MIC2299 Evaluation Board 3.5A ISWMIN, 2MHz, High Power LED Driver w/ 3 Preset LED Current Settings General Description This board enables the evaluation of the 3.5A switch, High Power white LED driver MIC2299. The board includes components necessary to set the LED current to 20%, 50% and 100% of the nominal LED current (1A). The external inputs also allow this to be programmed either with additional resistors or voltages on the DIM or BRT pins. A load disconnect switch prevents leakage and protects the battery against short circuits while in shutdown mode. The evaluation board includes a push button switch which sends a one shot pulse of 300ms to the enable pin to prevent overheating when testing high power LEDs. Also the enable pin can be driven to force the part into low Iq mode. The MIC2299, 2 MHz, Integrated Step-Up current regulator, allows the use of small and very few external components to create a compact boosted supply up to 13.5V with a core component footprint of just 0.25in2 (1.61cm2). The evaluation board has been configured with 3 fixed current settings chosen using JP1 and all externally programmable inputs are accessible via board pins. Requirements The MIC2299 evaluation board requires an input power source that is able to deliver at least 5A over the desired input voltage range. For the load, an electronic load (ELoad) capable of constant voltage testing is required or a high power LED mounted on a fan cooled heat sink. Note that stability measurements must be carried out on an LED load as E-Loads do not have the same dynamic characteristics of a high power LED. Precautions The evaluation board does not have reverse polarity protection. Applying a negative voltage to the VIN (J1) terminal may damage the device. The load current is only regulated if connected between VOUT and FB terminals, the GND terminal close to the VOUT terminal is provided for voltage measurements only. The MIC2299 has a maximum input voltage rating of 10V therefore the supply voltage should never exceed this value. Getting Started 1. Connect the input supply to the input terminals. Take note of the polarity to prevent damage. An ammeter can be used in-line with the VIN terminal to measure input current. The Input voltage should be measured at the input terminals to account for any drops in test leads and amp meter. 2. Ensuring the jumper JP1 is at the left position (50% load), connect the load to the output terminals: +VO connects to the positive E-Load input or Anode of the test LEDs, FB connects to the negative E-Load input or the Cathode of the test LEDs. A low impedance ammeter can be connected inline with the +VO terminal for current measurements. The output voltage should be measured between the evaluation board terminals +VO and GND (to measure converter efficiency) or +VO and FB (to measure the voltage of the LED load). 3. Switch on the E-Load (if using), then the input supply. Measurements can now be taken of efficiency, switching waveform and output current regulation. When testing 1A load (JP1 open), ensure that these are pulse tests only to prevent damage to the LED. LED manufacturers recommend <10% duty cycle and 3s period. Ordering Information Part Number Description MIC2299-15YML EV Evaluation Board with MIC2299YML 15V OVP Device Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com September 2007 M9999-092707-A Micrel, Inc. MIC2299 Evaluation Board The push button switch is set to give a nominal 300ms pulse to the load to prevent damage to external LEDs. For testing continuous loading at lower currents, this monostable can be bypassed by driving the EN terminal with a voltage source above the enable threshold level. The external pins can be driven to set any current between the minimum and maximum values. See table. The nominal current setting can be reduced by choosing a larger value for R1 (current sense resistor). The 100% current level can be set by using the following equation: ILED100% = 0.2/R1 The values in the table will scale with