LM2670SD-5.0/NOPB [TI]
具有同步的 SIMPLE SWITCHER 高效 3A 降压电压稳压器 | NHM | 14 | -40 to 125;
| 型号： | LM2670SD-5.0/NOPB |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 具有同步的 SIMPLE SWITCHER 高效 3A 降压电压稳压器 | NHM | 14 | -40 to 125 开关 控制器 开关式稳压器 开关式控制器 电源电路 开关式稳压器或控制器 |
| 文件： | 总36页 (文件大小：1459K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LM2670
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SNVS036J –APRIL 2000–REVISED APRIL 2013
®
LM2670 SIMPLE SWITCHER High Efficiency 3A Step-Down Voltage Regulator with Sync
Check for Samples: LM2670
1
FEATURES
DESCRIPTION
The LM2670 series of regulators are monolithic
integrated circuits which provide all of the active
functions for a step-down (buck) switching regulator
capable of driving up to 3A loads with excellent line
and load regulation characteristics. High efficiency
(>90%) is obtained through the use of a low ON-
resistance DMOS power switch. The series consists
of fixed output voltages of 3.3V, 5V and 12V output
version.
2
•
Efficiency Up to 94%
•
Simple and Easy to Design with (Using Off-
The-Shelf External Components)
•
•
150 mΩ DMOS Output Switch
3.3V, 5V and 12V Fixed Output and Adjustable
(1.2V to 37V) Versions
•
•
50μA Standby Current When Switched OFF
±2% Maximum Output Tolerance Over Full
Line and Load Conditions
The SIMPLE SWITCHER concept provides for a
complete design using a minimum number of external
components. The switching clock frequency can be
provided by an internal fixed frequency oscillator
(260KHz) or from an externally provided clock in the
range of 280 kHz to 400 kHz which allows the use of
physically smaller sized components. A family of
standard inductors for use with the LM2670 are
available from several manufacturers to greatly
simplify the design process. The external Sync clock
provides direct and precise control of the output ripple
frequency for consistent filtering or frequency
spectrum positioning.
•
•
Wide Input Voltage Range: 8V to 40V
External Sync Clock Capability (280kHz to
400kHz)
•
•
260 kHz Fixed Frequency Internal Oscillator
−40 to +125°C Operating Junction Temperature
Range
APPLICATIONS
•
Simple to Design, High Efficiency (>90%) Step-
Down Switching Regulators
The LM2670 series also has built in thermal
shutdown, current limiting and an ON/OFF control
input that can power down the regulator to a low
50μA quiescent current standby condition. The output
voltage is ensured to a ±2% tolerance.
•
Efficient System Pre-Regulator for Linear
Voltage Regulators
•
•
Battery Chargers
Communications and Radio Equipment
Regulator with Synchronized Clock Frequency
Typical Application
1
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.
SIMPLE SWITCHER, Switchers Made Simple are registered trademarks of Texas Instruments.
2
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 © 2000–2013, Texas Instruments Incorporated
LM2670
SNVS036J –APRIL 2000–REVISED APRIL 2013
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Connection Diagram
Figure 1. DDPAK Package (Top View)
See Package Number KTW
Figure 2. TO-220 Package (Top View)
See Package Number NDZ
VSW
VSW
VSW
1
14
13
12
11
10
9
*
VIN
VIN
CB
2
3
4
5
6
7
DAP**
*
*
*
SYNC
GND
FB
ON/OFF
8
No Connections
*
Connect to Pin 9 on PCB
**
Figure 3. VSON-14 Package (Top View)
See Package Number NHM
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.
Absolute Maximum Ratings(1)(2)
Input Supply Voltage
ON/OFF Pin Voltage
Switch Voltage to Ground(3)
Boost Pin Voltage
45V
−0.1V to 6V
−1V to VIN
VSW + 8V
Feedback Pin Voltage
Power Dissipation
ESD(4)
−0.3V to 14V
Internally Limited
2 kV
Storage Temperature Range
Soldering Temperature
−65°C to 150°C
4 sec, 260°C
10 sec, 240°C
75 sec, 219°C
Wave
Infrared
Vapor Phase
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings indicate conditions under
which of the device is ensured. Operating Ratings do not imply ensured performance limits. For ensured performance limits and
associated test condition, see the Electrical Characteristics tables
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and
specifications.
(3) The absolute maximum specification of Switch Voltage to Ground applies to DC voltage. An extended negative voltage limit of -8V
applies to a pulse of up to 20 ns, -6V of 60 ns and -3V of up to 100 ns.
(4) ESD was applied using the human-body model, a 100pF capacitor discharged through a 1.5 kΩ resistor into each pin.
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Operating Ratings
Supply Voltage
8V to 40V
Junction Temperature Range (TJ)
−40°C to 125°C
Electrical Characteristics
LM2670-3.3
Limits appearing in bold type face apply over the entire junction temperature range of operation, −40°C to 125°C.
Specifications appearing in normal type apply for TA = TJ = 25°C. Sync pin open circuited.
Symbol
VOUT
η
Parameter
Output Voltage
Efficiency
Conditions
VIN = 8V to 40V, 100mA ≤ IOUT ≤ 3A
VIN = 12V, ILOAD = 3A
Typ(1)
Min(2)
Max(2)
Units
V
3.3
3.234/3.201
3.366/3.399
86
%
(1) Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
(2) All limits are ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature
limits are 100% tested during production with TA = TJ = 25°C. All limits at temperature extremes are ensured via correlation using
standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
LM2670-5.0 Electrical Characteristics
Symbol
VOUT
η
Parameter
Output Voltage
Efficiency
Conditions
VIN = 8V to 40V, 100mA ≤ IOUT ≤ 3A
VIN = 12V, ILOAD = 3A
Typ(1)
5.0
Min(2)
Max(2)
Units
V
4.900/4.850
5.100/5.150
88
%
(1) Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
(2) All limits are ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature
limits are 100% tested during production with TA = TJ = 25°C. All limits at temperature extremes are ensured via correlation using
standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
LM2670-12 Electrical Characteristics
Symbol
VOUT
η
Parameter
Output Voltage
Efficiency
Conditions
VIN = 15V to 40V, 100mA ≤ IOUT ≤ 3A
VIN = 24V, ILOAD = 3A
Typ(1)
12
Min(2)
Max(2)
Units
V
11.76/11.64
12.24/12.36
94
%
(1) Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
(2) All limits are ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature
limits are 100% tested during production with TA = TJ = 25°C. All limits at temperature extremes are ensured via correlation using
standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).
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All Output Voltage Versions Electrical Characteristics
Limits appearing in bold type face apply over the entire junction temperature range of operation, −40°C to 125°C.
Specifications appearing in normal type apply for TA = TJ = 25°C. Unless otherwise specified VIN=12V for the 3.3V, 5V and
Adjustable versions and VIN=24V for the 12V version, Sync pin open circuited..
