MC33441 Electroluminescent Lamp Driver IC The MC33441 is a DC−AC inverter integrated circuit for driving EL lamps. It can boost the supply voltage to the level required by EL lamps and also provide high voltage AC lamp excitation. It consists of an oscillator, a frequency divider, a coil driving circuit and a switched H−bridge network. The input supply voltage range is from 1.8 V to 3.5 V and is capable to supply a typical 140 Vpp AC output voltage. The standby current of the device is typically 10 nA which is ideal for low power portable products. Externally, one inductor and one resistor are needed to generate the desirable voltage charge and to fine tune the oscillator’s frequency. This device is offered in 8−Pin TSSOP miniature package. The operating temperature is −20°C to 70°C. http://onsemi.com 8 1 TSSOP−8 DTB SUFFIX CASE 948J Features Battery Operation 1.8 V − 3.5 V Typical Voltage Output 140 Vpp Typical Standby Current 10 nA Internal Oscillator with External Tuning Resistor Enable Control Pin with a 300 K Internal Pull−Down Resistor 8−Pin TSSOP Package (Thickness = 1.05 mm, Width = 4.5 mm, Length = 3.1 mm & Lead Pitch = 0.65 mm) Types of Applications 1 ENB 2 EL1 7 EL2 RT1 3 6 FILTER VSS 4 5 COIL FEL FREQUENCY DIVIDER FCOIL H−BRIDGE 8 EL1 ENB 2 7 EL2 RT1 3 6 FILTER 5 COIL (Top View) 8 OSC VDD 1 VSS 4 • Pagers, Cellular Phones, Portable CD Players/Minidisks • Databanks, Calculators VDD PIN CONNECTIONS AND MARKING DIAGRAM M33 441 ALY W • • • • • • A L Y W = Assembly Location = Wafer Lot = Year = Work Week ORDERING INFORMATION Device Package Shipping MC33441DTBR2 TSSOP−8 2500 Units / Reel COIL DRIVER Simplified Block Diagram © Semiconductor Components Industries, LLC, 2006 July, 2006 − Rev. 3 1 Publication Order Number: MC33441/D MC33441 Battery / VDD INDUCTOR VSS REXT RT1 ENB MAIN SWITCH 5 4 COIL DRIVER OSC & FREQ. DIVIDER 3 2 6 CFILTER AND2 AND2 1 OPTIONAL FILTER H−BRIDGE FCOIL VDD COIL 7 EL2 8 EL1 AND2 FEL EL LAMP Figure 1. Test Circuit PIN FUNCTION DESCRIPTION Pin No. (TSSOP−8) Name Pin 1 VDD Input voltage supply Pin 2 ENB Enable the whole device to operate Pin 3 RT1 Internal oscillator’s fine tuning resistance input Pin 4 VSS Analog/Power ground Pin 5 COIL Coil/Inductance input Pin 6 Filter EL Filter Pin 7 EL2 EL lamp driver output 2 Pin 8 EL1 EL lamp driver output 1 ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Description http://onsemi.com 2 MC33441 MAXIMUM RATINGS (TC = 25°C, unless otherwise noted.) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Rating Symbol Max Unit VDD 7.5 V LOGIC = 0 LOGIC = 1 0.5 VDD V TJ(max) 150 °C Power Supply Voltage Digital Input Voltage Range Operating Junction Temperature Operating Ambient Temperature TA −20 to +70 °C Storage Temperature Range Tstg −50 to +150 °C Power Dissipation PD 300 mW RθJA 178 °C/W Thermal Resistance, Junction−to−Air DC ELECTRICAL CHARACTERISTICS (VDD = 2.65 V, TA = 25°C, Lamp Capacitance = 2.2 nF, Coil = 1 mH unless otherwise noted.) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Symbol Min Typ Max Unit Supply Voltage VDD 1.8 − 3.5 V Output Voltage (1.8 V < VDD ≤ 3.5 V) VEL 120 140 160 V Peak Coil Current (1.8 V < VDD ≤ 3.5 V) ICOIL − 70 150 mA Average Coil Current from Battery (1.8 V < VDD ≤ 3.5 V) IVDD − 35 75 mA dc avg Characteristic Standby Current (VDD = 3.0 V, ENB = 0) ISTAND − 10 100 nA Clock Frequency (REXT = 125 KW) Fosc 112 140 168 kHz Lamp Drive Frequency (Fosc Divide by 384) FEL − 364.6 − Hz FCOIL − 35 − kHz DCCOIL − 75 − % CEL − 2.2 − nF Coil Drive Frequency ( Fosc Divide by 4) Coil Drive Clock Duty Cycle EL Lamp Capacitance Range VEL1 TIME VEL2 TIME VEL Typical Vpp = 140 V (160 V max) TIME Figure 2. Output Waveform http://onsemi.com 