STLD40DPUR

STLD40D White LED power supply for large display backlight Features ■ Inductor switches boost controller ■ PFM mode control ■ High efficiency over wide range of input voltage from 3.0 V to 5.5 V ■ Over voltage protection with automatic restart ■ Adjustable peak current limit ■ Enable pin with possibility of PWM dimming control ■ Low shutdown current < 1 µA ■ Small external component ■ Good load and line regulation ■ QFN8 3 x 3 mm QFN8 (3 x 3 mm) resistor RLED. The device can be turned ON/OFF through the logic enable signal pin EN. By applying a low frequency PWM signal the LEDs can be dimmed. The maximum peak inductor current can be programmed by connected a resistor RSET to the pin RSET. Applications ■ White LED supply for LCD backlight ■ Mobile phone ■ PDA and organizers ■ Any handsets powered form 3.0 V to 5.5 V Description STLD40D is a boost converter that operates from 3.0 V to 5.5 V. It can provide an output voltage as high as 37 V and can drive up to 10 white LEDs in series. The converter is a PFM (pulse frequency modulation) inductor switch that can work in discontinuous (DCM) mode operation. A minimum OFF time of the embedded boost switch TSW is fixed internally and allows limiting the switching frequency. The output current capability is 20 mA with an output voltage of 37 V. The regulation is done by sensing the LED current through the Table 1. May 2011 Device summary Order code Package Packaging STLD40DPUR QFN8 (3 x 3 mm) 3000 parts per reel Doc ID 12203 Rev 7 1/16 www.st.com 16 Contents STLD40D Contents 1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1 Boost controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2 Adjustable peak inductor current limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.3 Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.4 OVP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2/16 Doc ID 12203 Rev 7 STLD40D Block diagram 1 Block diagram Figure 1. Block diagram Doc ID 12203 Rev 7 3/16 Pin configuration STLD40D 2 Pin configuration Figure 2. Pin connections (top through view) Table 2. Pin description Pin n° Symbol 1 VI 2 RSET Peak inductor current adjust 3 GND Analog ground 4 FB 5 N.C. 6 VO Output voltage for LED supply 7 EN IC enable signal 8 SW Boost switch drain PGND 4/16 Note Supply voltage Feedback for the LED current regulation Not connected Power ground Doc ID 12203 Rev 7 STLD40D Maximum ratings 3 Maximum ratings Table 3. Absolute maximum ratings Symbol Parameter Value Unit VBSW, VBO Breakdown voltage at VO and SW pin 44 V EN Maximum voltage applied on pin EN VI V VI Supply voltage range 6 V VESD ESD ratings - (HBM MIL STD 883C) 2 kV TOP Operating temperature - 40 to 85 °C TSTG Storage temperature range - 65 to 150 °C Value Unit 52 °C/W Table 4. Symbol RthJA Thermal data Parameter Thermal resistance junction-ambient Doc ID 12203 Rev 7 5/16 Electrical characteristics 4 STLD40D Electrical characteristics TJ = - 40 °C to 85 °C, VI = 3.6 V, VEN = 3 V, CI = 2.2 µF, CO = 4.7 µF, L = 4.7 µH, RLED = 8 Ω VO = 32 V, typ. values @ 25 °C, unless otherwise specified. Table 5. Electrical characteristics Symbol Parameter Test conditions Min. Typ. Max. Unit VI Input voltage range 3.0 5.5 V VO Output voltage range VI 37 V IO Regulated output current ISD Stand-by current IQ Quiescent current RDSON VO = 36 V (10 white LEDs) 20 VEN = Low, VI = 3.6 V, TJ = 25 °C mA 1 µA VEN = Low, VI = 3 V to 4.2 V Boost switch RDSON 3 10 VI = 3 V to 4.2 V, TJ = 25 °C 0.4 0.8 VI = 5.5 V, TJ = 25 °C 0.8 1.2 VI = 5.5 V, I = 100 mA 0.4 VI = 4.2 V, I = 100 mA 0.4 VI = 3.0 V, I = 100 mA 0.5 BVDS breakdown voltage mA Ω 38 V ILIM-ADJ Maximum peak inductor limit adjust range (1) RSET = 12 kΩ to 100 kΩ 0.2 1 A ILIM Maximum peak inductor limit when RSET = VI (1) VI = 3 V to 5.5 V 0.75 1.1 A VFB Feedback voltage VI = 3.6 V 130 165 200 mV Line FB Line feedback voltage VI = 3 V to 5.5 V 5 35 mV TON_MAX Maximum ON time VI = 4.2 V 5.5 µs TOFF_MIN Minimum OFF time VI = 4.2 V 250 ns ν Efficiency at VI = 3.0 VDC (1) IO = 20 mA, VO = 36 VDC 75 Efficiency at VI = 5.5 VDC (1) IO = 20 mA, VO = 36 VDC 80 OVP Over voltage protection OVHYS Over voltage hysteresis VEN 36 42 1.5 Enable input logic low Disable Low VIL Enable input logic high Enable High VIH 1. Guaranteed by design. 6/16 % Doc ID 12203 Rev 7 V V 0.3 V 1.2 STLD40D Functional description 5 Functional description 5.1 Boost controller The STLD40D is a boost converter operating in PFM (pulsed frequency modulation) mode. The converter monitors the LED current through the resistor RLED and when the feedback voltage falls below the reference voltage REF2, the boost switch TSW turns ON and the current ramps up. The inductor current is measured by sensing the temperature compensated drain voltage of the boost MOSFET. The boost turns off when its drain voltage reaches the internally reference REF1, the main switch remains off until the minimum off time (250 ns typical) has passed and the feedback voltage is below the reference again. A maximum ON time of 4 µs typical prevents the switch