Symbol
Parameter
Conditions
Typ
Min
Max
Units
DEVICE PARAMETERS
IQ
Quiescent Current VFEEDBACK = 8V
4.2
6
mA
For 3.3V, 5.0V, and ADJ Versions
VFEEDBACK = 15V
For 12V Versions
ISTBY
Standby Quiescent ON/OFF Pin = 0V
Current
50
100/150
5.25/5.4
μA
ICL
IL
Current Limit
4.5
3.8/3.6
A
Output Leakage
Current
VIN = 40V, ON/OFF Pin = 0V
VSWITCH = 0V
200
15
μA
mA
16
VSWITCH = −1V
RDS(ON)
Switch On-
Resistance
ISWITCH = 3A
0.15
260
0.17/0.29
Ω
fO
D
Oscillator
Frequency
Measured at Switch Pin
225
280
kHz
Duty Cycle
Maximum Duty Cycle
Minimum Duty Cycle
91
0
%
%
IBIAS
Feedback Bias
Current
VFEEDBACK = 1.3V
ADJ Version Only
85
1.4
20
nA
V
VON/OFF
ION/OFF
FSYNC
VSYNC
ON/OFF Threshold
Voltage
0.8
2.0
45
ON/OFF Input
Current
ON/OFF Input = 0V
μA
KHz
V
Synchronization
Frequency
VSYNC(Pin 5)=3.5V, 50% Duty Cycle
400
1.4
SYNC Threshold
Voltage
θJA
θJA
θJC
θJA
θJA
θJA
θJC
θJA
θJA
Thermal
Resistance
NDZ Package, Junction to Ambient(1)
NDZ Package, Junction to Ambient(2)
NDZ Package, Junction to Case
KTW Package, Junction to Ambient(3)
KTW Package, Junction to Ambient(4)
KTW Package, Junction to Ambient(5)
KTW Package, Junction to Case
65
45
2
56
35
26
2
°C/W
++
NHM Package, Junction to Ambient(6)
NHM Package, Junction to Ambient(7)
55
29
°C/W
(1) Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with ½ inch leads in a
socket, or on a PC board with minimum copper area.
(2) Junction to ambient thermal resistance (no external heat sink) for the 7 lead TO-220 package mounted vertically, with ½ inch leads
soldered to a PC board containing approximately 4 square inches of (1 oz.) copper area surrounding the leads.
(3) Junction to ambient thermal resistance for the 7 lead DDPAK mounted horizontally against a PC board area of 0.136 square inches (the
same size as the DDPAK package) of 1 oz. (0.0014 in. thick) copper.
(4) Junction to ambient thermal resistance for the 7 lead DDPAK mounted horizontally against a PC board area of 0.4896 square inches
(3.6 times the area of the DDPAK package) of 1 oz. (0.0014 in. thick) copper.
(5) Junction to ambient thermal resistance for the 7 lead DDPAK mounted horizontally against a PC board copper area of 1.0064 square
inches (7.4 times the area of the DDPAK package) of 1 oz. (0.0014 in. thick) copper. Additional copper area will reduce thermal
resistance further. See the thermal model in Switchers Made Simple® software.
(6) Junction to ambient thermal resistance for the 14-lead VSON mounted on a PC board copper area equal to the die attach paddle.
(7) Junction to ambient thermal resistance for the 14-lead VSON mounted on a PC board copper area using 12 vias to a second layer of
copper equal to die attach paddle. Additional copper area will reduce thermal resistance further. For layout recommendations, refer to
Application Note AN-1187 SNOA401at www.ti.com/lsds/ti/analog/powermanagement/power_portal.page.
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Typical Performance Characteristics
Normalized Output Voltage
Line Regulation
Figure 4.
Figure 5.
Efficiency vs Input Voltage
Efficiency vs ILOAD
Figure 6.
Figure 7.
Switch Current Limit
Operating Quiescent Current
Figure 8.
Figure 9.
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Typical Performance Characteristics (continued)
Standby Quiescent Current
ON/OFF Threshold Voltage
Figure 10.
Figure 11.
ON/OFF Pin Current (Sourcing)
Switching Frequency
Figure 12.
Figure 13.
Continuous Mode Switching Waveforms
VIN = 20V, VOUT = 5V, ILOAD = 3A
L = 33 μH, COUT = 200 μF, COUTESR = 26 mΩ
Feedback Pin Bias Current
A: VSW Pin Voltage, 10 V/div
B: Inductor Current, 1 A/div
C: Output Ripple Voltage, 20 mV/div AC-Coupled
Figure 14.
Figure 15.
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Typical Performance Characteristics (continued)
Discontinuous Mode Switching Waveforms
VIN = 20V, VOUT = 5V, ILOAD = 500 mA
L = 10 μH, COUT = 400 μF, COUTESR = 13 mΩ
Load Transient Response for Continuous Mode
VIN = 20V, VOUT = 5V
L = 33 μH, COUT = 200 μF, COUTESR = 26 mΩ
A: Output Voltage, 100 mV//div, AC-Coupled
A: VSW Pin Voltage, 10 V/div
B: Inductor Current, 1 A/div
B: Load Current: 500 mA to 3A Load Pulse
C: Output Ripple Voltage, 20 mV/div AC-Coupled
Figure 16.
Figure 17.
Load Transient Response for Discontinuous Mode
VIN = 20V, VOUT = 5V,
L = 10 μH, COUT = 400 μF, COUTESR = 13 mΩ
A: Output Voltage, 100 mV/div, AC-Coupled
B: Load Current: 200 mA to 3A Load Pulse
Figure 18.
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Block Diagram
* Active Inductor Patent Number 5,514,947
† Active Capacitor Patent Number 5,382,918
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SNVS036J –APRIL 2000–REVISED APRIL 2013
APPLICATION HINTS
The LM2670 provides all of the active functions required for a step-down (buck) switching regulator. The internal
power switch is a DMOS power MOSFET to provide power supply designs with high current capability, up to 3A,
and highly efficient operation.
The LM2670 is part of the SIMPLE SWITCHER family of power converters. A complete design uses a minimum
number of external components, which have been pre-determined from a variety of manufacturers. Using either
this data sheet or a design software program called LM267X Made Simple (version 2.0) a complete switching
power supply can be designed quickly. The software is provided free of charge and can be downloaded from
Texas Instrument's Internet site located at www.ti.com.
SWITCH OUTPUT
This is the output of a power MOSFET switch connected directly to the input voltage. The switch provides energy
to an inductor, an output capacitor and the load circuitry under control of an internal pulse-width-modulator
(PWM). The PWM controller is internally clocked by a fixed 260KHz oscillator. In a standard step-down
application the duty cycle (Time ON/Time OFF) of the power switch is proportional to the ratio of the power
supply output voltage to the input voltage. The voltage on pin 1 switches between Vin (switch ON) and below
ground by the voltage drop of the external Schottky diode (switch OFF).
INPUT
The input voltage for the power supply is connected to pin 2. In addition to providing energy to the load the input
voltage also provides bias for the internal circuitry of the LM2670. For ensured performance the input voltage
must be in the range of 8V to 40V. For best performance of the power supply the input pin should always be
bypassed with an input capacitor located close to pin 2.
C BOOST
A capacitor must be connected from pin 3 to the switch output, pin 1. This capacitor boosts the gate drive to the
internal MOSFET above Vin to fully turn it ON. This minimizes conduction losses in the power switch to maintain
high efficiency. The recommended value for C Boost is 0.01μF.
