Order
Now
Product
Folder
Support &
Community
Tools &
Software
Technical
Documents
LM2623
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
LM2623 General-Purpose, Gated-Oscillator-Based DC-DC Boost Converter
1 Features
3 Description
•
•
•
•
•
•
•
•
•
•
The LM2623 is a high-efficiency, general-purpose,
step-up DC-DC switching regulator for batterypowered and low input voltage systems. It accepts an
input voltage between 0.8 V and 14 V and converts it
into a regulated output voltage between 1.24 V and
14 V. Efficiencies up to 90% are achievable with the
LM2623.
1
•
•
•
Good Efficiency Over a Very Wide Load Range
Very Low Output Voltage Ripple
Up to 2-MHz Switching Frequency
0.8-V to 14-V Operating Voltage
1.1-V Start-up Voltage
1.24-V to 14-V Adjustable Output Voltage
Up to 2-A Load Current at Low Output Voltages
0.17-Ω Internal MOSFET
Up to 90% Regulator Efficiency
80-µA Typical Operating Current (Into VDD Pin of
Supply)
< 2.5-µA Ensured Supply Current In Shutdown
Small 8-Pin VSSOP Package (Half the Footprint
of Standard 8-Pin SOIC Package); 1.09-mm
Package Height
4-mm × 4-mm Thermally Enhanced WSON
Package Option
In order to adapt to a number of applications, the
LM2623 allows the designer to vary the output
voltage, the operating frequency (300 kHz to 2 MHz)
and duty cycle (17% to 90%) to optimize the part's
performance. The selected values can be fixed or can
vary with battery voltage or input to output voltage
ratio. The LM2623 uses a very simple, on/off
regulation mode to produce good efficiency and
stable operation over a wide operating range. It
normally regulates by skipping switching cycles when
it reaches the regulation limit (Pulse Frequency
Modulation).
Note: See Non-Linear Effect and Choosing The
Correct C3 Capacitor so that any challenges with
designing with this part can be taken into account
before a board design/layout is finalized.
2 Applications
•
•
•
•
•
•
•
Cameras, Pagers and Cell Phones
PDAs, Palmtop Computers, GPS devices
White LED Drive, TFT, or Scanned LCDs
Flash Memory Programming
Hand-Held Instruments
1, 2, 3, or 4 Cell Alkaline Systems
1, 2, or 3 Cell Lithium-ion Systems
For alternative solutions, See Also: LM2700, LM2622,
LM2731, LM2733, and LM2621.
Device Information(1)
PART NUMBER
LM2623
PACKAGE
BODY SIZE (NOM)
WSON (14)
4.00 mm × 4.00 mm
VSSOP (8)
3.00 mm × 3.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application Circuit
D1
L1
4.7PH
R3
150k
3A
C3
V IN
2 Cells
4.7pF
+ C1
22PF
8
SW
3
BOOT
FREQ
EN
LM2623
1
V DD
PGND
FB
7
5V
2
6
C2
100PF
tant
RF1
300k
4
SGND
5
RF2
100k
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM2623
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration And Functions ........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
5
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 7
7.1
7.2
7.3
7.4
Overview ...................................................................
Functional Block Diagram .........................................
Feature Description...................................................
Device Functional Modes..........................................
7
7
7
9
8
Applications And Implementation...................... 10
8.1 Application Information............................................ 10
8.2 Typical Application .................................................. 10
9 Power Supply Recommendations...................... 12
10 Layout................................................................... 12
10.1 Layout Guidelines ................................................. 12
10.2 Layout Example .................................................... 13
10.3 WSON Package Devices ...................................... 13
11 Device And Documentation Support................. 14
11.1
11.2
11.3
11.4
11.5
11.6
11.7
Device Support......................................................
