MIC4827 Micrel MIC4827 Low Input Voltage, 180VPP Output Voltage, EL Driver Final Information 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 3-cell alkaline/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 boost- and 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. The MIC4827 uses a single inductor and a minimum number of external components, making it ideal for portable, spacesensitive applications. The MIC4827 is available in an 8-pin MSOP package with an ambient temperature range of –40°C to +85°C. • • • • • 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 Pagers Calculators Remote controls Portable phones Ordering Information Part Number Ambient Temp. Range Package MIC4827BMM –40°C to +85°C MSOP-8 Typical Application VIN L1 220µH CIN 10µF MIC4827 3 4 VDD SW RSW CS REL VA GND VB VA (50V/div) VB (50V/div) 3.32M 2 COUT 0.033µF/100V 5 6 8 7 VA — VB (50V/div) 1 332k D1 1N4148 2in2 EL LAMP TIME (2ms/div) High Voltage EL Driver Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com September 2001 1 MIC4827 MIC4827 Micrel Pin Configuration VDD 1 8 VA RSW 2 7 VB REL 3 6 CS GND 4 5 SW 8-Pin MSOP Package (MM) Pin Description Pin Number Pin Name 1 VDD Supply (Input): 1.8V to 5.5V for internal circuitry. 2 RSW Switch 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 to 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. MIC4827 Pin Function 2 September 2001 MIC4827 Micrel Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply Voltage (VDD) ....................................... –0.5V to 6V Output Voltage (VCS) ................................... –0.5V to 100V Frequency Control Voltage (VRSW, VREL) ... –0.5V to (VDD +0.3V) Power Dissipation @ TA = 85°C ............................. 200mW Storage Temperature (TS) ....................... –65°C to +150°C ESD Rating .............................................................. Note 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 Package Thermal Resistance MSOP (θJA) ....................................................... 206°C/W Electrical Characteristics VIN = VDD = 3.0V, RSW = 560KΩ, REL = 1.0MΩ. TA = 25°C unless otherwise specified. Bold values indicate –40°C ≤ TA ≤ +85°C Symbol Parameter Condition Min RDS(ON) On-resistance of switching transistor ISW = 100 mA, VCS = 85V VCS Output voltage regulation VDD = 1.8V to 5.5V 85 Typ Max Units 3.8 7.0 Ω 90 95 V 97 V 190 V 194 V 0.5 V 83 VA – VB Output peak-to-peak voltage VDD = 1.8V to 5.5V 170 180 166 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 4 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 fEL VA–VB output drive frequency 285 360 435 Hz fSW Switching transistor frequency 53 66 79 kHz D Switching transistor duty cycle VDD–0.5 V 90 Note 1. Exceeding the absolute maximum rating may damage the device. Note 2. The device is not guaranteed to function outside its operating rating. Note 3. Devices are ESD sensitive. Handling precautions recommended. Note 4. Shutdown current is defined as the sum of current going into pin 1, 5, and 6 when the device is disabled. mA % Test Circuit VIN L1 220µH CIN 10µF MIC4827 1 562k 2 3.32M 3 4 September 2001 D1 1N4148 COUT 0.033µF/100V VDD SW RSW CS REL VA GND VB 3 5 6 8 7 100Ω 10nF MIC4827 MIC4827 Micrel Typical Characteristics EL = 1M 40 REL = 2M 20 2in2 10 0 0 Lamp = L = 220µH COUT = 0.1µF RSW = 332k D = BAV20WS R = 3.32M EL 1 