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YB1303
Low Dropout LED Driver
Description
The YB1303 provides a simple solution for driving three channels of any color LEDs with current matching ability. The ultra low dropout LED driver features higher peak efficiency and very low shutdown current. The LED current can be adjusted by an external resistor or the control voltage. The YB1303 can work independently or combine with any boost converters which need to have current matching function for LED drivers. The YB1303 is available in 6-pin tiny SC70-6 package.
Features
LED Drivers for Parallel Connected LEDs Only One External Resistor is Needed PWM and Analog Brightness Control No EMI and Switching Noise Power Saving Shutdown Mode (<0.1A) Small Footprint SC70-6 Package
Applications
LCD Display Modules Keyboard Backlight PDA, DSC, MP3 players LED Displays Handheld Computers Cell Phones
Typical Application Circuit
Figure 1: Typical Application Circuit
YB1303 Rev.1.0
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YB1303
Low Dropout LED Driver
Pin Configuration
CTR LED2 LED1
1 2 3
SC70-6
6 5 4
EN LED3 GND
Figure 2: Pin Configuration
Pin Assignment &Description
Table 1
Pin 1 2 3 4 5 6
Name CTR LED2 LED1 GND LED3 EN
Description Connect this pin with a resistor to set the LED current. Connect this pin to LED cathode. Connect this pin to LED cathode. Ground pin. Connect this pin to LED cathode. Connect this pin to logic high to enable this chip, logic low to disable this chip.
Ordering Information
Table 2
Order Number YB1303SC76A
Package Type SC70-6
Supplied As 3000 Units Tape & Reel
Package Marking Please contact sales representative
YB1303 Rev.1.0
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YB1303
Low Dropout LED Driver
Absolute Maximum Ratings
LED1, LED2, LED3 to GND ........ -0.3V to 6V EN to GND.................................. -0.3V to 6V CTR to GND ............................... -0.3V to 3V Power Dissipation by SC70-6 TA=85........133mW Junction Temperature Range...............150 Storage Temperature Range .....-55 to 150 Lead Temperature................................250 ESD HBM .......................................... 1.5KV ESD CDM ...........................................750V
Recommended Operating Conditions
LED Cathode Voltage ................. 0.3V to1V Operating Temperature.........-40 to 85
Electrical Characteristics
Table 3 (VIN=3.3 to 5.5V, VEN=3V, TA=25C, unless otherwise noted. VF is LED forward voltage.) Description LED Cathode Voltage Output Current Multiplication Factor Shutdown Current LED Current LED to LED Current Matching Efficiency SHDN Logic Low Level SHDN Logic High Level VIL VIH VIN =3.3V, (VIN - VCATHODE) / VIN ILED < 1A ISET = 100A 3 ISD ILED Symbol VCATHODE ISET = 100A, VLED = 300mV VEN = 0V ISET = 100A -3 90 0.5 Test Conditions MIN 0.3 140 TYP 0.5 200 0.1 20 +3 MAX 1 260 1 A mA % % V V Units V
YB1303 Rev.1.0
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YB1303
Low Dropout LED Driver
Typical Performance Characteristics
VIN=3.3 to 5.5V, VEN=3V, TA=25C, unless otherwise noted. VF is LED forward voltage.
Iset vs. Control Voltage
(RSET=17.4k, Vcathode=0.3V) 160 140 120
22 20 18
LED Current vs. LED Cathode Voltage
(Vcontrol=3V, VEN=3V)
Rset=17.4k Iset=100uA
LED Current (mA)
16 14 12 10 8 6 4 2 0 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20
100 Iset (uA) 80 60 40 20 0 0.0 0.5 1.0 1.5 2.0 Vcontrol (V) 2.5 3.0 3.5 4.0
Cathode Voltage (V)
LED Current vs. Enable Voltage
(Vcontrol=3V, Vcathode=0.3V, Rset=17.4k) 22 20 18 16 LED Current (mA)
LED Current (mA) 45 40 35 30 25 20 15 10 5 0
LED Current vs. Rset
(VEN=3V, Vcontrol=3V)
14 12 10 8 6 4 2 0 0 1 2 3 VEN Voltage (V) 4 5 6
Vcathode=0.3 Vcathode=0.5 Vcathode=1
0
10
20
30
40 Rset (kOhms)
50
60
70
80
Control Voltage Transient Response
Enable Voltage Transient Response
YB1303 Rev.1.0
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YB1303
Low Dropout LED Driver
Application Information
Analog Dimming Control Table
Table 4 VEN=3V, VCONTROL=3V
voltage. The lower the VLED voltage, the higher the system efficiency. The system efficiency can be calculated as follows: Efficiency = (VIN-VCATHODE) / VIN Thermal Considerations At any given ambient temperature, the maximum package power dissipation can be determined by the following equation: PD(MAX) = [TJ(MAX)-TA] / JA Constraints for the YB1303 are maximum junction temperature TJ(MAX)=125 , and package thermal resistance, JA=300/W. The maximum total LED current for YB1303 depends on package power dissipation and the LED cathode voltage at TJ(MAX). At 85, PD(MAX)=133mW. At TA = 25, PD(MAX)=333mW. The maximum current is calculated by the following equation: ILED < (PD(MAX) / VLED(MAX)) For example, if ILED = 60mA, and TA = 85, VLED(MAX) = 2.2V. If the ambient temperature were to increase, the internal die temperature would increase, and the device would be damaged.
