CAT4137TS

CAT4137 CATALYST | Alldatasheet

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Technical content

© Catalyst Semiconductor, Inc. 1 Doc. No. MD-5012 Rev. B Characteristics subject to change without notice CMOS Boost Converter – White LED Driver

FEATURES

„ Drives up to 5 White LEDs from 3V „ Power Efficiency up to 87% „ Low Quiescent Ground Current 0.1mA „ Adjustable Output Current (up to 30mA) „ High Frequency 1MHz Operation „ “Zero” current shutdown mode „ Operates down to 2V (from two AA batteries) „ Soft start power-up „ Open LED low power mode „ Automatic shutdown at 1.9V (UVLO) „ Thermal shutdown protection „ Thin SOT23 5-Lead (1mm max height)

APPLICATIONS

„ LCD Backlighting „ Cellular Phones „ Handheld Devices „ Digital Cameras

ORDERING INFORMATION

CAT4137TD-T3 TSOT23-5 (1) 3000 LX CAT4137TD-GT3 TSOT23-5 (2) 3000 UE Notes: (1) Matte-Tin Plated Finish (RoHS-compliant). (2) NiPdAu Plated Finish (RoHS-compliant).

DESCRIPTION

The CAT4137 is a DC/DC step-up converter that delivers a regulated output current. Operation at a constant switching frequency of 1MHz allows the device to be used with small value external ceramic capacitors and inductor. The device drives a string of white LEDs connected in series and provides the regulated current to control the LEDs with inherent uniform brightness and matching. An external resistor R1 sets the output current and allows up to 30mA current to be supported over a wide range of input supply voltages from 2.2V to 5.5V, making the device ideal for battery-powered applications. LED dimming can be done by using a DC voltage, a logic signal, or a pulse width modulation (PWM) signal. The shutdown control pin allows the device to be placed in power-down mode with “zero” quiescent current. In addition to thermal protection and overload current limiting, the device also enters a very low power operating mode during “Open LED” fault conditions. The device is housed in a low profile (1mm max height) 5-lead thin SOT23 package for space critical applications. For Ordering Information details see page 15. PIN CONFIGURATION TSOT-23 5-Lead 1mm max height (Top View) TYPICAL APPLICATION CIRCUIT VIN CAT4137 VIN LD VOUT 15Ω VFB = 300mV 1µF 0.22µF FBSHDN SW GND ON 22µH OFF 2.2 to 5.5V L: Murata LQH32CN220 D: Central CMDSH2-3 (rated 30V) VIN FB SHDN SW GND

Doc. No. MD-5012 Rev. B 2 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice ABSOLUTE MAXIMUM RATINGS Parameter Rating Unit VIN, FB voltage -0.3 to +7 V SHDN¯¯¯¯¯ voltage -0.3 to +7 V SW voltage -0.3 to 40 V Storage Temperature Range -65 to +160 °C Junction Temperature Range -40 to +150 °C Lead Temperature 300 °C RECOMMENDED OPERATING CONDITIONS Parameter Range Unit VIN 2.2 to 5.5 V SW pin voltage 0 to 24 V Ambient Temperature Range -40 to +85 °C LED Bias Current 1 to 30 mA ELECTRICAL OPERATING CHARACTERISTICS VIN = 3.6V, ambient temperature of 25ºC (over recommended operating conditions unless specified otherwise) Symbol Parameter Conditions Min Typ Max Unit IQ Operating Current VFB = 0.3V VFB = 0.4V (not switching) 0.4 0.1 1.5 0.3 mA ISD Shutdown Current VSHDN¯¯¯¯¯ = 0V 0.1 1 µA VFB FB Pin Voltage 3 LEDs with I LED=20mA 285 300 315 mV IFB FB pin input leakage 0.1 1 µA ILED Programmed LED Current R1 = 10Ω R1 = 15Ω R1 = 20Ω 28.5 14.25 31.5 15.75 mA VIH VIL Enable Threshold Level Shutdown Threshold Level 0.4 0.8 0.7 1.5 V V FSW Switching Frequency 0.7 1 1.3 MHz ILIM Switch Current Limit 250 300 400 mA RSW Switch “On” Resistance I SW = 100mA 1.0 2.0 Ω ILEAK Switch Leakage Cu rrent Switch Off, V SW = 5V 1 5 µA TSD Thermal Shutdown 150 ºC THYS Thermal Hysteresis 20 ºC η Efficiency Typical Application Circuit 86 % VUVLO Under-voltage lock out (UVLO) threshold 1.9 V VOV-SW Output Clamp Voltage “Open LED” fault 29 V

