1. Sales Training Presentation
FAN5640: Dual High-Side Constant Current Source for High Voltage LCD or Keypad LED Illumination
Sales Training Presentation

2. Introduction
FAN5640 is a dual channel high-side constant current source LED driver
Simple and very small form factor lighting solution that is easy to use:
VIN range: 6.0V to 20.0V
Up to 25mA LED current per channel
±3% LED matching between channels
Only 2 passive components required – input capacitor and resistor
SC70-6 package
Ideal solution to backlight keypads in mobile handsets and other portable electronics by utilizing the output of a step-up DC-DC converter

3. FAN5640 Dual High-Side Constant Current Source LED Driver
Features
2-channel constant current source LED driver
Drives 2 to 4 LEDs per channel
Up to 25mA per channel
Input voltage range: 6.0V to 20.0V
Fast turn-on/off capability
High-side current driver
48µA operating quiescent current
Thermal shutdown protection
Pkg: 6-lead SC70
Applications
Keypad Illumination
Mobile Handsets/Smartphones
PMP and MP3 Players

4. FAN5640 Key Advantages Ease of Use High Input Supply Voltage Range
High-side Current Driver

5. 1. Ease of Use
Simple LED driver that requires only 2 external passive components
Input capacitor
Resistor to set maximum LED current
Connect it to output of boost regulator
No EMI issues

6. 2. High Input Voltage Range
High input supply voltage range to enable capability to drive up to 4 LEDs in series
Also use in industrial applications where there are +12V rails to power LEDs
Also able to support applications where 2 Li-Ion batteries are in series

7. 3. High-side Current Driver
Connect LEDs from FAN5640 to ground – simplifies PCB layout
No need to worry about PCB layout and minimize current loops for LEDs to return to LEAD driver
Current flows to ground

8. FAN5640 Objections No Boost Capability
Cannot Backlight Very Large LCD Displays
VIN Range is 6V to 20V

9. 1. No Boost Capability
FAN5640 was designed to be a linear LED driver that was powered by higher input voltage to drive LEDs
# of LEDs dependent on input voltage
It is to be used in conjunction with a series boost LED driver (that can act as a voltage regulator) which powers it
LED brightness dependent on output power capability of series boost LED driver
If boost capability is required for your solution then Fairchild offers: FAN5331, FAN5333A/B, FAN5340, FAN5341, and FAN5343

10. 2. Cannot Backlight Very Large Displays
FAN5640 was not intended to provide backlight for displays since it is mainly for keypad lighting
If there is a high voltage supply in the application 12V, then it can drive a total of 6 LEDs (2 strings of 3 LEDs)
If there is a need to power many LEDs to backlight a large LCD display then it is recommended to use FAN5331 or FAN5333A/B which can drive up to 10 LEDs in series

11. 3. VIN Range is 6V to 20V
FAN5640 cannot be powered directly from Li-Ion battery (2.7V to 4.2V) since it has high input voltage range
It was designed to be a companion chip to a series boost LED driver to provide auxiliary lighting
If there is a requirement to power the LEDs from a Li-Ion battery source then Fairchild has a number of solutions:
FAN562x: 2/4/6-channel Linear LED Drivers
FAN5701: 6-channel Charge Pump LED Driver
FAN5341: 5-LED Series Boost LED Driver

12. FAN FAN5333 Application
To realize the features of FAN5640, it is best used in conjunction with a series boost LED driver such as FAN5333 or others such as FAN5340, FAN5341 and FAN5343
By feeding the output voltage from the FAN5333 (as shown in the diagram below) it can then power FAN5640 to light the LEDs
The number of LEDs driven by FAN5640 is dependent upon the output voltage from the series boost LED driver
Nominal drop-out voltage of FAN5640 is 1.80V

13. FAN FAN534x Application
FAN FAN5343
FAN FAN5340

14. FAN5640 Applications Ultra-Portables PC Products Consumer Other
Mobile Handsets
MP3 Players
PMP Players
Mobile Internet Devices
PC Products
Printers (All-in-One)
Consumer
Copiers / Fax Machines
Set-top Boxes
Other
Embedded/Industrial PCs
Payment Kiosks
Measurement Equipment
Bench
Medical Equipment
Stationary

15. Potential FAN5640 Customers
Mobile Handsets
MP3/PMP Players
PC Products
Printers & Fax Machines
Test & Measurement
Nokia
Apple
Dell HP
Agilent
Sony/Ericsson
Samsung
Brother
Rohde & Schwarz
Sony
Lenovo
Anritsu
Motorola
iRiver
Toshiba
Lexmark
Tektronix
LG Mobile
Creative Labs
Fujitsu
Canon
Fluke
Philips
Epson
Pantechl
Microsoft
Huawei
OKI
NEC
Qualcomm
Broadcom
Infineon
ST/EMP

16. Pricing & Availability
Fairchild Part Number
Package
Unit 1ku
Availability
FAN5640S7X
SC70-6
$0.51
Now

17. Summary
FAN5640 is compact yet cost effective solution to enhance lighting for keypads in portable electronics applications
Ideal solution is to combine it with FAN5331/3, FAN5341/3 or FAN5340 to achieve a turn-key lighting solution
Key benefit FAN5640 offers:
Matched LED brightness between channels and equal brightness within each channel
Excellent dimming capability to set LED brightness based on lighting conditions or event
Very small form factor that only requires 2 passive components (resistor and capacitor)

18. Technical Materials FAN5640 Datasheet
FAN5640 Product Overview
Evaluation Boards
Request via Sales Center or external web
Samples

19. Marketing & Apps Contacts
Marketing Contact
Wayne Seto
Applications Support
Juha Talonen