Document
FSP3307
WHITE LED STEP-UP CONVERTER
N
FEATURES
s Inherently Matched LED Current s Drives Up to 8 LEDs from a 3.6V Supply s No External Schottky Diode Required s 1.2MHz Switching Frequency
s Automatic Soft-Start s Open LED Protection s High Efficiency: 81%
s Requires Only 0.22uF Output Capacitor s Low Profile (1mm) SOT-23 Packaging
APPLICATION
s Cellular Phones s PDAs, Handheld Computers s Digital Cameras s MP3 Players s GPS Receivers
DESCRIPTIO
The FSP3307 IS step-up DC/DC converters designed to drive up to six LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents and eliminates the need for ballast resistors. These devices integrate the Schottky diode required externally on competing devices. Additional features include output voltage limiting when LEDs are disconnected, onepin shutdown and dimming control. The FSP3307has internal soft-start.
TheFSP3307switches at 1.2MHz, allowing the use of tiny external components. Constant frequency switching results in low input noise and a small output capacitor. Just 0.22µF is required for 4-, 6- or 8-LED applications. The FSP3307 is available in low profile(1mm)6-lead
TYPICAL APPLICATION
FSP3307
Figure 1. Li-Ion Powered Driver for Eight White LEDs
EFFICIENCY (%)
Conversion Efficiency
82 VIN = 3.6V 80 4 LEDs 78 76 74 72 70 68 66 64 62 60
0 5 10 15 LED CURRENT (mA)
20
1
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Voltage (VIN) ................................................. 16V SW Voltage ............................................................. 36V
FB Voltage ................................................................ 2V
CTRL Voltage .......................................................... 10V
Operating Temperature Range (Note 2) .. – 40°C to 85°C Maximum Junction Temperature ......................... 125°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C
PACKAGE/ORDER INFORMATION
TOP VIEW
SW 1 GND 2
FB 3
6 IN 5 Vout 4 CTRL
SOT-23-6
ELECTRICAL CHARACTERISTICS The q denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 3V, VCTRL = 3V, unless otherwise noted.
PARAMETER Minimum Operating Voltage Maximum Operating Voltag Feedback Voltage FB Pin Bias Current Supply Current
Switching Frequency Maximum Duty Cycle Switch Current Limit Switch VCESAT Switch Leakage Current VCTRL for Full LED Current VCTRL to Shut Down Chip CTRL Pin Bias Current
Soft-Start Time Schottky Forward Drop Schottky Leakage Current
CONDITIONS
0°C ≤ TA ≤ 85°C Not Switching CTRL = 0V
ISW = 250mA VSW = 5V
TA = 85°C TA = –40°C ID = 150mA VR = 30V
q q
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
Note 2: The FSP3307are guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls.
MIN 2.7
188 10 1.9 2.0 0.8 90 225
1.8
48 40 60
TYP MAX UNITS V
16 V 200 212 mV 35 100 nA 2.6 3.3 mA 3.2 5.0 uA 1.2 1.6 MHz 93 % 340 mA 30 mV
0.01 5 uA V
50 mV 60 70 uA 50 60 uA 75 90 uA 600 µs 0.7 V
4 uA
2
SWITCH SATURATION VOLTAGE (mV)
TYPICALA PERFORMANCE CHARACTERISTICS
Switch Saturation Voltage (VCESAT)
450 TA = 25°C
400
350
300
250
200
150
100
50
0 0 50 100 150 200 250 300 350 SWITCH CURRENT (mA)
FEEDBACK VOLTAGE (mV)
VFB vs VCTRL
250 TA = 25°C 200
150
100
50
0 0 0.5 1 1.5 CONTROL VOLTAGE (V)
2
Switching Waveforms
VSW 10V/DIV
IL 100mA/DIV
VOUT 100mV/DIV
VIN = 3.6V 4 LEDs
20mA, 22µH
200ns/DIV
OUTPUT CLAMP VOLTAGE (V)
SCHOTTKY FORWARD CURRENT (mA)
SWITCHING FREQUENCY (MHz)
Schottky Forward Voltage Drop
300 TA = 25°C
250
200
150
100
50
0 0 200 400 600 800 1000 1200 SCHOTTKY FORWARD DROP (mV)
Open-Circuit Output Clamp Voltage
35 TA = 25°C
30
25
20
15
10
5
0 2 4 6 8 10 12 14 16 INPUT VOLTAGE (V)
Switching Frequency
3.0
2.5
2.0
1.5
1.0
0.5
0 –50 0
50 100
TEMPERATURE (°C)
INPUT CURRENT (mA)
IQ (µA)
Shutdown Quiescent Current (CTRL = 0V)
30 TA = 25°C 27
24
21
18
15
12
9
6
3
0 2 4 6 8 10 12 14 VIN (V)
16
Input Current in Output Open Circuit
5 TA = 25°C
4
3
2
1
0 2 2.5 3 3.5 4 4.5 5
INPUT VOLTAGE (V)
3
TYPICAL PERFORMANCE CHARACTERISTICS
FEEDBACK VOLTAGE (mV)
Feedback Voltage
210 208
206
204 202 200 198 196 194 192
190 –50 –30 –10 10 30 50 70 TEMPERATURE (°C)
90
IQ (mA)
Quiescent Current (CTRL = 3V)
3.0
2.5
2.0
1.5
1.0
0.5
0 0
–50°C 25°C 100°C
5 10 15 VIN (V)
20
CURRENT LIMIT (mA)
Switching Current Limit
400
350
300 250
200 150
100 50 0 0
–50°C 25°C 100°C
20 40 60 80 DUTY CYCLE (%)
100
EFFICIENCY (%)
VIN = 3.6V, 4 LEDs
85
80
20mA
75 15mA 10mA
70
65
60 –50
0 50 TEMPERATURE (°C)
100
SCHOTTKY LEAKAGE CURRENT (µA)
Schottky Leakage Current
8
7 VR = 25
6
VR = 16 5
VR = 10
4
3
2
1
0 –50 0
50 100
TEMPERATURE (°C)
PIN FUNCTIONS
VOUT (Pin 1): Output.