2 3 4 5 INPUT VOLTAGE (V) 50 RSW = 442k REL = 2M 40 30 V IN 20 10 2 RSW = 332k REL = 3.32M VCS (VAVG) 100 R = 442k 90 SW REL = 2M 80 70 20 10 0 0 SWITCHING FREQUENCY (kHz) SWITCH RESISTANCE (Ω) 6 5 4 3 2 1 6 EL FREQUENCY (Hz) SWITCHING FREQUENCY (Hz) RSW = 562k 40 20 MIC4827 1 2 3 4 5 INPUT VOLTAGE (V) CS Voltage vs. Temperature 60 RSW = 442k REL = 2M RSW = 332k REL = 3.32M VIN = 4.0V Lamp = 2in2 L = 220µH COUT = 0.1µF D = BAV20WS 30 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 6 EL Frequency vs. EL Resistor 1000 100 10 0.1 1000 10000 SWITCH RESISTOR (kΩ) 1 EL RESISTOR (MΩ) 10 Switching Frequency vs. Temperature 120 300 REL = 1M 250 REL = 2M 200 150 100 0 1 6 10000 REL = 3.32M 50 6 1 2 3 4 5 INPUT VOLTAGE (V) 80 RSW = 562k REL = 1M 70 40 350 RSW = 442k Lamp = 2in2 L = 220µH COUT = 0.1µF D = BAV20WS 40 20 EL Frequency vs. Input Voltage RSW = 332k 2 3 4 5 INPUT VOLTAGE (V) 80 RSW = 332k 60 REL = 3.32M 50 Lamp = 2in2 L = 220µH COUT = 0.1µF D = BAV20WS 400 60 0 1 RSW = 562k REL = 1M 10 1 100 RSW = 562k REL = 1M 120 100 100 100 Switching Frequency vs. Input Voltage 80 140 0 0 1000 120 100 R = 442k 180 SW R = 2M 160 EL Switching Frequency vs. Switch Resistor 7 Output Voltage vs. Input Voltage 90 60 RSW = 332k 50 REL = 3.32M 40 30 Switch Resistance vs. Input Voltage 2 3 4 5 INPUT VOLTAGE (V) Lamp = 2in L = 220µH COUT = 0.1µF D = BAV20WS CS Voltage vs. Input Voltage 240 R = 562k RSW = 442k SW 220 R = 1M REL = 2M EL 200 180 160 140 120 RSW = 332k 100 REL = 3.32M VIN = 3.0V 80 Lamp = 2in2 60 L = 220µH 40 COUT = 0.1µF 20 D = BAV20WS 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 0 1 = 3.0V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 6 Output Voltage vs. Temperature OUTPUT VOLTAGE (VPP) RSW = 562k REL = 1M FREQUENCY (KHz) 30 RSW = 442k 60 VCS (VAVG) R = 562k 200 EL FREQUENCY (Hz) SW INPUT CURRENT (mA) INPUT CURRENT (mA) R 50 Total Input Current vs. Temperature 70 OUTPUT VOLTAGE (VP-P) Total Input Current vs. Input Voltage 60 2 3 4 5 INPUT VOLTAGE (V) 4 100 80 60 RSW = 332k RSW = 442k RSW = 562k 40 20 VIN = 3.0V 6 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) September 2001 MIC4827 Micrel EL Frequency vs. Temperature 250 RSW = 2M 200 150 100 50 RSW = 3.32M VIN = 3.0V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) September 2001 180 160 140 120 RSW = 332k REL = 3.32M 100 80 VIN = 3.0V L = 220µH COUT = 0.1µF D = BAV20WS 60 40 20 0 0 30 INPUT CURRENT (mA) RSW =1M 300 OUTPUT VOLTAGE (VPP) FREQUENCY (KHz) 350 Total Input Current vs. Lamp Size Output Voltage vs. Lamp Size 200 400 1 2 3 4 5 6 LAMP SIZE (sq. in.) 5 7 25 20 RSW = 332k REL = 3.32M 15 VIN = 3.0V L = 220µH COUT = 0.1µF D = BAV20WS 10 5 0 0 1 2 3 4 5 6 LAMP SIZE (sq. in.) 7 MIC4827 MIC4827 Micrel 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 VB 3 /Q4 REL 4 GND Figure 1. MIC4827 Block Diagram 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. Functional Description VA (50V/div) 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 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. VA — VB (50V/div) VB (50V/div) VIN = 3.0V L = 220µH COUT = 0.033µF Lamp = 2in2 RSW = 442k REL = 2M TIME (2ms/div) Figure 2. 