© Catalyst Semiconductor, Inc. 3 Doc. No. MD-5012 Rev. B Characteristics subject to change without notice TYPICAL CHARACTERISTICS VIN = 3.6V, CIN = 1.0uF, COUT = 0.22µF, L = 22µH with 3 LEDs at 20mA, TAMB=25ºC, unless otherwise specified. Quiescent Current vs. VIN (Not Switching) 100 120 INPUT VOLTAGE [V] SUPPLY CURRENT [uA] VFB = 0.4V Quiescent Current vs. VIN (Switching) 0.00 0.25 0.50 0.75 1.00 INPUT VOLTAGE [V] SUPPLY CURRENT [mA] FB Pin Voltage vs. Supply Voltage 290 295 300 305 310 INPUT VOLTAGE [V] FB PIN VOLTAGE [mV]

3 LEDs

FB Pin Voltage vs. Output Current 290 295 300 305 310 0 5 10 15 20 25 30 OUTPUT CURRENT [mA] FB PIN VOLTAGE [mV] Switching Frequency vs. Supply Voltage 0.90 0.95 1.00 1.05 1.10 INPUT VOLTAGE [V] CLOCK FREQUENCY [MHz].

3 LEDs at 20mA

Switch ON Resistance vs. Input Voltage 0.0 0.5 1.0 1.5 2.0 INPUT VOLTAGE [V] SWITCH RESISTANCE [ohm]

Doc. No. MD-5012 Rev. B 4 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice TYPICAL CHARACTERISTICS VIN = 3.6V, CIN = 1.0uF, COUT = 0.22µF, L = 22µH, with 3 LEDs at 20mA, TAMB=25ºC, unless otherwise specified. LED Current vs. Input Voltage (3 LEDs) INPUT VOLTAGE [V] LED CURRENT [mA] Rfb = 10Ω Rfb = 15Ω Rfb = 20Ω LED Current Regulation -0.4 -0.2 0.0 0.2 0.4 INPUT VOLTAGE [V] LED CURRENT VARIATION [%] Efficiency across Supply Voltage (3 LEDs) 100 INPUT VOLTAGE [V] EFFICIENCY [%] 20mA 15mA Efficiency across Load Current (3 LEDs) 100 0 5 10 15 20 25 30 LED CURRENT [mA] EFFICIENCY [%] VIN = 3.6V VIN = 4.2V Efficiency across Supply Voltage (4 LEDs) 100 INPUT VOLTAGE [V] EFFICIENCY [%] 20mA 15mA Efficiency across Load Current (4 LEDs) 100 0 5 10 15 20 25 30 LED CURRENT [mA] EFFICIENCY [%] VIN = 3.6V VIN = 4.2V

