MCP1630
Boost Mode LED Driver
Demo Board
User’s Guide
© 2007 Microchip Technology Inc.
DS51665B
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
QUALITY, PERFORMANCE, MERCHANTABILITY OR
FITNESS FOR PURPOSE. Microchip disclaims all liability
arising from this information and its use. Use of Microchip
devices in life support and/or safety applications is entirely at
the buyer’s risk, and the buyer agrees to defend, indemnify and
hold harmless Microchip from any and all damages, claims,
suits, or expenses resulting from such use. No licenses are
conveyed, implicitly or otherwise, under any Microchip
intellectual property rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, KEELOQ logo, microID, MPLAB, PIC,
PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, Linear Active Thermistor, 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, Mindi, MiWi,
MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit,
PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal,
PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, 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.
© 2007, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
DS51665B-page ii
© 2007 Microchip Technology Inc.
MCP1630 BOOST MODE LED DRIVER
DEMO BOARD USER’S GUIDE
Table of Contents
Preface ........................................................................................................................... 1
Introduction............................................................................................................ 1
Document Layout .................................................................................................. 1
Conventions Used in this Guide ............................................................................ 2
Recommended Reading........................................................................................ 3
The Microchip Web Site ........................................................................................ 3
Customer Support ................................................................................................. 3
Document Revision History ................................................................................... 4
Chapter 1. Product Overview ....................................................................................... 5
1.1 Introduction ..................................................................................................... 5
1.2 Features ......................................................................................................... 5
1.3 Device Summary ............................................................................................ 5
1.4 Technical Specifications ................................................................................. 6
Chapter 2. Installation and Operation ......................................................................... 7
2.1 Getting Started ............................................................................................... 7
2.2 What the MCP1630 Boost Mode LED Driver Demo Board Kit includes ......... 7
2.3 Setup Procedures ........................................................................................... 8
2.4 Circuit Description .......................................................................................... 9
2.5 Firmware Description ................................................................................... 10
Appendix A. Schematic and Layouts ........................................................................ 13
A.1 Introduction .................................................................................................. 13
A.2 Board - Schematic ....................................................................................... 14
A.3 Board - Top Layer ........................................................................................ 15
A.4 Board - Top Silk Layer ................................................................................. 16
A.5 Board - Bottom Layer ................................................................................... 17
Appendix B. Bill Of Materials (BOM) ......................................................................... 19
Appendix C. Firmware Flowchart .............................................................................. 21
Worldwide Sales and Service .................................................................................... 24
© 2007 Microchip Technology Inc.
DS51665B-page iii
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
NOTES:
DS51665B-page iv
© 2007 Microchip Technology Inc.
MCP1630 BOOST MODE LED DRIVER
DEMO BOARD USER’S GUIDE
Preface
NOTICE TO CUSTOMERS
All documentation becomes dated, and this manual is no exception. Microchip tools and
documentation are constantly evolving to meet customer needs, so some actual dialogs
and/or tool descriptions may differ from those in this document. Please refer to our web site
(www.microchip.com) to obtain the latest documentation available.
Documents are identified with a “DS” number. This number is located on the bottom of each
page, in front of the page number. The numbering convention for the DS number is
“DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the
document.
For the most up-to-date information on development tools, see the MPLAB® IDE on-line help.
Select the Help menu, and then Topics to open a list of available on-line help files.
INTRODUCTION
This chapter contains general information that will be useful to know before using the
MCP1630 Boost Mode LED Driver Demo Board. Items discussed in this chapter
include:
•
•
•
•
•
•
Document Layout
Conventions Used in this Guide
Recommended Reading
The Microchip Web Site
Customer Support
Document Revision History
DOCUMENT LAYOUT
This document describes how to use the MCP1630 Boost Mode LED Driver Demo
Board as a development tool to evaluate the MCP1630 and other Microchip
components.. The manual layout is as follows:
• Chapter 1. “Product Overview” – Important information about the MCP1630
Boost Mode LED Driver Demo Board.
• Chapter 2. “Installation and Operation” – Includes instructions on how to get
started with this user’s guide and a description of the user’s guide.
• Appendix A. “Schematic and Layouts” – Shows the schematic and layout
diagrams for the MCP1630 Boost Mode LED Driver Demo Board.
• Appendix B. “Bill Of Materials (BOM)” – Lists the parts used to build the
MCP1630 Boost Mode LED Driver Demo Board.
• Appendix C. “Firmware Flowchart” - Provides a flow chart of the firmware for
the MCP1630 Boost Mode LED Driver Demo Board
© 2007 Microchip Technology Inc.
