MIC4827 Low Input Voltage, 180VPP Output Voltage, EL Driver General Description Features Micrel’s MIC4827 is a high output voltage, DC to AC converter, designed for driving EL (Electroluminescent) lamps. The device operates from an input voltage range of 1.8V to 5.5V, making it suitable for 1-cell Li-Ion and 2- or 3cellalkaline/NiCad/NiMH battery applications. The MIC4827 converts a low voltage DC input to a 180VPP AC output signal that drives the EL lamp. The MIC4827 is comprised of two stages: a boost stage, and an H-bridge, lamp driver, stage. The boost stage steps the input voltage up to +90V. The H-bridge stage then alternately switches the +90V output to each terminal of the EL lamp, thus creating a 180VPP AC signal to drive the EL lamp and generate light. The MIC4827 features separate oscillators for the boostand H-bridge stages. External resistors independently set the operating frequency of each stage. This flexibility allows the EL lamp circuit to be optimized for maximum efficiency and brightness. • 1.8V to 5.5V DC input voltage • 180VPP regulated AC output waveform • Independently adjustable EL lamp frequency • Independently adjustable boost converter frequency • 0.1µA shutdown current Applications • LCD panel backlight • Cellular phones • PDAs • Pager • Calculators • Remote controls • Portable phones The MIC4827 uses a single inductor and a minimum number of external components, making it ideal for portable, space-sensitive applications. The MIC4827 is available in an 8-pin MSOP package with an ambient temperature range of –40°C to +85°C. VIN L1 220µH CIN 10µF MIC4827 3.32M 2 3 4 COUT 0.033µF/100V VDD SW RSW CS REL VA GND VB 5 6 VA— VB (50V/div) 1 332k D1 BAV20WS VB VA (50V/div) (50V/div) Typical Application 8 7 TIME (2ms/div) 2in2 EL LAMP High Voltage EL Driver Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com July 2009 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 Ordering Information Part Number Standard Pb-Free MIC4827BMM MIC4827YMM Ambient Temp. Range Package –40° to +85°C 8-Pin MSOP Pin Configuration 8-Pin MSOP (MM) Pin Description Pin Number July 2009 Pin Name Pin Function 1 VDD Supply (Input): 1.8V to 5.5V. 2 RSW Switcher Resistor (External Component): Set switch frequency of the internal power MOSFET by connecting an external resistor to VDD. Connecting the external resistor to GND disables the switch oscillator and shuts down the device. 3 REL EL Resistor (External Component): Set EL frequency of the internal H-bridge driver by connecting an external resistor to VDD. Connecting the external resistor to GND disables the EL oscillator. 4 GND Ground Return. 5 SW Switch Node (Input): Internal high-voltage power MOSFET drain. 6 CS Regulated Boost Output (External Component): Connect the output capacitor of the boost regulator and connect to the cathode of the diode. 7 VB EL Output: Connect to one end of the EL lamp. Polarity is not important. 8 VA EL Output: Connect to the other end of the EL lamp. Polarity is not important. 2 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 Operating Ratings(2) Absolute Maximum Ratings(1) Supply Voltage (VDD)............................................–0.5 to 6V Output Voltage (VCS) ........................................–0.5 to 100V Freq. Control Voltage (VRSW, VREL)....... –0.5 to (VDD + 0.3V) Power Dissipation @ TA = 85°C ..............................200mW Storage Temperature (Ts) .........................