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Issue 3, December 2006
IntroductionStephen CaldwellDirector, Home Appliance Solutions
Group
Welcome to the third issue of the 3V Newsletter created by
theApplication Engineering community at Microchip Technology.This
exciting series of newsletters is designed to cover thetechnical
and logistical challenges of migrating from 5V to 3V.In previous
editions, we discussed the business need formoving to 3V only
products. We touched upon some of thetechnical advantages that 3V
can provide. We provided hintson creating basic 3V power supplies
and hints on how tointerface 3V and 5V products. Historically,
Microchip has released microcontrollers thatoperated from 2V to 5V.
To take advantage of advancedtechnologies, we introduced several
product families that runfrom 2V to 3.6V. Check out Microchip’s
newest 16-bit productfamilies – www.microchip.com/16bit. In the
future, Microchipwill continue to introduce both 5V and 3V new
products.
This issue covers a broad range of subjects including anarticle
that introduces Microchip’s next generation high-speedemulator for
PIC® Microcontrollers. Other articles coverrobustness, interface
solution and standby current.Future 3V newsletters will cover
topics such as powersupplies, noise, sensors, communications, and
drivers. Thisseries of newsletters will also inform the reader of
availableapplication notes, migration documents and web
resourcesapplicable of this topic. For the latest information, make
sureto visit www.microchip.com/3volts. If you have comments or
suggestions for an article, pleasesend an e-mail to
[email protected]!
Need Help?We can help you select the device and tool that is
right for you, andhelp you with a number of different technical
challenges. Submit aticket to support.microchip.com to get your
questions answered.
© 2006 Microchip Technology Inc. 1
In This IssueRobustness of 3V Systems
.............................................. 2Using MPLAB® REAL
ICE™ Probe In
Low-VoltageApplications......................................................................3PICDEM™
HPC Explorer Board ......................................
4dsPICDEM™ 1.1
Plus...................................................... 4Tip #1
Standby Current Reduction Techniquefor J Devices
....................................................................
4Bridging The Rails
............................................................ 5Tip
#2 Driving Bipolar Transistors
....................................7
Recommended ReadingEMC NewsletterIn these newsletters, you will
find a wealth of information including ideas and design tips you
can use to improve Electromagnetic Compatibility (EMC) when using
our products. To obtain copies of these newsletters, go to
www.microchip.com/emc.
Tips and TricksRemember to Read the Electrical
Specifications
It is very important to read the electrical specificationswhen
mixing 3V and 5V devices. Specifically, you mustreview the input
and output thresholds and output currentdrive capabilities. The VIL
and VOL specs are usually notan issue since CMOS outputs drive very
close to groundfor a low signal, no matter what the technology.
The major concern is, can a 3V output drive a 5V input andvice
versa. A 3V output will typically drive within no lowerthan 2.3V
(VDD-0.7V). A 5V TTL input will accept 2V as aminimum to be
recognized as a logic ‘1’. A Schmitt Trigger(ST) type input will
typically require 4V (VDD * 0.8) as aminimum. Therefore, 3V outputs
can drive 5V TTL inputsbut not 5V ST inputs.
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3V Newsletter
Robustness of 3V SystemsSteve CaldwellDirector, Home Appliance
Solutions Group
System designers with experience designing 5Vsystems may have
concerns when migrating to theirfirst 3V system. They will need to
redesign the powersupply. They will need to source 3V equivalent
prod-ucts. They may even need to tweak the gain on the opamps. Most
designers are able to negotiate thechallenges and deliver a
functional board with minimalimpact to the schedule. However, these
designers maybe uncertain about the robustness of a 3V
systemcompared to their existing 5V systems.
A system is robust if it behaves predictably andrecovers
gracefully after a catastrophic event. A plan toimprove robustness
should address schematics, firm-ware, PCB layout, filters,
component selection, testingand disciplined engineering work.
Typically there is nota one panacea to designing a robust system.