DS51665B-page 1
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
CONVENTIONS USED IN THIS GUIDE
This manual uses the following documentation conventions:
DOCUMENTATION CONVENTIONS
Description
Arial font:
Italic characters
Represents
Referenced books
Emphasized text
A window
A dialog
A menu selection
A field name in a window or
dialog
A menu path
MPLAB® IDE User’s Guide
...is the only compiler...
the Output window
the Settings dialog
select Enable Programmer
“Save project before build”
A dialog button
A tab
A number in verilog format,
where N is the total number of
digits, R is the radix and n is a
digit.
A key on the keyboard
Click OK
Click the Power tab
4‘b0010, 2‘hF1
Italic Courier New
Sample source code
Filenames
File paths
Keywords
Command-line options
Bit values
Constants
A variable argument
Square brackets [ ]
Optional arguments
Curly brackets and pipe
character: { | }
Ellipses...
Choice of mutually exclusive
arguments; an OR selection
Replaces repeated text
#define START
autoexec.bat
c:\mcc18\h
_asm, _endasm, static
-Opa+, -Opa0, 1
0xFF, ‘A’
file.o, where file can be
any valid filename
mcc18 [options] file
[options]
errorlevel {0|1}
Initial caps
Quotes
Underlined, italic text with
right angle bracket
Bold characters
N‘Rnnnn
Text in angle brackets < >
Courier New font:
Plain Courier New
Represents code supplied by
user
DS51665B-page 2
Examples
File>Save
Press <Enter>, <F1>
var_name [,
var_name...]
void main (void)
{ ...
}
© 2007 Microchip Technology Inc.
Preface
RECOMMENDED READING
This user's guide describes how to use MCP1630 Boost Mode LED Driver Demo
Board. The following Microchip documents are available and recommended as
supplemental reference resources.
MCP1630/MCP1630V Data Sheet, "High-Speed, Microcontroller-Adaptable, Pulse
Width Modulator" (DS21896)
This data sheet provides detailed information regarding the MCP1630 family.
PIC12F683 Data Sheet, (DS41211)
This data sheet provides detailed information regarding the PIC12F683 product.
MCP1702 Data Sheet, "250 mA Low Quiescent Current LDO Regulator"
(DS22008)
This data sheet provides detailed information regarding the MCP1702 product.
THE MICROCHIP WEB SITE
Microchip provides online support via our web site at www.microchip.com. This web
site is used as a means to make files and information easily available to customers.
Accessible by using your favorite Internet browser, the web site contains the following
information:
• Product Support – Data sheets and errata, application notes and sample
programs, design resources, user’s guides and hardware support documents,
latest software releases and archived software
• General Technical Support – Frequently Asked Questions (FAQs), technical
support requests, online discussion groups, Microchip consultant program
member listing
• Business of Microchip – Product selector and ordering guides, latest Microchip
press releases, listing of seminars and events, listings of Microchip sales offices,
distributors and factory representatives
CUSTOMER SUPPORT
Users of Microchip products can receive assistance through several channels:
•
•
•
•
Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Customers should contact their distributor, representative or field application engineer
for support. Local sales offices are also available to help customers. A listing of sales
offices and locations is included in the back of this document.
Technical support is available through the web site at: http://support.microchip.com
© 2007 Microchip Technology Inc.
DS51665B-page 3
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
DOCUMENT REVISION HISTORY
Revision B (June 2007)
•
•
•
•
•
Changed MCP1630 device to MCP1630V throughout document
Added additional verbiage in Section 1.1 Introduction
Updated Figure 1-1
Updated schematic to show MPC1630V device
Changed MCP1630 device part number in BOM to MCP1630V device
Revision A (May 2007)
• Initial Release of this Document.
DS51665B-page 4
© 2007 Microchip Technology Inc.
MCP1630 BOOST MODE LED DRIVER
DEMO BOARD USER’S GUIDE
Chapter 1. Product Overview
1.1
INTRODUCTION
The MCP1630 Boost Mode LED Driver Demo Board is a step-up, switch-mode, dc-dc
converter used for power LED applications. The demo board provides a 350 mA or
700 mA constant current source with a jumper selection. Other output currents can be
obtained with minor modifications to the board.
The MCP1630 Boost Mode LED Driver Demo Board utilizes Microchip's MCP1630V
high-speed pulse width modulator. The 8-pin MCP1630V device contains the analog
components necessary for an analog switch-mode control loop including an error
amplifier, PWM comparator, and a high current driver pin. The switching frequency and
maximum duty cycle for the MCP1630V are determined by an external clock source.
