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LM5033
SNVS181C – APRIL 2004 – REVISED AUGUST 2016
LM5033 100-V Push-Pull Voltage Mode PWM Controller
1 Features
3 Description
•
•
•
•
•
•
•
•
•
The LM5033 high-voltage PWM controller contains all
the features necessary to implement push-pull, halfbridge, and full-bridge topologies. Applications
include closed-loop voltage mode converters with a
highly regulated output voltage, or open-loop DC
transformers such as an Intermediate bus converter
(IBC) with an efficiency greater than 95%. Two
alternating gate driver outputs with a specified
deadtime are provided.
1
Internal High-Voltage (100 V) Start-Up Regulator
Single Resistor Oscillator Setting
Synchronizable
Precision Reference Output
Adjustable Soft Start
Overcurrent Protection
Direct Optocoupler Interface
1.5-A Peak Gate Drivers
Thermal Shutdown
2 Applications
•
•
•
•
Intermediate DC-DC Bus Converter
Telecommunication Power Converters
Industrial Power Converters
42-V Automotive Systems
The LM5033 includes a start-up regulator that
operates over a wide input range from 15 V to 100 V.
Additional features include: precision voltage
reference output, current limit detection, remote
shutdown, soft start, sync capability, and thermal
shutdown. This high-speed IC has total propagation
delays less than 100 ns and a 1-MHz capable
oscillator.
Device Information(1)
PART NUMBER
LM5033
PACKAGE
BODY SIZE (NOM)
VSSOP (10)
3.00 mm × 3.00 mm
WSON (10)
4.00 mm × 4.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application Circuit
VIN
VOUT
LM5033
VIN
+
OUT1
OUT2
VCC
CS
REF
RT
SS
COMP
ISOLATED
FEEDBACK
GND
Copyright © 2016, Texas Instruments Incorporated
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM5033
SNVS181C – APRIL 2004 – REVISED AUGUST 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 8
7.1 Overview ................................................................... 8
7.2 Functional Block Diagram ......................................... 8
7.3 Feature Description................................................... 9
7.4 Device Functional Modes........................................ 11
8
Application and Implementation ........................ 12
8.1 Application Information............................................ 12
8.2 Typical Application .................................................. 12
9 Power Supply Recommendations...................... 15
10 Layout................................................................... 15
10.1 Layout Guidelines ................................................. 15
10.2 Layout Example .................................................... 16
11 Device and Documentation Support ................. 17
11.1
11.2
11.3
11.4
11.5
11.6
Documentation Support ........................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
17
17
17
17
17
17
12 Mechanical, Packaging, and Orderable
Information ........................................................... 17
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (April 2013) to Revision C
Page
•
Added Device Information table, Pin Configuration and Functions section, Specifications section, ESD Ratings table,
Thermal Information table, Detailed Description section, Application and Implementation section, Power Supply
Recommendations section, Layout section, Device and Documentation Support section, and Mechanical,
Packaging, and Orderable Information section ...................................................................................................................... 1
•
Deleted Ordering Information Table; see POA at the end of the datasheet .......................................................................... 1
•
Changed values in the Thermal Information table to align with JEDEC standards ............................................................... 4
Changes from Revision A (May 2005) to Revision B
•
2
Page
Changed layout of National Semiconductor Data Sheet to TI format .................................................................................... 1
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5 Pin Configuration and Functions
DGS and DPR Packages
10-Pin VSSOP and WSON
Top View
VIN
1
10
REF
2
9
RT/SYNC
COMP
3
8
CS
Thermal
SS
Pad
VCC
4
7
GND
OUT1
5
6
OUT2
Not to scale
Pin Functions
PIN
I/O
DESCRIPTION
NAME
NO.
COMP
3
I
Feedback to the inverting input of the PWM comparator, through a 3:1 divider. The output duty cycle
increases as the voltage to this pin increases. Internally there is a 5-kΩ pullup resistor to 5.2 V.
CS
8
I
Current sense input for the current limit detection. If voltage to this pin exceeds 0.5 V the outputs are
disabled and the soft-start (SS) pin is discharged to ground.
GND
7
—
Connections to external ground must be done with care for optimum performance. See Feature
Description and Application and Implementation for more information.
