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PDF FAN5607 Data sheet ( Hoja de datos )
| Número de pieza | FAN5607 | |
| Descripción | LED Driver with Adaptive Charge Pump DC/DC Converter | |
| Fabricantes | Fairchild Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de FAN5607 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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www.fairchildsemi.com
FAN5607
LED Driver with Adaptive Charge Pump DC/DC
Converter
Features
• Parallel LED Driver Supports all Forward Voltages
• Adaptive VOUT Adjustment to the Highest Diode Voltage
• 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 (4 × 30mA )
• 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
• ICC < 1µA in Shutdown Mode
• 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 bat-
tery 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 volt-
age. This adaptive nature of the FAN5607 eliminates the
need for LED pre-selection (matching) and ensures opera-
tion 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 regu-
lator, and the DC-DC converter is turned off. Only two 0.1µF
to 1µF bucket capacitors and two 4.7µF input/output capaci-
tors 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
COUT
VOUT
VIN
CIN
VOUT
VIN
EN
LED-
LED-
LED-
FAN5607
LED-
CAP-
CAP+
RSET
RSET
GND
CAP+
CAP-
CAP2
CAP1
REV. 1.0.0 6/22/04
1 page  
PRODUCT SPECIFICATION
Electrical Characteristics
VIN = 2.7V to 5.5V, TA = -40ºC to +85ºC, Test Circuit Figure 1, Unless otherwise noted.
Typical values are at TA = 25˚C
Parameter
Input Undervoltage Lockout
ILED Accuracy
Current Matching
Output Voltage (VOUT = Vf + VCathode)
Quiescent Current, IQ
Shutdown Supply Current
Output Short Circuit Current
VOUT Over Voltage Protection
VIN At Mode Transition From 1X to 1.5X
VIN At Mode Transition From 1.5X to 2X
Peak Efficiency
Oscillator Frequency
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
EN Logic Input High Voltage
EN Logic Input Low Voltage
EN Input Bias Current
Conditions
ILED ≤ 20mA
ILED ≤ 20mA
LED Vf = 3.5V
VIN = 5.5V,
IOUT = 0mA
VEN = 0V
VIN = 5.5V,
VOUT = 0V
LED Vf = 3.5V,
IOUT = 4 x 20mA
LED Vf = 3.5V,
IOUT = 4 x 20mA
VIN = 3.75V,
LED Vf = 3.5V,
ILED= 20mA
Min.
1.7
0.8
EN to VIN or GND
1.6
-1
Typ.
1.8
5
3
3.62
130
65
5.1
3.76
2.85
93
1
145
15
FAN5607
Max.
2.3
400
Units
V
%
%
V
µA
1 µA
mA
V
V
V
%
1.2 MHz
ºC
ºC
V
0.4 V
1 µA
REV. 1.0.0 6/22/04
5
5 Page 
PRODUCT SPECIFICATION
FAN5607
Selecting Capacitors
It is important to select the appropriate capacitor types and
the values for use with the FAN5607. These capacitors deter-
mine parameters such as power efficiency, maximum sus-
tainable load current by the charge pump, input and output
ripple and start-up process.
Input
Power
Supply
0.22Ω
10µF
4.7µF
VIN
FAN5607
GND
through the RC input filter, as shown in Figure 7. Two low
ESR bucket capacitors of value between 0.1µF to 1µF,
should be used for best efficiency in boost mode. The bucket
capacitor, CAP1 = CAP2 = 1µF is recommended, if the
FAN5607 is required to start at battery voltage lower than
3V.
PC Board Layout
For best performance, a solid ground plane is recommended
on the back side of the PCB. The ground tails of CIN and
COUT should be connected together close to the GND pin of
IC.
Figure 7. Battery Ripple Reduction
In order to reduce ripple, both CIN and COUT should be low
ESR capacitors. Increasing the COUT capacitor reduces the
output ripple voltage. However this will increase the power-
on time. The CIN value controls input ripple. If necessary,
this ripple can be further reduced by powering the FAN5607
REV. 1.0.0 6/22/04
11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet FAN5607.PDF ] | |
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