An 8-pin PIC12F683 microcontroller is used to provide a 500 kHz switching clock for
the MCP1630. In addition, the PIC12F683 firmware supervises the circuit output
voltage and can optionally dim the LEDs when a potentiometer is attached.
In this demo application, the MCP1630V device is used for Average Current mode
control using a voltage boost circuit. A ramp generator provides a reference signal to
the MCP1630V comparator. The ramp signal and error amplifier output voltage
determine the PWM duty cycle for the voltage boost circuit. The MCP1630V device is
used because its error amplifier provides a higher output voltage range than the
MCP1630 device (2.7V vs. 0.9V).
Note:
1.2
MCP1630 is used throughout this document for both the MCP1630 and
MCP1630V devices.
FEATURES
The MCP1630 Boost Mode LED Driver Demo Board has the following features:
•
•
•
•
•
•
•
Compact size with high output power
High efficiency over entire operating input voltage range
Selectable output current: 350 mA or 700 mA
Maximum output power: 30W
Optional software dimming control
Factory programmed source code provided
Switching frequency, maximum duty cycle, and MCP1630 reference voltage can
be modified in firmware
• Additional application functions can be provided in firmware
© 2007 Microchip Technology Inc.
DS51665B-page 5
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
1.3
DEVICE SUMMARY
The MCP1630 Boost Mode LED Driver Demo Board uses the following primary devices
on the board.
• A MCP1702 LDO regulator is used to supply the regulated voltage to the
PIC12F683 and the MCP1630. The MCP1702 is capable of delivering 250 mA
with only 650 mV (typical) of input to output voltage differential
• A MCP1630, a high-speed pulse width modulator IC, is used. When used in
conjunction with a microcontroller, the MCP1630 will control the power system
duty cycle to provide output current and/or voltage regulation
• A PIC12F683 microcontroller (MCU) is used to generate the MCP1630 reference
voltage and the oscillator signal at 500 kHz
1.4
TECHNICAL SPECIFICATIONS
•
•
•
•
•
Input Voltage: +9V to 16V
Maximum Output Voltage: 50V (limited to 40V by application software)
Typical Output Current: 700 mA
Maximum Output Current: 1A
Maximum Output Power: 30W
Figure 1-1 shows a simplified block diagram of the application
Bias Supply
9 - 16 VDC
MCP1702
+5
MCP1630V
+5
Vdd 7
2
+5
EA
+
PIC12F683
1 VDD
Vss
8
2 GP5
GP0
7
3 GP4
GP1
6
4 GP3
GP2/
CCP1
5
8
Vref
Ramp Generator
3
Clock
1
CS +
4 Osc
Comp
Output
Driver
6
Vss 5
LED String
Reference Circuit
Output Voltage Feedback
FIGURE 1-1:
DS51665B-page 6
MCP1630 Boost Mode LED Driver Demo Board Simplified Block Diagram.
© 2007 Microchip Technology Inc.
MCP1630 BOOST MODE LED DRIVER
DEMO BOARD USER’S GUIDE
Chapter 2. Installation and Operation
2.1
GETTING STARTED
The MCP1630 Boost Mode LED Driver Demo Board is fully assembled and tested. The
board requires the use of an external input voltage source (+9V to 16V) and an external
LED load (provided).
2.2
WHAT THE MCP1630 BOOST MODE LED DRIVER DEMO BOARD KIT
INCLUDES
The MCP1630 Boost Mode LED Driver Demo Board Kit includes:
• MCP1630 Boost Mode LED Driver Demo Board (102-00152)
• A PCB containing a string of LEDs
• Analog and Interface Products Demonstration Boards CD-ROM (DS21912):
- MCP1630 Boost Mode LED Driver Demo Board User’s Guide (DS51665)
2.2.1
Additional Components Required for Operation
1. A DC Power Supply. A 2.5 mm plug with positive polarity on the center pin is
required to connect the power supply to J1. A bench supply that can produce
12V, 2.5A is recommended to operate the board at the full rated power. A 9V,
750 mA power supply can be purchased through Microchip Inc., part #
AC162039, if needed. This power supply will drive the supplied string of LEDs at
350 mA only (5W output).
2. Oscilloscope and/or multi-meter to observe waveforms and measure electrical
parameters (optional).
© 2007 Microchip Technology Inc.
DS51665B-page 7
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
2.3
SETUP PROCEDURES
To operate the demonstration board, you need to complete the following steps:
1. Configure the board for the desired current output level.
2. Attach a LED load to the output terminals.
3. Connect a power supply to the input.
Detailed instructions are provided below for each step.
2.3.1
Demo Board Output Current Configuration
1. Remove jumper J4 for an output current of 350 mA. Install jumper J4 for an
output current of 700 mA.