108Hz Typical 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%. fSW (kHz) = MIC4827 6 36 RSW (MΩ) September 2001 MIC4827 Micrel VA — VB (50V/div) VB (50V/div) 360 REL (MΩ) VA (50V/div) fEL (Hz) = 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. VA (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%. VB (50V/div) VIN = 3.0V L = 220µH COUT = 0.033µF Lamp = 2in2 RSW = 562k REL = 1M TIME (2ms/div) VA — VB (50V/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. TIME (2ms/div) Figure 3. 180Hz Output Waveform September 2001 7 MIC4827 MIC4827 Micrel Diode The application circuit specifies the 1N4148 or equivalent. It has a forward current of 150mA and a typical forward voltage of 950mV. For applications that are not cost driven, a fastswitching diode with lower forward voltage and higher reverse voltage can be used to enhance the efficiency, such as BAV20WS or BAS20W. 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 surfacemount package. Typically, values ranging from 0.01µF to 0.1µF at 100V can be used for the regulated boost output capacitor. 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. Pre-designed Application Circuit L1 220µH D1 Murata Vishay Telefunken LQH4C221K04 MCL4148 Li-Ion Battery VIN 3.0V to 4.2V C2 10µF/6.3V Murata GRM42-6X5R106K6.3 COUT 0.01µF/100V GRM40X7R103K MIC4827 1 C1 0.22µF/10V Murata GRM39X7R 224K10 R1 R2 3.32M 2 332k VDD SW RSW CS REL VA GND VB 5 6 8 3 7 4 3in2 LAMP IIN VA–VB FEL Lamp Size 3.3V 28mA 180VPP 106Hz 3 in2 VA — VB (50V/div) VB (50V/div) VA (50V/div) VIN TIME (2ms/div) Figure 5. Typical 100Hz EL Driver for 3in2 Lamp MIC4827 8 September 2001 MIC4827 Micrel 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 R2 3.32M R1 332k 2 VDD SW RSW CS REL VA GND VB 3 5 6 8 4 7 EL LAMP LSI X533-13 IIN VA–VB FEL Lamp Size 3.3V 18mA 180VPP 104Hz 2in2 VA — VB (50V/div) VB (50V/div) VA (50V/div) VIN TIME (2ms/div) Figure 6. Typical EL Driver for 2in2 Lamp with CS = 0.033µF September 2001 9 MIC4827 MIC4827 Micrel 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 R2 3.32M R1 562k 2 VDD SW RSW CS REL VA GND VB 3 5 6 8 4 7 EL LAMP LSI X533-13 IIN VA–VB FEL Lamp Size 3.3V 21mA 180VPP 102Hz 2in2 VA — VB (50V/div) VB (50V/div) VA (50V/div) VIN TIME (2ms/div) Figure 7. Typical EL Driver for 2in2 Lamp with 560µH inductor MIC4827 10 September 2001 MIC4827 Micrel 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 VDD SW RSW CS REL VA GND VB 3 5 6 8 4 7 EL LAMP IIN VDD IDD VA–VB FEL Lamp Size 1.5V 26mA 3.0V 32µA 180VPP 104Hz 1.6in2 VA — VB (50V/div) VB (50V/div) VA (50V/div) VIN TIME (2ms/div) Figure 8. Typical Split Power Supplies Applications September 2001 11 MIC4827 MIC4827 Micrel 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 R2 3.32M R1 1M 2 VDD SW RSW CS REL VA GND VB 5 6 8 3 4 7 EL LAMP Elite 12607-N IIN VA–VB FEL Lamp Size 3.0V 31mA 180VPP 104Hz 5.3in2 VA — VB (50V/div) VB (50V/div) VA (50V/div) VIN TIME (2ms/div) Figure 9. Typical EL Driver for Remote Control Lamp (Blue Phosphor) Applications MIC4827 12 September 2001 MIC4827 Micrel Package Information 0.199 (5.05) 0.187 (4.74) 0.122 (3.10) 0.112 (2.84) DIMENSIONS: INCH (MM) 0.120 (3.05) 0.116 (2.95) 0.036 (0.90) 0.032 (0.81) 0.043 (1.09) 0.038 (0.97) 0.012 (0.30) R 0.012 (0.3) 0.0256 (0.65) TYP 0.008 (0.20) 0.004 (0.10) 5° MAX 0° MIN 0.007 (0.18) 0.005 (0.13) 0.012 (0.03) R 0.039 (0.99) 0.035 (0.89) 0.021 (0.53) 8-Lead MSOP (MM) MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB USA http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2001 Micrel Incorporated September 2001 13 MIC4827