MIC4833 Low Noise Dual 220 VPP EL Driver With Output Voltage Slew Rate Control General Description Features The MIC4833 is a low noise dual Electroluminescent (EL) Panel driver used in backlighting applications. The MIC4833 converts a low DC voltage to a high DC voltage using a boost converter and then alternates the high DC voltage across the EL panels using an H-bridge. The MIC4833 incorporates internal wave-shaping circuitry specifically designed to reduce audible noise emitted by EL panels. The two EL panels may be dimmed by applying a PWM signal to the device. The MIC4833 drives two outputs from a single inductor and requires a minimum number of passive components. It features an operating input voltage range of 2.3V to 5.8V, making it suitable for 1-cell Li-ion and 2- or 3-cell alkaline/NiCad/NiMH battery applications. An external resistor may be used to adjust the output voltage slew rate to reduce audible noise. The MIC4833 features separate oscillators for the boost and H-bridge stages to allow independent control. External resistors set the operating frequencies of each stage allowing the EL circuit to optimize efficiency and brightness. ® The MIC4833 is available in a 12 pin 3mmx3mm MLF package, and has an operating junction temperature range of –40°C to +125°C. • • • • • • • • • • • Drives two EL panels, up to 4 in2 each at full brightness Independent input control for each of the two panels and allows PWM dimming. 220Vpp regulated AC output waveform 2.3V to 5.8V DC input voltage Wave-shaping circuit to reduce audible noise Adjustable slew rate for audible noise reduction Independently adjustable boost converter and EL panel frequency Single inductor to power both panels 0.1uA typical shutdown current ® 12 pin 3mmx3mm MLF package o o –40 C to +125 C junction temperature range Applications • Mobile Phones • MP3s/Portable Media Players (PMP) • Clocks/ Watches • Remote Controls • Cordless Phones • GPS Devices • PDAs _________________________________________________________________________________________________ Typical Application High Low VIN Li Ion 3V to 4.2V 332k 0.01µF 1.78M High Low 50k ENA SLEW VDD ELA EL Lamp A ELB EL Lamp B RSW MIC4833 REL COM ENB CS GND SW High Low VIN Li Ion 3V to 4.2V 220µH 10µF 2.2nF 250V Low Noise Dual EL Driver MLF and MicroLead Frame are registered trademark of Amkor Technologies Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com October 2008 M9999-100308 (408) 955-1690 Micrel MIC4833 Ordering Information Part Number MIC4833YML Package Operating Junction Temp Range Lead Finish -40°C to +125°C Pb-free / RoHS Compliant 12 pin 3mmx3mm ® MLF Pin Configuration ENA 1 12 SLEW VDD 2 11 ELA RSW 3 10 ELB REL 4 9 COM ENB 5 8 CS GND 6 7 SW EP ® 12-Pin 3mm × 3mm MLF (ML) – Top View Pin Description October 2008 Pin Number Pin Name 1 ENA 2 3 VDD RSW 4 REL 5 ENB 6 7 GND SW 8 CS 9 COM 10 ELB 11 ELA 12 SLEW EPad HS Pad Pin Function EL Panel A Enable Pin: Logic high enables ELA and logic low disables ELA output. DC Input Supply Voltage: 2.3V to 5.8V RSW pin: Sets internal boost converter switch frequency by connecting an external resistor (RSW) to VDD. Connecting the RSW resistor to GND shuts down the device. REL pin: Sets internal H-bridge driver frequency by connecting an external resistor (REL) to VDD. Connecting the REL to GND disables the EL oscillator. EL Panel B enable pin: Logic high enables ELB and logic low disables ELB output. Ground. Switch Node: Drain of internal high-voltage power MOSFET for boost circuit. Regulated Boost Output: Connect to the output capacitor of the boost regulator and to the cathode of the diode. EL output: Common EL output terminal to both ELA and ELB. Connect one end of each EL panel to this pin. EL Panel B output: Connect the other end of the EL panel B to this pin. EL Panel A output: Connect the other end of the EL panel A to this pin. Optional resistor to set output current drive to control slew rate of load. If left open, the default slew current limit is 5mA. Heat Sink Pad. Connect to ground externally. 