2.3.2
Connecting the Load
A string of five LEDs mounted on a metal PCB has been provided for use with the demo
board. (See Figure 2-1).
When driven at 350 mA, the total power delivered to the five LEDs will be approximately
5 W. At 700 mA drive, the load power will be approximately 10W. Care must be taken
not to operate the LEDs beyond the maximum junction temperature specified in the
data sheet.
It is recommended that you mount the metal PCB to a heat-sink to allow continuous
operation. A heat-sink can be constructed using a length of 1-inch square aluminum
square tubing. The aluminum square tubing is available at most hardware stores. The
LED PCB can be mounted to the aluminum tubing using machine screws or self-tapping sheet metal screws.
Note:
Do not operate the LEDs for an extended period of time without mounting
the PCB to a suitable heat-sink. Operation beyond the maximum junction
temperature could cause early failure of the LEDs.
1. Connect the LED PCB to the demo board output terminals (TP1 and TP2) using
test clips (provided). The anode of the LEDs is indicated on the PCB with a '+'
marking and should be connected to the TP1 terminal on the demo board. The
cathode of the LEDs should be connected to the TP2 output terminal on the
demo board.
Note:
Do not connect the TP2 output terminal on the demo board or the cathode
of the LEDs to circuit ground. The TP2 terminal is connected to a current
sensing resistor and is not at ground potential during normal operation.
Damage to the circuit will occur if the TP2 terminal is connected to ground.
Connect to TP1
Connector wire
with 'alligator'
clip
Connect to TP2
D1
+
FIGURE 2-1:
DS51665B-page 8
D2
+
D3
+
D4
+
D5
+
LED Load Board.
© 2007 Microchip Technology Inc.
Installation and Operation
2.3.3
Powering the MCP1630 Boost Mode LED Driver Demo Board
1. Connect a power supply to J1 to power up the MCP1630 Boost Mode LED Driver
Demo Board. Ensure that the power supply has a 2.5 mm barrel connector with
the center pin positive. The input voltage source should be limited to the 9V to
+16V range. Ensure that the chosen power supply can provide enough current
at the selected voltage to properly power the LEDs.
Note:
The LEDs will be very bright during operation and provide a focused light
source! Avoid looking directly into the LEDs when power is applied to the
circuit. It is recommended that you cover the string of LEDs with a sheet of
paper or some other opaque material during testing to avoid discomfort.
An external potentiometer can be connected to the MCU to provide LED dimming
control. The 'Dimming Control' section of this document provides more information.
2.3.4
Verifying the Application
The best way to evaluate the MCP1630 is to dig into the circuit and measure voltages
and currents with a multi-meter and probe the board with an oscilloscope. You can use
the following procedure to verify the LED input power:
1. To measure the output voltage (VLED), connect the multi-meter across TP1 and
TP2.
2. The load current (ILED) passes through the LED load as well as current sense
resistor, R14. To measure the output current, connect the multi-meter across TP2
and TP3 to determine the voltage drop across R14. The current through resistor
R14 and the load is VR14 / R14.
3. The output power can be calculated as PLED = ILED * VLED.
2.4
CIRCUIT DESCRIPTION
Appendix A shows the circuit schematic for the MCP1630 Boost Mode LED Driver
Demo Board.
The input voltage to the circuit may vary from +9 V to +16 V. The MCP1702 voltage
regulator U1 generates a regulated 5 V output for the MCP1630 and the PIC12F683
devices. A 12V Zener diode, D1, is used to limit the maximum input voltage to the
MCP1702 device.
The MCP1630 PWM controller (U3) is comprised of a high-speed comparator, high
bandwidth amplifier and set/reset flip flop, and high current driver pin. It has the
necessary components to develop an analog switch-mode power supply control loop.
The MCP1630 is designed to operate from an external clock source. The clock
frequency sets the power supply switching frequency and the clock duty cycle sets the
maximum duty cycle for the supply.
The PIC12F683 MCU (U2) operates from its own 8 MHz internal oscillator and has an
on chip Capture/Compare/PWM (CCP) peripheral module. When operating in PWM
mode, the CCP module can generate a pulse-width modulated signal with variable frequency and duty cycles.
The CCP output of the MCU is connected to the oscillator input of the MCP1630 device.
For this application, the CCP module is configured to provide a 500 kHz clock source
with 20% duty cycle. The 20% duty cycle produced by the CCP module limits the
maximum duty cycle of the MCP1630 to 80%. Once configured, the CCP peripheral
does not need any control by the MCU software. If desired, the CCP can be reconfigured to obtain different clock frequencies up to the 2 MHz maximum specification for
the MCP1630.