GROUND
This is the ground reference connection for all components in the power supply. In fast-switching, high-current
applications such as those implemented with the LM2670, it is recommended that a broad ground plane be used
to minimize signal coupling throughout the circuit
SYNC
This input allows control of the switching clock frequency. If left open-circuited the regulator will be switched at
the internal oscillator frequency, between 225KHz and 280KHz. An external clock can be used to force the
switching frequency and thereby control the output ripple frequency of the regulator. This capability provides for
consistent filtering of the output ripple from system to system as well as precise frequency spectrum positioning
of the ripple frequency which is often desired in communications and radio applications. This external frequency
must be greater than the LM2670 internal oscillator frequency, which could be as high as 280KHz, to prevent an
erroneous reset of the internal ramp oscillator and PWM control of the power switch. The ramp oscillator is reset
on the positive going edge of the sync input signal. It is recommended that the external TTL or CMOS compatible
clock (between 0V and a level greater than 3V) be ac coupled to the sync input through a 100pf capacitor and a
1KΩ resistor to ground at pin 5 as shown in Figure 19.
When the SYNC function is used, current limit frequency foldback is not active. Therefore, the device my not be
fully protected against extreme output short circuit conditions. See ADDITIONAL APPLICATION INFORMATION.
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FEEDBACK
This is the input to a two-stage high gain amplifier, which drives the PWM controller. It is necessary to connect
pin 6 to the actual output of the power supply to set the dc output voltage. For the fixed output devices (3.3V, 5V
and 12V outputs), a direct wire connection to the output is all that is required as internal gain setting resistors are
provided inside the LM2670. For the adjustable output version two external resistors are required to set the dc
output voltage. For stable operation of the power supply it is important to prevent coupling of any inductor flux to
the feedback input.
ON/OFF
This input provides an electrical ON/OFF control of the power supply. Connecting this pin to ground or to any
voltage less than 0.8V will completely turn OFF the regulator. The current drain from the input supply when OFF
is only 50μA. Pin 7 has an internal pull-up current source of approximately 20μA and a protection clamp zener
diode of 7V to ground. When electrically driving the ON/OFF pin the high voltage level for the ON condition
should not exceed the 6V absolute maximum limit. When ON/OFF control is not required pin 7 should be left
open circuited.
DAP (VSON PACKAGE)
The Die Attach Pad (DAP) can and should be connected to PCB Ground plane/island. For CAD and assembly
guidelines
refer
to
Application
Note
AN-1187
SNOA401
at
www.ti.com/lsds/ti/analog/powermanagement/power_portal.page.
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DESIGN CONSIDERATIONS
Figure 19. Basic Circuit for Fixed Output Voltage Applications
Figure 20. Basic Circuit for Adjustable Output Voltage Applications
Power supply design using the LM2670 is greatly simplified by using recommended external components. A wide
range of inductors, capacitors and Schottky diodes from several manufacturers have been evaluated for use in
designs that cover the full range of capabilities (input voltage, output voltage and load current) of the LM2670. A
simple design procedure using nomographs and component tables provided in this data sheet leads to a working
design with very little effort. Alternatively, the design software, LM267X Made Simple (version 6.0), can also be
used to provide instant component selection, circuit performance calculations for evaluation, a bill of materials
component list and a circuit schematic.
The individual components from the various manufacturers called out for use are still just a small sample of the
vast array of components available in the industry. While these components are recommended, they are not
exclusively the only components for use in a design. After a close comparison of component specifications,
equivalent devices from other manufacturers could be substituted for use in an application.
Important considerations for each external component and an explanation of how the nomographs and selection
tables were developed follows.
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INDUCTOR
The inductor is the key component in a switching regulator. For efficiency the inductor stores energy during the
switch ON time and then transfers energy to the load while the switch is OFF.
Nomographs are used to select the inductance value required for a given set of operating conditions. The
nomographs assume that the circuit is operating in continuous mode (the current flowing through the inductor
never falls to zero). The magnitude of inductance is selected to maintain a maximum ripple current of 30% of the
maximum load current. If the ripple current exceeds this 30% limit the next larger value is selected.
The inductors offered have been specifically manufactured to provide proper operation under all operating
conditions of input and output voltage and load current. Several part types are offered for a given amount of
inductance. Both surface mount and through-hole devices are available. The inductors from each of the three
manufacturers have unique characteristics.
Renco: ferrite stick core inductors; benefits are typically lowest cost and can withstand ripple and transient peak
currents above the rated value. These inductors have an external magnetic field, which may generate EMI.
Pulse Engineering: powdered iron toroid core inductors; these also can withstand higher than rated currents and,
being toroid inductors, will have low EMI.
Coilcraft: ferrite drum core inductors; these are the smallest physical size inductors and are available only as
surface mount components. These inductors also generate EMI but less than stick inductors.
OUTPUT CAPACITOR
The output capacitor acts to smooth the dc output voltage and also provides energy storage. Selection of an
output capacitor, with an associated equivalent series resistance (ESR), impacts both the amount of output ripple
voltage and stability of the control loop.
The output ripple voltage of the power supply is the product of the capacitor ESR and the inductor ripple current.
The capacitor types recommended in the tables were selected for having low ESR ratings.
In addition, both surface mount tantalum capacitors and through-hole aluminum electrolytic capacitors are offered
as solutions.
Impacting frequency stability of the overall control loop, the output capacitance, in conjunction with the inductor,
creates a double pole inside the feedback loop. In addition the capacitance and the ESR value create a zero.
These frequency response effects together with the internal frequency compensation circuitry of the LM2670
modify the gain and phase shift of the closed loop system.
As a general rule for stable switching regulator circuits it is desired to have the unity gain bandwidth of the circuit
to be limited to no more than one-sixth of the controller switching frequency. With the fixed 260KHz switching
frequency of the LM2670, the output capacitor is selected to provide a unity gain bandwidth of 40KHz maximum.
Each recommended capacitor value has been chosen to achieve this result.
In some cases multiple capacitors are required either to reduce the ESR of the output capacitor, to minimize
output ripple (a ripple voltage of 1% of Vout or less is the assumed performance condition), or to increase the
output capacitance to reduce the closed loop unity gain bandwidth (to less than 40KHz). When parallel
combinations of capacitors are required it has been assumed that each capacitor is the exact same part type.
The RMS current and working voltage (WV) ratings of the output capacitor are also important considerations. In a
typical step-down switching regulator, the inductor ripple current (set to be no more than 30% of the maximum
load current by the inductor selection) is the current that flows through the output capacitor. The capacitor RMS
current rating must be greater than this ripple current. The voltage rating of the output capacitor should be
greater than 1.3 times the maximum output voltage of the power supply. If operation of the system at elevated
temperatures is required, the capacitor voltage rating may be de-rated to less than the nominal room temperature
rating. Careful inspection of the manufacturer's specification for de-rating of working voltage with temperature is
important.
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INPUT CAPACITOR
Fast changing currents in high current switching regulators place a significant dynamic load on the unregulated
power source. An input capacitor helps to provide additional current to the power supply as well as smooth out
input voltage variations.
Like the output capacitor, the key specifications for the input capacitor are RMS current rating and working
voltage. The RMS current flowing through the input capacitor is equal to one-half of the maximum dc load current
so the capacitor should be rated to handle this. Paralleling multiple capacitors proportionally increases the
current rating of the total capacitance. The voltage rating should also be selected to be 1.3 times the maximum
input voltage. Depending on the unregulated input power source, under light load conditions the maximum input
voltage could be significantly higher than normal operation and should be considered when selecting an input
capacitor.
