PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
30-W, 24-V/48-V INPUT DC/DC CONVERTERS
WITH AUTO-TRACK™ SEQUENCING
FEATURES
APPLICATIONS
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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Input Voltage: 18 V to 60 V
30-W Total Output Power
Output Voltages: 3.3 V, 5 V, and 12 V
Wide-Output Adjust/Trim
Up To 88% Efficiency
Overcurrent Protection
Overtemperature Shutdown
Undervoltage Lockout
Input Overvoltage Protection
Auto-Track™ Power-Up Sequencing
(Includes Sequenced Output with PTB78560B)
Smart-Sense Remote Sensing (PTB78560B)
Dual-Logic Enable Control
Space-Saving 1×2 Footprint
Surface Mount Package
Lead (Pb) - Free Option Available
1500-Vdc Isolation
Agency Approvals (Pending):
UL/cUL 60950, EN 60950
Intermediate Bus Architectures
Telecom, High-End Computing Platforms
Multi-Rail Power Systems with
Power-Up Sequencing
DESCRIPTION
The PTB78560x is a series of 30–W rated isolated dc/dc converters, designed to operate from a standard 24–V
or 48–V telecom central office (CO) supply. Housed in a 1×2 package, each model has a wide-adjust output
voltage that can be set to one of the common intermediate bus voltages of 3.3 V, 5 V, or 12 V.
The PTB78560 series incorporates Auto-Track™, a feature that simplifies the power-up sequencing of multiple
power modules that operate from the same intermediate bus. During a power-up cycle, modules with this feature
have the capability of following a common ramp voltage applied to an input called Track. The PTB78560 series
is specifically designed to control the Track voltage of any number of nonisolated downstream modules powered
from its output. This ensures that the outputs of the downstream modules all rise simultaneously during power
up. The PTB78560B (3.3 V) has an additional sequenced output, VO Seq, which also rises with the Track
voltage. This allows the VO Seq output to power up simultaneously with the outputs from other power modules
under the control of Auto-Track.
Whether used to facilitate power-up sequencing, or operated as a stand-alone module, the PTB78560 series
includes many other features expected of high-performance dc/dc converter modules. Precise output voltage
regulation is ensured with a differential remote sense. Operational features include an input undervoltage lockout
(UVLO) and a dual-logic output enable control. Overcurrent and overtemperature protection ensure survival
against load faults.
Typical applications include distributed power architectures in both telecom and computing environments,
particularly complex digital systems requiring power sequencing of multiple power supply rails.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Auto-Track is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2005, Texas Instruments Incorporated
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
Typical Circuit
Track
5
PTB78560x
+VI
1
*
+VI
+Sense
2
$
CI
(Required)
3
PEN
* See note
9
VO Seq 11
VO Bus
Track
10
Auto−Track V
O
VI
POL Module
VO Adjust 8
GND Adjust
#
CO
(Required)
NEN
VO COM
4
−Sense
VO Seq
(3.3 V)
CI #
VPOL1
CO
RSET
6
RSET
7
−VI
Track
−VI
Auto−Track V
O
VI
POL Module
Simultaneous Powerup
VOSeq
GND Adjust
VPOL1
CI #
VPOL2
RSET
To Other
POL Modules
Notes:
Sequenced output is available in the PTB78560B model only.
* The +Sense may be connected to either V Seq or V Bus output of the PTB78560B.
O
O
R
SET is required to set the output voltage higher than the minimum value. See the Application Information section for values.
# The PTB78560x modules require a minimum of 220 µF total output capacitance for proper operation.
$ A minimum of 100 µF input capacitance is recommended for proper operation.
2
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VPOL2
CO
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
ORDERING INFORMATION
PTB78560 (Base Pt. No.)
Output Voltage Range
Part Number
DESCRIPTION
PTB78560AAH
3.6 V to 5.5 V
1.8 V to 3.6 V
Horizontal T/H
SMD, Standard
(2)
PTB78560AAZ
SMD, Standard
(3)
(4)
PTB78560BAS
(4)
SMD, Standard
(2)
PTB78560BAZ
(4)
SMD, Standard
(3)
ERY
Horizontal T/H
PTB78560CAH
(1)
(2)
(3)
(4)
ERW
PTB78560AAS
PTB78560BAH
9 V to 13.2 V
(1)
Package Ref.
ERW
ERY
Horizontal T/H
ERW
PTB78560CAS
SMD, Standard
(2)
PTB78560CAZ
SMD, Standard
(3)
ERY
See the applicable package reference drawing for the dimensions and PC board layout.
Standard option specifies 63/37, Sn/Pb pin solder material.
Lead-free (Pb-free) option specifies Sn/Ag pin solder material.
Includes an Auto-Track compatible output, VO Seq, which sequences with the Track control during power up.
ABSOLUTE MAXIMUM RATINGS
UNIT
Continuous
VI
Input Voltage
V(Track)
Track input voltage
I(Track) max
Track input current
From external source
TA
Operating temperature range
Over VI range
Overtemperature protection
PCB temperature (near pin 1)
T(REFLOW)
Solder reflow temperature
Surface temperature of module
or pins
Tstg
Storage temperature
(1)
(2)
(3)
(4)
60 V
Surge, 1 s max
100 V
(1)
0 V to VO Bus + 0.3 V
10 mA
(2)
–40°C to 85°C
115°C
PTB78560xAS
PTB78560xAZ
235°C (3)
260°C (4)
–40°C to 125°C
The converter's internal protection circuitry may cause the output to turn off when the applied input voltage is greater than 60 V.
When the Track input is fed from an external voltage source, the input current must be limited. A 2.74-kΩ value series resistor is
recommended.
During solder reflow of standard SMD package version, do not elevate the module PCB, pins, or internal component temperatures
above a peak of 235°C.
During solder reflow of Pb - free SMD package version, do not elevate the module PCB, pins, or internal component temperatures
above a peak of 260°C.
PACKAGE SPECIFICATIONS
PTB78560x (Suffixes AH, AS, and AZ)
Weight
13.6 grams
Flammability
Meets UL94V-O
Mechanical shock
Per Mil-STD-883D, Method 2002.3, 1 ms,
1/2 Sine, mounted
Mechanical vibration
(1)
Mil-STD-883D, Method 2007.2, 20-2000 Hz,
PCB mounted
500 G
(1)
Horizontal SMD (Suffix AS)
250 G
(1)
Horizontal T/H (Suffix AH)
20 G
Horizontal T/H (Suffix AH)
Horizontal SMD (Suffix AS
and AZ)
5G
(1)
(1)
Qualification limit.