OUT1
5
O
Alternating output gate driver, which can source and sink 1.5 A.
OUT2
6
O
Alternating output gate driver, which can source and sink 1.5 A.
REF
2
O
Sink only, requires an external pullup resistor. This can be used as a 2.5-V precision output reference
for external circuitry.
RT/SYNC
9
I
Oscillator timing resistor pin and synchronization input. An external resistor to ground sets the oscillator
frequency. This pin also accepts AC-coupled synchronization pulses from an external source.
SS
10
I
Soft-start pin. An internal 10-µA current source and an external capacitor set the soft-start timing. This
pin can be externally pulled to below 0.5 V to disable the output drivers.
VCC
4
I/O
1
I
—
—
VIN
Exposed Pad
(1)
(1)
9.6-V output from the internal high voltage series pass regulator. An external voltage, 10 V to 15 V, can
be applied to this pin to shutdown the internal regulator, reducing internal dissipation. An internal diode
connects VCC to VIN.
Input to the start-up regulator. Input range from 15 V to 90 V, with transient capability to 100 V.
The exposed die attach pad on the WSON package must be connected to a PCB thermal pad at ground
potential. See AN-1187 Leadless Leadframe Package (LLP) (SNOA401).
Only available on the WSON package.
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6 Specifications
6.1 Absolute Maximum Ratings
see
(1)
MIN
MAX
UNIT
VIN to GND
–0.3
100
V
VCC to GND
–0.3
16
V
RT/SYNC to GND
–0.3
5.5
V
COMP, CS, and SS to GND
–0.3
7
V
Power dissipation
(2)
Internally Limited
Maximum junction temperature, TJ(MAX)
Storage temperature, Tstg
(1)
(2)
–65
150
°C
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
The maximum allowable power dissipation is a function of the maximum allowed junction temperature (TJ(max)), the ambient temperature
(TA), and the junction-to-ambient thermal resistance (θJA). The maximum allowable power dissipation can be calculated from PD =
(TJ(max) – TA) / θJA. Excessive power dissipation causes the thermal shutdown to activate.
6.2 ESD Ratings
V(ESD)
(1)
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
Electrostatic discharge
VALUE
UNIT
±2000
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
VIN
Input voltage
TJ
Operating junction temperature
MIN
MAX
15
99
UNIT
V
-40
125
°C
6.4 Thermal Information
LM5033
THERMAL METRIC (1)
DGS (VSSOP)
DPR (WSON)
UNIT
10 PINS
10 PINS
RθJA
Junction-to-ambient thermal resistance
158
38.1
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
52.2
36.7
°C/W
RθJB
Junction-to-board thermal resistance
78.1
15.2
°C/W
ψJT
Junction-to-top characterization parameter
4.8
0.3
°C/W
ψJB
Junction-to-board characterization parameter
76.8
15.5
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
—
4.7
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
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6.5 Electrical Characteristics
VIN = 48 V, VCC = 10 V (applied externally), and RT = 26.7 kΩ, Typical limits are given for TJ = 25°C, Minimum and Maximum
limits apply over TJ = –40°C to 125°C (unless otherwise noted). (1) (2)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
10
UNIT
VCC STARTUP REGULATOR
VCCReg
ICC(OUT)
VCC voltage
VCC is open
9.2
9.6
VCC current limit
OUT1 and OUT2 disabled, extended
supply to VCC disconnected
20
34
Normal operation, VIN = 90 V
IIN
Startup regulator current into VIN
150
Extended VCC supply disconnected,
output load = 1800 pF
VSS = 0 V
VCC undervoltage threshold (increasing VCC)
UVT
ICC(IN)
Supply current from external source to VCC
mA
500
µA
7
mA
3
mA
VCCReg – 300 mV
VCCReg – 100 mV
2.3
2.8
3.3
VSS = 0 V
2
3
SS is open, output load = 1800 pF
7
UVT hysteresis (decreasing VCC)
V
V