© 2007 Microchip Technology Inc.
DS51665B-page 9
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
The CCP output is also connected to a simple ramp generator that is reset at the beginning of each MCP1630 clock cycle. The ramp generator is composed of transistor Q2,
resistors R2, R3 and capacitor C6. It provides the reference signal to the MCP1630
comparator. The MCP1630 comparator compares this ramp reference signal to the
error amplifier output to generate a PWM signal.
A resistor voltage divider (R4, R5 and R6) and filter is used to set the reference voltage
for the constant current control and is driven by the GP5 pin of the MCU. Jumper J4 is
used to select two different reference voltages to drive the LED load at different current
levels. With J4 removed, resistors R4 and R5 provide a 206 mV reference voltage. This
setting provides 350 mA output current. With J4 installed, resistors R4, R5 and R6
provide a 412 mV reference voltage. (700 mA output)
R8 and C7 form an integrator circuit in the negative feedback path, providing high loop
gain at DC. This simple compensation network is sufficient for a constant current LED
driver. Places have been provided on the PCB for additional compensation
components, if required.
R12 and R13 form a voltage divider that is used to monitor the output voltage of the
boost circuit. The output of the voltage divider is connected to pin GP4 of the MCU and
monitored with the ADC.
L1, Q1, D2, C12, and C13 form the basic voltage boost circuit. C13 is not populated on
the PCB. The value of C12 has been selected to keep the LED current ripple less than
20% at the rated load conditions.
2.5
FIRMWARE DESCRIPTION
Appendix C shows the firmware flowchart. Different parts of the firmware operation are
described below.
2.5.1
Clock Generation
At a minimum, the PIC12F683 code must initialize the CCP module in PWM mode to
produce a clock signal for the MCP1630. The CCP is configured to produce 500 kHz
with a 20% duty cycle. The clock duty cycle limits the maximum on time of the power
MOSFET to 80% duty. I/O pins GP5 is driven high to enable the voltage reference for
the MCP1630 control loop. After these tasks are completed, the MCP1630 can begin
the current regulation function and the MCU can execute other tasks.
2.5.2
Open Circuit Detection
One potential problem that can occur with a constant current application is an open-circuit load condition. In this case, the power supply will try to raise the output voltage to
provide the required current. A boost converter circuit can continue to raise the output
voltage until component damage occurs. The software monitors the output voltage to
the MCP1630 using an ADC channel and disables the power supply when a maximum
output voltage of 40V is reached.
Once the output reference voltage reaches the allowable maximum limit, the GP2 pin
is driven high by writing a 100% duty cycle value to the CCP control registers. This high
signal effectively resets the MCP1630. The reference to the MCP1630 is also disabled
by clearing pin GP5. After the over-voltage event, the software provides a delay before
restarting the input clock to the MCP1630 PWM generator and turning on the reference
voltage. The delay reduces stress on the power supply components.
DS51665B-page 10
© 2007 Microchip Technology Inc.
Installation and Operation
2.5.3
Dimming Control
An external potentiometer can optionally be attached to the PCB to provide LED
dimming control. When a potentiometer is present, the demonstration software will
sample the voltage and modulate pin GP5 (MCP1630 reference) with a low-frequency
PWM signal. The PWM signal is generated in software using Timer0 as a timing
reference. The software PWM signal provides 63 LED brightness levels. If a
potentiometer is not present, pin GP5 is maintained at 100% duty to provide full LED
brightness.
If potentiometer dimming is desired, connect a 10 kohm potentiometer to the ICSP
programming header, J3. The resistive element of the potentiometer is connected
between pins 2 and 3 of J3 (Vdd and ground). The potentiometer wiper is connected to
pin 5 of J3 (GP1 pin).
Note:
Set the potentiometer to provide 0 output voltage when power is first
applied to the demo board. This will allow the potentiometer to be properly
detected as explained below.
The demonstration software detects whether a potentiometer has been attached to the
PCB using the weak pull-up (WPU) feature on pin GP1. At startup, the software
enables pin GP1 as a digital input with the WPU turned on. If no potentiometer is
present, the pin will float high due to the WPU and a logical '1' will be detected. If a
potentiometer is connected and the wiper is turned to the minimum setting, a logical '0'
will be detected on the I/O pin. If the potentiometer is detected, the ADC result is
allowed to set the dimming duty cycle.
2.5.4
Modifications
The hardware and software on this demonstration board can be modified to solve a
wide variety of application problems. A few modifications that you might desire to
support your application are described below.
