TI LM2670S-3.3 Lm2670 simple switcher high efficiency 3a step-down voltage regulator with sync Datasheet

LM2670
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LM2670 SIMPLE SWITCHER® High Efficiency 3A Step-Down Voltage Regulator with Sync
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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 ONresistance DMOS power switch. The series consists
of fixed output voltages of 3.3V, 5V and 12V output
version.
1
2
•
•
•
•
•
•
•
•
Efficiency Up to 94%
Simple and Easy to Design with (Using OffThe-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
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%) StepDown Switching Regulators
Efficient System Pre-Regulator for Linear
Voltage Regulators
Battery Chargers
Communications and Radio Equipment
Regulator with Synchronized Clock Frequency
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.
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.
Typical Application
1
2
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.
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.
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LM2670
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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
*
1
14
VSW
VIN
2
13
VSW
VIN
3
12
VSW
CB
4
11
*
*
5
10
*
SYNC
6
9
GND
FB
7
8
ON/OFF
DAP**
* 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
45V
ON/OFF Pin Voltage
−0.1V to 6V
Switch Voltage to Ground (3)
−1V to VIN
Boost Pin Voltage
VSW + 8V
−0.3V to 14V
Feedback Pin Voltage
Power Dissipation
ESD
Internally Limited
(4)
2 kV
−65°C to 150°C
Storage Temperature Range
Soldering Temperature
(1)
(2)
(3)
(4)
2
Wave
4 sec, 260°C
Infrared
10 sec, 240°C
Vapor Phase
75 sec, 219°C
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
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and
specifications.
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.
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
−40°C to 125°C
Junction Temperature Range (TJ)
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
Parameter
Conditions
Typ (1)
Min (2)
Max (2)
Units
3.234/3.201
3.366/3.399
V
VOUT
Output Voltage
VIN = 8V to 40V, 100mA ≤ IOUT ≤ 3A
3.3
η
Efficiency
VIN = 12V, ILOAD = 3A
86
(1)
(2)
%
Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
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
Parameter
Conditions
Typ (1)
Min (2)
Max (2)
4.900/4.850
5.100/5.150
VOUT
Output Voltage
VIN = 8V to 40V, 100mA ≤ IOUT ≤ 3A
5.0
η
Efficiency
VIN = 12V, ILOAD = 3A
88
(1)
(2)
Units
V
%
Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
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
Parameter
Conditions
Typ (1)
Min (2)
Max (2)
Units
11.76/11.64
12.24/12.36
V
VOUT
Output Voltage
VIN = 15V to 40V, 100mA ≤ IOUT ≤ 3A
12
η
Efficiency
VIN = 24V, ILOAD = 3A
94
(1)
(2)
%
Typical values are determined with TA = TJ = 25°C and represent the most likely norm.
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
4.2
6
mA
100/150
μA
5.25/5.4
A
16
200
15
μA
mA
0.15
0.17/0.29
Ω
280
kHz
DEVICE PARAMETERS
IQ
Quiescent Current
VFEEDBACK = 8V
For 3.3V, 5.0V, and ADJ Versions
VFEEDBACK = 15V
For 12V Versions
ISTBY
Standby Quiescent ON/OFF Pin = 0V
Current
50
ICL
Current Limit
4.5
IL
Output Leakage
Current
VIN = 40V, ON/OFF Pin = 0V
VSWITCH = 0V
VSWITCH = −1V
RDS(ON)
Switch OnResistance
ISWITCH = 3A
fO
Oscillator
Frequency
Measured at Switch Pin
D
Duty Cycle
Maximum Duty Cycle
91
%
Minimum Duty Cycle
0
%
IBIAS
Feedback Bias
Current
VFEEDBACK = 1.3V
ADJ Version Only
85
nA
VON/OFF
ON/OFF Threshold
Voltage
ION/OFF
ON/OFF Input
Current
ON/OFF Input = 0V
FSYNC
Synchronization
Frequency
VSYNC(Pin 5)=3.5V, 50% Duty Cycle
VSYNC
SYNC Threshold
Voltage
θJA
Thermal
Resistance
θJA
θJC
260
1.4
20
NDZ Package, Junction to Ambient (1)
65
NDZ Package, Junction to Ambient (2)
45
NDZ Package, Junction to Case
2
56
KTW Package, Junction to Ambient (4)
35
θJA
KTW Package, Junction to Ambient (5)
26
θJC
KTW Package, Junction to Case
2
θJA
NHM Package, Junction to Ambient
(6)
55
θJA
NHM Package, Junction to Ambient (7)
29
(5)
(6)
(7)
4
V
45
μA
V
KTW Package, Junction to Ambient
(4)
2.0
1.4
θJA
(3)
0.8
KHz
θJA
(2)
225
400
(3)
(1)
3.8/3.6
°C/W
++
°C/W
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.