mA
2.5-V REFERENCE
VREF
Output voltage
REF sink current = 5 mA
Current sink capability
2.44
2.5
5
13
0.45
0.5
2.56
V
mA
CURRENT SENSE
CS
Threshold voltage
CS delay to output
VCS taken from zero to 0.6 V, time for
VOUT1 or VOUT2 to fall to 90% of VCC,
CLOAD = 0 at OUT1 and OUT2
Current sink capability (clocked)
VCS ≤ 0.3 V
3
0.55
V
30
ns
6
mA
SOFT START
Soft-start current source
Soft-start to COMP offset
7
10
13
µA
0.25
0.5
0.75
V
Open circuit voltage
5
V
OSCILLATOR
FS1
Internal frequency
RT = 26.7 kΩ
FS2
Internal frequency
RT = 8.2 kΩ
VSYNC
Sync threshold
175
200
225
600
3.2
RT/SYNC DC voltage
kHz
kHz
3.8
2
V
V
PWM COMPARATOR INPUT
tPWM
Gain from COMP to PWM comparator
0.34
Maximum duty cycle at OUT1 and OUT2
See PWM Comparator
Minimum duty cycle at OUT1 and OUT2
VCOMP = 0 V
Open circuit voltage
V/V
100 × (0.5 tS – tD) / tS
%
0%
4.2
5.2
6.2
V
VCOMP = 0 V
0.6
1.1
1.5
mA
Deadtime
CLOAD = 0 at OUT1 and OUT2, time
measured from 10% of falling output
to 10% of rising output
85
135
185
ns
Rise time
CLOAD = 1 nF
Fall time
CLOAD = 1 nF
Output high voltage
IOUT = 50 mA (source)
Output low voltage
IOUT = 100 mA (sink)
Short circuit current
OUTPUT DRIVERS
tD
VCC – 0.75
16
ns
16
ns
VCC – 0.25
0.25
V
0.75
V
Maximum source current
1.5
A
Maximum sink current
1.5
A
165
°C
15
°C
THERMAL SHUTDOWN
tSD
Shutdown temperature
Shutdown temperature hysteresis
(1)
(2)
Minimum and maximum limits are 100% production tested at 25°C. Limits over the operating temperature range are specified through
correlation using Statistical Quality Control (SQC) methods. Limits are used to calculate TI’s Average Outgoing Quality Level (AOQL).
Typical specifications represent the most likely parametric norm at 25°C operation.
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16
16
14
14
12
12
10
10
VCC (V)
VCC (V)
6.6 Typical Characteristics
8
8
6
6
4
4
2
2
VCC not externally powered
0
0
0
2
4
6
8
10
12
14
16
0
5
10
VIN (V)
15
20
25
30
35
40
ICC (mA)
VIN = 48 V
Figure 1. VCC vs VIN
Figure 2. VCC vs ICC
202
OSCILLATOR FREQUENCY (kHz)
OSCILLATOR FREQUENCY (kHz)
1000
201
200
199
198
100
1
10
-50
100
0
50
100
150
200
o
TEMPERATURE ( C)
RT (k:)
RT = 26.7 kΩ
Figure 3. Oscillator Frequency vs RT
Figure 4. Oscillator Frequency vs Temperature
10.4
155
150
DEADTIME (ns)
ISS (PA)
10.2
10.0
9.8
9.6
9.4
-50
140
135
130
125
0
50
100
150
o
TEMPERATURE ( C)
-50
0
50
100
150
o
TEMPERATURE ( C)
Figure 5. Soft-Start Current vs Temperature
6
145
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Figure 6. Dead Time vs Temperature
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Typical Characteristics (continued)
3.5
50
OUTPUT DUTY CYCLE (%)
3.0
40
2.5
VREF (V)
30
20
2.0
1.5
1.0
10
0.5
0
0
0
1.0
2.0
3.0
4.0
0
5.0
5
10
15
20
25
IREF (mA)
COMP PIN VOLTAGE - PIN 3 (V)
RT = 16.5 kΩ
Figure 8. VREF vs IREF
Figure 7. Output Duty Cycle vs COMP Voltage
12
10
10
Output Load = 1500 pF
8
Output Load = 1500 pF
IIN (mA)
ICC (mA)
8
6
4
6
4
Pin 10 = 0V
SS Pin = 0V
2
Output Load = 0
2
Output Load = 0 pF
0
0
10
11
12
13
14
15
VCC (V)
0
20
40
60
80
100
VIN (V)
VCC powered externally
VCC not powered externally
Figure 9. ICC vs VCC
Figure 10. IIN vs VIN
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7 Detailed Description
7.1 Overview
The LM5033 high-voltage PWM controller contains all of the features necessary to implement push-pull and
bridge topologies, using voltage-mode control in a small 10-pin package. Features include a start-up regulator,
precision 2.5-V reference output, current limit detection, alternating gate drivers, sync capability, thermal
shutdown, soft start, and remote shutdown. This high-speed IC has total propagation delays less than 100 ns.