© Catalyst Semiconductor, Inc. 5 Doc. No. MD-5012 Rev. B Characteristics subject to change without notice TYPICAL CHARACTERISTICS VIN = 3.6V, CIN = 1.0uF, COUT = 0.22µF, L = 22µH, with 3 LEDs at 20mA, TAMB=25ºC, unless otherwise specified. FB Pin Voltage vs. Temperature 294 296 298 300 302 304 -50 -25 0 25 50 75 100 TEMPERATURE [°C] FB PIN VOLTAGE [mV] Shutdown Voltage vs. Input Voltage 0.2 0.4 0.6 0.8 1.0 INPUT VOLTAGE [V] SHUTDOWN VOLTAGE [V] 25°C 85°C -40°C Under Voltage Lock Out vs. Temperature 1.6 1.7 1.8 1.9 2.0 2.1 2.2 - 5 0 - 2 5 0 2 55 07 5 1 0 0 TEMPERATURE [°C] UVLO [V] Switching Frequency vs. Temperature 0.90 0.95 1.00 1.05 1.10 - 5 0 - 2 5 0 2 55 07 5 1 0 0 TEMPERATURE [ºC] CLOCK FREQUENCY[MHz]. 20mA per LED Switching Waveforms (3 LEDs in Series) Switching Waveforms (2 LEDs in Series)

Doc. No. MD-5012 Rev. B 6 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice TYPICAL CHARACTERISTICS VIN = 3.6V, CIN = 1.0uF, COUT = 0.22µF, L = 22µH, with 3 LEDs at 20mA, TAMB=25ºC, unless otherwise specified. Power-up with 3 LEDs at 20mA Line Transient Response (3V – 5.5V) Maximum Output Current vs. Input Voltage 100 120 140 INPUT VOLTAGE [V] MAX OUTPUT CURRENT [mA] VOUT = 17V VOUT = 10V

© Catalyst Semiconductor, Inc. 7 Doc. No. MD-5012 Rev. B Characteristics subject to change without notice PIN DESCRIPTION VIN is the supply input for the internal logic. The device is compatible with supply voltages down to 2.2V and up to 5.5V. A small bypass ceramic capacitor of 1µF is recommended between the VIN and GND pins near the device. The under-voltage lockout (UVLO) circuitry w ill place the device into an idle mode (not switching) whenever the supply falls below 1.9V. SHDN¯¯¯¯¯ is the shutdown logic input. When the pin voltage is taken below 0.4V, the device immediately enters shutdown mode, drawing nearly zero current. At voltages greater than 1.5V, the device becomes fully enabled and operational. GND is the ground reference pin. This pin should be connected directly to the ground plane on the PCB. SW pin is the drain terminal of the internal low resistance power switch. The inductor and the Schottky diode anode should be connected to the SW pin. Traces going to the SW pin should be as short as possible with minimum loop area. This pin contains over-voltage circuitry which becomes active above 24V. In the event of an “Open-Led” fault condition, the device will enter a low power mode and the SW pin will be clamped to approximately 30V. FB feedback pin is regulated at 0.3V. A resistor connected between the FB pin and ground sets the LED current according to the formula: I LED = 0.3V/R1 The lower LED cathode is connected to the FB pin. Pin # Name Function 1 SW Switch pin. This is the dr ain of the internal power switch. 2 GND Ground pin. Connect the pin to the ground plane. 3 FB Feedback pin. Connect to the last LED cathode. 4 SHDN¯¯¯¯¯ Shutdown pin (Logic Low). Set high to enable the driver. 5 VIN Power Supply input.

Doc. No. MD-5012 Rev. B 8 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice DEVICE OPERATION The CAT4137 is a fixed frequency (1MHz), low noise, inductive boost converter providing constant current to the load. A high voltage internal CMOS power switch is used to energize the external inductor. When the power switch is then turned off, the stored energy inductor is released into the load via the external Schottky diode. The on/off duty cycle of the power switch is internally adjusted and controlled to maintain a constant regulated voltage of 0.3V across the external feedback resistor connected to the feedback pin (FB). The value of external resistor will accurately set the LED bias current accordingly (0.3V/R1). During the initial power-up stage, the duty cycle of the internal power switch is limited to prevent excessive in-rush currents and thereby provide a “soft-start” mode of operation. While in normal operation, the device will comfortably deliver up to 30mA of bias current into a string of up to 5 white LEDs. In the event of a “Open-Led” fault condition, where the feedback control loop becomes open, the output voltage will continue to increase. Once this voltage exceeds 24V, an internal protection circuit will become active and place the device into a very low power safe operating mode. In addition, an internal clamping circuit will limit the peak output voltage to 29V. If this fault condition is repaired, the device will automatically resume normal operation. Thermal overload protection circuitry has been included to prevent the device from operating at unsafe junction temperatures above 150ºC. In the event of a thermal overlo ad condition the device will automatically shutdown and wait till the junction temperatures cools to 130ºC before normal operation is resumed. BLOCK DIAGRAM VREF Enable VIN VIN VOUT Current Sense 300mV ILED RS SHDN Thermal Shutdown & UVLO 1MHz Oscillator Over Voltage Protection PWM Logic Driver GND FB SW N1A2 RC CC 15Ω