The input capacitor should be placed very close to the input pin of the LM2670. Due to relative high current
operation with fast transient changes, the series inductance of input connecting wires or PCB traces can create
ringing signals at the input terminal which could possibly propagate to the output or other parts of the circuitry. It
may be necessary in some designs to add a small valued (0.1μF to 0.47μF) ceramic type capacitor in parallel
with the input capacitor to prevent or minimize any ringing.
CATCH DIODE
When the power switch in the LM2670 turns OFF, the current through the inductor continues to flow. The path for
this current is through the diode connected between the switch output and ground. This forward biased diode
clamps the switch output to a voltage less than ground. This negative voltage must be greater than −1V so a low
voltage drop (particularly at high current levels) Schottky diode is recommended. Total efficiency of the entire
power supply is significantly impacted by the power lost in the output catch diode. The average current through
the catch diode is dependent on the switch duty cycle (D) and is equal to the load current times (1-D). Use of a
diode rated for much higher current than is required by the actual application helps to minimize the voltage drop
and power loss in the diode.
During the switch ON time the diode will be reversed biased by the input voltage. The reverse voltage rating of
the diode should be at least 1.3 times greater than the maximum input voltage.
BOOST CAPACITOR
The boost capacitor creates a voltage used to overdrive the gate of the internal power MOSFET. This improves
efficiency by minimizing the on resistance of the switch and associated power loss. For all applications it is
recommended to use a 0.01μF/50V ceramic capacitor.
SYNC COMPONENTS
When synchronizing the LM2670 with an external clock it is recommended to connect the clock to pin 5 through
a series 100pf capacitor and connect a 1KΩ resistor to ground from pin 5. This RC network creates a short
100nS pulse on each positive edge of the clock to reset the internal ramp oscillator. The reset time of the
oscillator is approximately 300nS.
ADDITIONAL APPLICATION INFORMATION
When the output voltage is greater than approximately 6V, and the duty cycle at minimum input voltage is greater
than approximately 50%, the designer should exercise caution in selection of the output filter components. When
an application designed to these specific operating conditions is subjected to a current limit fault condition, it may
be possible to observe a large hysteresis in the current limit. This can affect the output voltage of the device until
the load current is reduced sufficiently to allow the current limit protection circuit to reset itself.
Under current limiting conditions, the LM267x is designed to respond in the following manner:
1. At the moment when the inductor current reaches the current limit threshold, the ON-pulse is immediately
terminated. This happens for any application condition.
2. However, the current limit block is also designed to momentarily reduce the duty cycle to below 50% to avoid
subharmonic oscillations, which could cause the inductor to saturate.
3. Thereafter, once the inductor current falls below the current limit threshold, there is a small relaxation time
during which the duty cycle progressively rises back above 50% to the value required to achieve regulation.
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If the output capacitance is sufficiently ‘large’, it may be possible that as the output tries to recover, the output
capacitor charging current is large enough to repeatedly re-trigger the current limit circuit before the output has
fully settled. This condition is exacerbated with higher output voltage settings because the energy requirement of
the output capacitor varies as the square of the output voltage (½CV2), thus requiring an increased charging
current.
A simple test to determine if this condition might exist for a suspect application is to apply a short circuit across
the output of the converter, and then remove the shorted output condition. In an application with properly
selected external components, the output will recover smoothly.
Practical values of external components that have been experimentally found to work well under these specific
operating conditions are COUT = 47µF, L = 22µH. It should be noted that even with these components, for a
device’s current limit of ICLIM, the maximum load current under which the possibility of the large current limit
hysteresis can be minimized is ICLIM/2. For example, if the input is 24V and the set output voltage is 18V, then for
a desired maximum current of 1.5A, the current limit of the chosen switcher must be confirmed to be at least 3A.
Under extreme over-current or short circuit conditions, the LM267X employs frequency foldback in addition to the
current limit. If the cycle-by-cycle inductor current increases above the current limit threshold (due to short circuit
or inductor saturation for example) the switching frequency will be automatically reduced to protect the IC.
Frequency below 100 KHz is typical for an extreme short circuit condition.
SIMPLE DESIGN PROCEDURE
Using the nomographs and tables in this data sheet (or use the available design software at www.ti.com) a
complete step-down regulator can be designed in a few simple steps.
Step 1: Define the power supply operating conditions:
Required output voltage
Maximum DC input voltage
Maximum output load current
Step 2: Set the output voltage by selecting a fixed output LM2670 (3.3V, 5V or 12V applications) or determine
the required feedback resistors for use with the adjustable LM2670−ADJ
Step 3: Determine the inductor required by using one of the four nomographs, Figure 21 through Figure 24.
Table 1 provides a specific manufacturer and part number for the inductor.
Step 4: Using Table 6 and Table 7 (fixed output voltage) or Table 12 and Table 13 (adjustable output voltage),
determine the output capacitance required for stable operation. Table 3 or Table 4 provide the specific capacitor
type from the manufacturer of choice.
Step 5: Determine an input capacitor from Table 8 or Table 9 for fixed output voltage applications. Use Table 3
or Table 4 to find the specific capacitor type. For adjustable output circuits select a capacitor from Table 3 or
Table 4 with a sufficient working voltage (WV) rating greater than Vin max, and an rms current rating greater than
one-half the maximum load current (2 or more capacitors in parallel may be required).
Step 6: Select a diode from Table 10. The current rating of the diode must be greater than I load max and the
Reverse Voltage rating must be greater than Vin max.
Step 7: Include a 0.01μF/50V capacitor for Cboost in the design.
FIXED OUTPUT VOLTAGE DESIGN EXAMPLE
A system logic power supply bus of 3.3V is to be generated from a wall adapter which provides an unregulated
DC voltage of 13V to 16V. The maximum load current is 2.5A. Through-hole components are preferred.
Step 1: Operating conditions are:
Vout = 3.3V
Vin max = 16V
Iload max = 2.5A
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Step 2: Select an LM2670T-3.3. The output voltage will have a tolerance of
±2% at room temperature and ±3% over the full operating temperature range.
Step 3: Use the nomograph for the 3.3V device, Figure 21. The intersection of the 16V horizontal line (Vin max)
and the 2.5A vertical line (Iload max) indicates that L33, a 22μH inductor, is required.
From Table 1, L33 in a through-hole component is available from Renco with part number RL-1283-22-43 or part
number PE-53933 from Pulse Engineering.
Step 4: Use Table 6 or Table 7 to determine an output capacitor. With a 3.3V output and a 22μH inductor there
are four through-hole output capacitor solutions with the number of same type capacitors to be paralleled and an
identifying capacitor code given. Table 3 or Table 4 provide the actual capacitor characteristics. Any of the
following choices will work in the circuit:
1 x 220μF/10V Sanyo OS-CON (code C5)
1 x 1000μF/35V Sanyo MV-GX (code C10)
1 x 2200μF/10V Nichicon PL (code C5)
1 x 1000μF/35V Panasonic HFQ (code C7)
Step 5: Use Table 8 or Table 9 to select an input capacitor. With 3.3V output and 22μH there are three through-
hole solutions. These capacitors provide a sufficient voltage rating and an rms current rating greater than 1.25A
(1/2 Iload max). Again using Table 3 or Table 4 for specific component characteristics the following choices are
suitable:
1 x 1000μF/63V Sanyo MV-GX (code C14)
1 x 820μF/63V Nichicon PL (code C24)
1 x 560μF/50V Panasonic HFQ (code C13)
Step 6: From Table 10 a 3A Schottky diode must be selected. For through-hole components 20V rated diodes
are sufficient and 2 part types are suitable:
1N5820
SR302
Step 7: A 0.01μF capacitor will be used for Cboost.