EMC is a complex subject and is defined as the abilityof an
electrical system to function without error in itsintended
environment without disturbing anything else,including itself, in
that electromagnetic environment.EMC can be categorized as
emissions (EMI) orsusceptibility (ESD, EFT, Latch-up). There is
good news for emissions. With equalfrequency and current, a 3V
system will use less powerthan an equivalent 5V system. Thus, 3V
systems willemit less conducted and radiated noise (see Figure
1).
FIGURE 1: 20 MHz CLOCK, VDD-5V AND 3V, X-AXIS
The first robustness thought of a system designer isthat as the
transistor geometry shrinks, the productsare inherently less robust
and more susceptible tonoise. The second thought is that there is
lessguardband at 3V compared to 5V. Addressing susceptibility is
not inherently easy.Whereas emissions can be measured for a
component,susceptibility is typically system related. The
appropri-ate question is not, “Is my component robust?”, butrather,
“Is my system robust?”Designers must defend their systems against
noise.They should, understand the noise source, reduce thegenerated
noise, filter the noise at the source, and thenlocally protect
critical components. There is a wealth ofdata at
www.microchip.com/EMC on this subject.Whether a critical component
is 3V or 5V, a systemdesigner should take precautions to protect
this com-ponent. Of course, every component inherentlybehaves
uniquely in a given system and situation. So,it behooves a designer
to select a robust component.
Microchip Technology has designed the 3V PIC®Microcontroller
families to help our customer meet theirdemanding robust
requirements. These productsinclude watchdog timers, brown-out
detects, power-uptimers, and reliable Flash memory. Additionally,
thesefamilies were produced with proprietary, advanceddesign and
manufacturing techniques to negate theeffects of the smaller
transistors. The 3V PIC Microcon-troller families have similar or
better susceptibilityresults in equivalent systems compared to
oldergeneration PIC Microcontroller families. Microchip will
publish a white paper on the Robustnessof the PIC18FXXJXX family in
1CQ07. This paper willinclude EMI, ESD, EFT and latch-up data as
well asADC performance. Check www.microchip.com/3v fordetails. The
system designer is ultimately responsible forsystem robustness. The
designer should understandthe noise sources, work to reduce this
noise, appropri-ately filter the remaining noise, and protect
criticalcomponents from residual noise. Selecting Microchip’sPIC
microcontrollers on your next design will give youa head start in
designing a robust system.
Microcontroller, 20 MHz Clock, Vdd=5V, X-Axis, IEC61967-2, SAE
J1752/3 Band E (400 - 600 MHz)
-10
-5
0
5
10
15
20
25
400 425 450 475 500 525 550 575 600
Frequency (MHz)
dBuV
Level 1Level 2Level 3
Microcontroller, 20 MHz Clock, Vdd=3V, X-Axis, IEC61967-2, SAE
J1752/3 Band E (400 - 600 MHz)
-10
-5
0
5
10
15
20
25
400 425 450 475 500 525 550 575 600
Frequency (MHz)
dBuV
Level 1Level 2Level 3
2 © 2006 Microchip Technology Inc.
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3V Newsletter
Using MPLAB® REAL ICE™ Probe In Low-Voltage ApplicationsAl
RodriguezStaff Engineer, Dev. Tools HW
MPLAB REAL ICE In-Circuit Emulator System isMicrochip’s next
generation high-speed emulator forMicrochip Flash DSC and MCU
devices. It debugs andprograms PIC® and dsPIC® Flash
microcontrollers withthe easy-to-use but powerful graphical user
interface ofthe MPLAB Integrated Development Environment(IDE),
included with each kit. MPLAB REAL ICE is ideal for 3V
applications. MPLABREAL ICE operates over a target VDD range of 2V
to5V. One of the key characteristics of MPLAB REAL ICEis that it
senses the target voltage level. Once the volt-age level is known,
it is used as a voltage reference toits own internal power supply
and powers up the clockand data signal drivers. Additionally, the
current consumption from the target isless than 1 ma and is ideal
for battery-powered appli-cations where the current drain by an
external systemcan not be tolerated.Not requiring an external
supply is another significantcharacteristic of MPLAB REAL ICE. All
power isderived from the USB port, eliminating power
supplysequencing issues in a multiple voltage system.This approach
makes automatic target detect possibleand the behavior is more like
a plug and play featurewhen connected to the target
application.During power-up, as the MPLAB REAL ICE is
initializ-ing, it conducts a self-test and diagnostics sequenceand
is able to detect the target and a device attached.The MPLAB REAL
ICE also contains a 14-pin headerthat includes eight logic probes.