3 MC33441 VDD = 2.65 V Lamp Freq. = 365 Hz EL Lamp = 2.2 nF X = 1 ms/div, Y = 50 V/div Figure 3. Output Waveform versus Time OPERATING DESCRIPTION General F The MC33441 is a DC−AC inverter integrated circuit for driving EL lamps. It can boost the supply voltage to the level required by EL lamps and also provide high voltage AC lamp excitation. It consists of an oscillator, a frequency divider, a coil driving circuit and a switched H−bridge network. The input supply voltage range is from 1.8 V to 3.5 V and is capable to supply a typical 140 Vpp AC output voltage. The standby current of the device is typically 10 nA which is ideal for low power portable products. Externally, one inductor and one resistor are needed to generate the desirable voltage charge and to fine tune the oscillator’s frequency. This device is offered in 8−Pin TSSOP packages. The operating temperature is −20°C to 70°C. OSC + ǒ 6 R 1 EXT C INT Hz Ǔ + 1.667 10 Hz R EXT 10 FCOIL = FOSC B 4 FEL = FOSC B 384 where CINT is about 10pF. Coil Driver The coil driver is basically a simplified boost converter. It takes a higher frequency clock signal from the frequency divider to turn on/off the main switch alternatively. When the main switch is on, current will flow through the coil to ground. Once the switch is being turned off, the energy stored in the coil will be released to the external capacitor (EL lamp) through an internal diode. According to the frequency of the clock signals between the coil driver and the H−bridge, the external capacitor (EL lamp) will be charging to the desirable level. Current limit circuit (typical 70 mA & max. 150 mA) is implemented in this device. Since the current through the coil will increase corresponding to the input voltage, if the input voltage is high and the inductance of the coil is small, the coil can be saturated. The current limit feature is used to avoid this happen. The main switch is parallel to a much smaller switch which has their collector and their base connected together. However, the emitter of the smaller switch is tied to a sensing resistor while the emitter of the main switch is connected to ground. The coil current will split into two according to the sizing ratio between the main and the smaller switch. The current through the smaller switch will also flow through the sensing resistor and generates a voltage. If the voltage across this sensing resistor is above the pre−set value, then both switches Oscillator and Frequency Divider Two circuits are put together to form the oscillator. They are Vref and Ibias. The functionality of Vref block is to generate a zero temperature coefficient (TC) voltage reference which is about 1.27 V. This 1.27 V will then be used in Ibias circuit to provide current biasing to all of the internal circuits with the value equal to Vref divided by an internal resistor. Besides of that, an external resistor is also connected to this circuit block for setting the oscillator’s frequency. The temperature coefficient is dominated by the value of that resistor. Therefore, if a low TC resistor is used, the oscillator frequency’s TC can be kept low. The current mirrors with the induced current equal to the Vref divided by an external resistor are used to charge and discharge an internal capacitor to provide a 50% duty cycle clock signal. This original clock pulse will then be fed into the frequency divider which will generate two additional clock signals with different frequency and duty cycle to the coil−driver and the H−bridge circuits. The oscillator frequency is governed by the following equation: http://onsemi.com 4 MC33441 will be turned off and the energy will release to