Documentation Support ........................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
14
14
14
14
14
14
14
12 Mechanical, Packaging, And Orderable
Information ........................................................... 14
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision H (November 2014) to Revision I
Page
•
Changed Handling Ratings table to ESD Ratings to comply with current format .................................................................. 4
•
Moved Storage temperature spec to Abs Max table ............................................................................................................. 4
•
Added separate row for SW pin HBM ESD rating ................................................................................................................. 4
•
Added condition to Recommended Operating Conditions table ............................................................................................ 4
•
Changed Updated RθJA value for NHE package from "40 – 56" to "46.5"°C/W and DGK package from "240" to
152.5" °C/W; added additional thermal information................................................................................................................ 4
Changes from Revision G (December 2005) to Revision H
•
2
Page
Added Device Information and Handling Rating tables, Feature Description, Device Functional Modes, Application
and Implementation, Power Supply Recommendations, Layout, Device and Documentation Support, and
Mechanical, Packaging, and Orderable Information sections; moved some curves to Application Curves section .............. 1
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
LM2623
www.ti.com
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
5 Pin Configuration And Functions
NHE Package
14-Pin WSON
Top View
DGK Package
8-Pin VSSOP
Top View
Pin Functions
PIN
NAME
TYPE
DESCRIPTION
WSON
VSSOP
1
—
NC
N/A
No Connect
2, 3
1
PGND
GND
Power Ground (WSON Pins 2 and 3 must be shorted together).
4
2
EN
Digital
Active-Low Shutdown Input
5
3
FREQ
Analog
Frequency Adjust. An external resistor connected between this pin and a
voltage source sets the switching frequency of the LM2623.
6
4
FB
Analog
Output Voltage Feedback
7
—
NC
N/A
No Connect
8
—
NC
N/A
No connect
9
5
SGND
GND
Signal Ground
10
6
VDD
Power
Power Supply for Internal Circuitry
11
7
BOOT
Analog
Bootstrap Supply for the Gate Drive of Internal MOSFET Power Switch
12, 13
8
SW
Analog
Drain of the Internal MOSFET Power Switch. (WSON pins 12 and 13 must
be shorted together.)
14
—
NC
N/A
DAP
—
DAP
Thermal
No Connect
To be soldered to board for enhanced thermal dissipation. To be
electrically isolated/floating.
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
3
LM2623
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
www.ti.com
6 Specifications
6.1 Absolute Maximum Ratings (1) (2)
MIN
MAX
UNIT
SW pin voltage
–0.5
14.5
V
BOOT, VDD, EN and FB pins
–0.5
10
V
FREQ pin
100
µA
TJmax (3)
150
°C
Lead temp. (soldering, 5 sec)
260
°C
Power dissipation (TA=25°C) (3)
500
mW
150
°C
Storage temperature, Tstg
(1)
(2)
(3)
–65
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If Military/Aerospace specified devices are required, contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
The maximum power dissipation must be derated at elevated temperatures and is dictated by Tjmax (maximum junction temperature),
RθJA (junction-to-ambient thermal resistance), and TA (ambient temperature). The maximum allowable power dissipation at any
temperature is Pdmax = (Tjmax – TA) / RθJA or the number given in the Absolute Maximum Ratings, whichever is lower.
6.2 ESD Ratings
VALUE
Electrostatic
discharge
V(ESD)
Human-body model (HBM), per
ANSI/ESDA/JEDEC JS-001 (1)
Charged-device model (CDM), per JEDEC
specification JESD22-C101 (2)
(1)
(2)
All pins except SW pin
±2000
SW pin (VSSOP package pin 8)
(WSON package pin 12 and pin
13)
±1000
All pins
±500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
VDD pin
3
5
FB, EN pins
0
VDD
0
10
V
−40
85
°C
BOOT pin
Ambient temperature (TA)
(1)
V
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
6.4 Thermal Information
LM2623
THERMAL METRIC (1)
NHE (WSON)
DGK (VSSOP
UNIT
14 PINS
8 PINS
RθJA
Junction-to-ambient thermal resistance
46.5
152.5
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
37.7
53.9
°C/W
RθJB
Junction-to-board thermal resistance
23.6
73.2
°C/W
ψJT
Junction-to-top characterization parameter
0.4
5.5
°C/W
ψJB
Junction-to-board characterization parameter
23.8
72.0
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
4.6
N/A
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
LM2623
www.ti.com
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
6.5 Electrical Characteristics
Limits apply for TJ = 25°C and VDD = VOUT = 3.3 V, unless otherwise specified.
