analog_switches.pdf
-
Upload
nimiosound -
Category
Documents
-
view
216 -
download
0
Transcript of analog_switches.pdf
-
8/12/2019 analog_switches.pdf
1/18
-
8/12/2019 analog_switches.pdf
2/18
Introduction
Purpose:
To introduce NXPs high performance analog switch offering.
Objectives
Review analog switches configurations & critical electrical parameters.
Review NXP portfolio & nomenclature.
Review package offering & trends.
Review of 3 simple application examples.
2
The purpose of this module is to introduce you to NXPs analog switchoffering.
It will first cover analog switch basics: what are the different types ofswitches out there, what are the critical parameters and what they mean
for a particular application.
In a second time, we will go over the NXP analog switch portfolio and
nomenclature.
Then we will look at the latest packaging trends in leadless packages.
We will conclude with 3 simple applications examples using low ohmic
analog switches.
2
-
8/12/2019 analog_switches.pdf
3/18
-
8/12/2019 analog_switches.pdf
4/18
-
8/12/2019 analog_switches.pdf
5/185
5
The T (translator/level shifter) functionincluded in many switches
3.6 V
ASIC
1.8 V 3.6 V
1T34
ASIC NX3L1G315774AUP1T34
The T feature: Reduces part count Saves space Lowers cost Simplifies overall design
ASIC
ASIC
1.8 V 3.6 V
T
NX3L1T3157
In some applications, analog switches are at the interface between a lowvoltage ASIC and a higher supply voltage component. In order for the
switch to be activated properly, a voltage translator (or level shifter) istypically used on the select pin to insure the minimum activation threshold
is met.
NXP analog switches offer a complete family of devices that integrate thetranslator function, thus saving part count, PCB space, and lowering
overall system cost.
-
8/12/2019 analog_switches.pdf
6/186
6
SPDTSPST
(NO)
SPST
(NC)
SPST 2x
(NC)
SPST 2x(NO)
NX3L1G66
NX3L2G66
NX3L1G384
NX3L2G384
NX3L1G3157
NX3L4684NX3L2267
NX3L4357
DPDT DPDT2x
NX3L2467
NX3L1G53
SPDT
Enable
NX3L1T66 NX3L1T384 NX3L1T3157NX3L1T53
NX3L2T66 NX3L2T384
SPDT
2x
SP3T
Enable
NX3L2467
NX3 Family Switches by Function
The T in the part number distinguishes analog switches with theintegrated translator function. Some part numbers are highlighted in this
slide for the low ohmic NX3 family of switches. The G parts do notinclude the translator function.
-
8/12/2019 analog_switches.pdf
7/18
Critical Parameters what they mean
7
Switch configuration (SPST, SPDT, DPDT) pick the right configurationand control pin option for the application.
Supply voltage (VCC) is the biasing voltage required to power the switch.Lower VCC means less head room to pass a signal. Some applications likeaudio, may require negative voltage capability to maintain signal integrity.
ON resistance (RON) is the resistance from input to output when the switch isclosed. The lower the RON, the less the signal passing through the switch willbe attenuated. RON will vary with voltage, temperature, and load current. Ameasure of this variation is delta RON (RON). Selecting a low RON device willminimize signal distortion.
Bandwidth (f-3dB) is the frequency at which the signal is attenuated by -3 dBfrom its dc level. It represents the upper cutoff frequency of the switch. The
higher the bandwidth, the higher the data rate it can support and the larger theamount of information it can handle.
Particular attention should be given to the following parameters whenselecting a switch.
Switch configuration this is the first step in selecting a switch. Choosethe right configuration (SPST, SPDT, DPDT) for the application. Insure
to use the correct control pin option to toggle switches independently or all
together.
Supply voltage (VCC). is the biasing voltage required to power up the
switch. A lower VCC means there is less head room to pass a signal.Some applications like audio, may require negative voltage capability to
maintain signal integrity as some audio signals have a negative
component.
ON Resistance (RON) is the resistance from input to output when theswitch is closed. The lower the line resistance, the less the signal passingthrough the switch will be attenuated. RON will vary with voltage,
temperature, and load current. A measure of this variation is delta RON .
Selecting a low RON device will minimize signal distortion.
Bandwidth (f-3dB) is the frequency at which the signal is attenuated by -3dB from its DC level. In other words, it represents the upper cutoff
frequency of the switch. It is directly related to data rate. The higher the
bandwidth, the higher the data rate it can support and the larger the
amount of information it can handle. This is particularly important when
dealing with fast signal applications like video or USB. A good rule ofthumb is to select a switch with 3 times the bandwidth of the signal
frequency to maintain good signal integrity.