These features simplify the design of an open-loop DC-DC converter, or a voltage controlled closed-loop
converter.
7.2 Functional Block Diagram
9.6V SERIES
REGULATOR
(1) VIN
VCC (4)
5.2V
4.9V
2.5V
0.5V
REFERENCE
GENERATOR
Disable
START UP
CIRCUIT
2.5V
REF (2)
UNDERVOLTAGE
SENSOR
THERMAL
SHUTDOWN
SENSOR
VCC
OUT2 (6)
CLK
DRIVER
(9) Rt /Sync
OSC
D
C
0.65V
Q
Q
0V
5.2V
RAMP
GENERATOR
5k
PWM
10k
(3) COMP
S SET Q
R
CLR
Q
+
-
5k
VCC
Offset
+
-
OUT1 (5)
Current Sense
SS
(8) CS
0.5V
DRIVER
+
-
GND (7)
5.0V
SS
10
A
(10) SS
LOGIC
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7.3 Feature Description
7.3.1 High Voltage Start-Up Regulator (VIN and VCC)
The LM5033 contains an internal high-voltage start-up regulator. The input pin (VIN) can be connected directly to
line voltages as high as 90 V for normal operation, and can withstand transients to 100 V. The regulator output at
VCC, 9.6 V (typical), is internally current limited to 20 mA (minimum). Upon power up, the capacitor at VCC
charges up, providing a time delay while internal circuits stabilize. When VCC reaches the upper threshold of the
undervoltage sensor (typically 9.5 V), the undervoltage sensor resets, enabling the output drivers, although the
PWM duty cycle is initially at zero. As the soft-start capacitor charges up, the output duty cycle increases until
regulated by the PWM control loop. The value of the VCC capacitor which affects the start-up delay depends on
the total system design and its start-up characteristics. TI recommends the VCC capacitor to be from 0.1 µF to
50 µF.
The lower threshold of the undervoltage sensor is typically at 6.8 V. If VCC falls below this value the outputs are
disabled and the soft-start capacitor is discharged. When VCC increases above the upper threshold the outputs
are enabled, and the soft-start sequence repeats.
The internal power dissipation of the LM5033 can be reduced by powering VCC from an external supply.
Typically this is done by means of an auxiliary transformer winding which is diode connected to the VCC pin to
provide 10 V to 15 V as the controller completes the start-up sequence. The externally applied VCC voltage
causes the internal regulator to shut off. The undervoltage sensor circuit still functions in this mode, requiring that
the external VCC capacitor be sized so that VCC never falls below 6.8 V. The required current into the VCC pin
from the external source is shown in Figure 9.
If a fault condition occurs such that the external supply to VCC fails, external current draw from the VCC pin
must be limited to not exceed the current limit of the regulator, or the maximum power dissipation of the IC. An
external start-up or other bias rail can be used instead of the internal start-up regulator by connecting the VCC
and the VIN pins together and feeding the external bias voltage, 10 V to 15 V, into that node.
7.3.2 Reference (REF)
The REF pin provides a reference voltage of 2.5 V ± 2.4%. The pin is internally connected to an NMOS FET
drain at the output of the buffer amplifier, allowing it to sink, but not source current. An external pullup resistor is
required. Current into the pin must be limited to less than 20 mA to maintain regulation (see Figure 8).
During start-up if the pullup voltage is present before the reference amplifier establishes regulation, the voltage
on REF must not exceed 5.5 V. If this reference is not used the REF pin can float or be connected to ground.