PARAMETER
TEST CONDITION
VDD_ST
Start-up supply voltage 25°C
ILOAD = 0 mA
VIN_OP
Minimum operating supply
voltage (once started)
ILOAD = 0 mA
VFB
FB pin voltage
VOUT_MAX
Maximum output voltage
TYP
MAX
0.65
UNIT
1.1
V
0.8
V
1.24
−40°C to 85°C
1.2028
V
1.2772
14
Efficiency
η
MIN
(1)
D
Switch duty cycle
IDD
Operating quiescent current (2)
ISD
Shutdown quiescent current (3)
VIN = 3.6 V; VOUT = 5 V;
ILOAD = 500 mA
87%
VIN = 2.5 V; VOUT = 3.3 V;
ILOAD = 200 mA
87%
V
17
FB Pin > 1.3 V; EN Pin at VDD
80
FB Pin > 1.3 V; EN Pin at VDD, −40°C to
85°C
µA
110
VDD, BOOT and SW Pins at 5 V;
EN Pin < 200 mV
0.01
µA
VDD, BOOT and SW Pins at 5 V;
EN Pin < 200 mV, −40°C to 85°C
2.5
ICL
Switch peak current limit
LM2623A
2.2
IC
Switch peak current limit
LM2623
1.2
RDS_ON
MOSFET switch on resistance
2. 85
A
0.17
−40°C to 85°C
Ω
0.26
ENABLE SECTION
VEN_LO
EN pin voltage low (4)
−40°C to 85°C
VEN_HI
EN pin voltage high (4)
−40°C to 85°C
(1)
(2)
(3)
(4)
0.15 VDD
V
0.7 VDD
VDD tied to BOOT and EN pins. Frequency pin tied to VDD through 121-KΩ resistor. VDD_ST = VDD when start-up occurs. VIN is VDD + D1
voltage (usually 10 mV to 50 mV at start-up).
This is the current into the VDD pin.
This is the total current into pins VDD, BOOT, SW, and FREQ.
When the EN pin is below VEN_LO, the regulator is shut down; when it is above VEN_HI, the regulator is operating.
6.6 Typical Characteristics
1.2365
95.0
10mA
1.236
1.2355
85.0
V FB (V)
Efficiency (%)
90.0
80.0
75.0
V DD = 3.3V
1.235
1.2345
1.234
600mA
70.0
1.2335
300mA
65.0
60.0
1.8
2.1 2.4 2.7 3.0 3.3
1.233
3.6 3.9 4.2 4.5
1.2325
-40
-25
-10
5
20
35
50
65
80
TEMPERATURE (ºC)
Vin
VOUT = 5 V
Figure 1. Efficiency vs Supply Voltage
Figure 2. VFB vs Temperature
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
5
LM2623
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
www.ti.com
Typical Characteristics (continued)
1.30
0
2
300k
75k
Start-Up Voltage
Frequency (Mhz)
225k
1.5
150
1
0.5
1.20
0
1.100
1.00
0
0.90
0
0
1.2
1.7
2.2
2.7
3.2
3.7
0.800
-50
4.2
0
50
100
Temperatur
e
Vin (V)
Figure 3. Frequency vs VIN
Figure 4. Maximum Start-Up Voltage vs Temperature
0.300
3.000
2.900
0.250
Current Limit
2.800
Rds on
0.200
0.150
2A
0.100
1A
2.700
2.600
2.500
2.400
2.300
2.200
0.050
2.100
0.000
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
2.000
- - - 0 10 20 30 40 50 60 70 80
40 30 20 10
Temperature (ºC)
Temperature (ºC)
Figure 5. Typical RDS(ON) vs Temperature
Figure 6. Typical Current Limit vs Temperature
VOUT = 5 V
Figure 7. Output Voltage vs Supply Voltage
6
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
LM2623
www.ti.com
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
7 Detailed Description
7.1 Overview
The LM2623 is designed to provide step-up DC-DC voltage regulation in battery-powered and low-input voltage
systems. It combines a step-up switching regulator, N-channel power MOSFET, built-in current limit, thermal
limit, and voltage reference in a single 8-pin VSSOP package Functional Block Diagram. The switching DC-DC
regulator boosts an input voltage between 0.8 V and 14 V to a regulated output voltage between 1.24 V and 14
V. The LM2623 starts from a low 1.1 V input and remains operational down to below 0.8 V.
This device is optimized for use in cellular phones and other applications requiring a small size, low profile, as
well as low quiescent current for maximum battery life during stand-by and shutdown. A high-efficiency gatedoscillator topology offers an output of up to 2 A at low output voltages.
Additional features include a built-in peak switch current limit, and thermal protection circuitry.
