LMS4684
LMS4684 0.5Ω Low-Voltage, Dual SPDT Analog Switch
Literature Number: SNOSAL0B
LMS4684
0.5ΩLow-Voltage, Dual SPDT Analog Switch
General Description
The LMS4684 is a low on-resistance, low voltage dual SPDT
(Single-Pole/Double-Throw) analog switch that operates
from a 1.8V to 5.5V supply. The LMS4684 features a 0.5Ω
R
ON
for its NC switch and 0.8ΩR
ON
for its NO switch at a
2.7V supply. The digital logic inputs are 1.8V logic-
compatible with a 2.7V to 3.3V supply and features break-
before-make switching action.
The LMS4684 is available in the 12-bump micro SMD and
the 10-lead LLP miniature packages. These PCB real estate
saving packages offer extreme performance while saving
money with small footprints.
Features
nNC switch R
ON
0.5Ωmax @2.7V
nNO switch R
ON
0.8Ωmax @2.7V
n5 nA (typ) supply current T
A
= 25˚C
n1.8 to 5.5V single supply operation
n12-Bump micro SMD package
nLLP-10 package, 3x4mm
Applications
nPower routing
nBattery-operated equipment
nCommunications circuits
nModems
nCell phones
Connection Diagrams
10-LLP Package 12-Bump micro SMD Package
20136701
Exposed pad on back of package needs to be connected to pin 6 on the
board
Top View
20136702
Center Bumps B2 and C2 are Not Electrically Connected
Top View
(Bumped Side Down)
Ordering Information
Package Part Number Package
Marking Transport Media NSC Drawing
12-Bump
micro SMD
LMS4684ITL F09A 250 Units Tape and Reel TLA12DPA
LMS4684ITLX 3k Units Tape and Reel
10-Pin LLP LMS4684LD L4684 1k Units Tape and Reel LDA10B
LMS4684LDX 4.5k Units Tape and Reel
September 2005
LMS4684 0.5ΩLow-Voltage, Dual SPDT Analog Switch
© 2005 National Semiconductor Corporation DS201367 www.national.com
Schematic Diagram
20136703
IN NO NC
0 Off On
1 On Off
Switches shown for Logic "0" input
Pin Descriptions
Name Pin ID Description
LLP micro SMD
NC 5, 7 D3, D1 Analog switch normally closed terminal
IN 4, 8 C3, C1 Digital control input
COM 3, 9 B3, B1 Analog switch common terminal
NO 2, 10 A3, A1 Analog switch normally open terminal
V
+
1 A2 Positive supply voltage
GND 6 D2 Ground
B2, C2 Not electrically connected. Can be used to help dissipate heat by connecting to
GND pin.
LMS4684
www.national.com 2
Absolute Maximum Ratings (Notes 1, 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
V
+
−0.3V to 6.0V
IN −0.3V to 6.0V
COM, NO, NC −0.3V to (V
+
+ 0.3V)
Continuous Switch Current ±400 mA
ESD Tolerance (Note 3)
Human Body Model 2000V
Machine Model 200V
Storage Temperature Range −65˚C to 150˚C
Junction Temperature (Note 4) 150˚C Max
Operating Ratings (Notes 1, 2)
Nominal Supply Voltage 1.8V to 5.5V
IN Voltage
(regardless of supply)
−0.3V to 5.5V
Temperature Range −40˚C to 85˚C
Package Thermal Resistance
Package θ
J-A
LLP-10 43˚C / W
micro SMD-12 57˚C / W
Electrical Characteristics
Unless otherwise specified, V
+
= 2.7 to 3.3V, V
IH
= 1.4V, V
IL
= 0.5V. Typical values are measured at 3V, and T
J
= 25˚C. Bold-
face limits apply at temperature extremes.