7.3.3 PWM Comparator (COMP), Duty Cycle and Deadtime
The PWM comparator compares an internal ramp signal, 0 V to 0.65 V, with the loop-error voltage derived from
the COMP pin. The COMP voltage is typically set by an external error amplifier through an optocoupler for
closed-loop applications. Internally, the voltage at the COMP pin passes through two level shifting diodes, and a
gain reducing, 3:1 resistor divider. The output of the PWM comparator provides the pulse width information to the
output drivers (OUT1 and OUT2). This comparator is optimized for speed to achieve minimum discernable duty
cycles. The output duty cycle is 0% for VCOMP < 1.5 V, and maximum for VCOMP > 3.5 V (see Figure 7). The
maximum duty cycle for each output is limited to less than 50% due to the forced deadtime. The typical deadtime
from the falling edge of one gate driver output to the rising edge of the other gate driver output is 135 ns, and
does not vary with frequency. The maximum duty cycle for each output can be calculated with Equation 1.
(0.5 ´ t S ) - t D
DC =
tS
where
•
•
tS is the period of each output
tD is the deadtime
(1)
For example, if the oscillator frequency is 200 kHz, each output cycles at 100 kHz, and tS = 10 µs. Using the
nominal deadtime of 135 ns, the maximum duty cycle at this frequency is 48.65%. Using the minimum deadtime
of 85 ns, the maximum duty cycle increases to 49.15%.
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Feature Description (continued)
When the SS pin is pulled down, internally or externally, the COMP pin voltage is pulled down with it, with a
difference of 0.5 V. When SS voltage increases the COMP voltage is allowed to increase, pulled up by an
internal 5.2-V supply through a 5-kΩ resistor.
In an open-loop application, such as an intermediate bus converter, COMP can be left open resulting in
maximum duty cycle at the output drivers.
7.3.4 Current Sense (CS)
The current sense circuit is intended to protect the power converter when an abnormal primary current is sensed
by initiating a low duty cycle hiccup mode. When the threshold, 0.5 V, at CS is exceeded the outputs are
disabled, and the soft-start capacitor is internally discharged. When the soft-start capacitor is fully discharged
and the voltage at the CS pin is below 0.5 V, the outputs are re-enabled allowing the soft-start capacitor voltage
and the output duty cycle to increase.
The external current sensing circuit must include an RC filter placed near the IC to prevent false triggering of the
current sense comparator due to transients or noise. An internal MOSFET discharges the external filter capacitor
at the conclusion of each PWM cycle to improve dynamic performance. The discharge time is equal to the
deadtime between OUT1 and OUT2 at maximum duty cycle. Additionally, CS is pulled low when VCC is below the
undervoltage threshold or when an overtemperature condition occurs.
7.3.5 Oscillator, Sync Capability (RT/SYNC)
The LM5033 oscillator frequency is set by a single external resistor (RT) connected between RT/SYNC and
ground. The value of the required RT resistor is calculated with Equation 2.
1 - 172 ´ 10 -9
FOSC
RT =
182 ´ 10 -12
where
•
FOSC is the desired oscillator frequency
(2)
The outputs (OUT1 and OUT2) alternate at half the oscillator frequency. The voltage at the RT/SYNC pin is
internally regulated to a nominal 2 V. The RT resistor must be placed as close as possible to the IC, and
connected directly to the pins (RT/SYNC and GND).
The LM5033 can be synchronized to an external clock by applying a narrow pulse to RT/SYNC. The external
clock must be a higher frequency than the free running frequency set by the RT resistor, and the pulse width
must be from 15 ns to 150 ns. The clock signal must be coupled into the RT/SYNC pin through a 100-pF
capacitor. When the synchronizing pulse transitions low-to-high, the voltage at RT/SYNC must exceed 3.8 V from
its nominal 2-V DC level. During the clock signal low time the voltage at RT/SYNC is clamped at 2 V by an
internal regulator. The RT resistor is always required, whether the oscillator is free running or externally
synchronized.
7.3.6 Soft Start (SS)
The soft-start feature allows the converter to gradually reach a steady state operating point, thereby reducing
start-up stresses and current surges. Upon turnon, after the undervoltage sensor resets at VCC, an internal
10‑µA current source charges an external capacitor at SS to generate a ramping voltage, 0 V to 5 V, which
allows the voltage on the COMP pin to increase gradually. As the COMP voltage increases the output duty cycle
increases from zero to the value required for regulation. Internally, the SS pin is pulled low when a current fault is
detected at CS, the VCC voltage is below the lower threshold of the under-voltage sensor, or when a thermal
shutdown occurs. Additionally, the SS pin can be pulled low by an external device.