ADJUSTABLE OUTPUT DESIGN EXAMPLE
In this example it is desired to convert the voltage from a two battery automotive power supply (voltage range of
20V to 28V, typical in large truck applications) to the 14.8VDC alternator supply typically used to power electronic
equipment from single battery 12V vehicle systems. The load current required is 2A maximum. It is also desired
to implement the power supply with all surface mount components.
Step 1: Operating conditions are:
Vout = 14.8V
Vin max = 28V
Iload max = 2A
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Step 2: Select an LM2670S-ADJ. To set the output voltage to 14.9V two resistors need to be chosen (R1 and R2
in Figure 20). For the adjustable device the output voltage is set by the following relationship:
where
•
VFB is the feedback voltage of typically 1.21V
(1)
(2)
A recommended value to use for R1 is 1K. In this example then R2 is determined to be:
R2 = 11.23KΩ
The closest standard 1% tolerance value to use is 11.3KΩ
This will set the nominal output voltage to 14.88V which is within 0.5% of the target value.
Step 3: To use the nomograph for the adjustable device, Figure 24, requires a calculation of the inductor
Volt•microsecond constant (E•T expressed in V•μS) from the following formula:
where
•
VSAT is the voltage drop across the internal power switch which is Rds(ON) times Iload
(3)
In this example this would be typically 0.15Ω x 2A or 0.3V and VD is the voltage drop across the forward bisased
Schottky diode, typically 0.5V. The switching frequency of 260KHz is the nominal value to use to estimate the
ON time of the switch during which energy is stored in the inductor.
For this example E•T is found to be:
(4)
(5)
Using Figure 24, the intersection of 27V•μS horizontally and the 2A vertical line (Iload max) indicates that L38 , a
68μH inductor, should be used.
From Table 1, L38 in a surface mount component is available from Pulse Engineering with part number PE-
54038S.
Step 4: Use Table 12 or Table 13 to determine an output capacitor. With a 14.8V output the 12.5 to 15V row is
used and with a 68μH inductor there are three surface mount output capacitor solutions. Table 3 or Table 4
provides the actual capacitor characteristics based on the C Code number. Any of the following choices can be
used:
1 x 33μF/20V AVX TPS (code C6)
1 x 47μF/20V Sprague 594 (code C8)
1 x 47μF/20V Kemet T495 (code C8)
NOTE
When using the adjustable device in low voltage applications (less than 3V output), if the
nomograph, Figure 24, selects an inductance of 22μH or less, Table 12 and Table 13 do
not provide an output capacitor solution. With these conditions the number of output
capacitors required for stable operation becomes impractical. It is recommended to use
either a 33μH or 47μH inductor and the output capacitors from Table 12 or Table 13.
Step 5: An input capacitor for this example will require at least a 35V WV rating with an rms current rating of 1A
(1/2 Iout max). From Table 3 or Table 4 it can be seen that C12, a 33μF/35V capacitor from Sprague, has the
required voltage/current rating of the surface mount components.
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Step 6: From Table 10 a 3A Schottky diode must be selected. For surface mount diodes with a margin of safety
on the voltage rating one of five diodes can be used:
SK34
30BQ040
30WQ04F
MBRS340
MBRD340
Step 7: A 0.01μF capacitor will be used for Cboost.
VSON PACKAGE DEVICES
The LM2670 is offered in the 14 lead VSON surface mount package to allow for a significantly decreased
footprint with equivalent power dissipation compared to the DDPAK. For details on mounting and soldering
specifications,
refer
to
Application
Note
AN-1187
SNOA401
at
www.ti.com/lsds/ti/analog/powermanagement/power_portal.page.
Inductor Selection Guides
For Continuous Mode Operation
Figure 21. LM2670-3.3
Figure 22. LM2670-5.0
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Figure 23. LM2670-12
Figure 24. LM2670-ADJ
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Table 1. Inductor Manufacturer Part Numbers
Renco
Through Hole
Pulse Engineering
Through Surface
Hole Mount
Coilcraft
Inductor
Reference
Number
Inductance
(µH)
Current
(A)
Surface Mount
Surface Mount
L23
L24
L25
L29
L30
L31
L32
L33
L34
L38
L39
L40
L41
L44
L45
33
22
15
100
68
47
33
22
15
68
47
33
22
68
10
1.35
1.65
2.00
1.41
1.71
2.06
2.46
3.02
3.65
2.97
3.57
4.26
5.22
3.45
4.47
RL-5471-7
RL-1283-22-43
RL-1283-15-43
RL-5471-4
RL1500-33
RL1500-22
RL1500-15
RL-6050-100
RL6050-68
RL6050-47
RL6050-33
RL6050-22
—
PE-53823
PE-53824
PE-53825
PE-53829
PE-53830
PE-53831
PE-53932
PE-53933
PE-53934
PE-54038
PE-54039
PE-54040
PE-54041
PE-54044
—
PE-53823S
PE-53824S
PE-53825S
PE-53829S
PE-53830S
PE-53831S
PE-53932S
PE-53933S
PE-53934S
PE-54038S
PE-54039S
PE-54040S
P0841
DO3316-333
DO3316-223
DO3316-153
DO5022P-104
DO5022P-683
DO5022P-473
DO5022P-333
DO5022P-223
DO5022P-153
—
RL-5471-5
RL-5471-6
RL-5471-7
RL-1283-22-43
RL-1283-15-43
RL-5472-2
—
RL-5472-3
—
—
RL-1283-33-43
RL-1283-22-43
RL-5473-3
—
—
—
—
—
—
—
RL-1283-10-43
—
P0845
DO5022P-103HC
Table 2. Inductor Manufacturer Contact Numbers
Coilcraft
Phone
FAX
(800) 322-2645
(708) 639-1469
+44 1236 730 595
+44 1236 730 627