2 M9999-100308 (408) 955-1690 Micrel MIC4833 Absolute Maximum Rating (1) Operating Range (2) Supply voltage (VDD)…………………………..-0.5V to 6.5V Output voltage (VCS) …………..……….…... -0.5V to 130V Switch Node (VSW)……...…………………….-0.5V to 130V Enable Voltage (VENA, VENB) ..…...……………-0.5V to 6.5V Voltage (VREL, VRSW, VSLEW) ......………...….…-0.5V to 6.5V Ambient Storage Temperature (TS) …. ..... -65°C to +150°C ESD Rating(3)…..……………………..………ESD Sensitive Supply Voltage (VDD) ..………………………...2.3V to 5.8V Panel Drive Frequency (fEL)……………..100Hz to 1500Hz Switching MOSFET Frequency (fSW)…...35kHz to 350kHz Enable Voltage (VENA, VENB) ……………………...0V to VDD Junction Temperature Range (TJ) ………-40°C to +125°C Package Thermal Impedance θJA MLF®-12L …………………….................... 60°C/W Electrical Characteristics(4) TA=25oC, Vdd = 3.0V unless otherwise noted. Bold values indicate -40°C ≤ TJ ≤ 85°C. Parameter Symbol Condition Supply Voltage Range Input Supply Current VDD Shutdown Current On-resistance Of Switching Transistor Output voltage Regulation ISD Boost Switching Frequency IDD RDS(ON) VCS fSw ELA, ELB and COM Drive Frequency fEL Switching Transistor Duty Cycle D Output Current Drive Limit Programmability ISLEW Enable Logic Threshold Enable Logic Hysteresis Enable Input Current Min Typ Max Units 5.8 V 152 220 µA 0.1 1 µA 6.0 12.0 Ω 90 109 120 V 25 35 45 kHz 75 100 125 kHz 250 350 450 kHz 175 235 295 Hz 445 565 685 Hz 95 % 2.3 RSW=High; VCS=105V; ELA, ELB, COM, SLEW = Open RSW=Low; VDD=5.8v ISW=100mA, VCS=105V VDD=2.3V to 5.8v VDD=3.0V (RSW = 1.3MΩ ) VDD=3.0V (RSW = 450kΩ) VDD=3.0V (RSW = 125kΩ) VDD=3.0V (REL = 1.8 MΩ) ELA, ELB = Open Vdd=3.0V (REL = 712kΩ) ELA, ELB = Open 80 SLEW = Open 2.5 5 7.5 mA RSLEW =10kΩ 7 10 13 mA 50 0.1 1.2 150 1 V mV µA 0.4 20 VENA, VENB VHYS IENA, IENB Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF. 4. Specification for packaged product only. October 2008 3 M9999-100308 (408) 955-1690 Micrel MIC4833 1 2 3 4 ELRESISTOR (MOhm) Input Current vs. EL Frequency (Dual EL Lamp) 2× 2 in 2× 1 in 2 VIN = 3.6V f = 75kHz 140 120 100 80 300Hz 60 400Hz 40 20 VIN = 3.0V f EL 35 = 200Hz C = 2.2nF f = 100kHz OUT 30 25 SW Size = 2in 20 2 15 10 5 f SW = 122kHz 2 500 350 450 CS Voltage vs. Input Voltage SW 400 Total Input Current vs. Input Voltage 300 Total Input Current vs. Input Voltage 250 TOTAL LAMP SIZE (in ) 200 EL FREQUENCY (Hz) Size = 1in 0 2 2.5 3 3.5 4 4.5 5 5.5 6 INPUT VOLTAGE (V) 80 75 OUT f SW = 2.2nF = 68kHz 2 Size = 4in 35 30 25 20 f = 88kHz SW 15 Size = 3in2 10 2 2.5 3 3.5 4 4.5 5 5.5 6 INPUT VOLTAGE (V) INPUT CURRENT (mA) C 0 0 1 2 3 4 5 6 2 fEL = 200Hz 50 45 40 240 f EL OUT f = 2.2nF = 47kHz SW 2 Size = 6in 55 50 45 40 f = 55kHz SW 35 Size = 5in2 30 2 2.5 3 3.5 4 4.5 5 5.5 6 INPUT VOLTAGE (V) 16 120 = 200Hz C 70 65 60 Output Voltage vs. Input Voltage 100 80 60 40 f SW = 45kHz 20 fEL = 200Hz COUT = 2.2nF 0 2 2.5 3 3.5 4 4.5 5 5.5 6 INPUT VOLTAGE (V) Brightness vs. Input Voltage 14 160 120 SW = 45kHz 40 fEL = 200Hz C = 2.2nF OUT 0 2 2.5 3 3.5 4 4.5 5 5.5 6 INPUT VOLTAGE (V) October 2008 BRIGHTNESS (lux) 200 80 f 150Hz 200Hz Total Input Current vs. Input Voltage 40 CS VOLTAGE (V) 60 55 INPUT CURRENT (mA) 2 2 150 25 20 15 10 2× 3 in 160 INPUT CURRENT (mA) 50 45 40 35 30 EL FREQUENCY (Hz) Recommended Switching Frequency vs. Total Lamp Size SWITCHING FREQUENCY (kHz) 2× 4 in2 100 INPUT CURRENT (mA) 60 55 10 0 5 2 500 0 0 1400 1200 800 1000 200 600 0 400 200 1 in 20 450 400 2 2 2 in2 30 400 50 600 3 in 40 350 100 800 4 in 300 150 1000 250 200 1200 VIN = 3.6V 50 fSW = 75kHz 200 250 INPUT CURRENT (mA) EL FREQUENCY (Hz) 300 SWITCHING RESISTOR (kOhm) OUTPUT VOLTAGE (VP-P) 60 1400 150 1600 350 Input Current vs. EL Frequency (Single EL Lamp) EL Frequency vs EL Resistor 100 Switching Frequency vs SW Resistor 400 0 SWITCHING FREQUENCY (kHz) Typical Characteristics 12 10 8 6 Distance = 2 in fSW = 135kHz 4 f 2 EL = 225Hz L = 220µH 0 2 2.5 3 3.5 4 4.5 5 5.5 6 INPUT VOLTAGE (V) 4 M9999-100308 (408) 955-1690 Micrel MIC4833 Functional Diagram 220µH VDD SW CS VCS 2.2nF VDD Output ELA RSW SW Oscillator SW Driver VREF Driver PGND PGND VCS VSENSE Output COM Driver REL Driver Logic & PWM Dimming EL Oscillator PGND VCS VDD 0 VDD ENA EL-A Enable ENB EL-B Enable 0 SLEW Output ELB Driver Output Wave-Shaping PGND PGND GND GND Figure 1. MIC4833 Block Diagram October 2008 5 M9999-100308 (408) 955-1690 Micrel MIC4833 Functional Description Overview The MIC4833 is a high-voltage dual output EL driver with a peak-to-peak AC output voltage of 220V capable of driving two 4 in2 EL panels. The MIC4833 drives EL panels by converting a low DC input voltage to a DC high output voltage using the boost regulator circuit and then alternating the high DC voltage across the EL panel using an H-Bridge. Input supply current for the MIC4833 is typically 152µA. The high voltage EL driver has two internal oscillators to control the boost switching frequency and the H-bridge driver frequency. Both of the internal oscillators’ frequencies can be individually programmed through external resistors to maximize efficiency and brightness of the EL panel. The MIC4833 can be dimmed using a PWM signal applied to the REL pin with an external capacitor. An external resistor can be used to adjust the internal wave shaping circuit to reduce audible noise. Regulation Referring to Figure 1, power is initially applied to VDD. When the internal feedback voltage is less than the reference voltage, the internal comparator enables switching in the boost circuit. When the boost regulator is switching, current flows through the inductor into the switch. The switching MOSFET will typically turn on for 90% of the switching period. During the on-time, energy is stored in the inductor. When the switching MOSFET turns off, current flowing into the inductor forces the voltage across the inductor to reverse polarity. The voltage across the inductor rises until the external diode conducts and clamps the voltage at VOUT + VD1. The energy in the inductor is then discharged into the COUT capacitor. The internal comparator continues to turn the switching MOSFET on and off until the internal feedback voltage is above the reference voltage. Once the internal feedback voltage is above the reference voltage, the internal comparator disables switching. The control circuit will continue to turn the MOSFET’s on and off to maintain a constant DC voltage at the CS pin. When the MIC4833 EL Driver is enabled, ELA and ELB will switch in opposite states with COM to achieve a 220V peak-to-peak AC output signal needed to drive the two EL panels. RSW and VDD. The switching frequency increases as the resistor value decreases. In general, the lower the switching frequency, the greater the input current is drawn to deliver more power to the output. Lowering the switching frequency can be used to drive larger panels. However, the switching frequency should not be so low as to allow the voltage at the switch node or the CS pin to exceed the absolute maximum voltage of those pins. For resistor value selections, see the “Typical Characteristics: Switching Frequency vs. SW Resistor” graph on Page 4 or use the equation below. The switching frequency range is 35kHz to 350kHz, with an accuracy of ±20%. fSW (kHz) = 46 R SW (MΩ ) EL Frequency The EL panel frequency is controlled via an external resistor (REL) connected between REL and VDD. The panel frequency increases as the resistor value decreases. In general, as the EL panel frequency increases, the amount of current drawn from the battery will increase. The EL panel