ILED (mA) 5 10 15 20 25
RSET (k) 75 34 24 17.4 13
Table 5 VEN=3V, RSET=17.4k
ILED (mA) 5 10 15 20 25
VCONTROL (V) 1.5 2.1 2.5 3 3.6
Setting the LED Current The LED current can be set by the control voltage and the RSET resistor from the following equation. ILED=200x(VCONTROL-VCTR)/RSET The suggested values and relations between VCONTROL and RSET can also be found in the diagram of typical characteristics and table 4 and table5. The LED brightness can be controlled by either the above equation or applying a PWM signal to the EN pin. The driving signal frequency should be greater than 100Hz to avoid flickering, and increased to more than 1MHz if necessary. Efficiency Considerations The YB1303 featured low drop out can achieve excellent efficiency performance. The efficiency is mainly dominated by VLED
YB1303 Rev.1.0
Application Examples
The ultra-low voltage drop across the YB1303 allows the devices to drive white, blue and any color LEDs in a wide range of input voltages. The driver can be used in many applications presented in this document, due to their similar operation.
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YB1303
Low Dropout LED Driver
Example 1: Drive low VF white or blue LEDs directly from single cell Li-Ion battery When using white or blue low VF LEDs, and utilizing the driver's low voltage drop, only 3.4V in VIN is needed for the full 20mA LED current. At 3.2V, there is still 5mA typical current available for the LEDs. The single cell Li-Ion battery is utilized in many applications like cell-phones and digital still cameras. In most cases, the Li-Ion battery voltage level only goes down to 3V, and not down to the full discharged level (2.7V) before requesting the charger. Example 2: Drive high VF white or blue LEDs from exiting bus from 4.0V to 6V High VF white or blue LEDs have forward voltage drop in the range of 3.2V to 4.0V. To drive these LEDs with the maximum current of 20mA for maximum brightness, usually requires a boost circuit for a single cell Li-Ion voltage range. In some cases, there is already a voltage bus in the system, which can be utilized. Due to the ultra-low voltage drop of the YB1303 to drive high VF white or blue LEDs, the VIN needs to be only 300mV higher than the highest VF in the circuit.
-VDROP < 0.3V -VF (@20mA) < 3.1V (Low VF) -VIN (@20mA) = -VDROP+VF=3.4V -VIN (@5mA typical) ~3.1V Where VIN = Single cell Li-Ion Voltage Key advantages: No boost circuit needed for the LCD or keyboard backlight. Drivers directly connected to a Li-Ion battery. No EMI, no switching noise, no boost efficiency lost, no capacitor and no inductor.
YB1303 Rev.1.0
-VDROP < 0.3V -VF (@20mA) < 3.3V to 4.0V (High VF) -VIN (@20mA) = -VDROP+VF=3.6V to 4.3V -VIN (@5mA typical) ~3.3V Where VIN = Existing bus = 3.3V to 4.3V Key advantages: No boost circuit needed for the LCD or keyboard backlight. Driver utilizes the existing bus. Ultra-low voltage drop provides the full 20mA LED current at the lowest possible voltage level.
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YB1303
Low Dropout LED Driver
Example 3: Drive white, blue, red, amber LEDs string Assuming boost circuit, or existing voltage bus, the YB1303 can be used to drive a whole string of LEDs and flexible brightness control - whether using analog or PWM (Notes). LED Brightness Control The YB1303 LED drivers feature analog and PWM controls to give designers flexible brightness control. These control methods can be applied to the circuit in two different ways which provide flexible solution. To determine the value of RSET, use the "ISET vs. VCTR" graph under the "typical characteristics" section.
Scenario 1 - Analog -VDROP < 0.3V -VIN_MIN = NxVF + VDROP - VIN_MAX = NxVF + 6V -VIN (@5mA typical) ~3.3V Where VIN = Existing Bus / Boost Voltage Key advantages: No need for current matching resistors and discrete transistor for brightness control.
Notes: 1. Whether using analog or PWM signal, please notice to avoid from exceeding the absolute maximum rating claimed in this document. 2. EN must be turned on prior to VIN (delivered by boost circuit or existing bus) and avoid from VIN > 6V when EN is off. YB1303 Rev.1.0
Set VCONTROL and RSET for LED current ILED=200x(VCONTROL-VCTR)/RSET Scenario 2 - PWM - 1 ILED=200x(VCONTROL-VCTR)/RSET VCONTROL = PWM Amplitude sets maximum LED current Pulse width controls between 0 and maximum Scenario 3 - PWM - 2 ILED ~ 200xISET VEN = PWM Amplitude has no effect on current Pulse width controls between 0 and maximum
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YB1303
Low Dropout LED Driver
Package Information (SC70-6)
NOTICE: The information described herein is subject to change without notice. Yobon does not assume any responsibility for use of any circuitry or applications described herein, nor does it convey any patent license.
YB1303 Rev.1.0
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