Fairchild FAN5607 service manual
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FAN5607
LED Driver with Adaptive Charge Pump DC/DC
Converter
Features
•Parallel LED Driver Supports all Forward Voltages
• Adaptive V
Adjustment to the Highest Diode Voltage
OUT
• Internally Matched LED Current Sources
• Built-in Charge Pump has Three Modes of Operation:
– 1X, 1.5X, and 2X Mode
• Up to 93% Efficiency
•Low EMI, Low Ripple
• Up to 120mA Output Current ( )
30mA×
4
• External Resistor to Set Maximum (100%) LED Current
• Enable Input Can be Duty-Cycle-Modulated to Control
LED Current Level Between 0 and 100%
• 2.4V to 5.5V Input Voltage Range
•I
< 1µA in Shutdown Mode
CC
• 1MHz Operating Frequency
• Shutdown Isolates Output from Input
• Soft-Start Limits Inrush Current
• Short Circuit Protection
• Minimal External Components Needed
•Available in a 4x4mm 16-lead MLP Package
Applications
• Cell Phones
• Handheld Computers
•PDA, DSC, MP3 Players
•Keyboard Backlight
• LED Displays
Description
The FAN5607 generates regulated output current from a battery with input voltage varying between 2.7V to 5.5V.
Switch reconfiguration and fractional switching techniques
are utilized to achieve high efficiency over the entire input
voltage range. A proprietary internal circuitry continuously
monitors each LED current loop and automatically adjusts
the generated output DC voltage to the lowest minimum
value required by the LED having the highest forward voltage. This adaptive nature of the FAN5607 eliminates the
need for LED pre-selection (matching) and ensures operation at high efficiency. When the input voltage is sufficiently
high to sustain the programmed current level in the LEDs,
the FAN5607 re-configures itself to operate as a linear regulator, and the DC-DC converter is turned off. Only two 0.1µF
to 1µF bucket capacitors and two 4.7µF input/output capacitors are needed for proper operation. LED current can be
programmed using an external resistor. The resistor sets the
maximum LED current and a PWM signal applied to the
enable pin can modulate that current level between 0mA
(off) and the maximum level.
Soft-start circuitry prevents excessive current draw during
power on. The device has built-in short circuit protection.
The device is available in 4x4mm 16-lead MLP package.
Typical Application
V
OUT
C
OUT
V
IN
C
IN
V
OUT
V
IN
EN
R
SET
R
SET
FAN5607
GND
LED-LED-LED-LED-
CAP-
CAP+
CAP+
CAP-
CAP2
CAP1
REV. 1.0.0 6/22/04
FAN5607 PRODUCT SPECIFICATION
Definition of Terms
Output Current Accuracy: reflects the difference between the measured value of the output current (LED) and
programmed value of this current .
I
Output Current Accuracy (%)
=
-------------------------------------------------------------------------------------------------------------------I
OUT
measured I
OUT
Current Matching: refers to the absolute value of difference in current between the two LED branches.
programmed–()100×
OUT
programmed
Current Matching (%)
branch 1 I
I
LED
=
----------------------------------------------------------------------------------------------------I
branch 1 I
LED
branch 2–()100×
LED
branch 2+()
LED
Efficiency: is expressed as a ratio between the electrical power into the LEDs and the total power consumed from the input
power supply.
4
V
∑
i1=
Efficiency
Note:
1. Some competitors calculate the power efficiency as a function of V
due to the cathode and provides an efficiency “improved” up to 5%.
=
--------------------------------------------
×
LEDiILEDi
VINIIN×
voltage 0≠
instead of V
OUT
. This method neglects the power lost
LED
2
REV. 1.0.0 6/22/04
PRODUCT SPECIFICATION FAN5607
Pin Assignments
Top-View
LED-
LED-
LED-
LED-
1
EN
2
NC
3
NC
4
NC
13141516
12
GND
11
CAP2+
10
CAP2-
9
CAP1-
7
5
6
8
IN
SET
V
OUT
R
V
CAP1+
FAN5607
4x4mm 16-Lead MLP
Pin Descriptions
Pin No. Pin Name Pin Function Description
1ENEnable Pin
2NCNo Connection
3NCNo Connection
4NCNo Connection
5R
6V
7V
SET
OUT
IN
8 CAP1+ Bucket capacitor positive connection
9 CAP1- Bucket capacitor negative terminal
10 CAP2- Bucket capacitor negative connection
11 CAP2+ Bucket capacitor positive terminal
12 GND Ground
13 LED- 4th LED Cathode
14 LED- 3rd LED Cathode
15 LED- 2nd LED Cathode
16 LED- 1st LED Cathode
External resistor to set LED current
Output to LEDs Anode
Input
Test Circuit
REV. 1.0.0 6/22/04
To V
Pin
OUT
16
1
EN
NC
FAN5607
NC
4
NC
5
R
SET
V
= 2.7V to 5.5V
IN
4.7µF
C
IN
All capacitors are Ceramic chip capacitors
Figure 1. Test Circuit
4.7µF
13
12
CAP2
1µF
OUT
OUT
CAP1
1µF
4 White LEDs
Fairchild QTLP670C-IW
Super Bright LED
9
8
V
C
3
FAN5607 PRODUCT SPECIFICATION
Absolute Maximum Ratings
Parameter Min Max Unit
V
, V
IN
Any other Pin Voltage to GND -0.3 V
Power Dissipation Internally
Lead Soldering Temperature (10 seconds) 300 °C
Operating Junction Temperature Range 150 °C
Storage Temperature -55 150 °C
Electrostatic Discharge Protection Level (Note 3) HBM 4 kV
Voltage to GND -0.3 6.0 V
OUT
(
Note 2)
CDM 2
+ 0.3 V
IN
Limited
Recommended Operating Conditions
Parameter Min Typ Max Unit
Input Voltage Range, V
Operating Ambient Temperature Range -40 25 85 °C
LED Forward Voltage 4V
Current through each LED 2 30 mA
Note:
2. Operation beyond the absolute maximum ratings may cause damage to device.
3. Using Mil Std. 883E, method 3015.7(Human Body Model) and EIA/JESD22C101-A (Charge Device Model)
2.4 5.5 V
IN
4
REV. 1.0.0 6/22/04
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