the EL lamp. And, those switches will remain off until the next clock cycle. Moreover, if a low TC resistor is used, the oscillator frequency’s TC can be kept low. The filter capacitor is to provide a smooth and more stable output waveform for the EL lamp. The value of this capacitor depends on the input voltage and the coil’s inductance value. Equations below can be used to estimate filter capacitor’s value at different input voltage. H−Bridge Network To achieve the 140 V peak−to−peak voltage, H−bridge network is used to charge and discharge the EL lamp. The switching frequency of the bridge network is controlled by a clock signal from the divider with its frequency much lower than the one to the coil−driver. Moreover, to reduce the current consumption, the biasing current to the two low−side switches of the H−bridge is not activated until the coil−driver circuit needed to release the energy to the EL lamp. Then, the biasing circuit will be on and be ready before the main switch in the coil−driver really starts to turn off. Best Case Approximation for the Filter Capacitor: C C By substitute the equation of FOSC from Oscillator & Frequency Divider. + 4.341 10 Hz R EXT 7 so FILTER *V SW ) 2ń(L F OSC 2 ) + 0.085 (V in *V SW ) 2ń(L F OSC 2 ) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ + 4.341 10 W F EL 7 EXT in Table 1: Reference for CFILTER FEL = FOSC B 384 R (V where VIN is the input voltage, VSW is voltage across the switch when it is on, L is the coil’s value and FOSC is the clock frequency. Measurement below is recorded with the condition: coil = 1 mH, EL lamp = 2.2 nF and at room temperature. System designer will base on the application to decide the size and the type of the EL lamp to be used. The external resistance (REXT) at RT1 pin determines the excitation frequency (FEL) for the lamp. The relationship between REXT and the frequency is: EL + 0.026 Worst Case Approximation for the Filter Capacitor: External Components F FILTER http://onsemi.com 5 VDD REXT CFILTER 1.8 V 100 K−130 KW 5 n−10 nF 2.0 V 100 K−130 KW 10 n−22 nF 2.5 V 100 K−130 KW 10 n−22 nF 3.0 V 100 K−130 KW 22 nF−33 nF MC33441 TYPICAL OPERATING CHARACTERISTICS 700 300 VDD = 2.65 V Coil = 1 mH EL lamp = 2.2 nF 200 VDD = 2.65 V Coil = 1 mH EL lamp = 2.2 nF 600 LAMP FREQ (Hz) OSC, FREQ (KHz) 250 150 100 50 500 400 300 200 100 0 50K 75K 100K 0 50K 200K 150K 75K REXT (Ω) 25 30 20 25 10 0.82 15 10 VDD = 2.65 V Lamp Freq. = 365 Hz EL lamp = 2.2 nF 0 0.56 5 1 1.33 0 1.8 1.47 Coil = 1 mH Lamp Freq. = 365 Hz EL Lamp = 2.2nF 2 2.65 3 3.5 VDD (V) COIL INDUCTANCE (mH) Figure 6. Current Consumption versus Coil Inductance Figure 7. Current Consumption versus VDD 138 150 136 145 134 140 VOUT (V) 132 VOUT (V) 200K 20 15 130 128 126 122 75K 100K 150K 135 130 125 120 VDD = 2.65 V Coil = 1 mH EL Lamp = 2.2 nF 124 120 50K 150K Figure 5. Lamp Frequency versus REXT 1 (mA) 1 (mA) Figure 4. Oscillator Frequency versus REXT 5 100K REXT (Ω) 115 VDD = 2.65 V Lamp Freq. = 365 Hz EL Lamp = 2.2 nF 110 0.56 200K 0.82 1 1.33 1.47 COIL INDUCTANCE (mH) REXT (Ω) Figure 8. Output Voltage versus REXT Figure 9. Output Voltage versus Coil Inductance http://onsemi.com 6 MC33441 APPLICATION INFORMATION EL Lamp Selection The inductor must have a saturation current rating equal to or bigger than the peak coil current which is 150 mA. EL lamps are a laminate which exhibit a capacitance on the order of 2.5 nF to 3.5 nF per square inch. The light will emit as the high voltage is applied across the electrodes of this capacitance. The color of the emitted light is determined by the type of chemical used and the frequency of the excitation voltage. On the other hand, the lamp brightness increases