Symbol Parameter Conditions Min Typ Max Units
V
NO
,V
NC
,
V
COM
Analog Signal Range 0 V
+
V
R
ON (NC)
NC On-Resistance
(Note 6)
V
+
= 2.7V, I
COM
= 100 mA,
V
NC
=0 to V
+
0.3 0.5 Ω
R
ON (NO)
NO On-Resistance
(Note 6)
V
+
= 2.7V, I
COM
= 100 mA,
V
NO
=0 to V
+
0.45 0.8 Ω
∆R
ON
On-Resistance Match
Between Channels (Note 6),
(Note 7)
V
+
= 2.7V, I
COM
= 100 mA,
V
NC
or V
NO
=1.5V 1.11 60 mΩ
R
FLAT(NC)
NC-On-Resistance Flatness
(Note 8)
V
+
= 2.7V,
I
COM
= 100 mA,
V
NC
=0toV
+
LLP
T
J
= -40˚C to 85˚C 0.1 0.25
Ω
micro SMD
T
J
= -40˚C to 85˚C 0.1 0.25
R
FLAT(NO)
NO On-Resistance Flatness
(Note 8)
V
+
= 2.7V, I
COM
= 100 mA,
V
NO
=0toV
+
0.18 0.35 Ω
I
NO(OFF)
or
I
NC(OFF)
NO or NC Off Leakage
Current
V
+
= 3.3V, V
NO
or V
NC
= 3V,
0.3V; V
COM
= 0.3V, 3V
−1 0.014 1 nA
−10 10
I
COM
(ON) COM On Leakage Current V
+
= 3.3V, V
NO
or V
NC
= 3V,
0.3V, or floating; V
COM
= 3V, or floating
−2 2 nA
−20 20
Dynamic Characteristics
t
ON
Turn-On Time V
+
= 2.7V, V
NO
or V
NC
= 1.5V;
R
L
=50Ω;C
L
=35pF;
38 60 ns
70
t
OFF
Turn-Off Time V
+
= 2.7V, V
NO
or V
NC
= 1.5V;
R
L
=50Ω;C
L
=35pF;
22 40 ns
50
t
BBM
Break-Before-Make Delay V
+
= 2.7V, V
NO
or V
NC
= 1.5V;
R
L
=50Ω;C
L
=35pF; 215 ns
Q Charge Injection COM = 0; R
S
=0;C
L
= 1 nF; 200 pC
V
ISO
Off-Isolation (Note 5) R
L
=50Ω;C
L
= 5 pF; f = 100 kHz -68 dB
V
CT
Crosstalk -72 dB
Digital I/O
V
IH
Input Logic High 1.4 V
V
IL
Input Logic Low 0.5 V
I
IN
IN Input Leakage Current V
IN
=0orV
+
−1 1 µA
LMS4684
www.national.com3
Electrical Characteristics (Continued)
Unless otherwise specified, V
+
= 2.7 to 3.3V, V
IH
= 1.4V, V
IL
= 0.5V. Typical values are measured at 3V, and T
J
= 25˚C. Bold-
face limits apply at temperature extremes.
Symbol Parameter Conditions Min Typ Max Units
Power Supply
V
+
Power-Supply Range 1.8 5.5 V
I+ Supply Current V+ = 5.5V 5 nA
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but specific performance is not guaranteed.
Note 2: All voltages are with respect to GND, unless otherwise specified.
Note 3: Human body model: 1.5 kΩin series with 100 pF. Machine model, 0Ωin series with 200 pF.
Note 4: The maximum power dissipation is a function of TJ(max),θJA and TA.
Note 5: Off-isolation = 20 log10(VCOM/V
NO), where VCOM = output, VNO = input switch off.
Note 6: Guaranteed by design.
Note 7: ∆RON is equal to the difference between NC1/NC2 RON or NO1/NO2 RON at a specified voltage.
Note 8: Flatness is defined as the difference between the maximum and minimum value of on-resistance as measured over the specified analog signal ranges.
LMS4684
www.national.com 4
Parametric Measurement Information
20136710
FIGURE 1. t
ON
/t
OFF
Time
20136711
FIGURE 2. Break-Before Make Delay
LMS4684
www.national.com5
Parametric Measurement Information (Continued)
20136713
FIGURE 3. Charge Injection
20136714
FIGURE 4. Channel Capacitance
LMS4684
www.national.com 6
Typical Performance Characteristics
NO ON Resistance vs. COM Voltage NC ON Resistance vs. COM Voltage
20136705 20136706
Logic Threshold Voltage vs. Supply Voltage Turn-on / Turn-off Times vs. Temperature
20136707
20136708
Charge Injection vs. COM Voltage NC On-Resistance vs. COM Voltage
20136709 20136715
LMS4684
www.national.com7
Typical Performance Characteristics (Continued)
NC On-Resistance vs. COM Voltage NO On-Resistance vs. COM Voltage
20136716 20136717
NO On-Resistance vs. COM Voltage
20136718
LMS4684
www.national.com 8
Functional Description
The LMS4684 is a low voltage dual, extremely low On-
Resistance analog switch that can operate over a supply
voltage range of 1.8V to 5.5V. The LMS4684 has been fully
characterized to operate in applications with 3V nominal
supply voltage and features very low on resistance and fast
Turn-Off and Turn-On times with break-before-make switch-
ing.
The switch operates asymmetrically; one terminal is nor-
mally closed (NC) and the other terminal normally open
(NO).
Both NC and NO terminals are connected to a common
terminal (COM). This configuration is ideal for applications
with asymmetric loads such as speaker handsets and inter-
nal speakers.
Applications Information
1.0 ANALOG INPUT SIGNAL
Analog input signals can range from GND to V
+
and are
passed through the switch with very little change. Each
switch is bidirectional so any pin can be an input or output.
Exercise care when making connection to an inductive load,
such as a motor. As is true with any analog switch used with
an inductive load, the back emf produced when the switch is
turned off can damage the LMS4684 by electrical overstress.
For such applications, a diode should be connected across
the motor to prevent damage to the switch, as indicated in
Figure 5. Be sure the diode has adequate current carrying
capabilities.
2.0 DIGITAL CONTROL INPUTS
The IN pin can be driven to 5.5V regardless of the voltage
level of the supply pin V
+
. For example, if the LMS4684 is
operated with a supply of 2V, the digital control input could
still be driven to 5V. Power consumption is increased when
the control pin is driven rail-to-rail.