–65°C to +150°C EDS Rating(3) Supply Voltage (VDD).................................... +1.8V to +5.5V Lamp Drive Frequency (fEL) ....................... 60Hz to 1000Hz Switching Transistor Frequency (fSW) ........8KHz to 200KHz Ambient Temperature (TA) .......................... –40°C to +85°C Junction Thermal Resistance PDIP (θJA) ........................................................206°C/W Electrical Characteristics(4) VIN = VDD = 3.0V; RSW = 560KΩ; REL = 1.0MΩ; TA = 25°C, bold values indicate –40°C< TA < +85°C, unless noted. Symbol Parameter Condition RDS(ON) On-resistance of switching transistor ISW = 100mA, VCS = 85V Min VCS Output voltage regulation VDD = 1.8V to 5.5V 85 Typ Max Units 3.8 7.0 Ω 90 83 170 180 95 V 97 V 190 V 194 V 0.5 V VA – VB Output peak-to-peak voltage VDD = 1.8V to 5.5V VEN-L Input low voltage (turn-off) VDD = 1.8V to 5.5V VEN-H Input high voltage (turn-on) VDD = 1.8V to 5.5V ISD Shutdown current, Note 5 RSW = LOW; REL = LOW; VDD = 5.5V 0.01 0.1 0.5 µA µA IVDD Input supply current RSW = HIGH; REL = HIGH; VCS = 85V; VA, VB OPEN 21 75 µA ICS Boosted supply current RSW = HIGH; REL = HIGH; VCS = 85V; VA, VB OPEN 200 400 µA IIN Input current including inductor current VIN = VDD = 1.8V (See Test Circuit) 28 166 VDD– 0.5 V mA fEL VA – VB output drive frequency 285 360 435 Hz fSW Switching transistor frequency 53 66 79 kHz D Switching transistor duty cycle 90 % 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. 4. Specification for packaged product only. 5. Shutdown current is defined as the sum of current going into pin 1, 5, and 6 when the device is disabled. July 2009 3 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 Test Circuit VIN L1 220µH CIN 10µF MIC4827 1 562k 2 3.32M 3 4 July 2009 D1 BAV20WS COUT 0.033µF/100V VDD SW RSW CS REL VA GND VB 4 5 6 8 7 10nF M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 Typical Characteristics 6 5 4 3 2 1 120 2 345 INPUT VOLTAGE (V) Switching Frequency vs. Input Voltage 100 80 60 10 1 100 EL Frequency vs. Input Voltage RSW = 562k 40 20 6 REL = 1M 250 REL = 2M 200 120 150 100 50 REL = 3.32M 0 12345 6 INPUT VOLTAGE (V) 5 100 10 0.1 1000 10000 SWITCH RESISTOR (k Ω) 300 EL Frequency vs. EL Resistor 1000 350 RSW = 442k 0 12345 10000 100 400 RSW = 332k INPUT VOLTAGE (V) July 2009 6 Switching Frequency vs. Switch Resistor FREQUENCY (KHz) SWITCHING FREQUENCY (Hz) 0 1 1000 EL FREQUENCY (Hz) SWITCHING FREQUENCY (kHz) Switch Resistance vs. Input Voltage EL FREQUENCY (Hz) SWITCH RESISTANCE (Ω) 7 100 80 60 1 EL RESISTOR (MΩ) 10 Switching Frequency vs. Temperature RSW = 332k RSW = 442k RSW = 562k 40 20 VIN = 3.0V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE °C) ( M9999-070709-A (408) 955-1690 Micrel, Inc. July 2009 MIC4827 6 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 Block Diagram L1 220µH VIN 1 CIN D1 VDD 5 RSW COUT SW 2 RSW Switch Oscillator 6 CS Q1 8 REL VA Q2 EL Oscillator VREF EL LAMP /Q3 7 3 /Q4 REL 4 VB GND Figure 1. MIC4827 Block Diagram Functional Description inductor and into the switch. The switching MOSFET will typically turn on for 90% of the switching frequency. 