CAT32 CMOS White LED Driver DESCRIPTION FEATURES Low quiescent ground current (0.5mA typical) Power efficiency over 80% Compatible pinout with LT1932 Adjustable output current (up to 40mA) High frequency 1.2MHz operation Input voltage operation down to 2.0V Low resistance (0.5Ω) high voltage power switch Drives up to 4 White LEDs in series Shutdown current less than 1µA Load fault protection against open-circuits Low value external components Low profile (1mm) TSOT-23 6-lead and TDFN 8-pad (0.8mm) package The CAT32 is a DC/DC step up converter that delivers a regulated output current. Operation at a constant switching frequency of 1.2MHz allows the device to be used with very small value external inductor and ceramic capacitors. The CAT32 is targeted to drive multiple white lightemitting diodes (LEDs) connected in series and provides the necessary regulated current to control the brightness and the color purity. An external resistor RSET controls the output current level. LED currents of up to 40mA can be supported over a wide range of input supply voltages from 2V to 7V, making the device ideal for battery-powered applications. A high voltage output stage allows up to 4 White LEDs to be driven in series. Series drive provides inherent current matching. APPLICATION LED dimming can be done by using a DC voltage, a logic signal, or a pulse width modulation (PWM) signal. The shutdown input pin allows the device to be placed in power-down mode with “near zero” quiescent current. Color LCD and keypad backlighting Cellular phones Handheld terminals Digital cameras PDAs/Games Portable MP3 players In addition to overcurrent limiting protection, the device also includes detection circuitry to ensure protection against open-circuit load fault conditions. For Ordering Information details, see page 14. TYPICAL APPLICATION CIRCUIT VIN 2.7V to 4.2V The device is available in a low profile (1mm max height) 6-lead TSOT-23 package and in an 8-pad TDFN (0.8mm max height) package. L1 6.8µH C1 4.7µF D1 6 VIN 1 SW CAT32 PWM DIMMING CONTROL 5 LED SHDN GND 2 RSET 4 RSET 1.50kΩ TSOT-23 Pin Numbers C2 1µF 3 15mA C1: Taiyo Yuden JMK212BJ475 C2: Taiyo Yuden EMK212BJ105 D1: Zetez ZHCS400 L1: Sumida CLQ4D106R8 (Panasonic ELJEA6R8) Figure 1. Li-Ion Driver for Four High-Brightness White LEDs © Catalyst Semiconductor, Inc. Characteristics subject to change without notice 1 Doc. No. MD-5001 Rev. AD CAT32 ORDERING INFORMATION Part Number CAT32TDI-T3 CAT32ZD4-GT3 CAT32TDI-GT3 Package TSOT23-6 TDFN-8 TSOT23-6 Reel Quantity 3000 3000 3000 Package Marking Code LL CCKV VF PIN CONFIGURATION TDFN 3 x 3mm TSOT-23 6-Lead Top View SW 1 6 Power GROUND 1 VIN 2 VIN GND 2 5 SHDN LED 3 4 RSET 8 SW 7 NC SHDN 3 6 LED RSET 4 5 GND 0.8mm maximum height (Top View) 1mm maximum height θJA = 250ºC/W [free air] PIN DESCRIPTION Pin Number SOT23 Pin Number TDFN Name 1 8 SW 2 5 GND Ground pin. Connect pin 2 to ground. 3 6 LED LED (cathode) connection pin. 4 4 RSET RESET pin. A resistor connected from pin 4 to ground sets the LED current. This pin is also used to dim the LEDs. 5 3 ¯¯¯¯¯ SHDN Shutdown pin. 6 2 VIN — 1 Power Ground Doc. No. MD-5001 Rev. AD Function Switch pin. This is the drain of the internal power switch. For minimum EMI, minimize the trace area connected to this pin. Input supply pin. This pin should be bypassed with a capacitor to ground. A 4.7µF capacitor mounted close to the pin is recommended. Power Ground 2 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT32 ABSOLUTE MAXIMUM RATINGS (1) Parameter VIN, LED, ¯¯¯¯¯ SHDN voltage SW voltage RSET voltage Storage Temperature Range Junction Temperature Lead Soldering Temperature (10 secs) ESD Rating – Human Body Model Rating 8 20 1 -65 to +150 125 300 2000 Unit V V V ºC ºC ºC V RECOMMENDED OPERATING CONDITIONS Parameter VIN Ambient Temperature Range Inductor L1 Input Capacitor C1 Output Capacitor