These logic probeinput and output connections can be used as
8-inde-pendent outputs that can be used for triggering
externalequipment or conversely can be used to halt theMPLAB REAL
ICE system from an external source withselectable logic transition
or level. The I/O levels alsomatch the application voltage
levels.The MPLAB REAL ICE comes with two-interfaceconfiguration.
The standard RJ11 6-pin jack connectorinterface can be used with
many Microchip Technologydemo boards, which follow the traditional
ICSP™interface. The high-speed interface uses two RJ45jacks and
includes LVDS level translators. This config-uration comes standard
with a CAT5 3-foot cable andcan easily be extended to other
lengths, which is handywhen the target device and development
computersystem are not in close proximity.
MPLAB REAL ICE offers focused debugging facilitiesfor finding
hard bugs. Among them are data capture forstreaming data valuation,
Trace for code execution,and Log for synchronized variable
valuation. Addition-ally, the register file and special function
registers canbe evaluated without a significant speed penalty
whileperforming debug operations such as single steps.
FIGURE 1: MPLAB® REAL ICE™ EMULATION
MPLAB REAL ICE offers the following advantages:- Low cost - Full
speed emulation- Fast debugging and programming- High speed USB 2.0
communication protocol- Trace analysis- Ruggedized probe interface-
Legacy And high speed connectivity- Long interconnection cables
MPLAB REAL ICE features:- Real-time execution- Fast programming-
USB 2.0 high speed interface to PC
(480 Mb/s) - MPLAB IDE integration (included free) - Over
voltage/short-circuit monitor protection- Low voltage: to 2.0 volts
(2.0 to 6.0 range) - Read/Write program and data memory of
microcontroller- Erase of program memory space with verifi-
cation- Stopwatch- Real time watch- Capture trace to log
instruction execution and
variable contents (~10KB/s at 4MHz 16-bit core)
- Port trace for high speed upload of trace data- High Speed
Option allows full speed emula-
tion, high speed trace upload and long (vali-dated to 3 meters)
cables
- Processor Paks provide debug interface with no reserved
pins
© 2006 Microchip Technology Inc. 3
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3V Newsletter
4 © 2006 Microchip Technology Inc.
PICDEM™ HPC Explorer BoardThis low-cost demo board is the ideal
tool to evaluatethe performance of Microchip high-end 8-bit
microcon-trollers of the PIC18F J-series 3V devices.The board
features a PIC18F8722 microcontroller,which is the superset of the
entire 64- and 80-pinPIC18FXXXX general purpose 5V MCU family.The
J-series products have Plug-in Modules that willautomatically
configure the voltage of the HPCExplorer Board to be 3V.Plug-in
Modules to HPC Explorer Board for PIC18J-series devices:• Part
Number: MA180011 – PIC18F25J10 Plug-in
Module (also used to evaluate PIC18F24J10) • Part Number:
MA180012 – PIC18LF25J10 Plug-in
Module (also used to evaluate PIC18LF24J10) • Part Number:
MA180013 – PIC18F45J10 Plug-in
Module (also used to evaluate PIC18F44J10) • Part Number:
MA180014 – PIC18LF45J10 Plug-in
Module (also used to evaluate PIC18LF44J10) • Part Number:
MA180015 - PIC18F87J10 Plug-in
Module (also used to evaluate PIC18F86J1X, PIC18F85J1X,
PIC18F67J10, PIC18F66J1X, PIC18F65J1X)
FIGURE 1: PICDEM™ HPC EXPLORER BOARD
dsPICDEM™ 1.1 PlusThe dsPICDEM 1.1 Plus Development Board kit
servesas a development and evaluation tool for dsPIC30F/33F High
Performance Digital Signal Controllers andPIC24H/PIC24F PIC
microcontrollers.The board features an active demonstration
programloaded on the installed device. Several programfunctions are
selectable via a menu system displayedon the LCD. These include:
temperature and voltagemeasurements, frequency domain
characteristics of asinewave signal generated on-board from a
digitalpotentiometer, FIR and IIR digital filter selections andDTMF
tone generation using the Codec interfaceperipheral (external
speaker required).