(619) 674-8100
(619) 674-8262
+353 93 24 107
+353 93 24 459
(800) 645-5828
(516) 586-5562
Coilcraft, Europe
Pulse Engineering
Pulse Engineering, Europe
Renco Electronics
Phone
FAX
Phone
FAX
Phone
FAX
Phone
FAX
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Capacitor Selection Guides
Table 3. Input and Output Capacitor Codes—Surface Mount
Surface Mount
Capacitor
Reference
Code
AVX TPS Series
Sprague 594D Series
Kemet T495 Series
C (µF)
330
100
220
47
WV (V)
6.3
10
Irms (A)
1.15
1.1
C (µF)
120
220
68
WV (V)
6.3
6.3
10
Irms (A)
C (µF)
100
220
330
100
150
220
33
WV (V)
6.3
6.3
6.3
10
Irms (A)
0.82
1.1
C1
C2
1.1
1.4
C3
10
1.15
0.89
1.15
0.77
0.94
0.77
0.63
0.66
1.05
1.35
1
1.1
C4
16
150
47
10
1.1
C5
100
33
16
16
10
1.1
C6
20
100
180
47
16
1.3
10
1.1
C7
68
20
16
1.95
1.15
1.05
1.6
20
0.78
0.94
0.94
0.63
0.63
0.66
C8
22
25
20
47
20
C9
10
35
33
25
68
20
C10
C11
C12
C13
22
35
68
25
10
35
15
35
0.75
1
22
35
33
35
4.7
50
15
50
0.9
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Table 4. Input and Output Capacitor Codes—Through Hole
Through Hole
Sanyo MV-GX Series Nichicon PL Series
Capacitor
Reference
Code
Sanyo OS-CON SA Series
Panasonic HFQ Series
C (µF)
WV (V)
Irms
(A)
C (µF)
WV (V)
Irms
(A)
C (µF)
WV (V)
Irms
(A)
C (µF)
WV (V)
Irms
(A)
C1
C2
47
6.3
6.3
6.3
10
10
16
16
16
20
25
1
1000
270
470
560
820
1000
150
470
680
1000
220
470
680
1000
6.3
16
16
16
16
16
35
35
35
35
63
63
63
63
0.8
0.6
680
820
10
10
10
10
10
10
10
10
16
16
16
16
16
16
25
35
35
35
50
50
50
63
63
63
63
0.8
82
120
220
330
560
820
1000
2200
56
35
35
35
35
35
35
35
35
50
50
50
50
50
50
63
63
0.4
0.44
0.76
1.01
1.4
150
330
100
220
33
1.95
2.45
1.87
2.36
0.96
1.92
2.28
2.25
2.09
0.98
1.06
1.28
1.71
2.18
2.36
2.68
0.41
0.55
0.77
1.02
1.22
1.88
0.63
0.79
1.43
2.68
0.82
1.04
1.3
C3
0.75
0.95
1.25
1.3
1000
1200
2200
3300
3900
6800
180
C4
C5
C6
1.62
1.73
2.8
C7
100
150
100
47
0.65
1.3
C8
C9
1.4
0.36
0.5
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
1.7
270
100
220
470
560
1200
330
1500
0.76
1.2
470
0.92
1.44
1.68
2.22
1.42
2.51
680
1.5
820
1.75
1800
220
220
560
2200
150
220
330
100
0.75
1.62
2.22
2.51
390
820
1200
Table 5. Capacitor Manufacturer Contact Numbers
Nichicon
Panasonic
AVX
Phone
FAX
(847) 843-7500
(847) 843-2798
(714) 373-7857
(714) 373-7102
(845) 448-9411
(845) 448-1943
(207) 324-4140
(207) 324-7223
(619) 661-6322
(619) 661-1055
(864) 963-6300
(864) 963-6521
Phone
FAX
Phone
FAX
Sprague/Vishay
Sanyo
Phone
FAX
Phone
FAX
Kemet
Phone
FAX
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Table 6. Output Capacitors for Fixed Output Voltage Application—Surface Mount(1)(2)
Surface Mount
Output Voltage
(V)
Inductance (µH)
AVX TPS Series
Sprague 594D Series
Kemet T495 Series
No.
C Code
C2
No.
3
C Code
C1
No.
4
C Code
C4
10
15
22
33
10
15
22
33
47
10
15
22
33
47
68
100
4
4
3
2
4
3
3
2
2
4
3
2
2
2
1
1
C2
3
C1
4
C4
3.3
C2
2
C7
3
C4
C2
2
C6
2
C4
C2
4
C6
4
C4
C2
2
C7
3
C4
5
C2
2
C7
3
C4
C2
2
C3
2
C4
C2
1
C7
2
C4
C5
3
C6
5
C9
C5
2
C7
4
C8
C5
2
C6
3
C8
12
C5
1
C7
2
C8
C4
1
C6
2
C8
C5
1
C5
2
C7
C4
1
C5
1
C8
(1) No. represents the number of identical capacitor types to be connected in parallel
(2) C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
Table 7. Output Capacitors for Fixed Output Voltage Application—Through Hole(1)(2)
Through Hole
Output
Voltage (V)
Inductance
(µH)
Sanyo OS-CON SA
Series
Sanyo MV-GX Series
Nichicon PL Series
Panasonic HFQ Series
No.
1
C Code
C3
No.
1
C Code
C10
C10
C10
C10
C10
C10
C5
No.
1
C Code
C6
No.
2
C Code
C6
10
15
22
33
10
15
22
33
47
10
15
22
33
47
68
100
1
C3
1
1
C6
2
C5
3.3
1
C5
1
1
C5
1
C7
1
C2
1
1
C13
C6
1
C5
2
C4
1
1
2
C5
1
C5
1
1
C5
1
C6
5
1
C5
1
1
C5
1
C5
1
C4
1
C5
1
C13
C13
C18
C17
C13
C11
C10
C10
C9
1
C5
1
C4
1
C4
1
2
C3
2
C7
1
C5
1
2
C5
1
C8
1
C5
1
1
C5
1
C7
1
C5
1
1
C5
12
1
C7
1
C3
1
1
C4
1
C7
1
C3
1
1
C3
1
C7
1
C2
1
1
C3
1
C7
1
C2
1
1
C1
(1) No. represents the number of identical capacitor types to be connected in parallel
(2) C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
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Table 8. Input Capacitors for Fixed Output Voltage Application—Surface Mount(1)(2)(3)
Surface Mount
Output Voltage
(V)
Inductance (µH)
AVX TPS Series
Sprague 594D Series
Kemet T495 Series
No.
C Code
C5
No.
1
C Code
C7
No.
2
C Code
10
15
22
33
10
15
22
33
47
10
15
22
33
47
68
100
2
C8
C10
C12
C12
C8
3
See(4)
See(4)
2
C9
1
C10
C13
C13
C7
3
3.3
See(4)
See(4)
C5
2
3
2
2
1
2
2
C5
1
C7
2
C8
5
3
C10
2
C12
C13
C13
C10
C10
C12
C12
C13
C13
C13
3
C11
C12
C12
C7
See(4)
See(4)
2
See(4)
See(4)
C7
2
3
1
2
2
2
2
C7
2
2
C7
3
C10
2
3
C10
C10
C12
C12
C12
12
3
C10
2
3
See(4)
See(4)
See(4)
See(4)
See(4)
See(4)
2
3
2
2
1
2
(1) Assumes worst case maximum input voltage and load current for a given inductance value
(2) No. represents the number of identical capacitor types to be connected in parallel
(3) C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
(4) Check voltage rating of capacitors to be greater than application input voltage
Table 9. Input Capacitors for Fixed Output Voltage Application—Through Hole(1)(2)(3)
Through Hole
Output
Voltage (V)
Inductance
(µH)
Sanyo OS-CON SA
Series
Sanyo MV-GX Series
Nichicon PL Series
Panasonic HFQ Series
No.
1
C Code
C7
No.
2
C Code
C4
No.
1
C Code
C5
No.