© Catalyst Semiconductor, Inc. 9 Doc. No. MD-5012Rev. B Characteristics subject to change without notice

APPLICATION INFORMATION

EXTERNAL COMPONENT SELECTION Capacitors The CAT4137 only requires small ceramic capacitors of 1uF on the input and 0.22µF on the output. The output capacitor should be rated at 30V or greater. Under normal conditions, a 1µF input capacitor is sufficient. For applications with higher output power, a larger input capacitor of 2.2µF or 4.7µF may be appropriate. X5R and X7R capacitor types are ideal due to their stability across temperature range. Inductor A 22µH inductor is recommended for most of the CAT4137 applications. In cases where the efficiency is critical, inductances with lower series resistance are preferred. Several inductor types from various vendors can be used. Figure 1 shows how different inductor types affect the efficiency across the load range. 100 5 1 01 52 02 53 0 LED CURRENT [mA] EFFICIENCY (%) SUMIDA CDRH3D16-220 MURATA LQH32CN220 PANASONIC ELJ-EA220 PANASONIC ELJ-PC220 VIN = 3.6V Figure 1. Efficiency for various inductors also critical since the driver is operating at 1MHz. recommended for most applications. Table 1. Resistor R1 and LED current

Doc. No. MD-5012 Rev. B 10 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice TYPICAL APPLICATIONS CAT4137 Driving Two LEDs L: Sumida CDRH3D16-330 D: Central CMDSH2-3 (rated 30V) C2: Taiyo Yuden GMK212BJ105KG-T (rated 35V) Efficiency vs. LED Current, Two LEDs 100 01 0 2 0 3 0 4 0 LED CURRENT [mA] EFFICIENCY [%] VIN = 3V VIN = 3.6V For best performance, a 33µH inductor and a 1µF output capacitor are recommended for 2-LED applications. In 2-LED configuration, the CAT4137 can be powered from two AA alkaline cells or from a Li-ion battery. VIN CAT4137 VIN VOUT LD 1µF 2.2V to 5.0V 1µF 15Ω FBSHDN SW GND ON 33µH OFF VFB = 300mV 20mA

Doc. No. MD-5012 Rev. B 12 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice OPEN LED PROTECTION In the event of an “Open LED” fault condition, the CAT4137 will continue to boost the output voltage with maximum power until the output voltage reaches approximately 24V. Once the output exceeds this level, internal circuitry immediately places the device into a very low power mode where the total input power consumed is less than 10mW. In low power mode, the input supply current will typically drop to 2mA. An internal clamping circuit will limit the subsequent output voltage to approximately 29V. This operating mode eliminates the need for any external protection zener diode. This protection scheme also fully protects the device against any malfunction in the external Schottky diode (open- circuit). Open LED Protection VIN CAT4137 VIN VOUT L (Central CMDSH2-3) D 1µF 0.22µF 15Ω FBSHDN SW GND ON 22µH OFF VFB = 300mV Open LED Power-up Waveforms Open LED Supply Current vs. VIN 1.0 1.5 2.0 2.5 INPUT VOLTAGE [V] SUPPLY CURRENT [mA]