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.
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.
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.
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.
Junction to ambient thermal resistance for the 14-lead VSON mounted on a PC board copper area equal to the die attach paddle.
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.
Feedback Pin Bias Current
Continuous Mode Switching Waveforms
VIN = 20V, VOUT = 5V, ILOAD = 3A
L = 33 μH, COUT = 200 μF, COUTESR = 26 mΩ
Figure 14.
6
A: VSW Pin Voltage, 10 V/div
B: Inductor Current, 1 A/div
C: Output Ripple Voltage, 20 mV/div AC-Coupled
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
A: VSW Pin Voltage, 10 V/div
B: Inductor Current, 1 A/div
C: Output Ripple Voltage, 20 mV/div AC-Coupled
Figure 16.
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
B: Load Current: 500 mA to 3A Load Pulse
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
8
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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 throughhole 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)
A recommended value to use for R1 is 1K. In this example then R2 is determined to be:
(2)
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 PE54038S.
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.
16
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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
Inductor
Reference
Number
Inductance
(µH)
Current
(A)
L23
33
L24
22
L25
Renco
Pulse Engineering
Through
Hole
Surface
Mount
Coilcraft
Through Hole
Surface Mount
1.35
RL-5471-7
RL1500-33
PE-53823
PE-53823S
DO3316-333
1.65
RL-1283-22-43
RL1500-22
PE-53824
PE-53824S
DO3316-223
15
2.00
RL-1283-15-43
RL1500-15
PE-53825
PE-53825S
DO3316-153
L29
100
1.41
RL-5471-4
RL-6050-100
PE-53829
PE-53829S
DO5022P-104
L30
68
1.71
RL-5471-5
RL6050-68
PE-53830
PE-53830S
DO5022P-683
L31
47
2.06
RL-5471-6
RL6050-47
PE-53831
PE-53831S
DO5022P-473
L32
33
2.46
RL-5471-7
RL6050-33
PE-53932
PE-53932S
DO5022P-333
L33
22
3.02
RL-1283-22-43
RL6050-22
PE-53933
PE-53933S
DO5022P-223
L34
15
3.65
RL-1283-15-43
—
PE-53934
PE-53934S
DO5022P-153
L38
68
2.97
RL-5472-2
—
PE-54038
PE-54038S
—
L39
47
3.57
RL-5472-3
—
PE-54039
PE-54039S
—
L40
33
4.26
RL-1283-33-43
—
PE-54040
PE-54040S
—
L41
22
5.22
RL-1283-22-43
—
PE-54041
P0841
—
L44
68
3.45
RL-5473-3
—
PE-54044
L45
10
4.47
RL-1283-10-43
—
—
—
P0845
Surface Mount
—
DO5022P-103HC
Table 2. Inductor Manufacturer Contact Numbers
Coilcraft
Coilcraft, Europe
Pulse Engineering
Pulse Engineering, Europe
Renco Electronics
Phone
(800) 322-2645
FAX
(708) 639-1469
Phone
+44 1236 730 595
FAX
+44 1236 730 627
Phone
(619) 674-8100
FAX
(619) 674-8262
Phone
+353 93 24 107
FAX
+353 93 24 459
Phone
(800) 645-5828
FAX
(516) 586-5562
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Capacitor Selection Guides
Table 3. Input and Output Capacitor Codes—Surface Mount
Capacitor
