RT Channel Low Dropout RGB LED Driver. General Description. Features. Applications. Ordering Information RT9301. Pin Configurations

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1 3-Channel Low Dropout RGB LED Driver General Description The is a 3-Channel current source driver for RGB LED. It is easy to be designed in applications that need mixing RGB light source for multi-color output. The also provide users with great flexibility and device performance. It uses externals resistor to set the bias current for three LEDs, which are matched to 5%(max.). Users can adjust the output current from ma to 50mA by setting the ISET resistor. The features very low dropout and under voltage lockout protection. It is available in a space-saving TSOT-3-8 and WDFN-8L 3x3 packages. Ordering Information Note : Package Type J8 : TSOT-3-8 QW : WDFN-8L 3x3 (Green Only) Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free) WDFN-8L 3x3 is in W-Type Richtek products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-00. Suitable for use in SnPb or Pb-free soldering processes. Marking Information Features Input Voltage Range :.8V to 5.5V Low 60/45mV Dropout at 0/5mA Individual Current Setting by External Resistor Individual On/Off Control by Baseband MPU Up to 50mA LED Bias Current Simple LED Brightness Control 5%(max.) LED Current Matching Low 0.uA Shutdown Current UVLO Protection RoHS Compliant and 00% Lead (Pb)-Free Applications Mobile phone, Smart Phone Multi-color LED Backlight Camera Flash White LED LCD Display Modules Keypad Backlight Pin Configurations (TOP VIEW) TSOT-3-8 For marking information, contact our sales representative directly or through a Richtek distributor located in your area WDFN-8L 3x3

2 Typical Application Circuit ON OFF V SET V SET V SET3 R SET R SET3 Figure. Application circuit for RGB LED R SET R SET3 Figure. Application Circuit for Backlight R SET R SET3 I ~ 3 Figure 3. Application Circuit for Keypad = 800 x I SET ~ 3 = 800 x V SET ~ 3 SET ~ 3 R 0.9V (V) I LED (ma) R SET (kw) Nearest Standard Values for R SET (kw)

3 Function Block Diagram + - V REF UVLO V REF + - Current Source + - V REF Functional Pin Description J8 Pin No. GQW Pin Name Pin Function 8 7, Exposed Pad (9) RGB or White LED cathode connection pin. ma to 50mA Current flows into LED. Floating or connection to ground is used to disable this pin. 3 6 Power Input Pin. Ground Pin. The exposed pad must be soldered to a large PCB and connected to for maximum power dissipation. 4 5 Current setting for. Connect to if not use. 5 4 Current setting for. Connect to if not use. 6 3 Current setting for. Connect to if not use. 7 8 RGB or White LED cathode connection pin. ma to 50mA Current flows into LED. Floating or connection to ground is used to disable this pin. RGB or White LED cathode connection pin. ma to 50mA Current flows into LED. Floating or connection to ground is used to disable this pin. 3

4 Absolute Maximum Ratings (Note ) Supply Input Voltage V to 6V,,3 Pin Voltage V to V IN + 0.3V Other I/O Pin Voltages V to 6V Power Dissipation, P T A = 5 C TSOT W WDFN-8L 3x W Package Thermal Resistance (Note ) TSOT-3-8, θ JA C/W WDFN-8L 3x3, θ JA C/W WDFN-8L 3x3, θ JC C/W Lead Temperature (Soldering, 0 sec.) C Junction Temperature C Storage Temperature Range C to 50 C ESD Susceptibility (Note 3) HBM (Human Body Mode) kv MM (Machine Mode) V Recommended Operating Conditions (Note 4) Junction Temperature Range C to 5 C Ambient Temperature Range C to 85 C Electrical Characteristics ( = 3.6V, TA = 5 C, Unless Otherwise specification) Parameter Symbol Test Conditions Min Typ Max Unit Input Supply Voltage V IN V UVLO Threshold V UVLO_L Falling..4 V UVLO Hysteresis mv Dropout Voltage V LED 90% of I LED = 6mA mv ISET Reference Voltage V Quiescent Current I Q LED Open, I SET = 0 ua ma I LED Matching I LED = 6mA % I LED Accuracy I LED I LED = 6mA % Shutdown current All V SET~3 < 0.5V µa V SET Enable Threshold V SET V SET connect R SET = 47kΩ to I SET V V SET Disable Threshold V IL V SET connect R SET = 47kΩ to I SET V Note. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note. θja is measured in the natural convection at TA = 5 C on a low effective single layer thermal conductivity test board of JEDEC 5-3 thermal measurement standard. The case point of θjc is on the expose pad for the WDFN package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. 4

