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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
August 2005
FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
Features
1.5MHz Switching Frequency Low Noise Adjustable Output Voltage 0.7W Output Power Capability Low Shutdown Current: <1A Cycle-by-Cycle Current Limit Low Feedback Voltage (110mV) Over-Voltage Protection Fixed-Frequency PWM Operation Internal Compensation Thermal Shutdown 5-Lead SOT23 Package
Description
The FAN5330 is an LED driver that features fixed frequency mode operation and an integrated FET switch. This device is designed to operate at high switching frequencies in order to minimize switching noise measured at the battery terminal of hand-held communications equipment. Quiescent current in both normal and shutdown mode is designed to be minimal in order to extend battery life. Normal or shutdown mode can be selected by a logic level shutdown circuitry. The low ON-resistance of the internal N-channel switch ensures high efficiency and low power dissipation. A cycle-by-cycle current limit circuit keeps the peak current of the switch below a typical value of 1.5A. The FAN5330 is available in a 5-lead SOT23 package.
Applications
Cell Phones PDAs Handheld Equipment Display Bias LED Bias
Typical Application
BAT54 COUT 0.47F ILED 5 V
IN
VIN CIN 2.2F
L 6.8H to 10H
VOUT
SW
1
FAN5330
FB
3
ON OFF
4
SHDN
GND
2
R
Figure 1. Typical Application Diagram
(c)2005 Fairchild Semiconductor Corporation
1
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FAN5330 Rev. 1.0.1
FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
Pin Assignment
Top View
SW GND FB SHDN VIN
5-Lead SOT-23
Figure 2. Pin Assignment
Pin Description
Pin No.
1 2 3 4 5
Pin Name
SW GND FB SHDN VIN Switching Node. Analog and Power Ground.
Pin Description
Feedback Pin. Feedback node that connects to an external current set resistor. Shutdown Control Pin. Logic HIGH enables, logic LOW disables the device. Input Voltage Pin.
2 FAN5330 Rev. 1.0.1
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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
Absolute Maximum Ratings (Note1)
Parameter
VIN to GND FB, SHDN to GND SW to GND Lead Soldering Temperature (10 seconds) Junction Temperature Storage Temperature Thermal Resistance (JA) Electrostatic Discharge Protection (ESD) Level (Note 2) HBM CDM 2 1 -55 -0.3 -0.3
Min.
Max.
6.0 VIN + 0.3 35 300 150 150 210
Unit
V V V C C C C/W KV
Recommended Operating Conditions
Parameter
Input Voltage Output Voltage Operating Ambient Temperature Output Capacitance Rated at the Required Output (Note 3)
Min.
1.8 VIN -40 0.1
Typ.
Max.
5.5 30
Unit
V V C F
25
85
Notes: 1. Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Absolute maximum ratings apply individually only, not in combination. 2. Using EIA/JESD22A114B (Human Body Model) and EIA/JESD22C101-A (Charge Device Model). 3. This load capacitance value is required for the loop stability. Tolerance, temperature variation, and voltage dependency of the capacitance must be considered. Typically a 0.47F ceramic capacitor is required to achieve specified value at V OUT = 30V.
3 FAN5330 Rev. 1.0.1
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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
Electrical Characteristics
Unless otherwise noted, VIN = 3.6V, ILED = 20mA, TA = -40C to 85C, Typical values are at TA = 25C, Test Circuit, Figure 3. Parameter
Feedback Voltage Switch Current Limit Load Current Capability Switch On-resistance Quiescent Current OFF Mode Current Shutdown Threshold Shutdown Pin Bias Current Feedback Pin Bias Current Feedback Voltage Line Regulation Switching Frequency Maximum Duty Cycle Switch Leakage Current OVP Thermal Shutdown Temperature No Switching, VIN = 5.5V 15 150 2.7V < VIN < 5.5V, VOUT 20V 1.25 87 VIN = 3.2V VOUT 20V VIN = 3.2V VIN = 5V VIN = 3.6V VSHDN = 3.6V, No Switching VSHDN = 0V Device ON Device OFF VSHDN = 0V or VSHDN = 5.5V 1 1 0.3 1.5 93 1 1.75 1.5 0.5 300 300
Conditions
Min.
