PT4661 [TI]
20-A 24-V Input Dual Output Isolated DC/DC Converter; 20 -A 24 - V输入双输出隔离式DC / DC转换器
| 型号： | PT4661 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 20-A 24-V Input Dual Output Isolated DC/DC Converter |
| 文件： | 总16页 (文件大小：288K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PT4680 Series
20-A 24-V Input Dual Output
Isolated DC/DC Converter
SLTS141A
(Revised 1/28/2002)
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 (Pending):
UL 60950
(Independently Regulated)
• Power-up/Down Sequencing
• Input Voltage Range:
18V to 36V
• 1500 VDC Isolation
• Temp Range: –40° to 100°C
• High Efficiency: 88%
• Fixed Frequency Operation
• Over-Current Protection
(Both Outputs)
CSA 22.2 60950
Description
Ordering Information
current limit, over-temperature pro-
tection, and an input under-voltage
lock-out. In addition, both output
voltages are designed to meet the
power-up/power -down sequencing
requirements of popular DSP ICs.
The PT4680 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 PT4680 Excalibur™ Series
is a dual-output isolated DC/DC
converter that combine state-of-the-
art power conversion technology with
unparalleled flexibility. Operating
from a (–24V) industry standard input
bus, the PT4680 series provides up to
20 ADC of output current from two
independently regulated voltages
(each output 15 ADC max).
The PT4680 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
PT 4681o
PT 4682o
PT 4683o
PT 4685o
PT 4686o
PT 4687o
= 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
PT Series Suffix
(PT1234x)
Case/Pin
Configuration
O rder
Suffix
Package
Code
Vertical
Horizontal
SMD
N
A
C
(EKD)
(EKA)
(EKC)
(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
PT4680
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
PT4680 Series
20-A 24-V Input Dual Output
Isolated DC/DC Converter
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. If powering the module from a -24V
telecom central office supply, this input is connected
to the primary system ground.
voltage, and is independant of the enable logic status.
(N ote: 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
+24V supply, this input is connected to the 24V 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 pin produces an output signal that tracks
the module’s metal case temperature. The output
voltage is referenced to –Vin and rises approximately
10mV/°C from an intital value of 0.1VDC at -40°C
(VTe mp =0.5 + 0.01·TCase). 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
PT4680 Series
20-A 24-V Input Dual Output
Isolated DC/DC Converter
Specifications (Unless otherwise stated, Ta =25°C, Vin =24V, & Io1=Io2=10A)
PT4680 SERIES
Typ
Characteristics
Symbols
Conditions
Min
Max
Units
Output Current
Io1
Io2
Vo1
Vo2
0
0
—
—
15
15
A
(1)
Io1+Io2
Vin
Votol
∆Regtemp
∆Regline
∆Regload
Total (both outputs)
0
—
24
1
0.5
5
2
2
2
2
20
36
2
A
V
%Vo
%Vo
mV
Input Voltage Range
Set Point Voltage Tolerance
Temperature Variation
Line Regulation
18
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
–40 to +100°C Case, Io1 =Io2 =0A
Over Vin range with Io1=Io2=5A
1A ≤Io1 ≤15A, Io2 =1A
1A ≤Io2 ≤15A, Io1 =1A
1A ≤Io2 ≤15A, Io1 =1A
1A ≤Io1 ≤15A, Io2 =1A
Includes set-point, line load,
–40°C to +100°C case
—
10
10
10
10
5
Load Regulation
∆Vo1
∆Vo2
∆Vo1
∆Vo2
∆Vo1
∆Vo2
PT4681
PT4682
PT4683
PT4685
PT4686
PT4687
mV
mV
Cross Regulation
Total Output Variation
Efficiency
∆Regcross
∆Votol
η
2
2
3
3
—
%Vo
Io1 =1o2 =10A
88
87
87
86
85
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
Von
OVP
fs
UVLO
Each output with other unloaded
At turn-on to within 90% of Vo
Either output; shutdown and latch off
15.5
—
—
280
—
15
18
5
125 (2)
—
17
16
—
10
—
320
18
—
A
mSec
%Vo
kHz
Rising
Falling
V
Internal Input Capacitance
Cin
—
2
—
µF
On/Off Control
Input High Voltage
Input Low Voltage
Referenced to –Vin
VIH
VIL
3.5
0
—
—
—
0.8
V
(3)
Input Low Current
Quiescent Current
IIL
—
—
0
0.5
3
—
mA
mA
µF
Iin standby
Cout
Viso
C iso
Riso
Pins 2, 3, & 4 connected
Per each output
5
External Output Capacitance
Primary/Secondary Isolation
—
5,000
1500
—
—
—
—
—
V
1500
—
pF
MΩ
10
(4)
(4)
Temperature Sense
Vtemp
Output voltage at temperatures:-
–40°C
100°C
—
—
0.1
—
—
V
1.5
Over-Temperature Shutdown
Operating Temperature Range
Storage Temperature
OTP
Case temperature (auto restart)
Over Vin range
—
—
110
—
—
—
°C
°C
°C
G’s
(5)
T
–40
–40
—
—
—
+85
+125
—
—
—
a
T
s
Mechanical Shock
—
—
Per Mil-STD-883D, Method 2002.3
500
(6)
(6)
Mechanical Vibration
Vertical
10
G’s
Per Mil-STD-883D, 20–2,000Hz
Horizontal
20
Weight
Flammability
—
—
—
—
90
—
grams
Materials meet UL 94V-0
Notes: (1) The sum-total current from Vo1 & Vo2 must not exceed 20ADC.