3.0 SUPPLY VOLTAGE
It is good general practice to first apply the supply voltage to
a CMOS device before sriving any other pins. This is also
true for the LMS4684 analog switch, which is a CMOS
device.
However, if it is necessary to have an analog signal applied
before the supply voltage is applied and the analog signal
source is not limited to 20 mA max, a diode connected
between the supply voltage and the V
+
pin as shown in
Figure 6 will provide input protection. This will limit the max
analog voltage to a diode drop below V
+
. This diode, D1, will
also provide protection against some over voltage situations.
It is also good practice to provide adequate supply bypass-
ing to all analog circuits. We recommend a that minimum
bypass capacitor value of 0.047µF be provided for the
LMS4684. An inadequate bypass capacitor can lead to ex-
cessive supply current.
4.0 OFF-ISOLATION
Analog switches are composed of FETs (field Effect Transis-
tors). The channel resistance is low when the pass transis-
tors are "on" and that resistance is high when the pass
transistors are "off". However, when the pass transistors are
"off", the source to drain capacitance of the pass transistors
will pass some energy. This capacitance is inversely propor-
tional to the switch "on" resistance, so a switch with a low
"on" resistance may not be suitable for some high frequency
applications.
Figure 7 shows the equivalent circuit of an analog switch.
Unless the load impedance after the switch is relatively low,
the switch capacitance will couple excessive energy across
the "open" switch at higher frequencies, degrading off isola-
tion performance. Off Isolation of the LMS4684 is specified
with a 50Ωload. Higher load impedances will degrade off
isolation performance compared with what is specified.
20136704
FIGURE 5. Inductive Load Over-Voltage Protection
20136719
FIGURE 6. Input Over Voltage Protection Circuitry
LMS4684
www.national.com9
Applications Information (Continued)
Off isolation may be improved by decreasing the LMS4684
load impedance below 50Ω. When doing this, be sure that
the LMS4684 maximum current rating is not exceeded. Also,
decreasing the load impedance too much can result in ex-
cessive signal distortion because the channel resistance
variation with input signal voltage would then be a greater
percentage of the load impedance.
If it is desired to extend the usable bandwidth of the
LMS4684 while maintaining reasonable off-isolation is
through the use of the circuit of Figure 8.
5.0 PCB LAYOUT AND THERMAL CONSIDERATIONS
Both the LLP and micro SMD packages offer enhanced
board real estate savings because of their small footprints.
These tiny packages are capable of handling high continu-
ous currents because of the advanced package thermal
handling capabilities.
The LLP package has the exposed die attach pad internally
connected to the internal circuit GND. When this pad is
soldered to copper on the PCB board according to Applica-
tion Note AN-1187, the full thermal capability of the LLP
package can be achieved without additional bulky heat sinks
to dissipate the heat generated. The micro SMD package
has a similar capability to dissipate heat through Bumps B2
and C2, which are not electrically connected. To enhance
heat dissipation of the micro SMD package B2 and C2 could
be connected to the GND pin through copper traces on the
board.
See Application Note AN-1112 for micro SMD package con-
siderations.
20136712
FIGURE 7. Equivalent Circuit of an Analog Switch
20136720
FIGURE 8. Using the LMS4684 at higher frequencies
LMS4684
www.national.com 10
Physical Dimensions inches (millimeters) unless otherwise noted
10-Lead LLP
NS Package Number LDA10B
X1 = 1590 ±30 µm; X2 = 2327 ±30 µm; X3 = 600 ±75 µm
12-Bump micro SMD
NS Package Number TLA12DPA
LMS4684
www.national.com11
Notes
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform when
properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result
in a significant injury to the user.
2. A critical component is any component of a life support
device or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.
BANNED SUBSTANCE COMPLIANCE
National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products
Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain
no ‘‘Banned Substances’’ as defined in CSP-9-111S2.
Leadfree products are RoHS compliant.
National Semiconductor
Americas Customer
Support Center
Email: new.feedback@nsc.com
Tel: 1-800-272-9959
National Semiconductor
Europe Customer Support Center
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
National Semiconductor
Asia Pacific Customer
Support Center
Email: ap.support@nsc.com
National Semiconductor
Japan Customer Support Center
Fax: 81-3-5639-7507
Email: jpn.feedback@nsc.com
Tel: 81-3-5639-7560
www.national.com
LMS4684 0.5ΩLow-Voltage, Dual SPDT Analog Switch
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic."Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Audio www.ti.com/audio Communications and Telecom www.ti.com/communications
Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers
Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps
DLP®Products www.dlp.com Energy and Lighting www.ti.com/energy
DSP dsp.ti.com Industrial www.ti.com/industrial
Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical
Interface interface.ti.com Security www.ti.com/security
Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense
Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive
Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video
RFID www.ti-rfid.com
OMAP Mobile Processors www.ti.com/omap
Wireless Connectivity www.ti.com/wirelessconnectivity
TI E2E Community Home Page e2e.ti.com
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright ©2011, Texas Instruments Incorporated