TSW to stay ON during a too long period of time. 5.2 Adjustable peak inductor current limit The peak inductor current is monitored by sensing the drain voltage of the switch TSW. Since it exceeds the temperature compensated and supply voltage compensated reference REF1, the RS flip flop is reset and TSW is turned OFF. By connecting a resistance to the pin RSET the peak current limit can be adjusted from 200 mA to 1 A. When RSET resistor value is about 12 kΩ is connected directly to GND, the default value is 1 A. 5.3 Enable The ENABLE pin is a high logic input signal and allows turning on/off the controller without cutting the input voltage from the boost regulator circuit. The pin ENABLE can be used to dim the LED by applying a low frequency PWM signal. 5.4 OVP If the regulation loop is cut, there is no signal at the feedback pin, the PFM controller will then continue to switch without control and generate an output voltage at the SW, and VO pin exceeding the breakdown value VBSW, and VBO. The over voltage protection (OVP) senses the voltage at the VO pin. When the voltage exceed 38 V min. the controller is automatically turned OFF. A hysteresis control allows the device restarting automatically since the output voltage drops down of 1.5 V. Doc ID 12203 Rev 7 7/16 Typical application STLD40D 6 Typical application Figure 3. Application circuit Table 6. External component proposal (see Figure 3) Symbol Parameter Test conditions VRRM Boost schottky diode D Typ. 40 0.5 V IR at VR = 10 V, TJ = 25 °C 30 µA 40 V VF at IF = 1 A, TJ = 25 °C RLED Feedback LED current regulation ILED = 20 mA resistor RSET Current peak setting resistor IPEAK = 0.2 A to 1 A CI Input filtering capacitor Ceramic Type CO Capacitance Output capacitance: ceramic low Voltage ESR ESR Note: 8/16 0.46 V 21 µA Ω 8 12 100 2.2 kΩ µF 4.7 µF 35 V 1.6 Ω 4.7 µH DCR 1 Ω ISATRSET = GND 1 A Inductance Boost inductor (height < 2 mm) Unit V IR at VR = 20 V, TJ = 25 °C L Max. VF at IF = 300 mA, TJ = 25 °C VRRM STPS1L40M Min. The external components proposal should be considered as a design reference guide.The performances mentioned in the electrical characteristics table are not guaranteed for all the possible electrical parameters of the components included in this list. On an other hand the operation of STLD40D is not limited with the use of components included in this list. Doc ID 12203 Rev 7 STLD40D 7 Typical performance characteristics Typical performance characteristics VI = 3.6 V, VEN = 3 V, CI = 2.2 µF, CO = 4.7 µF, L = 4.7 µH, RLED = 8 Ω VO = 32 V, 10 W LEDs load (VO = 32 V) typ. values @ 25 °C, unless otherwise specified. Figure 4. ILED vs. RLED Figure 5. ILED vs. VI Figure 6. IQ vs. temperature Figure 7. ISD vs. VI Figure 8. RDSON vs.VI Figure 9. ILIMIT vs. RSET Doc ID 12203 Rev 7 9/16 Typical performance characteristics STLD40D Figure 10. VFB vs. temperature Figure 11. VEN vs. temperature Figure 12. Efficiency vs. VI Figure 13. VOVP vs. temperature Figure 14. ILED vs. duty cycle EN pin (dimming) 10/16 Doc ID 12203 Rev 7 STLD40D 8 Package mechanical data Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark. Table 7. QFN8 (3 x 3 mm) mechanical data mm. Dim. Min. Typ. Max. A 0.80 0.90 1.00 A1 0 0.02 0.05 A3 0.20 b 0.25 0.30 0.35 D 2.85 3.00 3.15 D2 2.49 2.64 2.74 E 2.85 3.00 3.15 E2 1.75 1.90 2.00 e L 0.65 0.30 0.40 Doc ID 12203 Rev 7 0.50 11/16 Package mechanical data STLD40D Figure 15. Drawing dimension QFN8 (3 x 3 mm) 8057023_B 12/16 Doc ID 12203 Rev 7 STLD40D Package mechanical data Tape & reel QFNxx/DFNxx (3x3) mechanical data mm. inch. Dim. Min. Typ. A Max. Min. Typ. 180 13.2 7.087 C 12.8 D 20.2 0.795 N 60 2.362 T 0.504 0.519 14.4 0.567 Ao 3.3 0.130 Bo 3.3 0.130 Ko 1.1 0.043 Po 4 0.157 P 8 0.315 Doc ID 12203 Rev 7 Max. 13/16 Package mechanical data STLD40D Figure 16. QFN8 (3x3) footprint recommended data 14/16 Doc ID 12203 Rev 7 STLD40D Revision history 9 Revision history Table 8. Document revision history Date Revision Changes 20-Mar-2006 1 Initial release. 04-Apr-2006 2 Add RSET in table 4 and fig 2 has been updated. 27-Feb-2009 3 Modified mechanical data. 03-Mar-2009 4 Modified packaging Table 1 on page 1. 11-Mar-2009 5 Modified: Figure 2 on page 4 and added Figure 16 on page 14. 01-Jul-2010 6 Modified: Table 7 on page 11, Figure 15 on page 12 and Figure 16 on page 14. 31-May-2011 7 Modified: Table 6 on page 8. Doc ID 12203 Rev 7 15/16 STLD40D Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein. UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE, ST PRODUCTS ARE NOT RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY, DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER’S OWN RISK. Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any liability of ST. ST and the ST logo are trademarks or registered trademarks of ST in various countries. Information in this document supersedes and replaces all information previously supplied. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners. © 2011 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com 16/16 Doc ID 12203 Rev 7