brightness is dependent upon its frequency. For resistor value selections, see the “Typical Characteristics: EL Frequency vs. EL Resistor” graph on Page 4 or use the equation below. The EL panel frequency range is 100Hz to 1500Hz, with an accuracy of ±20%. ( ) fEL Hz = 425 ( ) R EL MΩ Enable Function There are a few different ways to enable and disable the MIC4833. The boost regulator may be disabled by pulling the RSW resistor to ground. This turns off both the EL panels by cutting power to the device completely. The EL panels can also be turned off by pulling the REL resistor to ground. Although this turns off the H-Bridge and the EL panels, the MIC4833 boost regulator will continue regulate. For individual panel control, the ENA and ENB pins can be used to enable ELA and ELB, respectively. Pulling ENA or ENB high or low will turn ELA and ELB panels on or off. Switching Frequency The switching frequency of the converter is controlled via an external resistor (RSW) between October 2008 6 M9999-100308 (408) 955-1690 Micrel MIC4833 Figure 2. 150Hz Output Waveform PWM Dimming The MIC4833 may be dimmed by adding a shunt capacitor (CPWM) to the REL pin, shown in Figure 5. The duty cycle of the PWM signal changes the frequency of the EL panel, thereby changing its brightness. Increasing the PWM duty cycle increases the EL frequency to a maximum set by REL (Duty Cycle = 100%). Decreasing the PWM duty cycle decreases the EL frequency. The PWM duty cycle should not be lowered to a level that may cause the EL frequency to be lower than 100Hz, since EL frequencies lower than 100Hz may cause the panel to flicker. The frequency of the PWM signal can range from 500Hz to 50kHz. The peak voltage of the PWM signal should be equal to VDD. VDD REL REL pin 0V PWM 1kHz CPWM 0.01µF Figure 5. PWM Dimming Circuit Figure 3. 250Hz Output Waveform Slew Resistor The MIC4833 is designed to reduce audible noise in EL panels by the use of the internal wave-shaping circuit. To further reduce audible noise, a Slew Resistor (RSLEW) can be added to limit the rate of change of the EL driver output voltage by limiting the output current. A slower rate of change in voltage across the EL panel creates less physical distortion in the material and therefore reduces the amount of audible noise. The lower the ISLEW, the slower the output voltage across the EL panel will change. If RSLEW is not used, the ISLEW is by default 5mA, equivalent to using a 22kΩ for RSLEW. Figure 4. 350Hz Output Waveform RSLEW ISLEW Open 5mA 125kΩ 1mA 22kΩ 5mA 10kΩ 10mA Table 1. Slew Resistor Setting October 2008 7 M9999-100308 (408) 955-1690 Micrel Application Information The MIC4833 is designed to use an inductance with a value between 100µH to 330µH. Choosing the right inductor is always a balance of size, inductance, efficiency, current rating and cost. A TDK (VLS4012T-221M) 220µH inductor is recommended based on size, efficiency and current rating. Generally, the lower the inductance, the more current the inductor can handle. Lowering the inductance allows the boost regulator to draw more input current to deliver more energy every switching cycle. As a result, a lower inductance may be used to drive larger panels or brighten similar sized panels. However, caution is required as using a low inductance with a low switching frequency may cause the voltage at the switch node and the CS pin to exceed the absolute maximum rating. If the application uses a low input voltage (2.3 to 3V), a lower value inductor, such as 100µH, may be used in order to drive the EL panel at maximum brightness. Diode The diode must have a high reverse voltage (150V), since the output voltage at the CS pin can reach up to 130V. A fast switching diode with lower forward voltage and higher reverse voltage (150V), such as BAV20WS/BAS20W, can be used to enhance efficiency. October 2008 MIC4833 