1. The reference voltage divider network comprising R4, R5, and R6 can be
modified to provide current output levels other than 350 mA and 700 mA. The
reference voltage supplied to the MCP1630 should be 560 mV or less to keep
the output current from exceeding 1A.
2. Some applications are sensitive to electromagnetic interference (EMI). One way
to reduce the impact of radiated EMI is to spread the noise across a portion of
the frequency spectrum. This is easy to do with the PIC12F683 by writing a value
to a tuning register that affects the frequency of the internal 8 MHz oscillator. If
you need this feature, uncomment the first four lines of code after the MainLoop
label in the code. This code reads a value from the free-running Timer0 and uses
it as a pseudo-random tuning value for the oscillator.
3. The switching frequency is set to 500 kHz to keep the size of inductor L1 small.
The clock frequency is set by the PR2 register, which is the timebase period register for the PIC12F683 CCP module. Other switching frequencies can be used
by writing a different value to PR2. The CCPR1L and CCP1CON registers also
need to be modified to adjust the duty cycle of the clock signal. Refer to the
PIC12F683 data sheet (DS41211) for more information.
4. A temperature sensor can also be used for thermal management of the LEDs.
Microchip Technology, Inc. provides a range of analog and digital output
temperature sensors for different application needs. The ICSP programming
header (J3) on the PCB provides a convenient method to access 5V, ground, and
two I/O pins. These pins could be used to interface a temperature sensor to the
PIC12F683, if desired.
© 2007 Microchip Technology Inc.
DS51665B-page 11
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
2.5.5
Programming
Header J3 is provided for in-circuit programming. The MCP1630 Boost Mode LED
Driver Demo Board comes pre-programmed with firmware to operate the system. The
PIC12F683 can be reprogrammed with the PICkit 2 Debug Express (Microchip P/N:
DV164121), which is a low-cost Flash microcontroller programmer and a debugger.
DS51665B-page 12
© 2007 Microchip Technology Inc.
MCP1630 BOOST MODE LED DRIVER
DEMO BOARD USER’S GUIDE
Appendix A. Schematic and Layouts
A.1
INTRODUCTION
This appendix contains the following schematics and layouts for the MCP1630 Boost
Mode LED Driver Demo Board:
•
•
•
•
Board – Schematic
Board – Top Layer
Board – Top Silk Layer
Board – Bottom Layer
© 2007 Microchip Technology Inc.
DS51665B-page 13
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
BOARD - SCHEMATIC
1
3
2
M
A.2
DS51665B-page 14
© 2007 Microchip Technology Inc.
Schematic and Layouts
A.3
BOARD - TOP LAYER
© 2007 Microchip Technology Inc.
DS51665B-page 15
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
A.4
BOARD - TOP SILK LAYER
DS51665B-page 16
© 2007 Microchip Technology Inc.
Schematic and Layouts
A.5
BOARD - BOTTOM LAYER
© 2007 Microchip Technology Inc.
DS51665B-page 17
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
NOTES:
DS51665B-page 18
© 2007 Microchip Technology Inc.
MCP1630 BOOST MODE LED DRIVER
DEMO BOARD USER’S GUIDE
Appendix B. Bill Of Materials (BOM)
TABLE B-1:
Qty
BILL OF MATERIALS (BOM)
Reference
Description
Manufacturer
Rohm
Part Number
1
C1
CAP TANT 4.7UF 16V 20% SMD 1206
5
C2, C3, C5,
C10, C11
CAP CERM .10UF 50V 20% 0805 SMD AVX Corporation
TCA1C475M8R
1
C4
CAP 4700PF 50V CERM CHIP 0805
Panasonic® - ECG
1
C6
CAP 1500PF 50V CERM CHIP 0805
Panasonic - ECG
ECJ-2VB1H152K
1
C7
CAP 220PF 50V CERM CHIP 0805
SMD
Panasonic - ECG
ECJ-2VC1H221J
3
C8, C9, C12
DO NOT POPULATE
—
—
1
C13
CAP 4.7UF 50V CERAMIC F 1210
Panasonic - ECG
ECJ-4YF1H475Z
2
C14,C15
CAP 4.7UF 25V CERAMIC X5R 1206
Panasonic - ECG
ECJ-3YB1E475M
1
D1
DIODE ZENER 500MW 12V SOD123
ON Semiconductor®
MMSZ5242BT1G
1
D2
DIODE SCHOTTKY 60V 1.5A SMA
International Rectifier
10MQ060NTRPBF
1
J1
CONN POWER JACK 2.5MM PCB
CIRC
CUI Inc
PJ-102B
1
J3
CONN HEADER RTANG 6POS .156
TIN
Tyco Electronics/Amp
640385-6
1
J4
CONN HEADER 2POS .100 VERT TIN
Molex®/Waldom®
Electronics Corp
22-28-4020
1
J4 SHUNT
CONN JUMPER SHORTING GOLD
FLASH
Sullins Electronics Corp.