C2 ILED with 1 to 4 LEDs in series Range 2 to 7 -40 to +85 6.8 ±20% typical 4.7 ±20% typical 1.0 ±20% typical 0 to 20 Unit V ºC µH µF µF mA Typical application circuit with external components is shown on page 1. ELECTRICAL OPERATING CHARACTERISTICS Over recommended operating conditions unless otherwise specified. TA = 25ºC, VIN = 2V and V¯¯¯¯¯ SHDN = 1.2V. Symbol Parameter Conditions Typ Max Unit Quiescent Current VRSET = 0.2V 0.5 0.7 mA IGND Ground Current in Shutdown V¯¯¯¯¯ SHDN = 0V 0.05 1 µA VLED LED Pin Voltage VIN < VOUT, ILED =15mA 120 180 mV ILED LED Current Adjust Range 40 mA IQ ILED Min 5 Programmed LED Current RSET = 562Ω 33 38 45 RSET = 750Ω 25 30 36 RSET = 1.5kΩ 12.5 15 17.5 RSET = 4.53kΩ ILED VRSET mA 5 LED Pin Current Temperature Coefficient ILED = 15mA -0.01 mA/°C RSET Pin Voltage RSET = 1.5kΩ 100 mV Shutdown Pin Logic High Level 0.85 V Shutdown Pin Logic Low Level 0.25 V fSW Boost Converter Frequency 0.8 1.2 1.6 MHz ISWL Switch Current Limit 400 550 780 mA RSW Switch Resistance VIN = 2V, ISW = 100mA 0.7 1.2 Ω VIN = 3V, ISW = 100mA 0.5 0.9 Ω Switch Off, VSW = 5V Components shown on Figure 1 0.01 5 µA Switch Leakage Current Efficiency 83 % Notes: (1) These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground. © Catalyst Semiconductor, Inc. Characteristics subject to change without notice 3 Doc. No. MD-5001 Rev. AD CAT32 TYPICAL CHARACTERISTICS VIN = 3.6V, TAMB = 25ºC, CIN = 4.7µF, COUT = 1µF, L = 6.8µH, unless otherwise specified. 600 QUIESCENT CURRENT [µA] QUIESCENT CURRENT [µA] Quiescent Current vs. Temperature Quiescent Current vs. Input Voltage 600 500 400 300 200 2 3 4 5 6 VIN = 2V 400 300 200 7 -50 INPUT VOLTAGE [V] 25 50 75 100 125 2.0 SWITCH FREQUENC Y [MHz] 1.60 1.20 0.80 0.40 0.00 2 3 4 5 6 1.6 1.2 0.8 0.4 0.0 7 -50 INPUT VOLTAGE [V] 35 RSET = 1.13kΩ 20 RSET = 1.50kΩ 15 RSET = 2.26kΩ 10 5 0 3 4 5 6 50 75 100 125 15 10 5 0 7 -50 INPUT VOLTAGE [V] Doc. No. MD-5001 Rev. AD 25 LED Current vs. Temperature LED CURRENT [mA] 25 0 20 RSET = 750Ω 30 -25 TEMPERATURE [ºC] LED Current vs. Input Voltage LED CURRENT [mA] 0 Switching Frequency vs. Temperature 2.00 2 -25 TEMPERATURE [ºC] Switching Frequency vs. Input Voltage SWITCH FREQUENC Y [MHz] VIN = 7V 500 -25 0 25 50 75 100 125 TEMPERATURE [ºC] 4 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT32 TYPICAL CHARACTERISTICS VIN = 3.6V, TAMB = 25ºC , CIN = 4.7µF, COUT = 1µF, L = 6.8µH, unless otherwise specified. Switch Resistance vs. Temperature Switch Resistance vs. Input Voltage 1.0 SWITCH RESISTANCE [Ω] SWITCH RESISTANCE [Ω] 1.0 0.8 0.6 0.4 0.2 0.0 VIN = 3V 0.6 0.4 0.2 0.0 2 3 4 5 6 -50 -25 0 25 50 75 100 125 TEMPERATURE [ºC] INPUT VOLTAGE [V] VSW, IL, & VOUT Signal Waveforms LED Pin Voltage vs. LED current 300 LED PIN VOLTAGE [mV] 0.8 250 200 150 100 50 0 0 8 16 24 32 40 LED CURRENT [mA] Efficiency vs. Input Voltage 85 PWM on ¯¯¯¯¯ SHDN pin Waveform EFFICIENCY [%] 80 75 4 LEDs at 15m A VOUT = 13V 70 65 60 2 3 4 5 6 INPUT VOLTAGE [V] © Catalyst Semiconductor, Inc. Characteristics subject to change without notice 5 Doc. No. MD-5001 Rev. AD CAT32 OPERATION The CAT32 device is a high efficiency, constant frequency, current regulating boost converter. as possible. A low LED pin voltage ensures high efficiency. The device includes a switch and an internally compensated loop for the regulation of the LED current. Current through the internal power switch is continuously monitored cycle-by-cycle. If the current limit is exceeded, the switch is immediately turned off, protecting the device, for the remainder of the cycle. Operation can be best understood by examining the block diagram. The RSET pin is regulated at 100mV and the current through the external resistor will set the regulated current in the LEDs (from 5mA to 40mA) with a multiplication factor of 225. PWM dimming operation can be achieved by switching the SHDN ¯¯¯¯¯ pin or by