Submit Documentation Feedback
3
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
PTB78560B ELECTRICAL CHARACTERISTICS
(Unless otherwise stated, TA = 25°C, VI = 24 V, VO = 3.3 V, CO = 330 µF, and IO = IOmax)
PARAMETER
PTB78560B
TEST CONDITIONS
MIN
8
(2)
IO Seq
0
4
(3)
Sum total, (IO Bus + IO Seq)
0.25
IO Bus
Output current
VI
Input voltage range
0.25
Over IO range
η
±1
Line regulation
Over VI range
±7
Load regulation
Over IO range
±13
Total output voltage variation
Includes set-point, line, load, –40°C ≤ TA ≤ 85°C
Adjust range
Over VI range
VO Ripple (peak-to-peak)
20-MHz bandwidth
Transient response
0.1 A/µs load step,
50% to 100%
IOmax , CO = 330
µF
Input current
±2
1.8
80%
RSET = 40.2 kΩ, VO = 2.5 V
77%
RSET = open , VO = 1.8 V
73%
µs
VO over/undershoot
±150
mV
Track connected to -Sense
-0.13
0
(1)
(2)
(3)
(4)
(5)
(6)
4
mA
VO Bus
(5)
1
Input high voltage (VIH)
2
(6)
Input low voltage (VIL)
-0.2
0.1
Shutdown, followed by autorecovery
Open
0.8
–0.8
8
17
VI decreasing
16
Over VI range
400
500
V/ms
V
mA
16
12
VI increasing
Internal input capacitance
MTBF
V
100
Overcurrent threshold
Switching frequency
mV
%VO
Recovery time
Input low current (IIL)
ƒS
(4)
mVpp
Pins 2 and 3 open
Undervoltage lockout
±33
±3
mV
50
Standby input current
UVLO
V
%VO
±33
3.6
RSET = 5.36 kΩ, VO = 3.3 V
Input slew rate limits
Referenced to -VI
A
%VO
±0.5
Open-circuit voltage
Output enable inputs (pins 2, 3)
60
(4)
-40°C ≤ TA ≤ 85°C
Track input (pin 5)
IO (tot)
24
Temperature variation
Efficiency
UNIT
8
18
Set-point voltage tolerance
VO
MAX
(1)
Over VI range
IO
TYP
mA
A
V
600
1
kHz
µF
External input capacitance
Between +VI and –VI
100
External output capacitance
Between both outputs and VO COM
Isolation voltage
Input-output
Isolation capacitance
Input-output
Isolation resistance
Input-output
10
MΩ
Reliability
Telcordia SR-332 50% stress, TA = 40°C, ground
benign
3.6
106 Hr
220
µF
330
1,500
5,000
µF
Vdc
2,000
pF
The converter requires a minimum load current at either the VO Seq or VO Bus output for proper operation. The converter is not
damaged when operated under a no-load condition.
See temperature derating curves for safe operating area (SOA), to determine output current derating at elevated ambient temperatures.
When load current is supplied from the VO Seq output, the module exhibits higher power dissipation and slightly lower operating
efficiency.
The set-point voltage tolerance is affected by the tolerance and stability of RSET. The stated limit is unconditionally met if RSET has a
tolerance of 1%, with 100 ppm/°C temperature stability.
When controlling the Track input from an external source, the slew rate of the applied signal must be greater than the minimum limit.
Failure to allow the voltage to completely rise to the voltage at the VO (bus) output, at no less than the minimum specified rate, may
thermally overstress the converter.
The PEN and NEN inputs each have an internal pullup resistor. If the enable feature is not used, the PEN input (pin 2) should be left
open circuit and the NEN input (pin 3) permanently connected to –VI. A discrete MOSFET or bipolar transistor is recommended for the
enable control. The open-circuit voltage is less than 10 V. See the Application Information for a more detailed description.
Submit Documentation Feedback
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
PTB78560A ELECTRICAL CHARACTERISTICS
(Unless otherwise stated, TA = 25°C, VI = 24 V, VO = 5 V, CO = 220 µF, and IO = IOmax)
PARAMETER
PTB78560A
TEST CONDITIONS
IO
Output current
Over VI range
VI
Input voltage range
Over IO range
MIN
IO Bus
0.25
(1)
η
%VO
%VO
Line regulation
Over VI range
±0.2
±1
%VO
Load regulation
Over IO range
±0.4
±1
%VO
Total output voltage variation
Includes set-point, line, load, –40°C ≤ TA ≤ 85°C
(3)
%VO
Adjust range
Over VI range
VO Ripple (peak-to-peak)
20-MHz bandwidth
Transient response
0.1 A/µs load step,
50% to 100%
IOmax
Input current
±2
3.6
5.5
Recovery time
100
µs
VO over/undershoot
±200
mV
Track connected to -Sense
–0.2
mA
1
Open-circuit voltage
0
Input high voltage (VIH)
2
Input low voltage (VIL)
-0.2
VO Bus
–0.8
8
Shutdown, followed by autorecovery
9
Switching frequency
VI increasing
17
VI decreasing
16
Over VI range
(4)
0.8
Pins 2 and 3 open
ƒS
%VO
Open
Overcurrent threshold
Undervoltage lockout
V
83%
Standby input current
UVLO
±3
RSET = 14.3 kΩ, VO =5 V
Input low current (IIL)
400
Internal input capacitance
(4)
V
(3)
±0.5
Output enable inputs (pins 2, 3)
(2)
(3)
60
A
-40°C ≤ TA ≤ 85°C
Referenced to -VI
(1)
(2)
UNIT
Temperature variation
Track input (pin 5)
MTBF
24
±1
Efficiency
IO Bus
MAX
6
18
Set-point voltage tolerance
VO
TYP
500
V
mA
16
mA
A
V
600
1
kHz
µF
External input capacitance
Between +VI and –VI
100
External output capacitance
Between both outputs and VO COM
220
µF
Isolation voltage
Input-output
Isolation capacitance
Input-output
Isolation resistance
Input-output
10
MΩ
Reliability
Telcordia SR-332 50% stress, TA = 40°C, ground
benign
3.6
106 Hr
5,000
1,500
µF
Vdc
2,000
pF
The converter requires a minimum load current for proper operation. The converter is not damaged when operated under a no-load
condition.