1
C Code
C6
10
15
22
33
10
15
22
33
47
10
15
22
33
47
68
100
1
C10
1
C10
C14
C12
C4
1
C18
C24
C20
C14
C14
C18
C23
C20
C18
C18
C18
C18
C23
C21
C22
1
C6
3.3
See(4)
See(4)
1
See(4)
See(4)
C7
1
1
1
C13
C12
C6
1
1
1
2
1
1
1
C7
2
C4
1
1
C6
5
See(4)
See(4)
See(4)
1
See(4)
See(4)
See(4)
C9
1
C10
C14
C12
C10
C10
C10
C10
C13
C12
C11
1
1
C13
C13
C12
C6
1
1
1
1
1
1
1
1
1
1
C10
1
1
1
C6
1
C10
1
1
1
C6
12
See(4)
See(4)
See(4)
See(4)
See(4)
See(4)
See(4)
See(4)
1
1
1
C6
1
1
1
C13
C12
C11
1
1
1
1
1
1
(1) Assumes worst case maximum input voltage and load current for a given inductance value
(2) No. represents the number of identical capacitor types to be connected in parallel
(3) C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
(4) Check voltage rating of capacitors to be greater than application input voltage
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Table 10. Schottky Diode Selection Table
Reverse
Voltage (V)
Surface Mount
5A or More
Through Hole
3A
3A
5A or More
20V
30V
40V
SK32
1N5820
SR302
SK33
MBRD835L
1N5821
31DQ03
1N5822
MBR340
31DQ04
SR403
30WQ03F
SK34
MBRB1545CT
6TQ045S
30BQ040
30WQ04F
MBRS340
MBRD340
SK35
MBR745
80SQ045
6TQ045
50V or More
MBR350
31DQ05
SR305
30WQ05F
Table 11. Diode Manufacturer Contact Numbers
International Rectifier
Phone
FAX
(310) 322-3331
(310) 322-3332
(800) 521-6274
(602) 244-6609
(516) 847-3000
(516) 847-3236
(805) 446-4800
(805) 446-4850
Motorola
Phone
FAX
General Semiconductor
Diodes, Inc.
Phone
FAX
Phone
FAX
24
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LM2670
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SNVS036J –APRIL 2000–REVISED APRIL 2013
Table 12. Output Capacitors for Adjustable Output Voltage Applications—Surface Mount(1)(2)
Surface Mount
Output Voltage (V)
Inductance (µH)
AVX TPS Series
No. C Code
Sprague 594D Series
Kemet T495 Series
No.
6
4
3
2
3
2
2
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
4
3
2
1
1
1
C Code
C2
No.
7
5
4
3
4
3
2
3
2
2
1
3
2
1
1
2
2
1
1
2
2
1
1
1
1
1
1
2
2
2
1
2
1
1
1
8
5
4
3
2
2
C Code
C3
33(3)
47(3)
33(3)
47(3)
22
7
5
4
3
4
3
2
3
2
2
1
3
2
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
C1
C1
C1
C1
C1
C1
C1
C2
C2
C2
C2
C2
C2
C3
C2
C5
C5
C5
C4
C5
C5
C5
C5
C6
C6
C6
C6
C8
C8
C8
C8
C9
C10
C9
C9
1.21 to 2.50
2.5 to 3.75
C2
C3
C2
C3
C2
C3
C2
C3
3.75 to 5
5 to 6.25
33
C2
C3
47
C2
C3
22
C3
C4
33
C3
C4
47
C3
C4
68
C3
C4
22
C4
C4
33
C3
C4
6.25 to 7.5
7.5 to 10
10 to 12.5
12.5 to 15
15 to 20
47
C4
C6
68
C3
C4
33
C6
C8
47
C6
C8
68
C6
C8
100
33
C5
C8
C6
C8
47
C6
C8
68
C6
C8
100
33
C6
C8
C8
C8
47
C8
C8
68
C8
C8
100
33
C8
C8
C10
C9
C10
C10
C10
C10
C11
C11
C11
C11
C12
C12
C12
C12
C12
C12
47
68
C9
100
33
C9
C11
C12
C12
C12
C13
C13
C13
C13
C13
C13
47
20 to 30
68
100
10
15
22
30 to 37
No Values Available
33
47
68
(1) No. represents the number of identical capacitor types to be connected in parallel
(2) C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
(3) Set to a higher value for a practical design solution. See Application Hints section
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Table 13. Output Capacitors for Adjustable Output Voltage Applications—Through Hole(1)(2)
Through Hole
Output Voltage
(V)
Inductance
(µH)
Sanyo OS-CON SA
Series
Panasonic HFQ
Series
Sanyo MV-GX Series
Nichicon PL Series
No.
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C Code
C3
No.
5
4
3
2
3
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C Code
C1
No.
5
3
3
2
3
2
1
2
2
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C Code
C3
No.
3
2
2
1
2
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C Code
33(3)
47(3)
33(3)
47(3)
22
C
C5
C5
C5
C5
C5
C5
C5
C5
C5
C5
C5
C5
C5
C5
C5
C5
C2
C2
C5
C5
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C10
C11
C10
C10
C10
C10
1.21 to 2.50
2.5 to 3.75
C2
C1
C3
C3
C1
C1
C2
C1
C3
C3
C1
C1
3.75 to 5
5 to 6.25
33
C2
C1
C1
47
C2
C1
C3
22
C5
C6
C3
33
C4
C6
C1
47
C4
C6
C3
68
C4
C6
C1
22
C5
C6
C1
33
C4
C6
C3
6.25 to 7.5
7.5 to 10
10 to 12.5
12.5 to 15
15 to 20
47
C4
C6
C1
68
C4
C2
C1
33
C7
C6
C14
C14
C14
C14
C14
C14
C9
47
C7
C6
68
C7
C2
100
33
C7
C2
C7
C6
47
C7
C2
68
C7
C2
100
33
C7
C2
C9
C9
C10
C10
C10
C10
C7
C15
C15
C15
C15
C15
C15
C15
C15
C16
C16
C16
C16
C20
C20
C20
C20
C20
C20
47
C9
68
C9
100
33
C9
C10
C10
C10
C10
47
C7
68
C7
100
33
C7
C7
47
C7
20 to 30
No Values Available
68
C7
100
10
C7
C12
C11
C11
C11
C11
C11
15
22
30 to 37
No Values Available
33
47
68
(1) No. represents the number of identical capacitor types to be connected in parallel
(2) C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
(3) Set to a higher value for a practical design solution. See Application Hints section
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SNVS036J –APRIL 2000–REVISED APRIL 2013
REVISION HISTORY
Changes from Revision I (April 2013) to Revision J
Page
•
Changed layout of National Data Sheet to TI format .......................................................................................................... 26
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Product Folder Links: LM2670
PACKAGE OPTION ADDENDUM