(2) 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.
(3) 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.
(4) 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.
(5) See SOA curves or consult the factory for the appropriate derating.
(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
PT4681—24V
20-A 24-V Input Dual Output
Isolated DC/DC Converter
PT4681 (Vo1/Vo2 =5.0V/3.3V); Vin =24V (See Notes A & B)
Efficiency vs Io1; Io2 @1A, 3A, and 6A
Power Dissipation vs Io1 and Io2
100
15
12
9
90
I
2 out
15
I
2 out
80
70
60
50
12
9
6
3
1
6
6
3
1
3
0
0
3
6
9
12
15
0
3
6
9
12
15
I1 out (A)
I1 out (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs Io1; Io2 @9A, 12A, and 15A
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
5
8
11
14
17
20
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: Vo1 vs Io2 @Io1 =1A
5.05
5.025
5
4.975
4.95
0
3
6
9
12
15
I2 out (A)
Cross Regulation: Vo2 vs Io1 @Io2 =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
PT4682—24V
20-A 24-V Input Dual Output
Isolated DC/DC Converter
PT4682 (Vo1/Vo2 =3.3V/2.5V); Vin =24V (See Notes A & B)
Efficiency vs Io1; Io2 @1A, 3A, and 6A
Power Dissipation vs Io1 and Io2
100
12
9
90
I2 out
I
2 out
15
80
70
60
50
12
9
6
3
1
6
6
3
1
3
0
0
3
6
9
12
15
0
3
6
9
12
15
I1 out (A)
I1 out (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs Io1; Io2 @9A, 12A, and 15A
100
90
80
70
60
50
90
80
70
60
50
40
30
20
Airflow
I
2 out
300LFM
100LFM
200LFM
Nat conv
9
12
15
0
3
6
9
12
15
5
8
11
14
17
20
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: Vo1 vs Io2 @I1out =1A
3.32
3.31
3.3
3.29
3.28
0
3
6
9
12
15
I2 out (A)
Cross Regulation: Vo2 vs Io1 @Io2 =1A
2.52
2.51
2.5
2.49
2.48
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
PT4683—24V
20-A 24-V Input Dual Output
Isolated DC/DC Converter
PT4683 (Vo1/Vo2 =3.3V/1.8V); Vin =24V (See Notes A & B)
Efficiency vs Io1; Io2 @1A, 3A, and 6A
Power Dissipation vs Io1 and Io2
100
10
8
90
I
2 out
15
I2 out
80
6
12
9
6
3
6
1
70
4
3
1
60
50
2
0
0
3
6
9
12
15
0
3
6
9
12
15
I1 out (A)
I1 out (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs Io1; Io2 @9A, 12A, and 15A
100
90
80
70
60
50
90
80
70
60
50
40
30
20
I2 out
9
Airflow
200LFM
100LFM
Nat conv
12
15
0
3
6
9
12
15
5
8
11
14
17
20
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: Vo1 vs Io2 @Io1 =1A
3.32
3.31
3.3
3.29
3.28
0
3
6
9
12
15
I2 out (A)
Cross Regulation: Vo2 vs Io1 @Io2 =1A
1.82
1.81
1.8
1.79
1.78
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
PT4685—24V
20-A 24-V Input Dual Output
Isolated DC/DC Converter
PT4685 (Vo1/Vo2 =3.3V/1.5V); Vin =24V
Efficiency vs Io1; Io2 @1A, 3A, and 6A
Power Dissipation vs Io1 and Io2
100
10
8
90
80
70
60
50
I2 out
15
I2 out
6
12
9
6
3
1
6
4
3
1
2
0
0
3
6
9
12
15
0
3
6
9
12
15
I1 out (A)