FIGURE 2: dsPICDEM™ 1.1 PLUS DEV. BOARD
TIP #1 Standby Current Reduction Technique for J-Series
DevicesThe standby current (base IPD) is an important param-eter
for some applications. This article describes a sim-ple design tip
to reduce IPD on PIC® J-series devices.They use an internal voltage
regulator to power coreand peripheral logic.Disabling it could save
approximately 20 μA in standbycurrent on initial PIC18 J-series
devices and around 3 μA in the newer one.In this case, 2.7V or less
must be supplied to VDDCOREpin. One option is to use the solution
described below.
FIGURE 1: DIODE AS A VOLTAGE REGULATOR
VDD
VDDCORE
VssENVREG+BuckBoost Conv
PICXXJXXXX
Constant 3V
A diode is used as a cheap voltage regulator. In thiscase due to
the diode drop, the VDDcore will remainconstant around 2.4V. This
circuit can be used if thevoltage source generates constant 3V.
Examples of voltage source:
- A battery like button cell that has almost flat discharge
curve. (i.e., the voltage stays constant at 3V throughout battery’s
useful life span).
- A battery that has a wide voltage range and using a voltage
regulator or buck boost converter to ensure constant voltage.
You must check VDD and VDDCORE voltage rangespecification before
selecting VDD source and thediode.
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3V Newsletter
Bridging The RailsGaurang KavaiyaManager, Applications Group
The 5V power supply used to be the most popular railin embedded
systems. But as discussed in the previ-ous 3V newsletter, most
components are movingtoward lower rails to take advantage of the
industry’snewest trends. On the other hand, some componentsin the
system take longer than others to transition.Therefore, in this
transition phase, some componentsin the system may require
different power-supply rails(i.e., a 5V device in a 3.3V system,
and vice versa). Itcreates some design challenges for an
embeddeddesigner.One solution is to use a 5V device with TTL
inputs(Figure 1). The VIH(min) for a TTL device is 2.1V (forthe VDD
of 5V). Most 3.3V devices can support a muchhigher VOH level, even
at a high load rate. In this case,the solution is to swap your
peripheral device with anequivalent device having TTL-compatible
inputs.
FIGURE 1: USE A 5V DEVICE WITH TTL INPUTS
If you are using a standard digital-logic family that mustrun at
5V, you can find an equivalent device with TTLinputs. For example,
instead of the 74HC family, youcan use the 74HCT family. If you
need level translator,then use the ‘HCT’ or ‘VHCT’ type of digital
buffer. Inmost situations, this TTL-input solution tends to
becheaper than the use of dedicated level translators.The VOH level
of the device operating at 3.3V is slightlybelow the VIH (0.7VDD =
3.5V) of the CMOS deviceoperating at 5V. One simple solution is to
use a diodeto provide the required voltage shift.