In the event of a current fault, the soft-start capacitor is discharged by an internal pulldown device (see Current
Sense (CS)). The falling voltage at SS pulls down the COMP pin, ensuring a minimum output duty cycle when
the outputs are re-enabled. Then he soft-start capacitor begins to ramp up, allowing the COMP voltage to
increase. As the COMP voltage increases, the output duty cycle increases from zero to the value required for
regulation. However, if the fault condition is still present the above sequence repeats until the fault is removed.
10
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Feature Description (continued)
If the VCC voltage falls below the lower undervoltage sensor threshold, typically 6.8 V, the outputs are disabled,
and the soft-start capacitor is discharged. The falling voltage at SS pulls down the COMP pin, thereby ensuring
minimum output duty cycle when the outputs are re-enabled. After the VCC voltage increases above the upper
threshold, typically 9.5 V, the outputs are enabled, and the soft-start capacitor begins to ramp up, allowing the
COMP pin voltage to increase. The output duty cycle then increases from zero to the value required for
regulation.
In the event of a fault which results in an excessively high die temperature, an internal thermal shutdown circuit is
provided to protect the IC. See Thermal Protection for more information.
Using an externally controlled switch, the outputs (OUT1 and OUT2) can be disabled at any time by pulling SS
below 0.5 V. This pulls down the COMP pin to near ground, causing the output duty cycle to go to zero. Upon
releasing SS, the soft-start capacitor ramps up, allowing the COMP pin voltage to increase. The output duty cycle
then increases from zero to the value required for regulation.
7.3.7 OUT1 and OUT2
The LM5033 provides two alternating outputs, OUT1 and OUT2, each capable of sourcing and sinking 1.5-A
peak current. Each toggles at one-half the internal oscillator frequency. The voltage output levels are nominally
ground and VCC, minus a saturation voltage at each level which depends on the current flow.
The outputs can drive power MOSFETs directly in a push-pull application, or they can drive a high voltage gate
driver (for example, LM5100) in a bridge application.
The outputs are disabled when any of the following conditions occur:
1. An overcurrent condition is detected at CS.
2. The VCC undervoltage sensor is active.
3. An overtemperature condition is detected.
4. The voltage at SS is below 0.5 V.
7.3.8 Thermal Protection
The system design must limit the LM5033 junction temperature to not exceed 125°C during normal operation.
However, in the event of a fault which results in a higher die temperature, an internal thermal shutdown circuit is
provided to protect the IC. When thermal shutdown is activated, typically at 165°C, the IC is forced into a low
power reset state disabling the output drivers and the VCC regulator. This feature helps prevent catastrophic
failures from accidental device overheating. When the die temperature drops below 150°C, typical hysteresis is
15°C, the VCC regulator is enabled and a soft-start sequence initiates.
7.4 Device Functional Modes
The LM5033 is a versatile PWM controller that can be used as a half-bridge PWM controller or as a push-pull
PWM controller. The LM5033 delivers 180º out-of-phase ground-referenced PWM signals to the gates of power
MOSFETs. The LM5033 can also operate in conjunction with a high-side driver, for example, LM5100, to
implement in a half-bridge application.
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The following information is intended to provide guidelines for implementing the LM5033. However, final selection
of all external components is dependent on the configuration and operating characteristics of the complete power
conversion system.
8.2 Typical Application
Figure 11 shows an example circuit for a half-bridge, 200-W, DC-DC converter built in a quarter brick format. The
circuit is that of an intermediate bus converter (IBC) which operates open-loop (unregulated output), converting a
nominal 48-V input to a nominal 9-V output with a 30-mΩ output impedance. The current sense transformer (T2),
and the associated filter at the CS pin, provide overcurrent detection at approximately 23 A. The auxiliary winding
on T1 powers VCC and the LM5100’s V+ pin (once the outputs are enabled) to reduce power dissipation within
the LM5033. The LM5100 provides appropriate level shifting for Q1. Synchronous rectifiers Q3 and Q4 minimize
conduction losses in the output stage. Dual comparators U2 and U3 provide undervoltage and overvoltage
sensing at VIN. The undervoltage sense levels are 37 V increasing, and 33 V decreasing. The overvoltage sense
levels are 63 V increasing, and 61.5 V decreasing. The circuit can be shut down by taking the ON/OFF input
below 0.8 V. An external synchronizing frequency can be applied to the SYNC input. Measured efficiency and
output characteristics for this circuit are shown in Figure 14 and Figure 15.