I1 out (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs Io1; Io2 @9A, 12A, and 15A
100
90
80
70
60
50
90
80
70
60
50
40
30
20
I2 out
Airflow
9
200LFM
100LFM
Nat conv
12
15
0
3
6
9
12
15
5
8
11
14
17
20
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: Vo1 vs Io2 @Io1 =1A
3.32
3.31
3.3
3.29
3.28
0
3
6
9
12
15
I2 out (A)
Cross Regulation: Vo2 vs Io1 @Io2 =1A
1.52
1.51
1.5
1.49
1.48
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
PT4686—24V
20-A 24-V Input Dual Output
Isolated DC/DC Converter
PT4686 (Vo1/Vo2 =2.5V/1.8V); Vin =24V
Efficiency vs Io1; Io2 @1A, 3A, and 6A
Power Dissipation vs Io1 and Io2
100
10
8
90
80
70
60
50
I2 out
15
I2 out
6
12
9
6
3
1
6
4
3
1
2
0
0
3
6
9
12
15
0
3
6
9
12
15
I1 out (A)
I1 out (A)
Efficiency vs Io1; Io2 @9A, 12A, and 15A
Safe Operating Area: (Io1 + Io2)
100
90
80
70
60
50
90
80
70
60
50
40
30
20
Airflow
I
2 out
300LFM
200LFM
100LFM
Nat conv
9
12
15
0
3
6
9
12
15
5
8
11
14
17
20
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: Vo1 vs Io2 @Io1 =1A
2.52
2.51
2.5
2.49
2.48
0
3
6
9
12
15
I2 out (A)
Cross Regulation: Vo2 vs Io1 @Io2 =1A
1.82
1.81
1.8
1.79
1.78
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
PT4687—24V
20-A 24-V Input Dual Output
Isolated DC/DC Converter
PT4687 (Vo1/Vo2 =5V/1.8V); Vin =24V
Efficiency vs Io1; Io2 @1A, 3A, and 6A
Power Dissipation vs Io1 and Io2
100
12
10
8
90
80
70
60
50
I2 out
15
I2 out
12
9
6
3
1
6
6
3
4
1
2
0
0
3
6
9
12
15
0
3
6
9
12
15
I1 out (A)
I1 out (A)
Safe Operating Area: (Io1 + Io2)
Efficiency vs Io1; Io2 @9A, 12A, and 15A
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
5
8
11
14
17
20
I1 out (A)
Io1 + Io2 (A)
Cross Regulation: Vo1 vs Io2 @Io1 =1A
5.05
5.025
5
4.975
4.95
0
3
6
9
12
15
I2 out (A)
Cross Regulation: Vo2 vs Io1 @Io2 =1A
1.82
1.81
1.8
1.79
1.78
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
Application Notes
PT4660 & PT4680 Series
Operating Features & System Considerations for the
PT4660/PT4680 Dual-Output DC/DC Converters
Under-Voltage Lock-Out
Over-Current Protection
The dual-outputs of the 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. There-
fore a current limit fault on Vo1 will also cause Vo2 to
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 voltage.
Below the UVLO threshold the module is off and the
enable control inputs, EN1 and EN2 are inoperative.
drop. Conversely, a current limit fault applied to Vo
2
will only cause Vo2 voltage to drop, and Vo1 will remain
in regulation.
Primary-Secondary Isolation
The PT4460/80 series of DC/DC converters incorporate
electrical isolation between the input terminals (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 regulation
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 Recommendations
If desired an input fuse may be added to protect against
the application of a reverse input voltage.