SPC02SYAN
1
L1
DO5010H-153MLD (MLD - Full Reel
250 MLB partial)
Coilcraft
DO5010H-153MLD
1
LED Strip
Cree® XLamp® XR-E LED
ETG, Corp
CR5UP-XRE
1*
LED Strip
1 Set of Alligator Test Clips per board.
—
—
08055C104MAT2A
ECJ-2VB1H472K
* These come in sets of ten, Ea. Will be cut in half resulting in two pieces. ( 20 pieces per set
of ten )
1
PCB
RoHS Compliant Bare PCB, MCP1630
Boost Mode LED Driver Demo Board
—
104-00152
1
Q1
MOSFET Transistor Polarity:N Channel Power Dissipation:2.1W
Drain-Source Breakdown Voltage:55V
International Rectifier
IRLL024NPBF
1
Q2
TRANS NPN SW 600MA 40V SOT23
NXP Semiconductors
PMBT4401 T/R
1
R1
RES 200 OHM 1/4W 5% 1206 SMD
Rohm
MCR18EZHJ201
1
R2
RES 470 OHM 1/8W 5% 0805 SMD
Rohm
MCR10EZPJ471
1
R3
RES 2.0K OHM 1/8W 5% 0805 SMD
Rohm
MCR10EZPJ202
2
R4, R6
RES 10K OHM 1/8W 5% 0805 SMD
Rohm
MCR10EZPJ103
1
R5
RES 430 OHM 1/8W 5% 0805 SMD
Rohm
MCR10EZPJ431
1
R8
RES 160K OHM 1/8W 5% 0805 SMD
Rohm
MCR10EZPJ164
Note 1:
The components listed in this Bill of Materials are representative of the PCB assembly. The released BOM
used in manufacturing uses all RoHS-compliant components.
© 2007 Microchip Technology Inc.
DS51665B-page 19
Bill Of Materials (BOM)
TABLE B-1:
Qty
BILL OF MATERIALS (BOM) (CONTINUED)
Reference
Description
Manufacturer
Part Number
3
R9, R10, R15
DO NOT POPULATE
—
—
1
R11
RES 0.0 OHM 1/8W 5% 0805 SMD
Rohm
MCR10EZPJ000
1
R12
RES 8.2K OHM 1/8W 5% 0805 SMD
Rohm
MCR10EZPJ822
1
R13
RES 1.0K OHM 1/8W 5% 0805 SMD
Rohm
MCR10EZPJ102
1
R14
RESISTOR .56 OHM 1/2W 5% 2010
Panasonic - ECG
ERJ-12ZQJR56U
1
TP-1
Test Point PC,multi-puporse Red
Keystone Electronics®
5010
1
TP-2
Test Point PC,multi-puporse White
Keystone Electronics
5012
1
TP-3
Test Point PC,multi-puporse Black
Keystone Electronics
5011
1
U1
5V Regulator, SOT-23A
Microchip Technology
Inc.
MCP1702T-5002E/CB
1
U2
MCU, 8-SOIC
Microchip Technology
Inc.
PIC12F683-E/SN
1
U3
PWM Peripheral, 8-MSOP
Microchip Technology
Inc.
MCP1630V-E/MS
Note 1:
The components listed in this Bill of Materials are representative of the PCB assembly. The released BOM
used in manufacturing uses all RoHS-compliant components.
© 2007 Microchip Technology Inc.
DS51665B-page 20
MCP1630 BOOST MODE LED DRIVER
DEMO BOARD USER’S GUIDE
Appendix C. Firmware Flowchart
Start
Initialize: GP2 (for Output PWM)
And GP5 (for Output VREF
Internal Osc Clock to 8 MHz, TMR0 = 0
Configure Ansel & CMCON0 as Digital I/O
Set Weak Pull-Up on GP1
Setup CCP module
and 20% duty cycle
(Clock for MCP1630)
Output VREF Signal
through GP5
(Reference Voltage for
MCP1630 )
Is GP1 = 1?
YES
NO
1. Clear Weak Pull-Up on GP1
2. Set a Flag for Potentiometer
Detected
3. Set GP1 for Analog Input
Clear the
Potentiometer flag
Start ADC
ADC
Channel1
or Channel3
CH3
CH1
B
A
Set ADC for CH3
Is
Potentiometer
Flag set?