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 turns off the switching MOSFET’s oscillator. Overview The MIC4827 is a high-voltage EL driver with an AC output voltage of 180V peak-to-peak capable of driving EL lamps up to 6in2. Input supply current for the MIC4827 is typically 21µA with a typical shutdown current of 10nA. The high voltage EL driver has two internal oscillators to control the switching MOSFET and the H-bridge driver. Both of the internal oscillators’ frequencies can be individually programmed through the external resistors to maximize the efficiency and the brightness of the lamps. Regulation Referring to Figure 1, initially power is applied to VDD. The internal feedback voltage is less than the reference voltage causing the internal comparator to go low which enables the switching MOSFET’s oscillator. When the switching MOSFET turns on, current flows through the July 2009 When the EL oscillator is enabled, VA and VB switch in opposite states to achieve a 180V peak-to-peak AC output signal. The external resistor that connects to the REL pin determines the EL frequency. 7 M9999-070709-A (408) 955-1690 VA VB (50V/div) (50V/div) MIC4827 VB VA (50V/div) (50V/div) Micrel, Inc. VIN = 3.0V L = 220µH COUT = 0.033µF Lamp = 2in2 RSW = 562k REL = 1M VA— VB (50V/div) VA — VB (50V/div) VIN = 3.0V L = 220µH COUT = 0.033µF Lamp = 2in2 RSW = 332k REL = 3.32M TIME (2ms/div) TIME (2ms/div) Figure 3. 180Hz Output Waveform Switching Frequency The switching frequency of the converter is controlled via an external resistor between RSW pin and VDD pin of the device. The switching frequency increases as the resistor value decreases. For resistor value selections, see the “Typical Characteristics: Switching Frequency vs. Switch Resistor” or use the equation below. The switching frequency range is 8kHz to 200kHz, with an accuracy of ±20%. In general, as the EL lamp frequency increases, the amount of current drawn from the battery will increase. The color of the EL lamp and the intensity are dependent upon its frequency. f SW (kHz) = VA VB (50V/div) (50V/div) Figure 2. 108Hz Typical Output Waveform 36 R SW (MΩ ) fEL (Hz ) July 2009 VA — VB (50V/div) EL Frequency The EL lamp frequency is controlled via an external resistor connected between REL pin and VDD pin of the device. The lamp frequency increases the resistor value decreases. For resistor value selections, see the “Typical Characteristics: EL Frequency vs. EL Resistor” or use the equation below. The switching frequency range is 60Hz to 1000Hz, with an accuracy of ±20%. TIME (2ms/div) Figure 4. 360Hz Output Waveform Enable Function The enable function of the MIC4827 is implemented by switching the RSW and REL resistor between ground and VDD. When RSW and REL are connected to ground, the switch and the EL oscillators are disabled; therefore the EL driver becomes disabled. When these resistors connect to VDD, both the oscillators will function and the EL driver is enabled. 360 R EL (MΩ ) 8 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 Diode The diode must have a high reverse voltage (150V), since the output voltage at the CS pin can reach up to 110V. A fast switching diode with lower forward voltage and higher reverse voltage (150V), such as BAV20WS, can be used to enhance efficiency. Application Information Inductor In general, smaller value inductors, which can handle more current, are more suitable to drive larger size lamps. As the inductor value decreases, the switching frequency (controlled by RSW) should be increased to avoid saturation or the input voltage should be increased. Typically, inductor values ranging from 220µH to 560µH can be used. Murata offers the