99 1.1 35
Typ.
110 1.5 0.6 0.7 0.6 0.1
Max.
121
Units
mV A mA mA
3
A V V nA nA % MHz % A % C
Test Circuit
VIN CIN 10F 5 VIN 1 L 10H 1F ILED BAT54 COUT VOUT
SW
FAN5330
Electronic Load FB 3
ON OFF
4
SHDN
GND
2
R
Figure 3. Test Circuit
4 FAN5330 Rev. 1.0.1
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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
Typical Performance Characteristics
TA = 25C, CIN = 4.7F, COUT = 0.47F, L = 10H, unless otherwise noted.
LED Current vs Temperature
10.8
SW Frequency vs. Temperature
2.0
VIN = 5.5V
10.6
VIN = 2.2V
SW Frequency (MHz)
LED Current (mA)
VOUT = 15V
VOUT = 15V
10.4 10.2 10.0 9.8 9.6 -40 -20 0 20 40 60 80
1.8
VIN = 3.6V
VIN = 3.6V
1.6
VIN = 5.5V
1.4
VIN = 2.2V
1.2 -40 -20 0 20 40 60 80
Temperature (C)
Load Current vs. Input Voltage
25
VOUT = 15V
Start-Up Response
L = 10H CIN = 10F COUT = 1F VIN = 2.7V
Load Current (mA)
20
15
10
5
0 2 3 4 5
Input Voltage (V)
EN Voltage (5V/div)
Battery Current (0.5A/div)
Output Voltage (5V/div)
Time (100s/div)
Efficiency vs. Input Voltage
100
VOUT = 9V
Efficiency vs. Input Voltage
100
VOUT = 15V
90
90
Efficiency (%)
80
ILED = 35mA
Efficiency (%)
80
ILED = 35mA
70
ILED = 30mA ILED = 20mA
ILE = 10mA D
70
ILED = 30mA ILED = 20mA ILED = 10mA
60
60
50 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
50 2.0 2.5 3.0 3.5 4.0 4.5 Input Voltage (V) 5.0 5.5
Input Voltage (V)
5 FAN5330 Rev. 1.0.1
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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
Block Diagram
SHDN 4
Shutdown Circuitry
VIN 5
SW 1
FB
+Over
Voltage
- Comp 1.15 x VREF
Thermal Shutdown
R FB 3 + Reference Ramp Generator Oscillator + Amp 30m
Error Amp
+ Comp -
R R S
Q
Driver
n
Current Limit Comparator -
+
2 GND
Figure 4. Block Diagram
Circuit Description
The FAN5330 is a pulse-width modulated (PWM) current-mode boost converter. The FAN5330 improves the performance of battery powered equipment by significantly minimizing the spectral distribution of noise at the input caused by the switching action of the regulator. In order to facilitate effective noise filtering, the switching frequency was chosen to be high, 1.5MHz. The device architecture is that of a current mode controller with an internal sense resistor connected in series with the N-channel switch. The voltage at the feedback pin tracks the output voltage at the cathode of the external Schottky diode (shown in the test circuit). The error amplifier amplifies the difference between the feedback voltage and the internal bandgap reference. The amplified error voltage serves as a reference voltage to the PWM comparator. The inverting input of the PWM comparator consists of the sum of two components: the amplified control signal received from the 30m current sense resistor and the ramp generator voltage derived from the oscillator. The oscillator sets the latch, and the latch turns on the FET switch. Under normal operating conditions, the PWM comparator resets the latch and turns off the FET, thus terminating the pulse. Since the comparator input contains information about the output voltage and the control loop is arranged to form a negative feedback loop, the value of the peak inductor current will be adjusted to maintain regulation. Every time the latch is reset, the FET is turned off and the current flow through the switch is terminated. The latch can be reset by other events as well. Over-current condition is monitored by the current limit comparator which resets the latch and turns off the switch instantaneously within each clock cycle.