pulling the RSET pin higher than 0.1V. While maintaining LED current regulation, the CAT32 automatically adjusts the LED pin voltage to be as low BLOCK DIAGRAM D1 L1 VIN 1 C1 C2 SW Over Voltage Protection (22V) 1.2MHz Oscillator LED 3 PWM & Logic Current Sense Amp 6 VIN 5 SHDN 100mV Current Control ILED = 225 x IS 225x IS CAT32 ILED GND RSET 2 4 RSET Figure 2. CAT32 Block Diagram Doc. No. MD-5001 Rev. AD 6 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT32 APPLICATION INFORMATION INDUCTOR SELECTION AND EFFICIENCY Inductor vendors are shown below. Contact the manufacturer for detailed technical data and new product information. Table 1: Inductor Manufacturers L (μH) Maximum DCR (mΩ) Maximum Height (mm) ELJEA4R7 4.7 180 2.2 ELJEA6R8 6.8 250 2.2 4.7 260 2.2 Inductor LQH3C4R7M24, LQH32CN4R7M11 LQH3C100K24, 10 300 2.2 LB2016B4R7 4.7 250 2.0 LB2016B100 3.8 350 2.0 CMD4D06-4R7 4.7 216 0.8 CMD4D06-6R8 6.8 296 0.8 CLQ4D10-4R7 4.7 162 1.2 CLQ4D10-6R8 6.8 195 1.2 LQH32CN100K11 Vendor Web Panasonic 714.373.7334 www.panasonic.com Murata 770.436.1300 www.murata.com Taiyo Yuden 408.573.4150 www.t-yuden.com Sumida 847.956.0666 www.sumida.com CAPACITOR SELECTION Low ESR (equivalent series resistance) capacitors should be used at the output to minimize the output ripple voltage. The low ESR and small package options available with multilayer ceramic capacitors make them excellent choices. The X5R and X7R capacitor types are preferred because they retain their capacitance over wider voltage and temperature ranges than the Y5V or Z5U types. A 1.0µF or 2.2µF output capacitor is recommended for most applications. Low profile ceramic capacitors with a 1mm maximum height/thickness are available for designs height requirements. Ceramic capacitors also make a good choice for the input capacitor, which should be mounted as close as possible to the CAT32. A 2.2µF or 4.7µF input capacitor is recommended. Table 2 shows a list of several ceramic capacitor manufacturers. Consult the manufacturers for detailed information as new products and package options are introduced regularly. The voltage rating of the output capacitor C2 depends on the number of LEDs driven in series. A 10V ceramic capacitor is recommended when driving two LEDs. A 16V ceramic capacitor is recommended when driving 3 or 4 LEDs. Table 2: Ceramic Capacitor Manufacturers Supplier Phone Web Taiyo Yuden 408.573.4150 www.t-yuden.com Murata 814.237.1431 www.murata.com Kemet 408.986.0424 www.kemet.com © Catalyst Semiconductor, Inc. Characteristics subject to change without notice 7 Doc. No. MD-5001 Rev. AD CAT32 DIODE SELECTION two parallel strings of LEDs for greater light output, resulting in 30mA to 40mA (two strings of 15mA to 20mA) flowing into the LED pin. Schottky diodes, with their low forward voltage drop and fast switching speed, are the ideal choice for high efficiency applications. Table 3 shows several different Schottky diodes that work well with the CAT32. Make sure that the diode has a voltage rating greater than the output voltage. The diode conducts current only when the power switch is turned off (typically less than one-third the time), so a 0.4A or 0.5A diode will be sufficient for most designs. LED DIMMING WITH PWM SIGNAL PWM brightness control provides the widest dimming range (greater than 20:1). By turning the LEDs ON and OFF using the control signal the LEDs operate at either zero or full current, but their average current changes with the PWM signal duty cycle. Typically, a 5kHz to 40kHz PWM signal is used. PWM dimming with the CAT32 can be accomplished two different ways. Table 3: Schottky Diode Suppliers Part Supplier MBR0520 MBR0540 ON Semiconductor www.onsemi.com 800.282.9855 ZHCS400 Zetex MBR0530 s The ¯¯¯¯¯ SHDN pin can be driven directly or a resistor can be added to drive the RSET pin. If the ¯¯¯¯¯ SHDN pin is used, increasing the