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Figure 11. Intermediate Bus Converter
40-V to 60-V Input; 7.5-V to 11.3-V, 20-A Output
12
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Typical Application (continued)
8.2.1 Design Requirements
Table 1 lists the input parameters for this design example.
Table 1. Example Parameters
PARAMETER
MIN
NOM
MAX
UNIT
Input voltage, VIN
40
48
60
V
Output voltage, VOUT
7.5
9
11.3
V
Output current, IOUT
0
20
A
Output current limit, ILIMIT
23
Load regulation
±4%
A
Oscillator frequency
315
kHz
Switching frequency
157
kHz
8.2.2 Detailed Design Procedure
8.2.2.1 VIN
The voltage applied at VIN, normally the same as that applied to the primary of the main transformer, can be
from 15 V to 90 V, with transient capability to 100 V. The current into VIN depends not only on VIN, but also on
the load on the output driver pins, any load on VCC, and whether or not an external voltage is applied to VCC. If
VIN is close to the absolute maximum rating of the LM5033, TI recommends the circuit of Figure 12 be used to
filter transients which may occur at the input supply.
Supply
Voltage
50
VIN
0.1 PF
LM5033
Figure 12. Input Transient Protection
If VCC is not powered externally, requiring all internal bias currents for the LM5033, and output driver currents, to
be supplied at VIN and through the internal regulator, the required input current (IIN) is shown in Figure 10.
If VCC is powered externally, IIN increases with VIN as shown in Figure 9 until the external voltage is applied to
VCC. In most applications, this occurs once the outputs are enabled and load current begins to flow. The current
into VIN then drops to a nominal 150 µA; SS is either open or grounded.
8.2.2.2 VCC
The capacitor at the VCC pin provides not only noise filtering and stability, but also a necessary time delay
during start-up. The time delay allows the internal circuitry of the LM5033, and associated external circuitry, to
stabilize before VCC reaches its final value, at which time the outputs are enabled and the soft-start sequence
begins. Any external circuitry connected to the REF output and SS must be designed to stabilize during the time
delay.
The current limit of the VCC regulator, and the external capacitor, determine the VCC turnon time delay.
Typically, a 1-µF capacitor provides approximately 300 µs of delay, with larger capacitors providing
proportionately longer delays. Experimentation with the final design may be necessary to determine the minimum
value for the VCC capacitor.
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8.2.2.3 Soft Start (SS)
The capacitor at SS determines the time required for the output duty cycle to increase from zero to the final value
for regulation. The minimum acceptable time is dependent on the response of the feedback loops to the COMP
pin, as well as the characteristics of the magnetic components. If the soft-start time is too quick, the system
output could significantly overshoot its intended voltage before the loop is able to establish regulation, possibly
adversely affecting the load. Experimentation with the final design is usually necessary to determine the
minimum value for the SS capacitor.
8.2.2.4 Current Sense (CS)
This pin typically receives an input representative of the primary current from the current sense elements of the
external circuitry. The peak amplitude at this pin must be less than 0.5 V for normal operation. Filtering at this pin
must be sufficient to prevent false triggering of the current sense comparator, but not significantly delay detection
of an overcurrent condition. The filter’s capacitor at CS must not be larger than 2200 pF.
8.2.2.5 Oscillator, Sync Input (RT/SYNC)
The internal oscillator frequency is generally selected in conjunction with the system magnetic components, and
any other aspects of the system which may be affected by the frequency. The RT resistor at RT/SYNC sets the
frequency according to Equation 2. Each output (OUT1 and OUT2) switches at half the oscillator frequency. If the
required frequency value is critical in a particular application, the tolerance of the external resistor, and the
frequency tolerance indicated in Electrical Characteristics, must be taken into account when selecting the
resistor.
