)/R2
PT4686
PT4666
(R1)/R2
Adj. Resistor
(R1)/R2
Vo(nom)
Va(req’d)
5.5
5.4
5.3
5.2
5.1
5.0
5.0V
3.3V
3.3V
2.5V
Va(req’d)
3.6
Va(req’d)
7.4kΩ
14.3kΩ
25.7kΩ
48.6kΩ
117.0kΩ
31.5kΩ
40.7kΩ
55.9kΩ
86.3kΩ
178.0kΩ
5.0kΩ
11.2kΩ
21.6kΩ
42.4kΩ
105.0kΩ
2.75
2.7
2.65
2.6
2.55
2.5
5.0kΩ
11.2kΩ
21.6kΩ
42.4kΩ
105.0kΩ
3.54
3.48
3.42
3.36
3.3
3.24
3.18
3.12
3.06
3.0
(112.0kΩ)
(43.6kΩ)
(20.8kΩ)
(9.3kΩ)
(49.1kΩ)
(19.9kΩ)
(10.1kΩ)
(5.2kΩ)
4.9
4.8
4.7
4.6
(99.8)kΩ
(37.4)kΩ
(16.6)kΩ
(6.2)kΩ
(0.0)
2.45
2.4
2.35
2.3
(99.8kΩ)
(37.4kΩ)
(16.6kΩ)
(6.2kΩ)
(2.5kΩ)
(2.3kΩ)
2.25
(0.0kΩ)
4.5
R1/R3 = (Blue), R2/R4 = Black
Table 3-2b; ADJUSTMENT RESISTOR VALUES, Vo2
24V Bus Pt.# PT4681
48V Bus Pt.# PT4661
PT4682
PT4662
(R3)/R4
PT4683/6/7
PT4663/6/7
(R3)/R4
PT4685
PT4665
(R3)/R4
PT4688
PT4668
(R3)/R4
Adj. Resistor
(R3)/R4
Vo(nom)
Va(req’d)
3.6
3.54
3.48
3.42
3.36
3.3
3.3V
2.5V
1.8V
1.5V
1.2V
Va(req’d)
1.95
1.9
1.85
1.8
1.0kΩ
2.5kΩ
5.0kΩ
10.0kΩ
25.0kΩ
9.4kΩ
15.7kΩ
34.7kΩ
1.75
1.7
(3.0)kΩ
3.24
3.18
3.12
3.06
3.0
2.75
2.7
2.65
2.6
2.55
2.5
2.45
2.4
2.35
2.3
2.25
(29.8)kΩ
(11.8)kΩ
(5.8)kΩ
(2.8)kΩ
(1.0)kΩ
1.65
1.6
1.55
1.5
1.45
1.4
1.35
1.3
1.275
1.25
1.225
1.2
1.175
1.15
1.125
1.1
TBD
TBD
TBD
(TBD)
(TBD)
(TBD)
4.7kΩ
6.7kΩ
10.0kΩ
16.7kΩ
36.7kΩ
3.0kΩ
5.5kΩ
10.3kΩ
24.8kΩ
(22.0)kΩ
(8.7)kΩ
(4.2)kΩ
(2.0)kΩ
(0.7)kΩ
(23.6)kΩ
(9.1)kΩ
(4.3)kΩ
(1.8)kΩ
R1/R3 = (Blue), R2/R4 = Black
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