Doc. No. MD-5012 Rev. B 14 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice PACKAGE OUTLINE DRAWING TSOT-23 5-Lead (TD) (1)(2) Notes: (1) All dimensions are in millimeters. Angles in degrees. (2) Complies with JEDEC standard MO-193. θ E1 E e b D c A TOP VIEW SIDE VIEW END VIEW L SYMBOL MIN NOM MAX A1 . 0 0 A1 0.01 0.05 0.10 A2 0.80 0.87 0.90 b 0.30 0.45 c 0.12 0.15 0.20 D 2.90 BSC E 2.80 BSC E1 1.60 BSC e0 . 9 5 T Y P L 0.30 0.40 0.50 L1 0.60 REF L2 0.25 BSC θ 0º 8º For current Tape and Reel information, download the PDF file from: http://www.catsemi.com/documents/tapeandreel.pdf.

© Catalyst Semiconductor, Inc. 15 Doc. No. MD-5012 Rev. B Characteristics subject to change without notice EXAMPLE OF ORDERING INFORMATION1 Notes: (1) All packages are RoHS-compliant (Lead-free, Halogen-free). (2) The standard lead finish is NiPdAu. (3) The device used in the above exampl e is a CAT4137TD–GT3 (TSOT-23, NiPdAu Plated Finish, Tape & Reel 3000). (4) For Matte-Tin package option, please contact y our nearest Catalyst Semiconductor Sales office. Prefix Device # Suffix CAT 4137 TD – G T3 Product Number 4137 Tape & Reel T: Tape & Reel 3: 3000/Reel Lead Finish G: NiPdAu Blank: Matte-Tin (4) Package TD: TSOT-23 Optional Company ID

REVISION HISTORY

Date Rev. Reason 12/13/2005 00 Initial Issue 01/11/2008 B Add NiPdAu lead finish Add Extended Temperature range Update Package Outline Drawing Add Example of Ordering Information Change Document Number from 25093, Rev. 00 to MD-5016, Rev. B Catalyst Semiconductor, Inc. Corporate Headquarters

2975 Stender Way

Santa Clara, CA 95054 Phone: 408.542.1000 Document No: MD-5012 Fax: 408.542.1200 Revision: B www.catsemi.com Issue date: 01/11 /08 Copyrights, Trademarks and Patents © Catalyst Semiconductor, Inc. Trademarks and registered trademarks of Catalyst Semiconductor include each of the following: Adaptive Analog™, Beyond Memory™, DPP™, EZDim™, LDD™, MiniPot™, Quad-Mode™ and Quant um Charge Programmable™ Catalyst Semiconductor has been issued U.S. and foreign patents and has patent applications pending that protect its products. CATALYST SEMICONDUCTOR MAKES NO WARRANTY, REPRESENTATION OR GUAR ANTEE, EXPRESS OR IMPLIED, REGARDING THE SUITABILITY OF ITS PRODUCTS FOR ANY PARTICULAR PURPOSE, NOR THAT THE USE OF ITS PRO DUCTS WILL NOT INFRINGE ITS INTELLECTUAL PROPERTY RIGHTS OR THE RIGHTS OF THIRD PARTIES WITH RESPECT TO ANY PARTICULAR USE OR APPLICATION AND SPECIFICALLY DISCLAIMS ANY AND ALL LIABILITY ARIS ING OUT OF ANY SUCH USE OR APPLICATION, INCLUDING BUT NOT LIMITED TO, CONSEQUENTIAL OR INCIDENTAL DAMAGES. Catalyst Semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgica l implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Catalyst Semiconduct or product could creat e a situation where personal injury or death may occur. Catalyst Semiconductor reserves the right to make changes to or discontinue any product or service described herein without not ice. Products with data sheets labeled "Advance Information" or "Preliminary" and other products described herein may not be in production or offered for sale. Catalyst Semiconductor advises customers to obtain the current version of the rele vant product informati on before placing order s. Circuit diagrams illustrate typical semiconductor applications and may not be complete.