approximately the square of the applied voltage and nearly linear to the excitation frequency. Once a lamp has been selected, the operating frequency and the essential voltage for the optimum performance is determined. Then, the driver circuit can begin to design. Filter Capacitor Selection (C2) See Table 1 for the estimated value of the filter capacitors based on the input voltage supply. Since the maximum voltage of the filter capacitor can reach 70 V or even 80 V, capacitor with high voltage rating will be required. Resistor Selection (R1) Since the fundamental frequency of the oscillator is set by the external resistor (R1), the temperature coefficient of the frequency is dominated by the value of this resistor. A low temperature coefficient (TC) resistor is suggested to use for keeping the variation of oscillator’s frequency low against the operation temperature range. (See Page 4, Fig. 3 & Fig. 4) Inductor Selection (L1) Use a 1 mH/0.15 A inductor for MC33441. Higher inductor values can be used to reduce the peak transient coil current from the battery supply. As the value of the inductor (L1), increases, the resistor (R1) value may need to increase correspondingly to provide optimum performance. While a lower inductor values lead to smaller physical size, it will generate a higher peak coil current. A lower resistor (R1) value should be used when a lower inductance coil is being used. R1 + R + 4.341 10 W F EL 7 EXT Layout The MC33441 is high output voltage operation make PC board layout critical to minimize ground bounce and noise. Locate input bypass capacitor, filter capacitor and oscillator’s resistor as close to the device pins as possible. L1 1 mH PB1 U1 1 ENABLE C1 0.1 μF 2 3 BATTERY 4 R1 130 K 8 EL1 VDD ENB EL2 RT1 FILTER VSS COIL MC33441 EL−LAMP 7 6 5 (TSSOP−8) C2 27 nF/100 V Figure 10. MC33441 Demo Board Schematic COMPONENT SUPPLIER ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Supplier Part Number Description Phone Tech−Wave Industrial Co., Ltd. Part# CC−0012 EL−Lamp: 14.5 mm x 47 mm Color: Yellow−Green (886)−2−22692827 Coils Electronics Co., Ltd. Part# CRCH664− 102K−831015 Inductor: 1 mH / 0.15 A (852)−2341−5539 http://onsemi.com 7 MC33441 Figure 11. MC33441 PC Board − Top View Figure 12. MC33441 Component Placement Guide − Component Side Figure 13. MC33441 PC Board − Bottom View http://onsemi.com 8 MC33441 PACKAGE DIMENSIONS TSSOP−8 DTB SUFFIX CASE 948J−01 ISSUE O 8x 0.15 (0.006) T U K REF 0.10 (0.004) S M T U S V K 2X L/2 8 J J1 B −U− PIN 1 IDENT. ÉÉ ÇÇ ÇÇ ÉÉ K1 5 L SECTION N−N 4 1 N 0.15 (0.006) T U NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A DOES NOT INCLUDE MOLD FLASH. PROTRUSIONS OR GATE BURRS. MOLD FLASH OR GATE BURRS SHALL NOT EXCEED 0.15 (0.006) PER SIDE. 4. DIMENSION B DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. INTERLEAD FLASH OR PROTRUSION SHALL NOT EXCEED 0.25 (0.010) PER SIDE. 5. DIMENSION K DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.08 (0.003) TOTAL IN EXCESS OF THE K DIMENSION AT MAXIMUM MATERIAL CONDITION. 6. TERMINAL NUMBERS ARE SHOWN FOR REFERENCE ONLY. 7. DIMENSION A AND B ARE TO BE DETERMINED AT DATUM PLANE −W−. S S 0.25 (0.010) A −V− M N F DETAIL E −W− C 0.10 (0.004) −T− SEATING PLANE D G SEE DETAIL E H DIM A B C D F G H J J1 K K1 L M MILLIMETERS MIN MAX 2.90 3.10 4.30 4.50 −−− 1.20 0.05 0.15 0.50 0.75 0.65 BSC 0.50 0.60 0.09 0.20 0.09 0.16 0.19 0.30 0.19 0.25 6.40 BSC 0_ 8_ INCHES MIN MAX 0.114 0.122 0.169 0.177 −−− 0.047 0.002 0.006 0.020 0.030 0.026 BSC 0.020 0.024 0.004 0.008 0.004 0.006 0.007 0.012 0.007 0.010 0.252 BSC 0_ 8_ ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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