FIGURE 2: CIRCUIT SHIFTS OUTPUT TO BRING IN RANGE FOR 5V
INPUT
The Figure 2 circuit shifts the output by approximately0.6V on
the positive side. This 0.6V shift to the CMOSoutput brings it in
range for 5V CMOS input. The sameamount of shift is applied to the
logic low signal. How-ever, VIL (max) for the CMOS input tends to
be around1.5V, so the shifted signal does not violate the VIL
spec.You need to consider a few things regarding this
con-figuration. When the 3.3V device outputs a zero logiclevel, it
increases the current draw. You should alsolook at the VOL spec of
the 3.3V device for this currentsink. Typically, the higher the
sink current, the higherthe VIL. Here, you should be careful to
avoid violationof the VIL spec. If the CMOS output VOL is higher,
thenyou should consider increasing the pull-up resistorvalue. If
the resistor value is too high, the diode biascurrent will be low
and it may not be able to switch fast.Devices like Microchip’s
PIC18F J-series and thePIC24F 16-bit family offer unique features
to simplifythe 5V interface. They provide the option to generate
a5V output with an external 5V pull-up resistor. The 3.3Vdevice
drives a 3.3V output, but it can tolerate a 5Vinput. The digitally
controlled open-drain output capa-bility on these pins allows you
to pull this pin to 5V, with-out violating any specs. This feature
supports a simpleinterface to 5V devices with CMOS inputs (Figure
3).
FIGURE 3: A PULL-UP RESISTOR ON OPEN DRAIN OUTPUT TO GENERATE 5V
OUTPUT
MCU Peripheral
+3.3V +5V
TTL InputsVih(min) = 2.1V
CMOSoutput
MCU Peripheral
+3.3V +5V
CMOS InputsVih(min) = 3.5VVil(max) = 1.5V
CMOS output
PIC24F MCU Peripheral
+3.3V +5V
CMOS InputsVih(min) = 3.5V
CMOS output
5V tolerant input
CMOS output
© 2006 Microchip Technology Inc. 5
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3V Newsletter
When using a pull-up resistor configuration (Figure 3),you need
to consider the capacitance of the connectionbetween the two
devices to determine the rise/fall rate(as does the maximum
switching frequency) of thesignal on this port pin, and the
resistor value that isappropriate for the application. Consider the
followingequation:
Where τ = RC time constant, R * CPVDD = VDD of he Peripheral
voltagePVIH(min) = The VIH(min) value of the peripheral.
If we use the following typical values,
Pull up resistor R = 1KResultant capacitance C due to pin and
PCB capacitance= 10 pF PVDD = 5VPVIH(min) = 0.7 * VDD = 3.5V
The resultant Rise/ fall time ≈ 12nSIf the minimum acceptable
pulse width for this rise/falltime is 50 nS, the maximum output
frequency is 20MHz, which is good enough for most
peripheralinteractions.This configuration has one side effect. When
the MCUdrives the logic low, the extra current is burned througha
pull-up resistor. The pull-up resistor offers designtrade-offs for
speed against current draw. You need toselect a compromise value
that provides the requiredspeed and current consumption for the
application.
Some may say that you can’t use this kind of configura-tion to
drive a low-impedance load. If you want to drivea 5V relay, what
should you do? Fortunately, the abovefeature is also helpful for
driving low-impedance loadslike relays. (See Figure 4 for the
circuit-configurationinformation.) To drive the load, define the
pin as an out-put and drive it low. The only limiting factor here
is thecurrent-sinking capability of the device. To turn off
theload, define the pin as an input. This will turn the load offand
will result in 5 Volts at input. The pin is 5V-tolerant,so this is
a valid operation. In other words, you need tomaintain logic low on
output latch and toggle TRIS(input/output control register) to turn
the load on/off.
FIGURE 4: A CIRCUIT CONFIGURATION FOR DRIVING LOW-IMPEDANCE
LOADS
You now have an effective way to bridge the 5V and3.3V rails.
It’s possible to come up with similar low-cost,intelligent
solutions to bridge two rails during the transi-tion phase. It is
also very likely that most devices willsoon move to a lower rail,
eliminating the need tobridge the rails. In the meantime, the
methods in thisarticle should help you to take advantage of the
newesttrends in the semiconductor industry and lower yoursystem
costs.