See temperature derating curves for safe operating area (SOA), to determine output current derating at elevated ambient temperatures.
The set-point voltage tolerance is affected by the tolerance and stability of RSET. The stated limit is unconditionally met if RSET has a
tolerance of 1%, with 100 ppm/°C temperature stability.
The PEN and NEN inputs each have an internal pullup resistor. If the enable feature is not used, the PEN input (pin 2) should be left
open circuit and the NEN input (pin 3) permanently connected to –VI. A discrete MOSFET or bipolar transistor is recommended for the
enable control. The open-circuit voltage is less than 10 V. See the Application Information for a more detailed description.
Submit Documentation Feedback
5
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
PTB78560C ELECTRICAL CHARACTERISTICS
(Unless otherwise stated, TA = 25°C, VI = 24 V, VO = 12 V, CO = 100 µF, and IO = IOmax)
PARAMETER
PTB78560C
TEST CONDITIONS
IO
Output current
Over VI range
VI
Input voltage range
Over IO range
MIN
IO Bus
0.1
(1)
η
%VO
%VO
Line regulation
Over VI range
±0.2
±1
%VO
Load regulation
Over IO range
±0.4
±1
%VO
Total output voltage variation
Includes set-point, line, load, –40°C ≤ TA ≤ 85°C
(3)
%VO
Adjust range
Over VI range
VO Ripple (peak-to-peak)
20-MHz bandwidth
Transient Response
0.1 A/µs load step,
50% to 100%
IOmax
Input current
±2
9
±3
13.2
RSET = 9.09 kΩ, VO =12 V
88%
RSET = open, VO = 9 V
86%
1
V
%VO
Recovery time
100
µs
VO over/undershoot
±150
mV
Track connected to -Sense
Open-circuit voltage
–0.48
0
Input high voltage (VIH)
2
Input low voltage (VIL)
-0.2
Input low current (IIL)
Standby input current
Pins 2 and 3 open
IO Bus
Overcurrent threshold
Shutdown, followed by autorecovery
UVLO
Undervoltage lockout
ƒS
Switching frequency
mA
VO Bus
Open
(4)
0.8
–0.8
8
VI increasing
17
VI decreasing
16
500
V
mA
16
3.75
mA
A
V
Over VI range
400
External input capacitance
Between +VI and –VI
100
External output capacitance
Between both outputs and VO COM
100
Isolation voltage
Input-output
Isolation capacitance
Input-output
Isolation resistance
Input-output
10
MΩ
Reliability
Telcordia SR-332 50% stress, TA = 40°C, ground
benign
3.4
106 Hrs
Internal input capacitance
6
V
(3)
±0.5
Output enable inputs (pins 2, 3)
(4)
60
A
-40°C ≤ TA ≤ 85°C
Referenced to -VI
(2)
(3)
(2)
UNIT
Temperature variation
Track input (pin 5)
(1)
24
±1
Efficiency
MTBF
MAX
2.5
18
Set-point voltage tolerance
VO
TYP
600
1
kHz
µF
µF
1,500
1,500
µF
Vdc
2,000
pF
The converter requires a minimum load current for proper operation. The converter is not damaged when operated under a no-load
condition.
See temperature derating curves for safe operating area (SOA), to determine output current derating at elevated ambient temperatures.
The set-point voltage tolerance is affected by the tolerance and stability of RSET. The stated limit is unconditionally met if RSET has a
tolerance of 1%, with 100 ppm/°C temperature stability.
The PEN and NEN enable inputs each have an internal pullup resistor. If the enable feature is not used, the PEN input (pin 2) should be
left open circuit and the NEN input (pin 3) permanently connected to –VI. A discrete MOSFET or bipolar transistor is recommended for
the enable control. The open-circuit voltage is less than 10 V. See the Application Information for a more detailed description.
Submit Documentation Feedback
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
TERMINAL FUNCTIONS
TERMINAL
NAME
DESCRIPTION
NO.
+VI (1)
1
The positive input for the module with respect to -VI. When powering the module from a negative input voltage,
this input is connected to the input source ground.
-VI (1)
4
The negative input supply for the module, and the 0-V reference for the PEN and NEN enable inputs. When
powering the module from a positive source, this input is connected to the input source return.
PEN
(1)
2
An open-collector (open-drain) positive logic input that is referenced to -VI. When this input is pulled to -VI
potential the converter output is disabled. This input must be open circuit for the converter to operate. The
converter then produces an output whenever a valid input source is applied.
NEN
(1) (2)
3
An open-collector (open-drain) negative logic input that is referenced to -VI. This input must be pulled to -VI
potential to enable the converter. When the input is open circuit, the converter output is disabled. If the enable
feature is not used, this input should be permanently connected to -VI. The module then produces an output
whenever a valid input source is applied.
VO Bus
10
This is the positive power output with respect to VO COM, and the main output from the converter. It is dc isolated
from the input power pins and produces a valid output voltage approximately 20 ms before the voltage at the
Track terminal is allowed to rise. This provides the required standby power source to any downstream
nonisolated modules in power-up sequencing applications.
VO Seq
11
This is a sequenced output voltage from the converter that is controlled by the Track terminal during power-up
transitions. It is only available to the PTB78560B, and used with the output voltage set to 3.3 V (an I/O supply
voltage). During power up, the voltage at VO Seq rises with the Track terminal, typically 20 ms after the VO Bus
output has reached regulation.
VO COM
6
This is the output power return for both the VO Bus and VO Seq output voltages. This terminal should be
connected to the common of the load circuit.
Track
5
This terminal is used in power-up sequencing applications to control the output voltage of Auto-Track compatible
modules, powered from the converter VOBus output. This includes the converter VOSeq output on the
PTB78560B. The converter Track control has an internal transistor, which holds the voltage close to VOCOM
potential for approximately 20 ms (40 ms with the PTB78560C) after the VOBus output is in regulation. Following
this delay, the Track voltage and VOSeq rises simultaneously with the output voltage of all other modules
controlled by Auto-Track.
–Sense
7
Provides the converter with a remote sense capability when used with +Sense. For optimum output voltage
accuracy, this pin should always be connected to VOCOM, close to the load circuit. This terminal is also the
reference connection for both the output voltage set-point resistor and Track control.
VO Adjust
8
A resistor must be connected between this terminal and -Sense to set the converter output voltage. A 0.05-W
rated resistor may be used, with tolerance and temperature stability of 1% and 100 ppm/°C, respectively. If left
open circuit, the converter output voltage defaults to its lowest value. The specification table gives the standard
resistor values for the most common output voltages.