Reference
Code
20
Surface Mount
AVX TPS Series
Sprague 594D Series
Kemet T495 Series
C (µF)
WV (V)
Irms (A)
C (µF)
WV (V)
Irms (A)
C (µF)
WV (V)
Irms (A)
C1
330
6.3
1.15
120
6.3
1.1
100
6.3
0.82
C2
100
10
1.1
220
6.3
1.4
220
6.3
1.1
C3
220
10
1.15
68
10
1.05
330
6.3
1.1
C4
47
16
0.89
150
10
1.35
100
10
1.1
C5
100
16
1.15
47
16
1
150
10
1.1
C6
33
20
0.77
100
16
1.3
220
10
1.1
C7
68
20
0.94
180
16
1.95
33
20
0.78
C8
22
25
0.77
47
20
1.15
47
20
0.94
C9
10
35
0.63
33
25
1.05
68
20
0.94
C10
22
35
0.66
68
25
1.6
10
35
0.63
C11
15
35
0.75
22
35
0.63
C12
33
35
1
4.7
50
0.66
C13
15
50
0.9
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Table 4. Input and Output Capacitor Codes—Through Hole
Through Hole
Capacitor
Reference
Code
Sanyo OS-CON SA Series
C (µF)
WV (V)
C1
47
C2
150
C3
C4
C5
Sanyo MV-GX Series
Nichicon PL Series
Irms
(A)
C (µF)
WV (V)
Irms
(A)
C (µF)
WV (V)
6.3
1
1000
6.3
0.8
680
10
6.3
1.95
270
16
0.6
820
10
330
6.3
2.45
470
16
0.75
1000
10
100
10
1.87
560
16
0.95
1200
10
220
10
2.36
820
16
1.25
2200
C6
33
16
0.96
1000
16
1.3
C7
100
16
1.92
150
35
0.65
C8
150
16
2.28
470
35
C9
100
20
2.25
680
35
C10
47
25
2.09
Irms
(A)
Panasonic HFQ Series
C (µF)
WV (V)
Irms
(A)
0.8
82
35
0.4
0.98
120
35
0.44
1.06
220
35
0.76
1.28
330
35
1.01
10
1.71
560
35
1.4
3300
10
2.18
820
35
1.62
3900
10
2.36
1000
35
1.73
1.3
6800
10
2.68
2200
35
2.8
1.4
180
16
0.41
56
50
0.36
1000
35
1.7
270
16
0.55
100
50
0.5
C11
220
63
0.76
470
16
0.77
220
50
0.92
C12
470
63
1.2
680
16
1.02
470
50
1.44
C13
680
63
1.5
820
16
1.22
560
50
1.68
C14
1000
63
1.75
1800
16
1.88
1200
50
2.22
C15
220
25
0.63
330
63
1.42
C16
220
35
0.79
1500
63
2.51
C17
560
35
1.43
C18
2200
35
2.68
C19
150
50
0.82
C20
220
50
1.04
C21
330
50
1.3
C22
100
63
0.75
C23
390
63
1.62
C24
820
63
2.22
C25
1200
63
2.51
Table 5. Capacitor Manufacturer Contact Numbers
Nichicon
Panasonic
AVX
Sprague/Vishay
Sanyo
Kemet
Phone
(847) 843-7500
FAX
(847) 843-2798
Phone
(714) 373-7857
FAX
(714) 373-7102
Phone
(845) 448-9411
FAX
(845) 448-1943
Phone
(207) 324-4140
FAX
(207) 324-7223
Phone
(619) 661-6322
FAX
(619) 661-1055
Phone
(864) 963-6300
FAX
(864) 963-6521
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Table 6. Output Capacitors for Fixed Output Voltage Application—Surface Mount (1) (2)
Surface Mount
Output Voltage
(V)
Inductance (µH)
3.3
5
12
(1)
(2)
AVX TPS Series
Sprague 594D Series
Kemet T495 Series
No.
C Code
No.
C Code
No.
C Code
10
4
C2
3
C1
4
C4
15
4
C2
3
C1
4
C4
22
3
C2
2
C7
3
C4
33
2
C2
2
C6
2
C4
10
4
C2
4
C6
4
C4
15
3
C2
2
C7
3
C4
22
3
C2
2
C7
3
C4
33
2
C2
2
C3
2
C4
47
2
C2
1
C7
2
C4
10
4
C5
3
C6
5
C9
15
3
C5
2
C7
4
C8
22
2
C5
2
C6
3
C8
33
2
C5
1
C7
2
C8
47
2
C4
1
C6
2
C8
68
1
C5
1
C5
2
C7
100
1
C4
1
C5
1
C8
No. represents the number of identical capacitor types to be connected in parallel
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)
3.3
5
12
(1)
(2)
22
Inductance
(µH)
Sanyo OS-CON SA
Series
Sanyo MV-GX Series
Nichicon PL Series
Panasonic HFQ Series
No.