⎟⎠⎞
⎜⎝⎛
−=
(min)ln/
IHDD
DD
PVPV
PVFalltimeRise τ
3.3V Device with5V tolerant I/P
5V
Load on MCU Pin defined as O/P
3.3V Device with 5V tolerant I/P
5V
Load Off MCU Pin defined as I/P
ELECTRICAL SPECIFICATIONS
Device VDD Supply Digital only I/O Ports Input High Voltage
Maximum Current Source/Sink
PIC® and dsPIC30F 5.5V 5.5V Max 25 mAPIC18F J-series 2.0-3.6V
5.5V Max 4/8/25 mA (I/O port dependent)PIC24F 2.0-3.6V 5.5V Max 18
mAPIC24H 3.0-3.6V 5.5V Max 4 mAdsPIC33F 3.0-3.6V 5.5V Max 4 mA
6 © 2006 Microchip Technology Inc.
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3V Newsletter
TIP #2 Driving Bipolar TransistorsWhen driving Bipolar
transistors, the amount of basecurrent “drive” and forward current
gain (Β/hFE) willdetermine how much current the transistor can
sink.When driven by a microcontroller I/O port, the basedrive
current is calculated using the port voltage andthe port current
limit (typically 20 mA). When using3.3V technology, smaller value
base current limitingresistors should be used to ensure sufficient
base driveto saturate the transistor.
FIGURE 1: DRIVING BIPOLAR TRANSISTORS USING MICROCONTROLLER I/O
PORT
The value of RBASE will depend on the microcontrollersupply
voltage. Equation 1 describes how to calculateRBASE.
TABLE 1: BIPOLAR TRANSISTOR DC SPECIFICATIONS
Characteristic Sym Min Max Unit Test Condition
OFF CHARACTERISTICSCollector-Base Breakdown voltage
V(BR)CBO 60 — V IC = 50 μA, IE = 0
Collector- Emitter Breakdown Voltage
V(BR)CEO 50 — V IC = 1.0 mA, IB = 0
Emitter-Base Breakdown Voltage
V(BR)EBO 7.0 — V IE = 50 μA, IC = 0
Collector Cutoff Current
ICBO — 100 nA VCB = 60V
Emitter Cutoff Current
IEBO — 100 nA VEB = 7.0V
ON CHARACTERISTICSDC Current Gain hFE 120
180270
270390560
—VCE = 6.0V, IC = 1.0 mA
Collector- Emitter Saturation Voltage
VCE(SAT) — 0.4 V IC = 50 mA, IB = 5.0 mA
VBE Forward Drop
+
-RLOAD
VLOAD
hFE (Forward Gain)
+VDD RBASE
When using bipolar transistors as switches to turn onand off
loads controlled by the microcontroller I/O portpin, use the
minimum hFE specification and margin toensure complete device
saturation.
EQUATION 1: CALCULATING THE BASE RESISTOR VALUE
3V technology example:VDD = +3V, VLOAD = +40V, RLOAD = 400Ω, hFE
min. = 180, VBE = 0.7VRBASE = 4.14 kΩ, I/O port current = 556 μA5V
technology example:VDD = +5V, VLOAD = +40V, RLOAD = 400Ω, hFE min.
= 180, VBE = 0.7VRBASE = 7.74 kΩ, I/O port current = 556 μAFor both
examples, it is good practice to increase basecurrent for margin.
Driving the base with 1 mA to 2 mAwould ensure saturation at the
expense of increasingthe input power consumption.
RBASE = (VDD – VBE)XhFEXRLOAD
VLOAD
© 2006 Microchip Technology Inc. 7
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3V Newsletter
NOTES:
8 © 2006 Microchip Technology Inc.
-
Recent IssuesThe current issue of this newsletter is available
from the Microchip web site at http://www.microchip.com/3Volts.