If the LM5033 is to be synchronized to an external clock, that signal must be coupled into RT/SYNC through a
100-pF capacitor. The RT resistor is still required in this case, and it must be selected to set the internal oscillator
to a frequency lower than the external synchronizing frequency. The amplitude of the external pulses must take
RT/SYNC above 3.8 V on the low-to-high transition but no higher than 5.5 V. The clock pulse width must be from
15 ns to 150 ns.
8.2.2.6 Deadtime Adjustment
TI recommends the circuits in Figure 13 if the application requires a change in the minimum deadtime between
the outputs. Suggested values for the resistor and capacitor at each output are 500 Ω, and 100 pF, respectively
for a nominal 50-ns change. The diodes can be 1N4148, or similar.
Reduce Deadtime
Out1
Hi
LM5033
LM5100
Out2
Li
Increase Deadtime
Out1
Hi
LM5100
LM5033
Out2
Li
Figure 13. Deadtime Adjustment
14
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100
14.0
95
12.0
VOUT (V)
EFFICIENCY (%)
8.2.3 Application Curves
90
85
VIN = 60V
10.0
VIN = 48V
8.0
40V < VIN < 60V
VIN = 40V
80
6.0
0
5
10
15
20
0
5
10
15
20
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Figure 14. Efficiency vs Output Current
Figure 15. VOUT vs Load Current and VIN
9 Power Supply Recommendations
The VCC pin requires a local decoupling capacitor that is connected to GND. This capacitor ensures stability of
the internal regulator from the VIN pin. The decoupling capacitor also provides the current pulses to drive the
gates of the external MOSFETs through the driver output (OUT1 and OUT2) pins. The decoupling capacitor must
be placed close to the VCC and GND pins, and must be tracked directly to the pins.
10 Layout
10.1 Layout Guidelines
The LM5033 current sense and PWM comparators are very fast, and as such responds to short-duration noise
pulses. Layout considerations are critical for the current sense filter. The components at COMP, CS, RT/SYNC,
and SS pins must be placed as close as possible to the IC, thereby minimizing noise pickup in the printed-circuit
tracks.
If a current sense transformer is used both leads of the transformer secondary must be routed to the sense filter
components, and to the IC pins. The ground side of the transformer must be connected through a dedicated
printed-circuit track to GND of the IC rather than through the ground plane.
If the current sense circuit employs a sense resistor in the drive transistor sources, a low-inductance resistor
must be used. In this case all the noise-sensitive low-power grounds must be connected in common near the IC,
and then a single connection made to the power ground (sense resistor ground point).
The outputs of the LM5033, or of the high-voltage gate driver (if used), must have short, direct paths to the
power MOSFETs to minimize the effects of inductance in the PCB traces.
If the internal dissipation of the LM5033 and any of the power devices produces high junction temperatures
during normal operation, good use of the PCB ground plane can help considerably to dissipate heat. The
exposed pad on the bottom of the 10-pin WSON package can be soldered to the ground plane on the PCB, and
the ground plane must extend out from beneath the IC to help dissipate the heat. The exposed pad is internally
connected to the IC substrate.
Additionally, the use of wide PCB traces where possible can help conduct heat away from the IC. Judicious
positioning of the PCB within the end product, along with use of any available air flow (forced or natural
convection) can help reduce the junction temperatures.
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10.2 Layout Example
From VIN
To Power Stage
CSS
CVIN
VIN
SS
REF
RT
CREF
RT
LM5033
COMP
CCS
CS
CVCC
VCC
GND
To Current Sense Resistor
OUT1
OUT2
To Gate Drive 2
To Gate Drive 1
To Isolated Feedback
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Figure 16. Layout Recommendation
16
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11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
For related documentation see the following:
AN-1187 Leadless Leadframe Package (LLP) (SNOA401)
11.2 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
11.3 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.4 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.5 Electrostatic Discharge Caution
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.
11.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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10-Dec-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)
Device Marking
(3)
(4/5)
(6)
LM5033MM/NOPB
ACTIVE
VSSOP
DGS
10
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
SCVB
LM5033MMX/NOPB
ACTIVE
VSSOP
DGS
10
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
SCVB
LM5033SD/NOPB
ACTIVE
WSON
DPR
10
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
5033SD
LM5033SDX/NOPB
ACTIVE
WSON
DPR
10
4500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
5033SD
(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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