C Code
No.
C Code
No.
C Code
No.
C Code
10
1
C3
1
C10
1
C6
2
C6
15
1
C3
1
C10
1
C6
2
C5
22
1
C5
1
C10
1
C5
1
C7
33
1
C2
1
C10
1
C13
1
C5
10
2
C4
1
C10
1
C6
2
C5
15
1
C5
1
C10
1
C5
1
C6
22
1
C5
1
C5
1
C5
1
C5
33
1
C4
1
C5
1
C13
1
C5
47
1
C4
1
C4
1
C13
2
C3
10
2
C7
1
C5
1
C18
2
C5
15
1
C8
1
C5
1
C17
1
C5
22
1
C7
1
C5
1
C13
1
C5
33
1
C7
1
C3
1
C11
1
C4
47
1
C7
1
C3
1
C10
1
C3
68
1
C7
1
C2
1
C10
1
C3
100
1
C7
1
C2
1
C9
1
C1
No. represents the number of identical capacitor types to be connected in parallel
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)
3.3
5
12
(1)
(2)
(3)
(4)
AVX TPS Series
Sprague 594D Series
Kemet T495 Series
No.
C Code
No.
C Code
No.
10
2
C5
1
C7
2
C8
15
3
C9
1
C10
3
C10
22
See (4)
See (4)
2
C13
3
C12
33
See
(4)
(4)
2
C13
2
C12
10
2
C5
1
C7
2
C8
15
2
C5
1
C7
2
C8
See
C Code
22
3
C10
2
C12
3
C11
33
See (4)
See (4)
2
C13
3
C12
47
See (4)
See (4)
1
C13
2
C12
10
2
C7
2
C10
2
C7
15
2
C7
2
C10
2
C7
22
3
C10
2
C12
3
C10
33
3
C10
(4)
See
2
C12
3
C10
(4)
47
See
2
C13
3
C12
68
See (4)
See (4)
2
C13
2
C12
100
See (4)
See (4)
1
C13
2
C12
Assumes worst case maximum input voltage and load current for a given inductance value
No. represents the number of identical capacitor types to be connected in parallel
C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
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
No.
3.3
5
12
(1)
(2)
(3)
(4)
Sanyo MV-GX Series
C Code
No.
Nichicon PL Series
C Code
No.
Panasonic HFQ Series
C Code
No.
C Code
C6
10
1
C7
2
C4
1
C5
1
15
1
C10
1
C10
1
C18
1
C6
22
See (4)
See (4)
1
C14
1
C24
1
C13
33
See (4)
See (4)
1
C12
1
C20
1
C12
10
1
C7
2
C4
1
C14
1
C6
15
1
C7
2
C4
1
C14
1
C6
(4)
(4)
22
See
1
C10
1
C18
1
C13
33
See (4)
See
See (4)
1
C14
1
C23
1
C13
47
See (4)
See (4)
1
C12
1
C20
1
C12
10
1
C9
1
C10
1
C18
1
C6
15
1
C10
1
C10
1
C18
1
C6
22
1
C10
1
C10
1
C18
1
C6
33
See (4)
See (4)
1
C10
1
C18
1
C6
47
See
(4)
(4)
1
C13
1
C23
1
C13
68
See (4)
See (4)
1
C12
1
C21
1
C12
100
See (4)
See (4)
1
C11
1
C22
1
C11
See
Assumes worst case maximum input voltage and load current for a given inductance value
No. represents the number of identical capacitor types to be connected in parallel
C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
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
3A
20V
SK32
30V
SK33
Through Hole
5A or More
3A
5A or More
1N5820
SR302
MBRD835L
30WQ03F
40V
1N5821
31DQ03
SK34
MBRB1545CT
1N5822
30BQ040
6TQ045S
MBR340
MBR745
30WQ04F
31DQ04
80SQ045
MBRS340
SR403
6TQ045
MBRD340
50V or More
SK35
MBR350
30WQ05F
31DQ05
SR305
Table 11. Diode Manufacturer Contact Numbers
International Rectifier
Motorola
General Semiconductor
Diodes, Inc.