7
-
8/12/2019 analog_switches.pdf
8/18
Critical Parameters what they mean (continued)
8
ON state capacitance (CS(ON)) is the equivalent capacitance of the switchwhile closed. This capacitive loading of the line will affect overall bandwidth and
drive current. A lower CS(ON) helps minimize negative effects to the signal.
Input voltage range (VI) is the maximum voltage that can be applied at thecontrol pin, that is between the control pin to ground.
Switch voltage (VSW) is the maximum voltage that can be applied at an inputpin with respect to ground.
Enable / disable time (ten/ tdis) is the take it takes for the switch to changestate from the time the select pin has been triggered.
Select/control pin threshold levels (TTL vs. CMOS) - Switches can betriggered at different threshold levels. TTL trigger levels are typically at 0.7
and1.4V. CMOS levels are at 30 and 70% of the supply voltage. Package size - multiple packages and pin configurations available. Select the
proper package option to ease PCB layout.
ON state capacitance (CS(ON)) is the equivalent capacitance of theswitch while closed. The capacitance will induce capacitive loading on
the line and affect overall bandwidth and drive current. A lower CS(ON) istypically desired to minimize negative effects to the signal.
Input voltage range (VI) is the maximum voltage that can be applied at
the control pin, that is between the control pin to ground. In somesituation, an external component may be required to level shift the input
to the right voltage level if the switch cannot meet the proper input level
for the application.
Switch voltage (VSW) is the maximum voltage that can be applied at the
input pin with respect to ground.
Enable / disable time (ten/ tdis) is the time it takes for the switch tochange state from the time the select pin has been triggered.
Select or control pin threshold level (TTL vs. CMOS). Switches can betriggered at different threshold levels. As an approximation, TTL
threshold levels are at 0.7 and 1.4V. CMOS levels are typically at 30%
and 70% of the supply voltage. One has to be careful to select the rightswitch to guarantee the select signal used can correctly trigger the
switch.
Package selection is important. There are multiple package and pin
configurations available. Be sure to select the proper package option to
ease the layout of the PCB.
8
-
8/12/2019 analog_switches.pdf
9/18
NX3 Offering Summary Table
9
No / NC = switch is normally opened or normally closed
NXP has already introduced over 47 part numbers in the low ohmic NX3analog switch family. These switches target applications where low ON
resistance is critical. They exhibit a resistance of less than 1 Ohm for theL series, and less than 0.5 Ohm for the V series. They also offer -90
dB isolation and crosstalk for superior signal integrity, and a low current
consumption for higher power savings. They are available in the Picogate
and the tiny leadless MicroPak packages, 0.35 mm pitch GF and GS, andthe newest 0.3 mm pitch GN package. The table in this slide summarizes
the critical parameters for each switch type of this family. This first portion
is for single switches in SPDT and SPST configurations.
9
-
8/12/2019 analog_switches.pdf
10/18
10
This is the continuation of the selection table showing the multipleswitches in SPST, SPDT, DPDT, SP3T configurations.
10
-
8/12/2019 analog_switches.pdf
11/18
11
NX3Lxxx Switches Nomenclature
This table summarizes the nomenclature for the NX3 family of switches,easing the selection process. The first 2 letters indicate the switch family.
The 3rd
digit represent the supply voltage capability of the device. A NX3device for example is rated for 3V. A NX5 device will be rated for 5V
applications. The on resistance, the 4th digit, is denoted by an C, L, or V.
A C for greater than 1 ohm resistance, L for less than 1 ohm, and V for
less than 0.5 ohm. The 5th character represent the number of switchesintegrated in the device. The next letter indicate if the translation function
is integrated on the select pin. A T meaning it is integrated, a G meaning
there is not translation on the select pin. The next 4 digits indicate the
function type. If the devices integrates a special function, such as shunt
resistors, negative swing or an enable pin, it will be indicated in this
section. Finally the last 2 letters indicate the package type. So anNX3L1G3157GW is a Single SPDT analog switch with 3 volt VCCcapability, 1 ohm or lower RON, in a SOT886 package.