+Sense
9
The +Sense pin can be connected to VOBus (or VOSeq) output. When connected to VOSeq, remote sense
compensation is delayed until the converter's power-up sequence is complete. The voltage at VOBus is also
raised slightly. The +Sense input may be left open circuit, but connecting it to one of the output terminals
improves load regulation of that output.
(1)
(2)
These functions indicate signals electrically common with the input.
Denotes negative logic: Low (–VI) = Normal operation, Open = Output off
Terminal Locations
1 +VI
VO Seq 11
VO Bus 10
2 PEN
PTB78560x
(Top View)
3 NEN
4 −VI
Submit Documentation Feedback
+Sense
9
VO Adjust
8
−Sense
7
VO COM
6
Track
5
7
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
TYPICAL CHARACTERISTICS
PTB78560B Characteristic Data (VO = 1.8 V)
EFFICIENCY
vs
OUTPUT CURRENT
(1) (2)
POWER DISSIPATION
vs
OUTPUT CURRENT
80
OUTPUT VOLTAGE RIPPLE
vs
OUTPUT CURRENT
7
35
VI=18 V
VI=24 V
6
PD − Power Dissipation − W
Efficiency − %
70
65
VI=36 V
60
VI=48 V
55
VI=60 V
50
45
30
VI=36 V
VO − Output Voltage − mVPP
75
5
VI=60 V
4
VI=48 V
3
2
.
VI=18 V
1
0
2
4
6
10
0
0
2
4
6
IO − Output Current − A
Figure 1.
90
80
80
70
400 LFM
60
200 LFM
50
100 LFM
TA − Ambient Temperature − °C
TA − Ambient Temperature − °C
0
1
2
3
4
5
6
IO − Output Current − A
7
8
Figure 3.
TEMPERATURE DERATING
vs
OUTPUT CURRENT (VI = 48 V)
90
40
8
Figure 2.
TEMPERATURE DERATING
vs
OUTPUT CURRENT (VI = 24 V)
0 LFM
(Natural Convection)
30
70
400 LFM
60
200 LFM
50
100 LFM
40
0 LFM
(Natural Convection)
30
20
0
1
2
3
4
5
IO − Output Current − A
6
7
8
20
0
1
2
3
4
5
6
IO − Output Current − A
Figure 4.
8
15
5
0
8
IO − Output Current − A
(2)
20
VI=24 V
40
(1)
25
7
8
Figure 5.
All data listed in Figure 1, Figure 3, and have been developed from actual products tested at 25°C. This data is considered typical data
for the dc-dc converter.
All data listed in Figure 1, Figure 3, and have been developed from actual products tested at 25°C. This data is considered typical data
for the dc-dc converter.
Submit Documentation Feedback
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
TYPICAL CHARACTERISTICS (continued)
PTB78560B Characteristic Data (VO = 3.3 V)
EFFICIENCY
vs
OUTPUT CURRENT
(3) (4)
POWER DISSIPATION
vs
OUTPUT CURRENT
OUTPUT VOLTAGE RIPPLE
vs
OUTPUT CURRENT
8
85
50
VI=18 V
PD − Power Dissipation − W
75
70
Efficiency − %
45
7
VI=24 V
65
VI=36 V
60
VI=48 V
55
50
VI=60 V
VI=36 V
VI=60 V
6
5
40
VI=48 V
4
VI=24 V
3
VI=18 V
2
1
45
40
2
4
6
8
2
4
6
IO − Output Current − A
Figure 6.
20
15
10
8
0
1
2
3
4
5
6
IO − Output Current − A
90
90
80
80
70
400 LFM
60
200 LFM
100 LFM
50
7
8
Figure 8.
TEMPERATURE DERATING
vs
OUTPUT CURRENT (VI = 48 V)
TA − Ambient Temperature − °C
TA − Ambient Temperature − °C
25
Figure 7.
TEMPERATURE DERATING
vs
OUTPUT CURRENT (VI = 24 V)
0 LFM
(Natural Convection)
70
400 LFM
60
200 LFM
50
100 LFM
0 LFM
(Natural Convection)
40
30
30
20
20
0
1
2
3
4
5
6
IO − Output Current − A
7
8
0
1
Figure 9.
(4)
30
0
0
IO − Output Current − A
40
35
5
0
0
(3)
VO − Output Voltage − mVPP
80
2
3
4
5
6
IO − Output Current − A
7
8
Figure 10.
All data listed in Figure 6, Figure 8, and Figure 7 have been developed from actual products tested at 25°C. This data is considered
typical data for the dc-dc converter.
The temperature derating curves represent operating conditions at which internal components are at or below manufacturer's maximum
rated operating temperature. Derating limits apply to modules soldered directly to a 100–mm × 100–mm, double-sided PCB with 2 oz.
copper. Applies to Figure 9, and Figure 10.
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TYPICAL CHARACTERISTICS (continued)
PTB78560A Characteristic Data (VO = 5 V)
EFFICIENCY
vs
OUTPUT CURRENT
(5) (6)
POWER DISSIPATION
vs
OUTPUT CURRENT
100
OUTPUT VOLTAGE RIPPLE
vs
OUTPUT CURRENT
8
60
95
VI=48 V
7
50
VI=18 V
75
VI=36 V
70
65
VI=48 V
60
55
VI=60 V
VO − Output Voltage − mVPP
85
VI=24 V
80
PD − Power Dissipation − W
Efficiency − %
90
6
VI=36 V
VI=60 V
5
VI=48 V
4
3
VI=24 V
2
VI=18 V
50
VI=60 V
40
30
VI=36 V
20
VI=24 V
VI=18 V
10
1
45
0
0
40
0
1
2
3
5
4
0
6
4
2
3
IO − Output Current − A
1
IO − Output Current − A
Figure 11.
90
80
80
70
400 LFM
60
200 LFM
50
TA − Ambient Temperature − °C
TA − Ambient Temperature − °C
90
100 LFM
0 LFM
(Natural Convection)
6
Figure 13.
400 LFM
70
60
200 LFM
50
100 LFM
40
0 LFM
(Natural Convection)
20
0
1
2
3
4
5
6
0
1
IO − Output Current − A
Figure 14.
10
5
30
20
(6)
2
3
4
IO − Output Current − A
TEMPERATURE DERATING
vs
OUTPUT CURRENT (VI = 48 V)
30
(5)
1
Figure 12.