Over-Temperature Protection
The PT4660/80 DC/DC converters have an internal
temperature sensor, which monitors the temperature of
the module’s metal case. If the case temperature exceeds
a nominal 115°C the converter will shut down. The
converter will automatically restart when the sensed
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 Descrip-
tions’ section of the data sheet for further information on
this feature.
For technical support and more information, see inside back cover or visit www.ti.com
Application Notes
PT4660 & PT4680 Series
enable the outputs of the converter. An example of this
configuration is detailed in Figure 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 PT4660
and PT4680 Series of DC/DC Converters
The PT4660 (48V input) and PT4680 (24V input) series
of 75-W dual-output DC/DC converters incorporates
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; 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 auto-
matic power up. (See data sheet “Typical Application”).
The converter control circuitry incorporates an “Under
Voltage Lockout” (UVLO) function, which disables the
converter 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 the PT4660 series of DC/
DC converters are independantly regulated, and are
internally sequenced to meet the power-up requirements
of popular microprocessor and DSP chipsets. Figure 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 1.
Figure 1; Positive Enable Configuration
Figure 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 pe-
riod. 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
For technical support and more information, see inside back cover or visit www.ti.com
Application Notes
PT4660 & PT4680 Series
Adjusting the Output Voltage of the PT4660 and
PT4680 Dual Output Voltage DC/DC Converters
3. Vo2 must always be at least 0.3V lower than Vo1.
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
transients.
The output voltages Vo1 and Vo2 from the PT4680
(24V Bus) and PT4660 (48V Bus) series of DC/DC
converters can be independantly adjusted higher or
lower than the factory trimmed pre-set voltage by up to
10%. The adjustment requires the addition of a single
1
external resistor . Table 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 the Vo1 Adjust or
Vo2 Adjust pins. Any capacitance added to these
control pins will affect the stability of the respective
regulated output.
Vo1 Adjust Up: To increase the output, add a resistor R2
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 1 for the out-
put 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 1 and Table 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 if Vo1 and Vo2 are to
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 1
Ko = The multiplier constant in Table 1
Rs = The series resistance from Table 1
2. Use only a single 1% resistor in either the (R1) or R2
location to adjust Vo1, and in the (R3) or R4 location
to adjust Vo2. Place the resistor as close to the DC/
DC/DC converter as possible.
Figure 1
Vo1
Vo2
9–12
Vo 1
+ VIN
1
+Vin
21–24
Vo 2
(R1)
(R3)
PT4660/80
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
For technical support and more information, see inside back cover or visit www.ti.com
Application Notes continued
PT4660 & PT4680 Series
Table 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 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 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
For technical support and more information, see inside back cover or visit www.ti.com
PACKAGE OPTION ADDENDUM
www.ti.com
24-Jun-2005
PACKAGING INFORMATION
Orderable Device
PT4681A
PT4681C
PT4681N
PT4682A
PT4682C
PT4682N
PT4683A
PT4683C
PT4683N
PT4685A
PT4685C
PT4685N
PT4686A
PT4686C
PT4686N
PT4687A
PT4687C
PT4687N
Status (1)
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
Package Package
Pins Package Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
Qty
Type
Drawing
SIP MOD
ULE
EKA
26
26
26
26
26
26
26
26
26
26
26
26
26
26
26
26
26
26
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
TBD
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Level-1-215C-UNLIM
Level-3-215C-168HRS
Level-1-215C-UNLIM
Level-1-215C-UNLIM
Level-3-215C-168HRS
Level-1-215C-UNLIM
Level-1-215C-UNLIM
Level-3-215C-168HRS
Level-1-215C-UNLIM
Level-1-215C-UNLIM
Level-3-215C-168HRS
Level-1-215C-UNLIM
Level-1-215C-UNLIM
Level-3-215C-168HRS
Level-1-215C-UNLIM
Level-1-215C-UNLIM
Level-3-215C-168HRS
Level-1-215C-UNLIM
SIP MOD
ULE
EKC
EKD
EKA
EKC
EKD
EKA
EKC
EKD
EKA
EKC
EKD
EKA
EKC
EKD
EKA
EKC
EKD
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
SIP MOD
ULE
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan
-
The planned eco-friendly classification: Pb-Free (RoHS) or Green (RoHS
&
no Sb/Br)
-
please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
24-Jun-2005
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
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to Customer on an annual basis.
Addendum-Page 2
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