11
-
8/12/2019 analog_switches.pdf
12/18
12
5 pins 6 pins 8 pins 10 pins 16 pins 20 pins
0.65mm
pitch
0.5mm
pitch
0.4mm
pitch
0.35mm
pitch
0.3mm
pitch
GF (SOT891)
1.0 x 1.0 x 0.5
GS (SOT1202)
1.0 x 1.0 x 0.35
GN (SOT1115)1.0 x 0.90 x 0.35
GN (SOT1116)
1.0 x 1.20 x 0.35
GS (SOT1203)1.0 x 1.35 x 0.35
GW (SOT353)2.0 x 2.0 x 1.0
GW (SOT363)2.0 x 2.0 x 1.0
GD (SOT996)
2.0 x 3.0 x 0.5
HR (SOT1039)3.0 x 3.0 x 0.5
TK (SOT650)3.0 x 3.0 x 0.85
BX (SOT1045)
2.5 x 4.5 x 0.5
GF(SOT1081)1.7 x 1.0 x 0.4
GM (SOT1049)
2.0 x 1.55 x 0.5
GU (SOT1161)1.8 x 2.6 x 0.5
GU (SOT1160)1.4 x 1.8 x 0.5
GF (SOT1089)1.0 x 1.35 x 0.5
NXP Common Switch Packages
GM - SOT8861.0 x 1.6 x 0.5
Dimensions: Width x Length x Height
NXP carries one of the most extensive array of leadless packages on themarket and offers the lowest 0.3 mm pitch package solution currently
available for switches. Most switches are offered in 5, 6, 8, 10, 16, and 20pin packages, with pitch ranging from 0.65 mm, all the way down to 0.3
mm. Most leaded and WCSP packages can be replaced by a leadless
package. There are multiple advantages in going to a leadless solution as
we will see in the next slide.
12
-
8/12/2019 analog_switches.pdf
13/181313
Same die used as in larger packages, all functions available.
Operating temp range 40oC to 125oC.
Automotive qualified; JEDEC-STD-20C and Q100.
Pad spacing: 0.5, 0.4, 0.35 and 0.30 mm.
Lowest profile height (down to 0.35mm) packages.
Stronger contact with PCB compared to WCSP packages.
Drop-in replacement for most leaded/WCSP packages.
Pb-free, RoHS and Dark Green compliant.
Eliminated risk of whisker growth (NiPdAu).
Unlimited out of bag floor life at 30C/85% RH
Benefits of Leadless Packages
13
Going to a leadless package allows to fit a larger die inside the samefootprint as a leaded package, therefore better performance can be
achieved for the same footprint. As an alternative, a smaller solution canalso be provided with the same electrical characteristics.
NXP leadless packages are characterized over an extended temperature
range of -40 to 125 degrees celcius, typical devices only go up to 85degree celcius. This make them suitable for high stress environment such
as automotive and military applications. Reliability is also superior to
WCSP and leaded packages, offering better adhesion to the PCB andbeing more impervious to chipping around the edges, these packages
yield far less failures during assembly and the overall life of the end
product. The leads are coated with Nickel Paladium Gold to prevent
oxidation. This allows an unlimited life time storage while out of the bagand negligible loss of inventory. All leadless packages are Pb-free, RoHS
and Dark Green compliant.
-
8/12/2019 analog_switches.pdf
14/18
-
8/12/2019 analog_switches.pdf
15/18
15
Application Example #2
This is another audio application. Here the baseband has two differentaudio sources. One from the handset itself, the other from a bluetooth
headset. The switch allows to route the audio signals to the internalspeaker and microphone, or to those of the headset. Again, this type of
setup allows part savings and PCB space savings.
15
-
8/12/2019 analog_switches.pdf
16/18
Test mode implementationprior to product release
By using two SPDT switches,
GPIO1 and 2 can be extended totest an external circuit, whenrequired, without modifying the
design.
16
Application Example #3
This last application example shows an NX3L1T3157 analog switch usedto route data signals. It is common for electronic devices to require testing
at the assembly site to ensure proper functioning. This is done byconnecting externally through GPIO ports to activate a test routine. Prior
to the product being released to the market, the test ports need to be
disabled to insure that no wrong user operation could damage the device.
A simple way to do this is through the use of analog switches. While inproduction, the switch allows connection from the GPIO connectors to the
internal test circuit. The switches are then toggled to prevent access,
while allowing reuse of the GPIOs for everydays use without risk to the
device.
16
-
8/12/2019 analog_switches.pdf
17/18
3
Brochure Sample kit
17http://ics.nxp.com/products/switches/
For further information on NXP analog switches, please visit our dedicatedwebsite at http://ics.nxp.com/products/switches/
You can also download data sheets and order brochures and sample kitsonline.
17
-
8/12/2019 analog_switches.pdf
18/18
Summary
While selecting analog switches, it is important to pay attention to the
key parameters (Configuration, RON, VCC, f-3dB, CS(ON), VI, package) tomeet the application requirements.
NXP provides high performance analog switches in all commonconfigurations tailored to answer specific application needs and easedesign effort.
The NX3 family of switches offers very low on resistance and is
available in a wide variety of leadless packages to meet todays
stringent board space constraints and reliability requirements.
18
In Summary, while selecting analog switches, it is important to payattention to the key parameters such as, switch configuration, on
resistance, supply voltage, bandwidth, on resistance, input voltage andpackage. This will insure the switch meets the applications requirements.
NXP provides high performance analog switches in all commonconfigurations tailored to answer specific application needs and easedesign effort.
The NX3 family of switches is offers very low on resistance and is
available in a wide variety of leadless packages to meet todays stringent
board space constraints and reliability requirements.