24
Phone
(310) 322-3331
FAX
(310) 322-3332
Phone
(800) 521-6274
FAX
(602) 244-6609
Phone
(516) 847-3000
FAX
(516) 847-3236
Phone
(805) 446-4800
FAX
(805) 446-4850
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Copyright © 2000–2013, Texas Instruments Incorporated
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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)
1.21 to 2.50
2.5 to 3.75
3.75 to 5
5 to 6.25
6.25 to 7.5
7.5 to 10
10 to 12.5
12.5 to 15
15 to 20
20 to 30
30 to 37
(1)
(2)
(3)
Inductance (µH)
AVX TPS Series
Sprague 594D Series
Kemet T495 Series
No.
C Code
No.
C Code
No.
C Code
33 (3)
7
C1
6
C2
7
C3
47 (3)
5
C1
4
C2
5
C3
33 (3)
4
C1
3
C2
4
C3
(3)
47
3
C1
2
C2
3
C3
22
4
C1
3
C2
4
C3
33
3
C1
2
C2
3
C3
47
2
C1
2
C2
2
C3
22
3
C2
1
C3
3
C4
33
2
C2
2
C3
2
C4
47
2
C2
2
C3
2
C4
68
1
C2
1
C3
1
C4
22
3
C2
1
C4
3
C4
33
2
C2
1
C3
2
C4
47
1
C3
1
C4
1
C6
68
1
C2
1
C3
1
C4
33
2
C5
1
C6
2
C8
47
1
C5
1
C6
2
C8
68
1
C5
1
C6
1
C8
100
1
C4
1
C5
1
C8
33
1
C5
1
C6
2
C8
47
1
C5
1
C6
2
C8
68
1
C5
1
C6
1
C8
100
1
C5
1
C6
1
C8
33
1
C6
1
C8
1
C8
47
1
C6
1
C8
1
C8
68
1
C6
1
C8
1
C8
100
1
C6
1
C8
1
C8
33
1
C8
1
C10
2
C10
47
1
C8
1
C9
2
C10
68
1
C8
1
C9
2
C10
100
1
C8
1
C9
1
C10
33
2
C9
2
C11
2
C11
47
1
C10
1
C12
1
C11
68
1
C9
1
C12
1
C11
100
1
C9
1
C12
1
C11
10
4
C13
8
C12
15
3
C13
5
C12
22
2
C13
4
C12
1
C13
3
C12
47
1
C13
2
C12
68
1
C13
2
C12
33
No Values Available
No. represents the number of identical capacitor types to be connected in parallel
C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
Set to a higher value for a practical design solution. See Application Hints section
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SNVS036J – APRIL 2000 – REVISED APRIL 2013
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Table 13. Output Capacitors for Adjustable Output Voltage Applications—Through Hole (1) (2)
Through Hole
Output Voltage
(V)
1.21 to 2.50
2.5 to 3.75
3.75 to 5
5 to 6.25
6.25 to 7.5
7.5 to 10
10 to 12.5
12.5 to 15
15 to 20
Inductance
(µH)
Sanyo OS-CON SA
Series
30 to 37
(1)
(2)
(3)
26
Nichicon PL Series
Panasonic HFQ
Series
No.
C Code
No.
C Code
No.
C Code
No.