5 Typical Operating Characteristics LED Current vs. Input Voltage LED Current vs. V SET LED Current (ma) Vf = 3.0V, Vf = 3.06V, Vf3 = 3.7V LED Current (ma) RSET = 36k RSET = 5k RSET = 75k RSET = 60k RSET = 360k Input Voltage (V) V SET (V) 0.4 ILED = 0mA LED Current vs. Temperature VBAT = 5.0V Dimming Operation 0.3 (V/Div) LED Current (ma) VSET (0mA/Div) 9.8 I LED Temperature ( C) Time (00μs/Div) Enable & Shutdown Response VBAT = 5.0V Line Transient Response VBAT = 3.7V to 4.V, ILED = 0mA (V/Div) V SET (V/Div) (0mA/Div) ILED (0mA/Div) ILED Time (50μs/Div) Time (50μs/Div) 5

6 Applications Information The is a 3-Channel current source driver for RGB LED or white LEDs. The output current can be controlled from ma to 50mA by adjusting the setting current from external. It is easy to support a multi-color RGB LED. The LED current of each channel can be controlled from ma to 50mA. It is easy to obtain a multi-color output by changing the current of,, and respectively. Input UVLO The input operating voltage range of the is.8v to RSET = 36k RSET = 5k RSET = 75k 5.5V. An input capacitor at the pin could reduce ripple voltage. It is recommended to use a ceramic or larger capacitance as the input capacitor. This IC provides an under voltage lockout (UVLO) function to prevent it from unstable issue when startup. The UVLO threshold of input falling voltage is set at.v typically with a hysteresis 0.V. LED Current (ma) RSET = 60k RSET = 360k Output Current Setting The LED current is setting by the current of ISET pin. The LED current of the three channels (,, ) could be set from the ISET (,, ) pins individually. The typical application circuit shows as Figure. R SET V SET R V SET SET R V SET3 SET V SET (V) Figure. LED Current Setting Figure shows the characteristics of I LED vs. V SET. If the R SET is selected, the LED current could be controlled from V SET. The voltage of VSET must be higher than.3v to enable the LED. For low LED current application, it is recommended to use a higher resistance on RSET (for example: R SET = 360kΩ). To disable the LED current, the ISET pin should be connected to ground or floating. For one LED or two LEDs application, the unused ISET pin should be connected to. In addition, don t short V SETx to ISETx pin. Figure. Typical Application Circuit The LED current can be controlled from an external voltage (V SET ) and a resistor (R SET ) between VSET and ISET pin. The voltage range of V SET is from.3v to 5.5V. The internal reference voltage at ISET pin is 0.9V typically. LED current is set as 800 times the current flowing into ISET pin. Therefore, the LED current can be calculated as the following equation. V SET V SET R SET I ~ 3 = 800 x ~ 3 = V 800 x SET ~ 3 R - 0.9V SET ~ 3 For example, = 45kΩ and V SET =.8V, the current of is equal to 6mA. Figure 3. Application Circuit for Two LEDs 6