7.2 Functional Block Diagram
7.3 Feature Description
7.3.1 Gated Oscillator Control Scheme.
The on/off regulation mode of the LM2623, along with its ultra-low quiescent current, results in good efficiency
over a very wide load range. The internal oscillator frequency can be programmed using an external resistor to
be constant or vary with the battery voltage. Adding a capacitor to program the frequency allows the designer to
adjust the duty cycle and optimize it for the application. Adding a resistor in addition to the capacitor allows the
duty cycle to dynamically compensate for changes to the input/output voltage ratio. We call this a Ratio Adaptive
Gated Oscillator circuit. See the Typical Application for sample application circuits. Using the correct RC
components to adjust the oscillator allows the part to run with low ripple and high efficiency over a wide range of
loads and input/output voltages.
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
7
LM2623
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
www.ti.com
Feature Description (continued)
Figure 8. Typical Step-Up Regulator Waveforms
7.3.2 Cycle-To-Cycle Pfm
When the load doesn't vary over a wide range (like zero to full load), ratio adaptive circuit techniques can be
used to achieve cycle to cycle PFM regulation and lower ripple (or smaller output capacitors). The key to success
here is matching the duty cycle of the circuit closely to what is required by the input to output voltage ratio. This
ratio then needs to be dynamically adjusted for input voltage changes (usually caused by batteries running
down). The chosen ratio should allow most of the energy in each switching cycle to be delivered to the load and
only a small amount to be stored. When the regulation limit is reached, the overshoot will be small and the
system will settle at an equilibrium point where it adjusts the off time in each switching cycle to meet the current
requirements of the load. The off time adjustment is done by exceeding the regulation limit during each switching
cycle and waiting until the voltage drops below the limit again to start the next switching cycle. The current in the
coil never goes to zero like it frequently does in the hysteretic operating mode of circuits with wide load variations
or duty cycles that aren't matched to the input/output voltage ratio. Optimizing the duty cycle for a given set of
input/output voltages conditions can be done by using the circuit values in the Application Notes.
7.3.3 Shutdown
The LM2623 features a shutdown mode that reduces the quiescent current to less than an ensured 2.5 µA over
temperature. This extends the life of the battery in battery powered applications. During shutdown, all feedback
and control circuitry is turned off. The regulator's output voltage drops to one diode drop below the input voltage.
Entry into the shutdown mode is controlled by the active-low logic input pin EN (pin-2). When the logic input to
this pin is pulled below 0.15 VDD, the device goes into shutdown mode. The logic input to this pin should be
above 0.7 VDD for the device to work in normal stepup mode.
7.3.4 Internal Current Limit And Thermal Protection
An internal cycle-by-cycle current limit serves as a protection feature. This is set high enough (2.85 A typical,
approximately 4 A maximum) so as not to come into effect during normal operating conditions. An internal
thermal protection circuit disables the MOSFET power switch when the junction temperature (TJ) exceeds about
160°C. The switch is re-enabled when TJ drops below approximately 135°C.
8
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
LM2623
www.ti.com
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
7.4 Device Functional Modes
7.4.1 Pulse Frequency Modulation (Pfm)
Pulse Frequency Modulation is typically accomplished by switching continuously until the voltage limit is reached
and skipping cycles after that to just maintain it. This results in a somewhat hysteretic mode of operation. The
coil stores more energy each cycle as the current ramps up to high levels. When the voltage limit is reached, the
system usually overshoots to a higher voltage than required, due to the stored energy in the coil (see Figure 8).
The system will also undershoot somewhat when it starts switching again because it has depleted all the stored
energy in the coil and needs to store more energy to reach equilibrium with the load. Larger output capacitors
and smaller inductors reduce the ripple in these situations. The frequency being filtered, however, is not the basic
switching frequency. It is a lower frequency determined by the load, the input/output voltage and the circuit
parameters. This mode of operation is useful in situations where the load variation is significant. Power managed
computer systems, for instance, may vary from zero to full load while the system is on and this is usually the
preferred regulation mode for such systems.
7.4.2 Low Voltage Start-Up
The LM2623 can start up from voltages as low as 1.1 V. On start-up, the control circuitry switches the N-channel
MOSFET continuously until the output reaches 3 V. After this output voltage is reached, the normal step-up
regulator feedback and gated oscillator control scheme take over. Once the device is in regulation, it can operate
down to below 0.8 V input, since the internal power for the IC can be boot-strapped from the output using the
VDD pin.
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
9
LM2623
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
www.ti.com
8 Applications And Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LM2623 features a shutdown mode, entry into the shutdown mode is controlled by the active-low logic input
pin EN (pin 2). When the logic input to this pin is pulled below 0.15 VDD, the device goes into shutdown mode.