Output Capacitor Low ESR capacitors should be used at the regulated boost output (CS pin), to minimize the switching output ripple voltage. The larger the output capacitance, the lower the output ripple at the CS pin. The reduced output ripple at the CS pin along with a low ESR capacitor improves the efficiency of the MIC4833 circuit. Selection of the capacitor value depends upon the peak inductor current, inductor size, and the load. The MIC4833 is designed for use with an output capacitance as low as 2.2nF. For minimum audible noise, the use of a C0G/NPO dielectric output capacitor is recommended. TDK and AVX offer C0G/NPO dielectric capacitors in capacitances up to 2.7nF capacitance at 200V to 250V voltage rating in 0805 size. EL Panel Terminals (ELA, ELB, COM) The two EL panels are connected from ELA to COM and ELB to COM. The ELA and ELB terminals are in phase with each other, while the COM is out of phase with both ELA and ELB. Since ELA and COM are out of phase, the high voltage generated by the boost regulator is alternated across ELA and COM by the H-Bridge. The frequency of each cycle is determined by REL. The alternating 220V peak-topeak causes the EL panel to emit light. Similarly, the ELB and COM are also out of phase and allows a second EL panel to be driven at the same time. Both EL panels may operate independently from each other and do not have to be the same size. For component selection, Table 2 lists recommended values for various panel sizes up to a total of 8in2 (For example, two 4in2 panels). Driving overly large panels will result in a dimmer display, but will not cause damage to the device. 8 M9999-100308 (408) 955-1690 Micrel MIC4833 Application Circuit High Low VIN Li Ion 3V to 4.2V RSW 332k C1 0.01µF REL 1.78M High Low RSLEW 50k ENA SLEW VDD ELA EL Lamp A ELB EL Lamp B RSW MIC4833 REL COM ENB CS GND SW High Low L1 220µH VIN Li Ion 3V to 4.2V C3 2.2nF 250V C2 10µF Figure 6: Typical Li-Ion Powered MIC4833 Circuit Note: Table 2 applies to circuit shown in Figure 6. Total Panel Area 2 (inch ) Capacitance (nF) 0.4 2 1 5 2 10 3 15 4 20 5 25 6 30 8 40 Panel Frequency (Hz) REL (MΩ) RSW (kΩ) fSW (kHz) RSW (kΩ) fSW (kHz) RSW (kΩ) fSW (kHz) RSW (kΩ) fSW (kHz) RSW (kΩ) fSW (kHz) RSW (kΩ) fSW (kHz) RSW (kΩ) fSW (kHz) RSW (kΩ) fSW (kHz) 150 200 250 300 350 400 500 2.80 324 138 357 125 402 112 464 98 523 86 619 72 698 65 1000 45 2.10 340 132 365 122 453 100 511 88 665 68 825 55 953 47 1.69 357 126 392 116 487 92 590 77 750 60 909 50 1000 45 1.40 383 118 422 108 549 83 698 65 909 50 1000 45 1.21 392 116 442 102 590 76 768 58 1000 45 1.05 402 112 475 95 649 70 909 50 1000 45 .850 442 102 511 88 681 66 1000 45 Table 2: Recommended RSW & REL Values For Total Panel Sizes October 2008 9 M9999-100308 (408) 955-1690 Micrel MIC4833 Bill of Materials Item Part Number Manufacturer C1 C1608X7R1A103K TDK(1) C1608X5R0J106K C2 C3 C2012C0G2E2222J L1 VLS4012T-221M Description Qty 0.01µF Ceramic Capacitor, 10V, X7R, Size 0603 1 TDK (1) 10 µF Ceramic Capacitor, 6.3V, X5R, Size 0603 1 TDK (1) 0.0022µF Ceramic Capacitor, 250V, C0G, Size 0805 1 TDK (1) 220µH, 210mA ISAT. (4mmx4mmx1.2mm) 1 (2) D1 BAS20-V-GS18 Vishay 200V/200mA Hi-Voltage Switching Diode 1 R1 or RSW CRCW06033323FKEYE3 Vishay(2) 332kΩ, 1%, 1/16W, Size 0603 1 CRCW06031784FKEYE3 (2) Vishay 1.78MΩ, 1%, 1/16W, Size 0603 1 Micrel(3) Low Noise Dual 220Vp-p EL Driver with Output Slew Control R2 or REL RSLEW Optional U1 MIC4833YML 1 Notes: 1. TDK: www.tdk.com 2. Vishay: www.vishay.com 3. Micrel, Inc.: www.micrel.com October 2008 10 M9999-100308 (408) 955-1690 Micrel MIC4833 Layout Recommendation Top Layer Bottom Layer October 2008 11 M9999-100308 (408) 955-1690 Micrel MIC4833 Package Information 12-Pin 3mm x 3mm MLF® (ML) 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. © 2008 Micrel, Incorporated. October 2008 12 M9999-100308 (408) 955-1690