7 Control Figure 4 shows an application circuit for backlight with. The three setting resistors are connected to. The LED current can be controlled by directly. The provides low dropout voltage and 5% maximum current matching. It also allows dimming control frequency up to 0kHz. Figure 5 shows another application circuit for keypad backlight with. There are 9 LEDs operation in parallel. A battery or a regulated power source drives the LEDs. Each channel supports three LEDs. The LED brightness adjustment can be set with proper setting resistor for each channel and be controlled from. Thermal Considerations For continuous operation, do not exceed absolute maximum operation junction temperature 5 C. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of R SET surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can R SET3 be calculated by following formula : P D(MAX) = ( T J(MAX) T A ) / θ JA Figure 4. Application Circuit for Backlight with The LED current can be set at different value with proper setting resistor. For typical application of.8v/.8v and LED current 5mA/0mA, the recommended current setting resistors are showed as below table. (V).8.8 I LED (ma) Table. R SET Value Selection R SET (kω) Nearest Standard Values for R SET (kω) Where T J(MAX) is the maximum operation junction temperature 5 C, T A is the ambient temperature and the θ JA is the junction to ambient thermal resistance. For recommended operating conditions specification of, where T J(MAX) is the maximum junction temperature of the die (5 C) and T A is the maximum ambient temperature. The junction to ambient thermal resistance θ JA is layout dependent. The thermal resistance θ JA for TSOT-3-8 is 6 C/W, and WDFN-8L 3x3 is 08 C/W on the standard JEDEC 5-3 single-layer thermal test board. The maximum power dissipation at T A = 5 C can be calculated by following formula : P D(MAX) = (5 C 5 C) / (6 C/W) = 0.38W for TSOT-3-8 packages P D(MAX)) = (5 C 5 C) / (08 C/W) = 0.96W for WDFN-8L 3x3 packages The maximum power dissipation depends on operating ambient temperature for fixed T J(MAX) and thermal resistance θ JA. For packages, the Figure of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. R SET R SET3 Figure 5. Application Circuit for Keypad Backlight 7

8 Maximum Power Dissipation (W) Single Layer PCB WDFN-8L 3x3 TSOT-3-8 Input capacitor (C IN ) should be placed close to LEDs Pin and connected to ground plane. The Anodes of LEDs must connect to C IN, not battery directly. Battery All the traces of LED and V IN running from chip to LEDs should be wide and short to reduce the parasitic connection resistance Ambient Temperature ( C) Figure 6. Derating Curves for Packages Layout Consideration For best performance, careful PCB layout is necessary. Place all peripheral components as close to the IC as possible. A short connection is highly recommended. The following guidelines should be strictly followed when designing a PCB layout for the.. All the traces of LED and pin running from chip to LEDs should be wide and short to reduce the parasitic connection resistance.. Input capacitor (C IN ) must be placed close to LEDs and connected to ground plane. The anodes of LEDs must be connected to C IN, not battery directly. 3. Current setting resistors R SET should be placed as close to the chip as possible. 4. The should be connected to a strong ground plane for heat sinking and noise protection. 5. The current setting resistors should be placed as close to the IC as possible. Ground Plane The should be connected to a strong ground plane for heat sinking and noise protection. Figure 7. ecommended PCB Layout of TSOT-3-8 Package All the traces of LED and running from chip to LEDs should be wide and short to reduce the parasitic connection resistance. Grand Plane Input capacitor (CIN) should be placed close to LEDs Pin and connected to ground plane. The Anodes of LEDs must connect to CIN, not battery directly. Battery The should be connected to a strong ground plane for heat sinking and noise protection. Figure 8. Recommended PCB Layout of WDFN-8L 3x3 Package 8

9 Outline Dimension D H L C B b A e A Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A A B b C D e H L TSOT-3-8 Surface Mount Package 9

10 D D L E E SEE DETAIL A A A A3 e b DETAIL A Pin # ID and Tie Bar Mark Options Note : The configuration of the Pin # identifier is optional, but must be located within the zone indicated. Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A A A b D D E E e L W-Type 8L DFN 3x3 Package Richtek Technology Corporation Headquarter 5F, No. 0, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863) Fax: (8863)5566 Richtek Technology Corporation Taipei Office (Marketing) 5F, No. 95, Minchiuan Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (886) Fax: (886) marketing@richtek.com Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. 0