33 (3)
2
C3
5
C1
5
C3
3
C
47 (3)
2
C2
4
C1
3
C3
2
C5
33 (3)
1
C3
3
C1
3
C1
2
C5
47 (3)
1
C2
2
C1
2
C3
1
C5
22
1
C3
3
C1
3
C1
2
C5
33
1
C2
2
C1
2
C1
1
C5
47
1
C2
2
C1
1
C3
1
C5
22
1
C5
2
C6
2
C3
2
C5
33
1
C4
1
C6
2
C1
1
C5
47
1
C4
1
C6
1
C3
1
C5
68
1
C4
1
C6
1
C1
1
C5
22
1
C5
1
C6
2
C1
1
C5
33
1
C4
1
C6
1
C3
1
C5
47
1
C4
1
C6
1
C1
1
C5
68
1
C4
1
C2
1
C1
1
C5
33
1
C7
1
C6
1
C14
1
C5
47
1
C7
1
C6
1
C14
1
C5
68
1
C7
1
C2
1
C14
1
C2
100
1
C7
1
C2
1
C14
1
C2
33
1
C7
1
C6
1
C14
1
C5
47
1
C7
1
C2
1
C14
1
C5
68
1
C7
1
C2
1
C9
1
C2
100
1
C7
1
C2
1
C9
1
C2
33
1
C9
1
C10
1
C15
1
C2
47
1
C9
1
C10
1
C15
1
C2
C Code
68
1
C9
1
C10
1
C15
1
C2
100
1
C9
1
C10
1
C15
1
C2
33
1
C10
1
C7
1
C15
1
C2
47
1
C10
1
C7
1
C15
1
C2
68
1
C10
1
C7
1
C15
1
C2
100
1
C10
1
C7
1
C15
1
C2
1
C7
1
C16
1
C2
1
C7
1
C16
1
C2
1
C7
1
C16
1
C2
100
1
C7
1
C16
1
C2
10
1
C12
1
C20
1
C10
15
1
C11
1
C20
1
C11
22
1
C11
1
C20
1
C10
1
C11
1
C20
1
C10
47
1
C11
1
C20
1
C10
68
1
C11
1
C20
1
C10
33
20 to 30
Sanyo MV-GX Series
47
68
33
No Values Available
No Values Available
No. represents the number of identical capacitor types to be connected in parallel
C Code indicates the Capacitor Reference number in Table 3 or Table 4 for identifying the specific component from the manufacturer
Set to a higher value for a practical design solution. See Application Hints section
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Copyright © 2000–2013, Texas Instruments Incorporated
Product Folder Links: LM2670
LM2670
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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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27
PACKAGE OPTION ADDENDUM
www.ti.com
1-Nov-2013
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LM2670S-12/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
45
Pb-Free (RoHS
Exempt)
CU SN
Level-3-245C-168 HR
-40 to 125
LM2670
S-12
LM2670S-3.3/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
45
Pb-Free (RoHS
Exempt)
CU SN
Level-3-245C-168 HR
-40 to 125
LM2670
S-3.3
LM2670S-5.0
NRND
DDPAK/
TO-263
KTW
7
45
TBD
Call TI
Call TI
-40 to 125
LM2670
S-5.0
LM2670S-5.0/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
45
Pb-Free (RoHS
Exempt)
CU SN
Level-3-245C-168 HR
-40 to 125
LM2670
S-5.0
LM2670S-ADJ
NRND
DDPAK/
TO-263
KTW
7
45
TBD
Call TI
Call TI
-40 to 125
LM2670
S-ADJ
LM2670S-ADJ/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
45
Pb-Free (RoHS
Exempt)
CU SN
Level-3-245C-168 HR
-40 to 125
LM2670
S-ADJ
LM2670SD-12/NOPB
ACTIVE
VSON
NHM
14
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
S0002LB
LM2670SD-3.3/NOPB
ACTIVE
VSON
NHM
14
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
S0002NB
LM2670SD-5.0/NOPB
ACTIVE
VSON
NHM
14
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
S0002PB
LM2670SD-ADJ/NOPB
ACTIVE
VSON
NHM
14
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
S0002RB
LM2670SDX-3.3/NOPB
ACTIVE
VSON
NHM
14
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
S0002NB
LM2670SDX-5.0/NOPB
ACTIVE
VSON
NHM
14
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
S0002PB
LM2670SDX-ADJ/NOPB
ACTIVE
VSON
NHM
14