Over-Voltage Protection
The voltage on the feedback pin is sensed by an OVP Comparator. When the feedback voltage is 15% higher than the nominal voltage, the OVP Comparator stops switching of the power transistor, thus preventing the output voltage from going higher.
Open-circuit protection
As in any current regulator, if the feedback loop is open, the output voltage increases until it is limited by some additional external circuitry. In the particular case of the FAN5330, the output voltage is limited by the switching transistor breakdown at around 45V, typically (assuming that COUT and the Schottky diode rating voltage are higher). Since at such high output voltage the output current is inherently limited by the discontinuous conduction mode, in most cases, the switching transistor enters non-destructive breakdown and the IC survives. However, to ensure 100% protection for LED disconnection, we recommend limiting VOUT with an external Zener diode or stopping the boost switching with an external voltage supervisory circuit.
Applications Information
Setting the Output Current
The internal reference (VREF) is 110mV (Typical). The output current is set by a resistor divider R connected between FB pin and ground. The output current is given by
V REF I LED = ------------R
6 FAN5330 Rev. 1.0.1
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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
Inductor Selection
The inductor parameters directly related to device performances are saturation current and dc resistance. The FAN5330 operates with a typical inductor value of 10H. The lower the dc resistance, the higher the efficiency. Usually a trade-off between inductor size, cost and overall efficiency is needed to make the optimum choice. The inductor saturation current should be rated around 1.5A, which is the threshold of the internal current limit circuit. This limit is reached only during the start-up and with heavy load condition; when this event occurs the converter can shift over in discontinuous conduction mode due to the automatic turn-off of the switching transistor, resulting in higher ripple and reduced efficiency. Some recommended inductors are suggested in the table below:
Brightness Control
1. Dimming Using PWM Logic Signal
A PWM signal applied to SHDN Table 5 on page 7 can control the LED's brightness in direct dependence with the duty cycle. The maximum frequency should not exceed 1kHz to ensure a linear dependence of the LED's average current. The amplitude of the PWM signal should be suitable to turn the FAN5333 ON and OFF. Alternatively, a PWM logic signal can be used to switch a FET ON/OFF to change the resistance that sets the LED's current Table 6 on page 7. Adjusting the duty cycle from 0% to 100% results in varying the LED's current between IMIN and IMAX. Where
Inductor Value
10H 10H 10H
Vendor
TDK MURATA COOPER
Part Number
SLF6025&-100M1R0 LQH66SN100M01C SD414-100
Comment
Highest Efficiency Small Size
V FB V FB I MIN = ------------- and I MAX = ------------------------------R MIN R MIN R SET
FAN5330
SHDN
Table 1: Recommended Inductors Capacitors Selection
For best performance, low ESR input and output capacitors are required. Ceramic capacitors of CIN = 4.7F and COUT = 0.47F placed close to the IC pins, are required for optimum performance. The capacitances (COUT) may be reduced to 0.1F, if higher ripple is acceptable. The output capacitor voltage rating should be according to the VOUT setting. Some capacitors are suggested in the table below
Figure 5. Dimming Using a PWM Signal
FAN5330
FB RSET RMIN
Capacitor Value
0.47F 4.7F
Vendor
Panasonic Murata
Part Number
ECJ-3YB1E474K GRM21BR61A475K
Figure 6. Dimming Using a PWM Logic Signal 2. Dimming Using DC Voltage
An external adjustable DC voltage Table 7 on page 7 between 0V to 2V can control the LED's current from 15mA to 0mA, respectively.
FAN5330
FB VDC 5 1.6K 90K
Table 2: Recommended Capacitors Diode Selection
The external diode used for rectification is usually a Schottky diode. Its average forward current and reverse voltage maximum ratings should exceed the load current and the voltage at the output of the converter respectively. A barrier Schottky diode such as BAT54 is preferred, due to its lower reverse current over the temperature range. Care should be taken to avoid any short circuit of VOUT to GND, even with the IC disabled, since the diode can be instantly damaged by the excessive current.
Figure 7. Dimming Using DC Voltage
7 FAN5330 Rev. 1.0.1
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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
3. Dimming Using Filtered PWM Signal
This method allows the use of a greater than 1kHz PWM frequency signal with minimum impact on the battery ripple. The filtered PWM signal Table 8 on page 8 acts as an adjustable DC voltage as long as its frequency is significantly higher than the corner frequency of the RC low pass filter.