duty cycle will increase the LED brightness. Using this method, the LEDs can be dimmed and turned off completely using the same control signal. A 0% duty cycle signal will turn off the CAT32, reducing the total quiescent current to near zero. LED CURRENT PROGRAMMING The LED current is programmed with a single resistor connected to the RSET pin The RSET pin is internally regulated to 100mV, which sets the current flowing out of this pin, ISET, equal to 100mV/RSET. The CAT32 regulates the current into the LED pin, ILED, to 225 times the value of ISET. For the best accuracy, a 1% or better resistor is recommended. Table 4 shows several typical 1% RSET values. RPWM = RSET × ( If the RSET pin is used, increasing the duty cycle will decrease the brightness. Using this method, the LEDs are dimmed using RSET and turned off completely using ¯¯¯¯¯ SHDN . If the RSET pin is used to provide PWM dimming, the approximate value of RPWM should be calculated (where VMAX is the “HIGH” value of the PWM signal): Table 4: RSET Resistor Values ILED (mA) RSET 40 562Ω 30 750Ω 25 909Ω 20 1.13kΩ 15 1.50kΩ 10 2.26kΩ 5 4.53kΩ In addition to providing the widest dimming range, PWM brightness control also ensures the “purest” white LED color over the entire dimming range. The true color of a white LED changes with operating current, and is the “purest” white at a specific forward current, usually 15mA or 20mA. If the LED current is less than or more than this value, the emitted light becomes more blue. Applications involving color LCDs can find the blue tint objectionable. When a PWM control signal is used to drive the ¯¯¯¯¯ SHDN pin of the CAT32, the LEDs are turned off and on at the PWM frequency. The current through them alternates between full current and zero current, so the average current changes with duty cycle. This ensures that when the LEDs are on, they can be driven at the appropriate current to give the purest white light. LED brightness varies linearly with the PWM duty cycle. For other LED current values, use the following equation to choose RSET. R SET = 255 × 0.1V ILED Most white LEDs are driven at maximum currents of 15mA to 20mA. Some higher power designs will use Doc. No. MD-5001 Rev. AD VMAX –1 ) 0.15 V 8 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT32 LED DIMMING WITH A LOGIC SIGNAL PCB Layout Guidelines For applications that need to adjust the LED brightness in discrete steps, a logic signal can be used. RMIN sets the minimum LED current value (when the NMOS is OFF): The CAT32 is a high-frequency switching regulator and therefore proper PCB board layout and component placement can minimize noise and radiation and increase efficiency. To maximize efficiency, the CAT32 design has fast switch rise and fall times. To prevent radiation and high frequency resonance problems minimize the length and area of all traces connected to the SW pin and use a ground plane under the switching regulator. RMIN = 255 × 0.1V ILED(MIN) RINCR determines how much LED current increases when the external NMOS switch is turned ON. RINCR = 255 × The switch, schottky output diode and output capacitor signal path should be kept as short as possible. The ground connection for the RSET resistor should be tied directly to the GND pin and not be shared with other components. 