LQH3C series up to 560µH and LQH4C series up to 470µH, with low DC resistance. A 220µH Murata (LQH4C221K04) inductor is recommended for driving a lamp size of 3 square inches. It has a maximum DC resistance of 4.0Ω Output Capacitor Low ESR capacitors should be used at the regulated boost output (CS pin) of the MIC4827 to minimize the switching output ripple voltage. Selection of the capacitor value will depend upon the peak inductor current, inductor size, and the load. MuRata offers the GRM42-6 series with up to 0.047µF at 100V, with a X7R temperature coefficient in 1206 surface-mount package. Typically, values ranging from 0.01µF to 0.1µF at 100V can be used for the regulated boost output capacitor Pre-designed Application Circuit L1 220 H Murata LQH4C221K04 Li-Ion Battery VIN 3.0V to 4.2V C2 10 F/6.3V Murata GRM42-6X5R106K6.3 D1 BAV20WS COUT 0.01 F/100V GRM40X7R103K MIC4827 1 C1 0.22 F/10V Murata GRM39X7R 224K10 R2 3.32M R1 332k 2 3 4 VDD SW RSW CS REL VA GND VB 5 6 8 7 3in2 LAMP IIN VA – VB FEL Lamp Size 3.3V 28mA 180VPP 106Hz 3in2 VA Ð VB (50V/div) VA VB (50V/div) (50V/div) VIN TIME (2ms/div) Figure 5. Typical 100Hz EL Driver for 3in2 Lamp July 2009 9 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 L1 220µH Murata LQH4C221K04 VIN 2.4V to 5.5V C2 10µF/6.3V Murata GRM42-6X5R106K6.3 D1 Diodes BAS20W COUT 0.033µF/100V GRM42-6X7R333K100 MIC4827 1 R1 R2 3.32M 332k 2 3 4 VDD SW RSW CS REL VA GND VB 5 6 8 7 EL LAMP LSI X533-13 IIN VA – VB FEL Lamp Size 18mA 180VPP 104Hz 2in2 VA — VB (50V/div) VB VA (50V/div) (50V/div) VIN 3.3V TIME (2ms/div) Figure 6. Typical EL Driver for 2in2 Lamp with CS = 0.033µF July 2009 10 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 L1 560k Murata LQ32CN561K21 VIN 3.3V to 5.5V C2 10µF/6.3V Murata GRM42-6X5R106K6.3 D1 Diodes BAS20W COUT 0.033µF/100V GRM42-2X7R104K100 MIC4827 1 R1 R2 3.32M 562k 2 3 4 VDD SW RSW CS REL VA GND VB 5 6 8 7 EL LAMP LSI X533-13 IIN VA – VB FEL Lamp Size 21mA 180VPP 102Hz 2in2 VA — VB (50V/div) VB VA (50V/div) (50V/div) VIN 3.3V TIME (2ms/div) Figure 7. Typical EL Driver for 2in2 Lamp with 560µH inductor July 2009 11 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 L1 220µH Murata LQH4C221K04 VIN 1.5V C2 10µF/6.3V Murata GRM42-6X5R106K6.3 VDD C1 1.8V to 5.5V 0.01µF/50V Murata GRM42-6X5R106K6.3 R1 562k R2 3.32M D1 Diodes BAS20W COUT 0.01µF/100V GRM42-2X7R104K100 MIC4827 1 2 3 4 VDD SW RSW CS REL VA GND VB 5 6 8 7 EL LAMP IIN VDD IDD VA – VB FEL Lamp Size 26mA 3.0V 32µA 180VPP 104Hz 1.6in2 VA — VB (50V/div) VB VA (50V/div) (50V/div) VIN 1.5V TIME (2ms/div) Figure 8. Typical Split Power Supplies Applications July 2009 12 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 L1 220µH Murata LQ32CN561K21 VIN 1.8V to 3.3V (2X Alkaline Batteries) C2 10µF/6.3V Murata GRM42-6X5R106K6.3 D1 Diodes BAS20W COUT 0.1µF/100V GRM42-2X7R104K100 MIC4827 1 R1 R2 3.32M 1M 2 3 4 VDD SW RSW CS REL VA GND VB 5 6 8 7 EL LAMP Elite 12607-N IIN VA – VB FEL Lamp Size 31mA 180VPP 104Hz 5.3in2 VA— VB (50V/div) VA VB (50V/div) (50V/div) VIN 3.0V TIME (2ms/div) Figure 9. Typical EL Driver Remote Control Lamp (Blue Phosphor) Applications July 2009 13 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 Package Information 8-Pin MSOP (MM) July 2009 14 M9999-070709-A (408) 955-1690 Micrel, Inc. MIC4827 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. © 2001 Micrel, Incorporated. July 2009 15 M9999-070709-A (408) 955-1690