Transcript The Design Process Abstraction & Synthesis

The Design Process
Applying Value Analysis to
Determine an Optimum
Solution
by
Prof. Bitar
Abstraction & Synthesis
Homework #2
Research Prior Art
Brainstorm
Possible Solutions
HW#2
Perform
Value Analysis
Viable
Options
Apply
Constraints
Preferred
Solution
Abstraction
&
Synthesis
Window Candle Block Diagram
with Two Defined Blocks
Photo
Sensor
Solar Cell
Charge
Controller
Rechargeable
Battery
1.2V NiCd
Mode
Selection
DC-DC
Boost
Converter
Flickering
Control
LED
3.2V
20mA
Agilent White LED Spec. Sheet
LED Specifications – Curves !
Max. Forward Current vs. Voltage
Check: 20mA @ 3.2V (Typical)
Battery Specifications
Battery Specification
Discharge Curve
DC-DC Boost Converter
Interface Specs
INPUT: 1.2V(Nominal)
Minimum ? (0.8V)
Maximum ? (1.6V)
OUTPUT: 20mA (constant current?)
3.2V (Nominal for White)
1.7V (Nominal for Red)
Searching for Possible Boost
Converters…
www.digikey.com
– DC-DC Converters (4,561 IN STOCK!)
Narrowing Search (down to 47)
– Step-Up (Boost)
– Vmin ≤ 0.8V (why?)
– Internal Switch
– Number of Outputs (1)
– Small Qty. Packaging (cut tape / tube)
Case…
Package/Case Concerns…
For prototypes, through-hole packages (8DIP, 16-Dip, etc.) are easiest to work with.
If chip is only available in surface-mount,
avoid DFN, QFN, LLP and BGA packages
since pins are underneath.
For surface-mount ic’s, try to get largest
packages possible with gull-wing pins.
Possible Manufacturers
Manufacturer
Part Number
Unit
Linear Technology
LTC3429ES6#TRMPBF
$4.56
Maximum Integrated
Products
MAX1724EZK50+T
$3.63
Texas Instruments
UCC3941DTR-3
$3.89
National Semiconductor
LM2623MM/NOPB
$2.91
ST Microelectronics
L6920DB
$2.07
Also Ran Across Another Device!
LED Driver IC’s…
www.digikey.com
– LED Drivers (1,319 IN STOCK!)
Narrowing Search (down to 47)
– Step-Up (Boost)
– Vmin ≤ 0.8V (why?)
– Internal Switch
– Number of Outputs (1)
– Small Qty. Packaging (cut tape / tube)
Case…avoid DFN, QFN, LLP, BGA
Possible LED Drivers
Manufacturer
Part Number
Linear Technology
LTC3490ES8#PBF
$4.20
LT1932ES6#TRMPBF
$4.17
ZXLD383ET5CT-ND
$1.56
Diodes/Zetex
Unit
IC’s Making the First Cut
(Just based on PRICE!)
Manufacturer
Part Number
Unit
National
Semiconductor
DC-DC Converter
LM2623MM/NOPB
$2.91
ST
Microelectronics
DC-DC Converter
L6920DB
$2.07
Diodes/Zetex
LED Driver
ZXLD383ET5CT
$1.56
National - LM2623
Typical Application Circuit
(Constant Voltage Output)
Note External Components…
Inductor
Capacitor(s)
Schottky Diode
Resistive Divider
ST - L6920DB
Typical Application Circuit
(Note Fewer External Components!)
Diodes/Zetex - ZXLD383ET5CT
Typical Application Circuit
Leaning Toward the
Diodes/Zetex LED Driver
http://www.diodes.com/datasheets/ZXLD3
83.pdf
Pro’s
– Price
– Ease of Use (Few External Components)
– Designed for My Application
Con’s
– Single Manufacturer (Not Multiple Source!)