TEMPERATURE DERATING
vs
OUTPUT CURRENT (VI = 24 V)
40
0
6
5
2
3
4
5
6
IO − Output Current − A
Figure 15.
All data listed in Figure 11, , and Figure 12 have been developed from actual products tested at 25°C. This data is considered typical
data for the dc-dc converter.
The temperature derating curves represent operating conditions at which internal components are at or below manufacturer's maximum
rated operating temperature. Derating limits apply to modules soldered directly to a 100–mm × 100–mm, double-sided PCB with 2 oz.
copper. Applies to Figure 14, and Figure 15.
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TYPICAL CHARACTERISTICS (continued)
PTB78560C Characteristic Data (VO = 12 V)
EFFICIENCY
vs
OUTPUT CURRENT
90
VI=18 V
85
(7) (8)
POWER DISSIPATION
vs
OUTPUT CURRENT
7
VI=24 V
45
PD − Power Dissipation − W
Efficiency − %
VI=48 V
70
65
VI=60 V
60
55
50
VI=60 V
5
4
VI=36 V
3
2
VI=24 V
40
0
0.5
1.0
2.0
1.5
2.5
VI=36 V
25
20
VI=24 V
15
10
5
0.5
1.5
1.0
2.0
IO − Output Current − A
2.5
0
0.5
1.0
1.5
2.0
IO − Output Current − A
Figure 17.
TEMPERATURE DERATING
vs
OUTPUT CURRENT (VI = 24 V)
2.5
Figure 18.
TEMPERATURE DERATING
vs
OUTPUT CURRENT (VI = 48 V)
90
80
80
TA − Ambient Temperature − °C
90
400 LFM
70
VI=18 V
0
0
Figure 16.
TA − Ambient Temperature − °C
30
0
IO − Output Current − A
200 LFM
60
100 LFM
50
35
VI=18 V
1
45
VO − Output Voltage − mVPP
VI=48 V
VI=36 V
75
0 LFM
(Natural Convection)
40
400 LFM
70
200 LFM
60
100 LFM
50
0 LFM
(Natural Convection)
40
30
30
20
20
0
0.5
1.0
1.5
2.0
IO − Output Current − A
2.5
0
0.5
Figure 19.
(8)
VI=48 V
VI=60 V
40
6
80
(7)
OUTPUT VOLTAGE RIPPLE
vs
OUTPUT CURRENT
1.0
1.5
2.0
IO − Output Current − A
2.5
Figure 20.
All data listed in Figure 16, Figure 18, and Figure 17 have been developed from actual products tested at 25°C. This data is considered
typical data for the dc-dc converter.
The temperature derating curves represent operating conditions at which internal components are at or below manufacturer's maximum
rated operating temperature. Derating limits apply to modules soldered directly to a 100–mm × 100–mm, double-sided PCB with 2 oz.
copper. Applies to Figure 19.
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APPLICATION INFORMATION
Operating Features and System Considerations for the PTB78560x DC/DC Converters
Primary-Secondary Isolation
These converters incorporate electrical isolation between the input terminals (primary) and the output terminals
(secondary). All converters are tested to a withstand voltage of 1500 VDC. This complies with UL/cUL 60950
and EN 60950 and the requirements for functional isolation. It allows the converter to be configured for either a
positive or negative input voltage source. The data sheet Terminal Functions table provides guidance as to the
correct reference that must be used for the external control signals.
Undervoltage Lockout
The undervoltage lockout (UVLO) is designed to prevent the operation of the converter until the input voltage is
close to the minimum operating voltage. The converter is held off when the input voltage is below the UVLO
threshold, and turns on when the input voltage rises above the threshold. This prevents 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 converter meets full specifications when the minimum specified input voltage is reached.
The UVLO circuitry also overrides the operation of the PEN and NEN enable controls. Only when the input
voltage is above the UVLO threshold do these inputs become functional.
Soft-Start Power Up
When the converter is first powered, the internal soft-start circuit limits how fast the output voltage can rise. The
soft-start circuit functions whenever the converter output is enabled from the PEN and NEN inputs, or when a
valid input source is first applied with the output enabled. It also functions on a recovery from a load fault,
overtemperature, or input overvoltage condition. The purpose of the soft-start feature is to limit the surge of
current drawn from the input source when the converter begins to operate. By limiting the rate at which the
output voltage rises, the magnitude of current required to charge up the load circuit capacitance is significantly
reduced.
Figure 21 shows the power-up characteristic of a PTB78560C converter. The output voltage is set to 12 V. The
soft-start circuit introduces a short time delay (typically 10-15 ms) before allowing the output to rise. The output
then progressively rises to the voltage set-point. The waveforms were recorded with a resistive load of 2.5 A.
VI (10 V/ div)
UVLO Threshold
VO (5 V/ div)
II (1 A/ div)
tDLY
t − Time − 5 ms/div
Figure 21. Soft-Start Waveform
Overcurrent Protection
To protect against load faults, these converters incorporate output overcurrent protection. Applying a load to the
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APPLICATION INFORMATION (continued)
output that exceeds the converter overcurrent threshold (see applicable specification) causes the output voltage
to momentarily fold back, and then shut down. Following shutdown, the module periodically attempts to
automatically recover by initiating a soft-start power up. This is often described as a hiccup mode of operation,
whereby the module continues in the cycle of successive shutdown and power up until the load fault is removed.
Once the fault is removed, the converter automatically recovers and returns to normal operation.
Input Overvoltage Protection
The converter protects itself against input voltage surges and transients of up to 100 V. This is above the
maximum continuous operating input voltage of 60 V. In order to protect itself, the converter output is disabled at
some voltage above 60 V. This is to ensure that the converter internal components are not exposed to voltages
above their stress ratings. The converter output remains off for some of the period that the input voltage is
above the maximum continuous rating. Once the overvoltage event has passed, the output from the converter
automatically restarts by executing a soft-start power up.
Differential Output Voltage Sense
A differential remote sense allows a converter regulation circuitry to compensate for limited amounts of IR drop,
that may be incurred between the converter and load, in either the positive or return PCB traces. Connecting the
+Sense and –Sense pins to the respective positive and ground reference of the load terminals improves the load
regulation of the converter output voltage at that connection point. The –Sense pin should always be connected
to the VO COM. The +Sense pin may be connected to either the +VO Bus or +VO Seq outputs.