The logic input to this pin should be above 0.7 VDD for the device to work in normal start-up mode.
8.2 Typical Application
D1
L1
4.7PH
R3
150k
3A
C3
V IN
2 Cells
4.7pF
+ C1
22PF
8
SW
3
BOOT
FREQ
EN
LM2623
1
V DD
PGND
FB
7
5V
2
6
C2
100PF
tant
RF1
300k
4
SGND
5
RF2
100k
Figure 9. LM2623 Typical Application
8.2.1 Design Requirements
The LM2623 allows the designer to vary output voltage, operating frequency and duty cycle to optimize the part
performance, please read Detailed Design Procedure for details.
8.2.2 Detailed Design Procedure
8.2.2.1 Non-Linear Effect
The LM2623 is very similar to the LM2621. The LM2623 is based on the LM2621, except for the fact that the
LM2623 takes advantage of a non-linear effect that allows for the duty cycle to be programmable. The C3
capacitor is used to dump charge on the FREQ pin in order to manipulate the duty cycle of the internal oscillator.
The part is being tricked to behave in a certain manner, in the effort to make this Pulse Frequency Modulated
(PFM) boost switching regulator behave as a Pulse Width Modulated (PWM) boost switching regulator.
8.2.2.2 Choosing The Correct C3 Capacitor
The C3 capacitor allows for the duty cycle of the internal oscillator to be programmable. Choosing the correct C3
capacitor to get the appropriate duty cycle for a particular application circuit is a trial and error process. The nonlinear effect that C3 produces is dependent on the input voltage and output voltage values. The correct C3
capacitor for particular input and output voltage values cannot be calculated. Choosing the correct C3
capacitance is best done by trial and error, in conjunction with the checking of the inductor peak current to make
sure your not too close to the current limit of the device. As the C3 capacitor value increases, so does the duty
cycle. And conversely as the C3 capacitor value decreases, the duty cycle decreases. An incorrect choice of the
C3 capacitor can result in the part prematurely tripping the current limit and/or double pulsing, which could lead
to the output voltage not being stable.
10
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
LM2623
www.ti.com
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
Typical Application (continued)
8.2.2.3 Setting The Output Voltage
The output voltage of the step-up regulator can be set by connecting a feedback resistive divider made of RF1
and RF2. The resistor values are selected as follows:
RF1 = RF2 * [(VOUT/ 1.24) −1]
(1)
A value of 50k to 100k is suggested for RF2. Then, RF1 can be selected using Equation 1.
8.2.2.4 VDD Supply
The VDD supply must be between 3 V to 5 V for the LM2623. This voltage can be bootstrapped from a much
lower input voltage by simply connecting the VDD pin to VOUT. In the event that the VDD supply voltage is not a
low ripple voltage source (less than 200 millivolts), it may be advisable to use an RC filter to clean it up.
Excessive ripple on VDD may reduce the efficiency.
8.2.2.5 Setting The Switching Frequency
The switching frequency of the oscillator is selected by choosing an external resistor (R3) connected between VIN
and the FREQ pin. See Figure 3 in the Typical Characteristics section of the data sheet for choosing the R3
value to achieve the desired switching frequency. A high switching frequency allows the use of very small surface
mount inductors and capacitors and results in a very small solution size. A switching frequency between 300 kHz
and 2 MHz is recommended.
8.2.2.6 Output Diode Selection
A Schottky diode should be used for the output diode. The forward current rating of the diode should be higher
than the peak input current, and the reverse voltage rating must be higher than the output voltage. Do not use
ordinary rectifier diodes, since slow switching speeds and long recovery times cause the efficiency and the load
regulation to suffer.
8.2.3 Application Curves
VOUT = 5 V
Figure 10. Efficiency vs Output Current
Figure 11. Output Voltage vs Output Current
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
11
LM2623
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
www.ti.com
9 Power Supply Recommendations
The LM2623 can start up from voltages as low as 1.1 V. On start-up, the control circuitry switches the N-channel
MOSFET continuously until the output reaches 3 V. After this output voltage is reached, the normal step-up
regulator feedback and gated oscillator control scheme take over. Once the device is in regulation, it can operate
down to below 0.8 V input, since the internal power for the IC can be boot-strapped from the output using the
VDD pin.