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
S0002RB
LM2670SX-12/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
500
Pb-Free (RoHS
Exempt)
CU SN
Level-3-245C-168 HR
-40 to 125
LM2670
S-12
LM2670SX-3.3/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
500
Pb-Free (RoHS
Exempt)
CU SN
Level-3-245C-168 HR
-40 to 125
LM2670
S-3.3
LM2670SX-5.0/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
500
Pb-Free (RoHS
Exempt)
CU SN
Level-3-245C-168 HR
-40 to 125
LM2670
S-5.0
LM2670SX-ADJ
NRND
DDPAK/
TO-263
KTW
7
500
TBD
Call TI
Call TI
-40 to 125
LM2670
S-ADJ
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
Orderable Device
1-Nov-2013
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LM2670SX-ADJ/NOPB
ACTIVE
DDPAK/
TO-263
KTW
7
500
Pb-Free (RoHS
Exempt)
CU SN
Level-3-245C-168 HR
-40 to 125
LM2670
S-ADJ
LM2670T-12/NOPB
ACTIVE
TO-220
NDZ
7
45
Green (RoHS
& no Sb/Br)
CU SN
Level-1-NA-UNLIM
-40 to 125
LM2670
T-12
LM2670T-3.3/NOPB
ACTIVE
TO-220
NDZ
7
45
Green (RoHS
& no Sb/Br)
CU SN
Level-1-NA-UNLIM
-40 to 125
LM2670
T-3.3
LM2670T-5.0/NOPB
ACTIVE
TO-220
NDZ
7
45
Green (RoHS
& no Sb/Br)
CU SN
Level-1-NA-UNLIM
-40 to 125
LM2670
T-5.0
LM2670T-ADJ/NOPB
ACTIVE
TO-220
NDZ
7
45
Green (RoHS
& no Sb/Br)
CU SN
Level-1-NA-UNLIM
-40 to 125
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
Samples
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
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
LM2670SD-12/NOPB
VSON
NHM
14
250
178.0
16.4
5.3
6.3
1.5
12.0
16.0
Q1
LM2670SD-3.3/NOPB
VSON
NHM
14
250
178.0
16.4
5.3
6.3
1.5
12.0
16.0
Q1
LM2670SD-5.0/NOPB
VSON
NHM
14
250
178.0
16.4
5.3
6.3
1.5
12.0
16.0
Q1
LM2670SD-ADJ/NOPB
VSON
NHM
14
250
178.0
16.4
5.3
6.3
1.5
12.0
16.0
Q1
LM2670SDX-3.3/NOPB
VSON
NHM
14
2500
330.0
16.4
5.3
6.3
1.5
12.0
16.0
Q1
LM2670SDX-5.0/NOPB
VSON
NHM
14
2500
330.0
16.4
5.3
6.3
1.5
12.0
16.0
Q1
LM2670SDX-ADJ/NOPB
VSON
NHM
14
2500
330.0
16.4
5.3
6.3
1.5
12.0
16.0
Q1
LM2670SX-12/NOPB
DDPAK/
TO-263
KTW
7
500
330.0
24.4
10.75
14.85
5.0
16.0
24.0
Q2
LM2670SX-3.3/NOPB
DDPAK/
TO-263
KTW
7
500
330.0
24.4
10.75
14.85
5.0
16.0
24.0
Q2
LM2670SX-5.0/NOPB
DDPAK/
TO-263
KTW
7
500
330.0
24.4
10.75
14.85
5.0
16.0
24.0
Q2
LM2670SX-ADJ
DDPAK/
TO-263
KTW
7
500
330.0
24.4
10.75
14.85
5.0
16.0
24.0
Q2
LM2670SX-ADJ/NOPB
DDPAK/
TO-263
KTW
7
500
330.0
24.4
10.75
14.85
5.0
16.0
24.0
Q2
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
VSON
NHM
14
250
210.0
185.0
35.0
LM2670SD-3.3/NOPB
VSON
NHM
14
250
210.0
185.0
35.0
LM2670SD-5.0/NOPB
VSON
NHM
14
250
210.0
185.0
35.0
LM2670SD-ADJ/NOPB
VSON
NHM
14
250
210.0
185.0
35.0
LM2670SDX-3.3/NOPB
VSON
NHM
14
2500
367.0
367.0
35.0
LM2670SDX-5.0/NOPB
VSON
NHM
14
2500
367.0
367.0
35.0
LM2670SDX-ADJ/NOPB
VSON
NHM
14
2500
367.0
367.0
35.0
LM2670SX-12/NOPB
DDPAK/TO-263
KTW
7
500
367.0
367.0
45.0
LM2670SX-3.3/NOPB
DDPAK/TO-263
KTW
7
500
367.0
367.0
45.0
LM2670SX-5.0/NOPB
DDPAK/TO-263
KTW
7
500
367.0
367.0
45.0
LM2670SX-ADJ
DDPAK/TO-263
KTW
7
500
367.0
367.0
45.0
LM2670SX-ADJ/NOPB
DDPAK/TO-263
KTW
7
500
367.0
367.0
45.0
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)
BOTTOM SIDE OF PACKAGE
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