When the +Sense pin is connected to the VO Seq output, the voltage at VO Bus voltage regulates slightly higher.
Depending on the load conditions on the VO Seq output, the voltage at VO Bus may be up to 100 mV higher than
the converter set-point voltage. In addition, the Smart-Sense feature (incorporated into the converter) only
engages sense compensation to the VO Seq output when that output voltage is close to the set-point. During a
power-up sequencing event, the sense circuit automatically defaults to sensing the VO Bus voltage, internal to
the converter.
Leaving the +Sense and –Sense pins open does not damage the converter or load circuit. The converter
includes default circuitry that keeps the output voltage in regulation. However, if the remote sense feature is not
used, the –Sense pin should still be connected to VOCOM.
Note: The remote sense feature is not designed to compensate for the forward drop of nonlinear or
frequency-dependent components that may be placed in series with the converter output. Examples include
OR-ing diodes, filter inductors, ferrite beads, and fuses. When these components are enclosed by the sense pin
connections, they are effectively placed inside the regulation control loop, which can adversely affect the stability
of the converter.
Overtemperature Protection
Overtemperature protection is provided by an internal temperature sensor, which monitors the temperature of
the converter PCB (close to pin 1). If the PCB temperature exceeds a nominal 115°C, the converter shuts down.
The converter then automatically restarts when the sensed temperature falls to approximately 105°C. When
operated outside its recommended thermal derating envelope (see data sheet derating curves), the converter
typcially cycles 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.
Output Voltage Adjustment
An external resistor is required to set the nominal output voltage(s) of the converter to a voltage higher than its
minimum value. The resistor, RSET, must be connected directly between the VO Adjust (pin 8) and –Sense (pin
7) terminals. A 0.05-W rated resistor can be used. The tolerance should be 1%, with a temperature stability of
100 ppm/°C (or better). Place the resistor close to the converter and connect it using dedicated PCB traces (see
Figure 22). Table 1 gives the nearest standard value of external resistor for the common voltages within each
model's adjust range. The actual output voltage that the resistor value provides is also provided.
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Table 1. Standard Values of RSET for Common Output Voltages
PTB78560A
PTB78560B
PTB78560C
VO (Required)
RSET
VO (Actual)
RSET
VO (Actual)
RSET
VO (Actual)
1.8 V
–
–
Open
1.802 V
–
–
2V
–
–
200 kΩ
2.004 V
–
–
2.5 V
–
–
40.2 kΩ
2.498 V
–
–
3.3 V
–
–
5.36 kΩ
3.300 V
–
–
3.6 V
Open
3.611 V
309 Ω
3.600 V
–
–
5V
14.3 kΩ
5.005 V
–
–
–
–
9V
–
–
–
–
Open
9.015 V
10 V
–
–
–
–
73.2 kΩ
9.993 V
12 V
–
–
–
–
9.09 kΩ
12 V
13.2 V
–
–
–
–
0Ω
13.23 V
For other output voltages, the value of the required adjust resistor may be calculated using Equation 1.
VR
R SET + RO
* RP
VO * VMIN
(1)
Table 2 gives the output voltage adjust range and the required equation constants for the converter model
selected. To calculate the required value of RSET, simply locate the applicable constants and substitute these
into the formula along with the desired output voltage.
Table 2. Adjust Ranges and Equation Constants
Model #
PTB78560A
PTB78560B
PTB78560C
VR
1.24 V
1.24 V
2.5 V
RO
49.91 kΩ
36.55 kΩ
37.27 kΩ
RP
30.1 kΩ
24.9 kΩ
22.1 kΩ
VMIN
3.61 V
1.8 V
9.02 V
VMAX
5.5 V
3.6 V
13.2 V
Track
5
PTB78560A
+VI
1
+VI
CI
100 µF
+Sense
VO Bus
2
PEN
VO Adjust
3
10
8
CO
220 µF
NEN
VO COM
4
9
−VI
6
RSET
7
−Sense
−VI
Figure 22. Output Voltage Adjustment
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Input Current Limiting
The converter is not internally fused. For safety and overall system protection, the maximum input current to
the converter must be limited. Active or passive current limiting can be used. Passive current limiting can be a
fast-acting fuse. A 125-V fuse, rated no more than 5 A, is recommended. Active current limiting can be
implemented with a current limited Hot-Swap controller.
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 is determined from the safe operating area (SOA). The
SOA is the area beneath the applicable airflow rate curve on the graph of temperature derating vs output
current. (See the Typical Characteristics.) Operating the converter within the SOA limits ensures that all the
internal components are at or below their stated maximum operating temperatures.
Using the On/Off Enable Controls on the PTB78560x Auto-Track Compatible DC/DC Converters
The converter incorporates two output enable controls. PEN (pin 2) is the positive enable input, and NEN (pin 3)
is the negative enable input. Both inputs are electrically referenced to -VI (pin 4) on the primary or input side of
the converter. The enable pins are ideally controlled with an open-collector (or open-drain) discrete transistor.
Each input has an internal pullup resistor to a reference. There is no benefit to adding pullup resistors external to
the module. If they are added, the maximum input voltage for these inputs must be limited to a maximum of
60 V.
Automatic (UVLO) Power Up
Connecting NEN (pin 3) to -VI (pin 4) and leaving PEN (pin 2) open-circuit, configures the converter for
automatic power up. The converter control circuitry incorporates an undervoltage lockout (UVLO) function, which
disables the converter until the minimum specified input voltage is present at ±VI (see the Electrical
Characteristics table). 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, the PEN and NEN enable controls
can be configured for automatic power up.
Positive Output Enable (Negative Inhibit)
To configure the converter for a positive enable function, connect NEN (pin 3) to -VI (pin 4), and apply the
system On/Off control signal to PEN (pin 2). In this configuration, applying less than 0.8 V (with respect to -VI
potential) to pin 2 disables the converter output. Figure 23 gives an example circuit that uses a MOSFET
transistor.
+VI
1
+VI
DC/DC
Module
2
3
Q1
BSS138
PEN
NEN
1 = Outputs Off
−VI
4
−VI
Figure 23. Positive Enable Configuration
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Negative Output Enable (Positive Inhibit)
To configure the converter for a negative enable function, PEN (pin 2) is left open circuit, and the system On/Off
control signal is applied to NEN (pin 3). A low-level control signal (less than 0.8 V) must then be applied to pin 3
to enable an output from the converter. An example of this configuration is detailed in Figure 24.