ISSUE 2, MARCH 2006• Introduction• “Different Ways to Develop 3V
From 5V for Multi-Voltage Applications”• “Fundamentals on Digital
Interface Using Two Rails”• “TIP #1 Lower Cost Alternative Power
System Using 3 Rectifier Diodes”• “3V VDD FAQ Items”• “Utilizing
CAN and LIN in 3 Volt Embedded Designs”• “TIP #2 Driving N-Channel
MOSFET Transistors”
ISSUE 1, DECEMBER 2005• “Why 3V”• “Programming at 3V VDD”•
“Serial EEPROMs for 3V Applications”• “Driving Microcontrollers to
3V”• “Microchip Provides an Impressive Portfolio of Low-Voltage
Analog and Interface Design Solutions”
IInformation contained in this publication regarding
deviceapplications and the like is provided only for your
convenienceand may be superseded by updates. It is your
responsibility toensure that your application meets with your
specifications.MICROCHIP MAKES NO REPRESENTATIONS OR WAR-RANTIES OF
ANY KIND WHETHER EXPRESS OR IMPLIED,WRITTEN OR ORAL, STATUTORY OR
OTHERWISE,RELATED TO THE INFORMATION, INCLUDING BUT NOTLIMITED TO
ITS CONDITION, QUALITY, PERFORMANCE,MERCHANTABILITY OR FITNESS FOR
PURPOSE.Microchip disclaims all liability arising from this
information andits use. Use of Microchip devices in life support
and/or safetyapplications is entirely at the buyer’s risk, and the
buyer agreesto defend, indemnify and hold harmless Microchip from
any andall damages, claims, suits, or expenses resulting from
suchuse. No licenses are conveyed, implicitly or otherwise,
underany Microchip intellectual property rights.
© 2006 Microchip Technology Inc.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron, dsPIC,
KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART, PRO MATE,
PowerSmart, rfPIC, and SmartShunt are registered trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB, SEEVAL,
SmartSensor and The Embedded Control Solutions Company are
registered trademarks of Microchip Technology Incorporated in the
U.S.A.
Analog-for-the-Digital Age, Application Maestro, CodeGuard,
dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense,
FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC,
Linear Active Thermistor, Mindi, MiWi, MPASM, MPLIB, MPLINK,
PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo,
PowerMate, PowerTool, REAL ICE, rfLAB, rfPICDEM, Select Mode, Smart
Serial, SmartTel, Total Endurance, UNI/O, WiperLock and ZENA are
trademarks of Microchip Technology Incorporated in the U.S.A. and
other countries.
SQTP is a service mark of Microchip Technology Incorporated in
the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2006, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
9
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10 © 2006 Microchip Technology Inc.
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WORLDWIDE SALES AND SERVICE
10/19/06
IntroductionIn This IssuePICDEM™ HPC Explorer BoardFIGURE 1:
PICDEM™ HPC Explorer Board
dsPICDEM™ 1.1 PlusFIGURE 2: dsPICDEM™ 1.1 Plus Dev. Board
TIP #1 Standby Current Reduction Technique for J-Series
DevicesFIGURE 1: Diode as a Voltage Regulator
Robustness of 3V SystemsFIGURE 1: 20 MHz Clock, Vdd-5V and 3V,
X-axis
Using MPLAB® REAL ICE™ Probe In Low-Voltage ApplicationsFIGURE
1: MPLAB® REAL ICE™ EMULATION
Bridging The RailsFIGURE 1: Use a 5V Device With TTL
InputsFIGURE 2: Circuit Shifts Output to Bring in Range for 5V
InputFIGURE 3: A Pull-Up Resistor on Open Drain Output to Generate
5V OutputFIGURE 4: A Circuit Configuration for Driving Low-
Impedance Loads
TIP #2 Driving Bipolar TransistorsFIGURE 1: Driving Bipolar
Transistors Using Microcontroller I/O PortTABLE 1: Bipolar
Transistor DC Specifications
Worldwide Sales and Service
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