www.ti.com
1-Nov-2013
PACKAGING INFORMATION
Orderable Device
LM2670S-12/NOPB
LM2670S-3.3/NOPB
LM2670S-5.0
Status Package Type Package Pins Package
Eco Plan
Lead/Ball Finish
MSL Peak Temp
Op Temp (°C)
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
Device Marking
Samples
Drawing
Qty
(1)
(2)
(6)
(3)
(4/5)
ACTIVE
DDPAK/
TO-263
KTW
7
7
45
Pb-Free (RoHS
Exempt)
CU SN
CU SN
Call TI
CU SN
Call TI
CU SN
CU SN
CU SN
CU SN
CU SN
CU SN
CU SN
CU SN
CU SN
CU SN
CU SN
Call TI
Level-3-245C-168 HR
Level-3-245C-168 HR
Call TI
LM2670
S-12
ACTIVE
NRND
DDPAK/
TO-263
KTW
KTW
KTW
KTW
KTW
NHM
NHM
NHM
NHM
NHM
NHM
NHM
KTW
KTW
KTW
KTW
45
45
Pb-Free (RoHS
Exempt)
LM2670
S-3.3
DDPAK/
TO-263
7
TBD
LM2670
S-5.0
LM2670S-5.0/NOPB
LM2670S-ADJ
ACTIVE
NRND
DDPAK/
TO-263
7
45
Pb-Free (RoHS
Exempt)
Level-3-245C-168 HR
Call TI
LM2670
S-5.0
DDPAK/
TO-263
7
45
TBD
LM2670
S-ADJ
LM2670S-ADJ/NOPB
LM2670SD-12/NOPB
LM2670SD-3.3/NOPB
LM2670SD-5.0/NOPB
LM2670SD-ADJ/NOPB
LM2670SDX-3.3/NOPB
LM2670SDX-5.0/NOPB
LM2670SDX-ADJ/NOPB
LM2670SX-12/NOPB
LM2670SX-3.3/NOPB
LM2670SX-5.0/NOPB
LM2670SX-ADJ
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
NRND
DDPAK/
TO-263
7
45
Pb-Free (RoHS
Exempt)
Level-3-245C-168 HR
Level-1-260C-UNLIM
Level-1-260C-UNLIM
Level-1-260C-UNLIM
Level-1-260C-UNLIM
Level-1-260C-UNLIM
Level-1-260C-UNLIM
Level-1-260C-UNLIM
Level-3-245C-168 HR
Level-3-245C-168 HR
Level-3-245C-168 HR
Call TI
LM2670
S-ADJ
VSON
VSON
VSON
VSON
VSON
VSON
VSON
14
14
14
14
14
14
14
7
250
250
250
250
2500
2500
2500
500
500
500
500
Green (RoHS
& no Sb/Br)
S0002LB
S0002NB
S0002PB
S0002RB
S0002NB
S0002PB
S0002RB
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
DDPAK/
TO-263
Pb-Free (RoHS
Exempt)
LM2670
S-12
DDPAK/
TO-263
7
Pb-Free (RoHS
Exempt)
LM2670
S-3.3
DDPAK/
TO-263
7
Pb-Free (RoHS
Exempt)
LM2670
S-5.0
DDPAK/
TO-263
7
TBD
LM2670
S-ADJ
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
1-Nov-2013
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead/Ball Finish
MSL Peak Temp
Op Temp (°C)
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
Device Marking
Samples
Drawing
Qty
(1)
(2)
(6)
(3)
(4/5)
LM2670SX-ADJ/NOPB
LM2670T-12/NOPB
LM2670T-3.3/NOPB
LM2670T-5.0/NOPB
LM2670T-ADJ/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
7
7
7
7
500
Pb-Free (RoHS
Exempt)
CU SN
CU SN
CU SN
CU SN
CU SN
Level-3-245C-168 HR
Level-1-NA-UNLIM
Level-1-NA-UNLIM
Level-1-NA-UNLIM
Level-1-NA-UNLIM
LM2670
S-ADJ
ACTIVE
ACTIVE
ACTIVE
ACTIVE
TO-220
TO-220
TO-220
TO-220
NDZ
NDZ
NDZ
NDZ
45
45
45
45
Green (RoHS
& no Sb/Br)
LM2670
T-12
Green (RoHS
& no Sb/Br)
LM2670
T-3.3
Green (RoHS
& no Sb/Br)
LM2670
T-5.0
Green (RoHS
& no Sb/Br)
LM2670
T-ADJ
(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), Pb-Free (RoHS Exempt), 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.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame 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.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Addendum-Page 2
PACKAGE OPTION ADDENDUM
www.ti.com
1-Nov-2013
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 3
PACKAGE MATERIALS INFORMATION
www.ti.com
11-Oct-2013
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
LM2670SD-12/NOPB
LM2670SD-3.3/NOPB
LM2670SD-5.0/NOPB
LM2670SD-ADJ/NOPB
LM2670SDX-3.3/NOPB
LM2670SDX-5.0/NOPB
VSON
VSON
VSON
VSON
VSON
VSON
NHM
NHM
NHM
NHM
NHM
NHM
NHM
KTW
14
14
14
14
14
14
14
7
250
250
178.0
178.0
178.0
178.0
330.0
330.0
330.0
330.0
16.4
16.4
16.4
16.4
16.4
16.4
16.4
24.4
5.3
5.3
5.3
5.3
5.3
5.3
5.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
1.5
1.5
1.5
1.5
1.5
1.5
1.5
5.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
24.0
Q1
Q1
Q1
Q1
Q1
Q1
Q1
Q2
250
250
2500
2500
2500
500
LM2670SDX-ADJ/NOPB VSON
LM2670SX-12/NOPB
LM2670SX-3.3/NOPB
LM2670SX-5.0/NOPB
LM2670SX-ADJ
DDPAK/
TO-263
10.75 14.85
10.75 14.85
10.75 14.85
10.75 14.85
10.75 14.85
DDPAK/
TO-263
KTW
KTW
KTW
KTW
7
7
7
7
500
500
500
500
330.0
330.0
330.0
330.0
24.4
24.4
24.4
24.4
5.0
5.0
5.0
5.0
16.0
16.0
16.0
16.0
24.0
24.0
24.0
24.0
Q2
Q2
Q2
Q2
DDPAK/
TO-263
DDPAK/
TO-263
LM2670SX-ADJ/NOPB DDPAK/
TO-263
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
11-Oct-2013
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
LM2670SD-12/NOPB
LM2670SD-3.3/NOPB
LM2670SD-5.0/NOPB
LM2670SD-ADJ/NOPB
LM2670SDX-3.3/NOPB
LM2670SDX-5.0/NOPB
LM2670SDX-ADJ/NOPB
LM2670SX-12/NOPB
LM2670SX-3.3/NOPB
LM2670SX-5.0/NOPB
LM2670SX-ADJ
VSON
VSON
NHM
NHM
NHM
NHM
NHM
NHM
NHM
KTW
KTW
KTW
KTW
KTW
14
14
14
14
14
14
14
7
250
250
250
250
2500
2500
2500
500
500
500
500
500
210.0
210.0
210.0
210.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
185.0
185.0
185.0
185.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
35.0
35.0
35.0
35.0
35.0
35.0
35.0
45.0
45.0
45.0
45.0
45.0
VSON
VSON
VSON
VSON
VSON
DDPAK/TO-263
DDPAK/TO-263
DDPAK/TO-263
DDPAK/TO-263
DDPAK/TO-263
7
7
7
LM2670SX-ADJ/NOPB
7
Pack Materials-Page 2
MECHANICAL DATA
NDZ0007B
TA07B (Rev E)
www.ti.com
MECHANICAL DATA
NHM0014A
SRC14A (Rev A)
www.ti.com
MECHANICAL DATA
KTW0007B
TS7B (Rev E)
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