Thermal Shutdown
When the die temperature exceeds 150C, a reset occurs and will remain in effect until the die cools to 130C, at that time the circuit will be allowed to restart.
PCB Layout Recommendations
The inherently high peak currents and switching frequency of power supplies require careful PCB layout design. Therefore, use wide traces for high current paths and place the input capacitor, the inductor, and the output capacitor as close as possible to the integrated circuit terminals. The FB pin connection should be routed away from the inductor proximity to prevent RF coupling. A PCB with at least one ground plane connected to pin 2 of the IC is recommended. This ground plane acts as an electromagnetic shield to reduce EMI and parasitic coupling between components.
FAN5330
FB 20K 5 1.6K 0.1F 15K
Figure 8. Dimming Using Filtered PWM Signal
8 FAN5330 Rev. 1.0.1
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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
Mechanical Dimensions
5-Lead SOT-23
B e c E H e1 D A A1 L
Symbol Min
A A1 B c D E e e1 H L .087 .004 0 .035 .000 .008 .003 .106 .059
Inches Max
.057 .006 .020 .010 .122 .071 .037 BSC .075 BSC .126 .024 10
Millimeters Min
.90 .00 .20 .08 2.70 1.50 .95 BSC 1.90 BSC 2.20 .10 0 3.20 .60 10
Notes
Max
1.45 .15 .50 .25 3.10 1.80
Ordering Information
Product Number
FAN5330
Package Type
5-Lead SOT23
Order Code
FAN5330SX
9 FAN5330 Rev. 1.0.1
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FAN5330 High Efficiency Serial LED Driver with 30V Integrated Switch
TRADEMARKS
The following are registered and unregistered trademarks Fairchild Semiconductor owns or is authorized to use and is not intended to be an exhaustive list of all such trademarks.
ACExTM FAST ActiveArrayTM FASTrTM BottomlessTM FPSTM Build it NowTM FRFETTM CoolFETTM GlobalOptoisolatorTM CROSSVOLTTM GTOTM DOMETM HiSeCTM EcoSPARKTM I2CTM E2CMOSTM i-LoTM EnSignaTM ImpliedDisconnectTM FACTTM IntelliMAXTM FACT Quiet SeriesTM Across the board. Around the world.TM The Power Franchise Programmable Active DroopTM
DISCLAIMER
ISOPLANARTM LittleFETTM MICROCOUPLERTM MicroFETTM MicroPakTM MICROWIRETM MSXTM MSXProTM OCXTM OCXProTM OPTOLOGIC OPTOPLANARTM PACMANTM POPTM Power247TM PowerEdgeTM
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SuperSOTTM-8 SyncFETTM TinyLogic TINYOPTOTM TruTranslationTM UHCTM UltraFET UniFETTM VCXTM WireTM
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 2. A critical component is any component of a life 1. Life support devices or systems are devices or support device or system whose failure to perform can systems which, (a) are intended for surgical implant into be reasonably expected to cause the failure of the life the body, or (b) support or sustain life, or (c) whose support device or system, or to affect its safety or failure to perform when properly used in accordance with instructions for use provided in the labeling, can be effectiveness. reasonably expected to result in significant injury to the user. PRODUCT STATUS DEFINITIONS Definition of Terms Datasheet Identification Advance Information Product Status Formative or In Design Definition This datasheet contains the design specifications for product development. Specifications may change in any manner without notice. This datasheet contains preliminary data, and supplementary data will be published at a later date. Fairchild Semiconductor reserves the right to make changes at any time without notice in order to improve design. This datasheet contains final specifications. Fairchild Semiconductor reserves the right to make changes at any time without notice in order to improve design.
Preliminary
First Production
No Identification Needed
Full Production
Obsolete
Not In Production
This datasheet contains specifications on a product that has been discontinued by Fairchild semiconductor. The datasheet is printed for reference information only.
Rev. I16
10 FAN5330 Rev. 1.0.1
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