the nominal 100% current setting. So for example, if the 100% current is set to 500mA, 0Ω on BRT will set LED current to 100mA, 50kΩ to 250mA etc. Evaluation Board DIM Voltage Board Description By default, the board is set to give 500mA nominal current into 2 series connected Power LEDs (JP1 at pre-FLSH position). If the load is not present, the over voltage protection (OVP) will limit VOUT to prevent damage to output devices. JP1 can be removed to set the load current higher to 1A (Flash) or moved to pins 1-2 to set a lower 200mA current (Torch). Care should be taken as removing the jumper sets the maximum current of 1A. 0V to 200mV LED Current RBRT = Open 40mA to 1A RBRT = GND 0 to 200mA RBRT Voltage LED Current 0V to 1V 200mA to 1A RBRT Resistance LED Current 0Ω to 100kΩ 200mA to 1A Board Performance High Power White LED Driver Efficiency VLED = 9V 100 90 80 50 40 ILED - 0.4A ILED - 0.2A 180 144 30 108 20 10 72 36 0 -10 70 -20 60 -30 -40 50 2.5 3 3.5 4 4.5 5 5.5 6 6.5 SUPPLY VOLTAGE (V) -50 1 Efficiency September 2007 Bode Plot 2.2µH (1A LED Load) -36 Gain (3VIN) Gain (4.2VIN) Phase (3VIN) Phase (4.2VIN) 10 100 FREQUENCY (kHz) -72 -108 -144 -180 1000 Stability 2.2µH Inductor 2 M9999-092707-A Micrel, Inc. MIC2299 Evaluation Board 1100 1000 900 800 700 600 500 400 300 200 100 0 0 LED Current vs. DIM Voltage 1100 1000 900 800 700 600 500 400 300 200 100 0 0 40 80 120 160 200 DIM VOLTAGE (mV) LED Current vs. RBRT VIN = 3.6V 20 40 60 80 100 120 140 LED Current Programming (VDIM) LED Current Programming (RBRT) Switching Waveforms (BRT – GND) PWM Programming 250 LED Current vs. DC (on EN Pin) 1200 LED Current vs. DC (on BRT Pin) 1000 200 800 150 600 100 400 50 0 0 200 20 40 60 DC (%) 80 0 0 100 LED Current Programming (100Hz PWM on Enable) September 2007 5 10 15 20 25 DC (%) 30 35 LED Current Programming (1kHz PWM on BRT) 3 M9999-092707-A Micrel, Inc. MIC2299 Evaluation Board Schematic September 2007 4 M9999-092707-A Micrel, Inc. MIC2299 Evaluation Board Bill of Materials Item Part Number Manufacturer Description Qty 2.2µF/10V, 0805 Ceramic Capacitor 1 Core Components C1 C2 C3 C4 C5 L1 R1 C1608X5R1A225M VJ0603Y104KXAAT C1608C0G1H101J C1608X5R1H333K C2012X5R1C475K TDK (1) (2) Vishay 0.1µF/ 16V, 0603 Ceramic Capacitor 1 TDK (1) 100pF/16V, 0603 Ceramic Capacitor 1 TDK (1) 33nF/6.3V, 0603 Ceramic Capacitor 1 TDK (1) 4.7µF/16V, 0805 Ceramic Capacitor 1 IHLP1616BZ11-2R2 Vishay(2) 2.2µH, 3.3A, 2mm Inductor SD414-2R2 Coiltronics(3) 2.2µH, 2.8A, 1.4mm Inductor L-0805M0R20FS Vishay(2) 200mΩ, 0.2W, 0805 Metal film, 200mW Resistor 1 R2 CRCW0603620RFKTA Q1 Si5857DU U1 MIC2299YML Item Part Number (2) Vishay Vishay(2) Micrel 1 620Ω, 0603 Resistor 1 2A Schotty & P-Channel MOSFET, 1206 package 1 3.5A 2MHz, High Power LED Driver 1 Description Qty (4) Manufacturer Required for Evaluation Board Operation C6 C7 TPSD107M016R0100 C1608JB1E105K AVX(5) TDK (1) (2) Vishay 100µF/16V, Tantalum Capacitor 1 1µF/25V, 0603 Ceramic capacitor 1 C8 VJ0603Y104KXAAT 100nF/16V, 0603 Ceramic Capacitor 1 R3 CRCW060349K9RFKTA Vishay(2) 49.9k, 0603 Resistor 1 R4 CRCW06031K0FKTA Vishay(2) 1k, 0603 Resistor 1 (2) R5 CRCW0603330KFKTA Vishay 330k, 0603 Resistor 1 R6 CRCW0603100KFKTA Vishay(2) 100k, 0603 Resistor 1 R7, R8, R9 CRCW060310K0FKTA Vishay(2) 10k, 0603 Resistor 3 Q2 2n7002 Vishay(2) N-Channel MOSFET 1 SPNO Momentary Push Button 1 SOD323 signal diode 1 Header for Current Setting 1 SOT-23-5 Timer IC 1 S1 FES311161 Z1 BZX84-C12 JP1 3 pin Header U2 MIC1555 Fujitsu (6) Infineon (7) Micrel(4) Notes: 1. TDK: www.tdk.com 2. Vishay: www.vishay.com 3. Coiltronics: www.mouser.com/coiltronics 4. Micrel, Inc: www.micrel.com 5. AVX: www.avx.com 6. Fujitsu: www.fujitsu.com 7. Infineon: www.infineon.com September 2007 5 M9999-092707-A Micrel, Inc. MIC2299 Evaluation Board PCB Layout Recommendations Top Layer Bottom Layer September 2007 6 M9999-092707-A Micrel, Inc. MIC2299 Evaluation Board MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2007 Micrel, Incorporated. September 2007 7 M9999-092707-A