NO
YES
Set DimDuty for the
potentiometer output
value
FIGURE C-1:
Set DimDuty
for maximum
duty cycle
Firmware Flowchart - Page 1.
© 2007 Microchip Technology Inc.
DS51665B-page 21
MCP1630 Boost Mode LED Driver Demo Board User’s Guide
A
Set ADC for CH1
Is Overvoltage
Flag set
already?
YES
NO
Check ADC for
Overvoltage
Is Delay
expired?
NO
YES
B
NO
Overvoltage?
1. Restart clock to MCP1630
2. Restart reference voltage to MCP1630
YES
1. Stop clock to MCP1630
2. Stop reference voltage to MCP1630
3. Initialize Delay for 25 mSec
FIGURE C-2:
DS51665B-page 22
Firmware Flowchart - Page 2.
© 2007 Microchip Technology Inc.
Firmware Flowchart
NOTES:
© 2007 Microchip Technology Inc.
DS51665B-page 23
WORLDWIDE SALES AND SERVICE
AMERICAS
ASIA/PACIFIC
ASIA/PACIFIC
EUROPE
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://support.microchip.com
Web Address:
www.microchip.com
Asia Pacific Office
Suites 3707-14, 37th Floor
Tower 6, The Gateway
Habour City, Kowloon
Hong Kong
Tel: 852-2401-1200
Fax: 852-2401-3431
India - Bangalore
Tel: 91-80-4182-8400
Fax: 91-80-4182-8422
India - New Delhi
Tel: 91-11-4160-8631
Fax: 91-11-4160-8632
Austria - Wels
Tel: 43-7242-2244-39
Fax: 43-7242-2244-393
Denmark - Copenhagen
Tel: 45-4450-2828
Fax: 45-4485-2829
India - Pune
Tel: 91-20-2566-1512
Fax: 91-20-2566-1513
France - Paris
Tel: 33-1-69-53-63-20
Fax: 33-1-69-30-90-79
Japan - Yokohama
Tel: 81-45-471- 6166
Fax: 81-45-471-6122
Germany - Munich
Tel: 49-89-627-144-0
Fax: 49-89-627-144-44
Atlanta
Duluth, GA
Tel: 678-957-9614
Fax: 678-957-1455
Boston
Westborough, MA
Tel: 774-760-0087
Fax: 774-760-0088
Chicago
Itasca, IL
Tel: 630-285-0071
Fax: 630-285-0075
Dallas
Addison, TX
Tel: 972-818-7423
Fax: 972-818-2924
Detroit
Farmington Hills, MI
Tel: 248-538-2250
Fax: 248-538-2260
Kokomo
Kokomo, IN
Tel: 765-864-8360
Fax: 765-864-8387
Los Angeles
Mission Viejo, CA
Tel: 949-462-9523
Fax: 949-462-9608
Santa Clara
Santa Clara, CA
Tel: 408-961-6444
Fax: 408-961-6445
Toronto
Mississauga, Ontario,
Canada
Tel: 905-673-0699
Fax: 905-673-6509
Australia - Sydney
Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
China - Beijing
Tel: 86-10-8528-2100
Fax: 86-10-8528-2104
China - Chengdu
Tel: 86-28-8665-5511
Fax: 86-28-8665-7889
Korea - Gumi
Tel: 82-54-473-4301
Fax: 82-54-473-4302
China - Fuzhou
Tel: 86-591-8750-3506
Fax: 86-591-8750-3521
Korea - Seoul
Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
China - Hong Kong SAR
Tel: 852-2401-1200
Fax: 852-2401-3431
Malaysia - Penang
Tel: 60-4-646-8870
Fax: 60-4-646-5086
China - Qingdao
Tel: 86-532-8502-7355
Fax: 86-532-8502-7205
Philippines - Manila
Tel: 63-2-634-9065
Fax: 63-2-634-9069
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
Taiwan - Hsin Chu
Tel: 886-3-572-9526
Fax: 886-3-572-6459
China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
Taiwan - Kaohsiung
Tel: 886-7-536-4818
Fax: 886-7-536-4803
China - Shunde
Tel: 86-757-2839-5507
Fax: 86-757-2839-5571
Taiwan - Taipei
Tel: 886-2-2500-6610
Fax: 886-2-2508-0102
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781
Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340
Spain - Madrid
Tel: 34-91-708-08-90
Fax: 34-91-708-08-91
UK - Wokingham
Tel: 44-118-921-5869
Fax: 44-118-921-5820
China - Xian
Tel: 86-29-8833-7250
Fax: 86-29-8833-7256
12/08/06
DS51665A-page 24
© 2007 Microchip Technology Inc.