0.1V ILED(Increase ) LED DIMMING WITH A DC VOLTAGE R ADJ = 225 × VMAX – 0.1V ILED(MAX ) – ILEAD(MIN) CAT32 CAT32 CAT32 SHDN 5 RSET 4 RSET 4 PWM RSET RPWM PWM RSET RPWM PWM 10kΩ 0.1µF CAT32 CAT32 RSET 4 RSET 4 RSET RADJ VDC RMIN RINCR Logic Signal Figure 3. LED Dimming Circuits © Catalyst Semiconductor, Inc. Characteristics subject to change without notice 9 Doc. No. MD-5001 Rev. AD CAT32 TYPICAL APPLICATION CIRCUITS The application diagrams below are shown for the TSOT-23 packages. Two LEDs with DC Level Dimming Control L1 6.8µH D1 VIN 6 VIN 1 SW CAT32 C1 4.7µF 5 2.5V DC DIMMING CONTROL SHDN LED RSET 4 GND 2 C2 2.2µF 3 15mA 60.40kΩ RSET 1.50kΩ Three LEDs with DC Level Dimming Control L1 6.8µH Efficiency - Three LEDs 85 D1 VIN = 4.2V VIN CAT32 C1 4.7µF 2.5V DC DIMMING CONTROL 5 SHDN LED RSET 4 GND 2 VIN = 3.0V 80 1 SW C2 1µF 3 EFFICIENCY [%] 6 VIN 75 70 65 15mA 60.40kΩ 60 0 RSET 1.50kΩ 5 10 Four LEDs with PWM Dimming Control L1 6.8µH 85 D1 VIN = 4.2V EFFICIENCY [%] 80 6 VIN 1 SW CAT32 PWM DIMMING CONTROL Doc. No. MD-5001 Rev. AD 5 SHDN RSET 4 RSET 1.50kΩ 20 Efficiency - Four LEDs VIN C1 4.7µF 15 LED CURRENT [mA] LED GND 2 C2 1µF 3 VIN = 3.0V 75 70 65 60 15mA 0 5 10 15 20 LED CURRENT [mA] 10 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT32 PACKAGE OUTLINE DRAWINGS TSOT-23 6-Lead (TD) (1)(2) SYMBOL D MIN NOM MAX A1 0.01 0.05 0.10 A2 0.80 0.87 0.90 b 0.30 c 0.12 A e E1 E 1.00 0.45 0.15 D 2.90 BSC E 2.80 BSC E1 1.60 BSC e 0.95 TYP L 0.30 0.40 L1 0.60 REF L2 0.25 BSC θ 0º 0.20 0.50 8º TOP VIEW A2 A b θ L A1 c L1 SIDE VIEW L2 END VIEW For current Tape and Reel information, download the PDF file from: http://www.catsemi.com/documents/TapeandReel.pdf Notes: (1) All dimensions are in millimeters. Angles in degrees. (2) Complies with JEDEC standard MO-193. © Catalyst Semiconductor, Inc. Characteristics subject to change without notice 11 Doc. No. MD-5001 Rev. AD CAT32 TDFN 8-Pad, 3 x 3mm (ZD4) (1)(2) D A e b L E E2 PIN#1 ID PIN#1 INDEX AREA A1 SIDE VIEW TOP VIEW SYMBOL MIN NOM MAX A 0.70 0.75 0.80 A1 0.00 0.02 0.05 A3 0.23 0.30 A3 A1 0.37 D 2.90 3.00 3.10 D2 2.20 — 2.50 E 2.90 3.00 3.10 E2 1.40 — 1.80 e BOTTOM VIEW A 0.20 REF b L D2 FRONT VIEW 0.65 TYP 0.20 0.30 0.40 For current Tape and Reel information, download the PDF file from: http://www.catsemi.com/documents/TapeandReel.pdf Notes: (1) All dimensions are in millimeters. (2) Complies with JEDEC standard MO-229. Doc. No. MD-5001 Rev. AD 12 © Catalyst Semiconductor, Inc. Characteristics subject to change without notice CAT32 EXAMPLE OF ORDERING INFORMATION 1 Prefix CAT Device # Suffix 32 ZD4 – Product Number 32 Optional Company ID G T3 Lead Finish G: NiPdAu Tape & Reel T: Tape & Reel 3: 3,000/Reel Package ZD4: TDFN TD: TSOT-23 For Product Top Mark Codes, click here: http://www.catsemi.com/techsupport/producttopmark.asp 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 example is a CAT32ZD4-GT3 (TDFN, NiPdAu, Tape & Reel, 3,000/Reel). (4) For additional package and temperature options, please contact your nearest Catalyst Semiconductor Sales office. © Catalyst Semiconductor, Inc. Characteristics subject to change without notice 13 Doc. No. MD-5001 Rev. AD REVISION HISTORY Date Rev. 9-Oct-03 11-Feb-04 AA AB 1-Nov-04 AC 23-May-08 AD Reason Revised Typical Characteristics plots Revised Efficiency plots Added Green package designation Eliminated TDFN (3 x 4.9mm) package Update Package Outline Drawings Delete PbSn plated finish; add NiPdAu plated finish Add Example of Ordering Information Add MD- to document number. 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 Quantum 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 GUARANTEE, EXPRESS OR IMPLIED, REGARDING THE SUITABILITY OF ITS PRODUCTS FOR ANY PARTICULAR PURPOSE, NOR THAT THE USE OF ITS PRODUCTS 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 ARISING 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 surgical 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 Semiconductor product could create 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 notice. 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 relevant product information before placing orders. Circuit diagrams illustrate typical semiconductor applications and may not be complete. Catalyst Semiconductor, Inc. Corporate Headquarters 2975 Stender Way Santa Clara, CA 95054 Phone: 408.542.1000 Fax: 408.542.1200 www.catsemi.com Document No: MD-5001 Revision: AD Issue date: 05/23/2008