10 Layout
10.1 Layout Guidelines
The example layouts below follow proper layout guidelines and should be used as a guide for laying out the
LM2623 circuit. The LM2623 inductive boost converter sees a high switched voltage at the SW pin, and a step
current through the Schottky diode and output capacitor each switching cycle. The high switching voltage can
create interference into nearby nodes due to electric field coupling (I = C x dV/dt). The large step current through
the diode and the output capacitor can cause a large voltage spike at the SW and BOOST pins due to parasitic
inductance in the step current conducting path (V = L x di/dt). Board layout guidelines are geared towards
minimizing this electric field coupling and conducted noise.
Boost Output Capacitor Placement, Schottky Diode Placement, and Boost Input / VDD Capacitor Placement detail
the main (layout sensitive) areas of the LM2623 inductive boost converter in order of decreasing importance:
10.1.1 Boost Output Capacitor Placement
Because the output capacitor is in the path of the inductor current discharge path, it will see a high-current step
from 0 to IPEAK each time the switch turns off and the Schottky diode turns on. Any inductance along this series
path from the diodes cathode, through COUT, and back into the LM2623 GND pin will contribute to voltage
spikes at SW. These spikes can potentially over-voltage the SW and BOOST pins, or feed through to GND. To
avoid this, COUT+ must be connected as close as possible to the cathode of the Schottky diode, and COUT−
must be connected as close as possible to the LM2623 GND bumps. The best placement for COUT is on the
same layer as the LM2623 to avoid any vias that can add excessive series inductance.
10.1.2 Schottky Diode Placement
In the LM2623 device boost circuit the Schottky diode is in the path of the inductor current discharge. As a result
the Schottky diode sees a high-current step from 0 to IPEAK each time the switch turns off, and the diode turns
on. Any inductance in series with the diode will cause a voltage spike at SW. This can potentially over-voltage
the SW pin, or feed through to VOUT and through the output capacitor, into GND. Connecting the anode of the
diode as close as possible to the SW pin, and connecting the cathode of the diode as close as possible to
COUT+, will reduce the inductance (LP_) and minimize these voltage spikes.
10.1.3 Boost Input / VDD Capacitor Placement
The LM2623 input capacitor filters the inductor current ripple and the internal MOSFET driver currents. The
inductor current ripple can add input voltage ripple due to any series resistance in the input power path. The
MOSFET driver currents can add voltage spikes on the input due to the inductance in series with the VIN/VDD
and the input capacitor. Close placement of the input capacitor to the VDD pin and to the GND pin is critical since
any series inductance between VIN/VDD and CIN+ or CIN– and GND can create voltage spikes that could appear
on the VIN/VDD supply line and GND.
12
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
LM2623
www.ti.com
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
10.2 Layout Example
10.3 WSON Package Devices
The LM2623 is offered in the 14-lead WSON surface mount package to allow for increased power dissipation
compared to the VSSOP-8. For details of the thermal performance as well as mounting and soldering
specifications, refer to Application Note AN-1187 Leadless Leadframe Package (LLP) (SNOA401).
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
13
LM2623
SNVS188I – MAY 2004 – REVISED OCTOBER 2017
www.ti.com
11 Device And Documentation Support
11.1 Device Support
11.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation, see the following:
Application Note AN-1187 Leadless Leadframe Package (LLP)
11.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
11.4 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.5 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.6 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.7 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, And Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
14
Submit Documentation Feedback
Copyright © 2004–2017, Texas Instruments Incorporated
Product Folder Links: LM2623
PACKAGE OPTION ADDENDUM
www.ti.com
24-Jul-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
Samples
(4/5)
(6)
LM2623ALD/NOPB
ACTIVE
WSON
NHE
14
1000
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 85
2623A
LM2623AMM
NRND
VSSOP
DGK
8
1000
Non-RoHS
& Green
Call TI
Level-1-260C-UNLIM
-40 to 85
S46A
LM2623AMM/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
S46A
Samples
LM2623AMMX/NOPB
ACTIVE
VSSOP
DGK
8
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
S46A
Samples
LM2623LD/NOPB
ACTIVE
WSON
NHE
14
1000
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 85
2623AB
Samples
LM2623LDX/NOPB
ACTIVE
WSON
NHE
14
4500
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 85
2623AB
Samples
LM2623MM/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
S46B
Samples
LM2623MMX/NOPB
ACTIVE
VSSOP
DGK
8
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
S46B
Samples
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
工商网监
湘ICP备2023018690号