+VI
1
+VI
DC/DC
Module
2
3
Q1
BSS138
PEN
NEN
1 = Outputs On
-VI
4
-VI
Figure 24. Negative Enable Configuration
On/Off Enable Turn-On Time
Once enabled, the converter executes a soft-start power up. The converter exibits a short delay of approximately
7 ms, measured from the transition of the enable signal to the instance the VO Bus output begins to rise. The
output is in regulation within 20 ms.
VOBus (5 V/div)
II (1 A/div)
Q1 VDS (5 V/div)
t − 5 ms/div
Figure 25. Output Enable Power-Up Characteristic
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Sequenced Power Up with POL Modules
Overview
The main output from the PTB78560x converters is VOBus. In power sequencing applications, VOBus is used as
the intermediate supply voltage for powering one or more downstream nonisolated power modules that
incorporate Auto-Track™1. The output voltage from Auto-Track compliant modules can be sequenced using a
control input called Track. The Track input directly controls the output of a module from zero to its set-point
voltage. The control is on a volt-for-volt basis, and allows multiple modules to follow a common analog signal
during power-up events.
The Track signal attempts to start rising when the nonisolated modules are first powered from VOBus. However,
for proper sequencing, the voltage must be held at ground potential for at least 20 ms (40 ms for 12-V input
modules) after VOBus is in regulation. This is necessary to allow time for the nonisolated modules to complete
their power-up initialization. The Track pin of each PTB78560x converter has an internal open-drain transistor
that automatically holds the Track signal at ground potential to comply with this requirement.
The PTB78560B (1.8 V to 3.6 V) has a VOSeq output. VOSeq is internally derived from VOBus and regulated to
the same set-point voltage. It has the added feature of being controlled by the Track input. During power up, this
output can sequence with the outputs of the nonisolated modules powered from VOBus.
Auto-Track Features
Figure 26 shows a block diagram of the converter Auto-Track features. The components shaded are only
present in the PTB78560B. During power up, VOBus rises promptly, after the converter is connected to a valid
input source and its output is enabled. VOSeq (PTB78560B) is the Auto-Track compatible output that is
controlled by the voltage presented at the Track terminal. The control is active from 0 V up to a voltage just
below the VOBus output. Between these limits, the voltage at VOSeq follows that at the Track terminal. Once the
Track voltage is at the VOBus voltage, raising it higher has no further effect. The voltage at VOSeq cannot go
higher than VOBus, and if connected to +Sense, it regulates at the set-point voltage.2
The Track input to the PTB78560x series of converters include a pullup resistor (RTRK) to VOBus, and a 1-µF
capacitor (CTRK) to -Sense. These components are standard on all Auto-Track compatible modules. They form
an R–C time constant that cause the Track voltage to rise when the internal MOSFET is turned off. The
unity-gain relationship between VOSeq and the Track input is the same as all other Auto-Track compliant
outputs.3 The VOSeq output also follows a compatible external ramp waveform applied to the Track pin.4, 5 The
internal MOSFET is designed to hold the Track voltage at ground potential for the required period after the
VOBus output is in regulation.
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ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
VO Bus
Smart Sense
To Internal
Error
Amplifier
+ Sense
VO Seq
RTRK
24.9 kΩ
Track
Supply
Supervisor
20 ms
Delay
CTRK
1 µF
VO COM
Note: Shaded functions are available only with the PTB78560B (3.3−V output)
Figure 26. Block Diagram of Auto-Track Features
Notes:
1. Auto-Track compatible modules incorporate a Track input that can take direct control of the output voltage
during power-up transistions. The control relationship is on a volt-for-volt basis and is active between the 0 V
and the module set-point voltage. Once the Track input is above the set-point voltage, the module remains at
its set-point. Connecting the Track input of a number of such modules together allows their outputs to follow
a common control voltage during power up.
2. When +Sense is connected to the VOSeq output of the PTB78560B, the VOSeq output is tightly regulated to
the set-point voltage. In this configuration, the voltage at the VOBus output is up to 100 mV higher.
3. The VOSeq output on the PTB78560B cannot sink load current. This constraint does not allow the module to
coordinate a sequenced power down.
4. The slew rate for the Track input signal must be between 0.1 V/ms and 1 V/ms. Above this range, the VOSeq
output may no longer accurately follow the Track input voltage. A slew rate below this range may thermally
stress the converter. These slew rate limits are automatically met whenever the Track voltage is controlled by
the internal R-C time constant of the modules being sequenced.
5. If an external voltage is used to control the Track terminal, the source current must be limited. A resistance
value of 2.74-kΩ is recommended for this purpose. This is necessary to protect the internal transistor to the
converter. This transistor holds the track control voltage at ground potential for at least 20 ms after the VOBus
output is in regulation.
Power-Up Sequencing With A VO SEQ Output (PTB78560B)
Figure 28 shows the PTB78560B converter (U1) providing two 3.3-V sources. This allows it to both power and
sequence with one or more downstream nonisolated modules. The example shows two 3.3-V input PTH04000W
modules (U2 and U3), each rated for up to 3 A of output current. The selection and current rating of the
nonisolated modules depends on the requirements of a specific application. The number of modules, their
respective output voltage, and load current rating combine with the load required at the VOSeq output. The total
must be supplied by the PTB78560B, and cannot exceed that available at the VOBus output.
The output voltage adjust range of the PTB78560B is 1.8 V to 3.6 V. In these applications, the output voltage
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must always be set to 3.3 V (R1 = 5.36 kΩ). This sets the output voltage of both the VOBus and VOSeq outputs.
The output voltage of the 3.3-V input (nonisolated) modules, U2 and U3, can be set to any voltage over the
range, 0.8 V to 2.5 V. In this example, they are set to 2.5 V (R2 = 2.32 kΩ) and 1.8 V (R3 = 6.65 kΩ),
respectively. Figure 27 shows the power-up waveforms from Figure 28 when the Track input to all three modules
are simply connected together.
The converter provides input power to the downstream nonisolated modules via the VOBus output. This output
rises first to allow the nonisolated modules to complete their power-up initialization. The VOSeq (3.3 V), V(POL)1
(2.5 V) and V(POL)2 (1.8 V), outputs supply the load circuit, and rise simultaneously when the converter removes
the internal ground signal to its own Track input. The VOSeq output rises with the outputs from the nonisolated
modules, until it reaches its set-point voltage.
VOBus (1 V/div)
VOSeq (1 V/div)
V(POL)1 (1 V/div)
V(POL)2 (1 V/div)
td = 20 ms
t − 20 ms/div
Figure 27. Power-Up Waveforms with POL Modules
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Track
5
VO Seq
(3.3 V)
U1
PTB78560B
+VI
1
CI
100 µF
2
3
+Sense
9
VO Seq
11
VO Bus
10
+VI
PEN
VO Adjust
4
3
8
NEN
−VI
−Sense
7
VI
U2
PTH04000W VO
6
Inhibit GND Adjust
4
1
5
C2
220 µF
VO COM 6
−VI
2
Track
VPOL1
(2.5 V)
C4
47 µF
R2
2.32 kΩ
C3
47 µF
R1
5.36 kΩ
2
Track
3
5
C5
47 µF
VI
U3
PTH04000W
VPOL2
(1.8 V)
VO
6
Inhibit GND Adjust
4
1
5
R3
6.65 kΩ
C6
47 µF
Figure 28. Power-Up Sequencing With Nonisolated POL Modules
Power-Up Sequencing Without A VOSEQ Output (PTB78560A/C)
Although the PTB78560A or PTB78560C do not have a VOSeq output, they can provide the input power and
coordinate the power-up sequencing to two or more nonisolated, Auto-Track compliant power modules.
Figure 30 shows the PTB78560A (5 V) converter (U1) configured to provide both the input source and the
power-up sequence timing to two 5-V input nonisolated modules. The example shows two PTH04000W modules
(U2 and U3), each rated for up to 3 A of output current. In this case, the number of downstream modules, and
their respective output voltage and load current rating, is only limited by the amount of current available at the
VOBus output.
The output voltage of the PTB78560 must be set to a valid intermediate supply voltage. This depends on the
input voltage requirements of the downstream modules. For 5-V input modules, the PTB78560A is selected and
adjusted for an output of 5 V. For 12-V input modules, the PTB78560C is used and adjusted for an output of
12 V. U2 and U3, can be set to any voltage over their applicable adjustment range. In this example, they are
again set to 2.5 V (R2 = 2.32 kΩ) and 1.8 V (R3 = 6.65 kΩ), respectively. Figure 29 shows the power-up
waveforms from Figure 30 when the Track control of all three modules are simply connected together.
The PTB78560 converter (U1) provides the required intermediate voltage from the VOBus output to power the
downstream modules, while holding the common Track control at ground potential. After allowing times for U2
and U3 to initialize, U1 removes the ground from the Track control, allowing this voltage to rise. The outputs
from the two nonisolated modules then rise simultaneously to their respective set-point voltages.
20
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PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
VOBus (1 V/div)
V(POL)1 (1 V/div)
V(POL)2 (1 V/div)
td = 20 ms
t − 10 ms/div
Figure 29. Power-Up Waveform
Track
U1
PTB78560A
+VI
1
+Sense
CI
100 µF
3
VO Bus
(5 V)
9
+VI
2
Track
VO Bus
2
5
PEN
VO Adjust
10
8
4
−VI
−Sense
7
VI
U2
PTH04000W VO
6
Inhibit GND Adjust
4
1
5
C2
220 µF
NEN
VO COM 6
−VI
3
VPOL1
(3.3 V)
C4
47 µF
R2
475 Ω
C3
47 µF
R1
13.7 kΩ
2
Track
3
5
C5
47 µF
VI
U3
PTH04000W
VPOL2
(1.5 V)
VO
6
Inhibit GND Adjust
4
1
5
R3
11.5 kΩ
C6
47 µF
Figure 30. Power-Up Sequencing With Nonisolated POL Modules
Submit Documentation Feedback
21
PTB78560A, PTB78560B
PTB78560C
www.ti.com
SLTS249 – JUNE 2005
Stand-Alone Operation
The wide output voltage adjust range makes either model of the PTB78560 series of converters an attractive
product as a stand-alone dc/dc converter. In these applications, it is not required to power up or sequence with
any nonisolated POL modules. The output voltage can be adjusted to any value within the applicable adjust
range. The Auto-Track features are simply not used.
Figure 31 shows the recommended configuration when these converters are used as a stand-alone regulator.
The main output (VO Bus) can be used to supply the load directly. Both the Track pin and the VO Seq output
(PTB78560B) are simply left open circuit. The +Sense pin should be connected to the VO Bus output for
improved load regulation.
When the converter is operated in this mode, the output from VO Bus rises promptly on power up.
PTB78560x
Track
5
+Sense 9
+VI
1
2
3
VO Seq
+VI
VO Bus
PEN
VO Adjust
11
10
8
NEN
C1
220 µF
RSET
VO COM 6
4
−VI
−Sense
7
−VI
Figure 31. Stand-Alone Configuration
22
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O
A
D
PACKAGE OPTION ADDENDUM
www.ti.com
14-Jul-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
(3)
Device Marking
(4/5)
(6)
PTB78560AAH
NRND
ThroughHole Module
ERW
11
12
RoHS (In Work)
& non-Green
SN
N / A for Pkg Type
-40 to 85
PTB78560AAS
NRND
Surface
Mount Module
ERY
11
12
Non-RoHS
& non-Green
SNPB
Level-1-235C-UNLIM/
Level-3-260C-168HRS
-40 to 85
PTB78560AAZ
NRND
Surface
Mount Module
ERY
11
12
RoHS (In Work)
& non-Green
SNAGCU
Level-3-260C-168 HR
-40 to 85
PTB78560BAH
NRND
ThroughHole Module
ERW
11
12
RoHS (In Work)
& non-Green
SN
N / A for Pkg Type
-40 to 85
PTB78560BAS
NRND
Surface
Mount Module
ERY
11
12
Non-RoHS
& non-Green
SNPB
Level-1-235C-UNLIM/
Level-3-260C-168HRS
-40 to 85
PTB78560CAH
NRND
ThroughHole Module
ERW
11
12
RoHS (In Work)
& non-Green
SN
N / A for Pkg Type
-40 to 85
PTB78560CAS
NRND
Surface
Mount Module
ERY
11
12
Non-RoHS
& non-Green
SNPB
Level-1-235C-UNLIM/
Level-3-260C-168HRS
-40 to 85
PTB78560CAZ
NRND
Surface
Mount Module
ERY
11
12
RoHS (In Work)
& non-Green
SNAGCU
Level-3-260C-168 HR
-40 to 85
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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