TK6593x LARGE EL LAMP DRIVER FEATURES APPLICATIONS ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ High Ratio of Brightness / Input Power Constant Brightness Versus Input Supply Changes Optimized for 15 nf to 45 nf Panel Capacitance Panel Voltage Slew Rates Controlled for Life Enhancement Panel Peak to Peak Voltage Independent of Input Voltage and Temperature Panel Peak to Peak Frequency Independent of Input Voltage and Temperature Miniature Package (SOT23L-6) Operates with Miniature Coil Minimum External Components Laser-Trimmed Fixed Frequency Operation PWM Control Method Adjustable Output Voltage Lower Noise (Audio and EMI) Intensity Control Application (Refer to Application Information) DESCRIPTION The TK6593x Electroluminescent (EL) Lamp Driver has been optimized for battery controlled systems where power consumption and size are primary concerns. The miniature device size (SOT23L-6), together with the miniature Toko EL coils (D32FU, D31FU, D52FU), further helps system designers reduce the space required to drive the small EL panels. Battery Powered Systems Cellular Telephones Pagers LCD Modules Wrist Watches Consumer Electronics The oscillator circuits for the boost converter and lamp driver are both internally generated in the TK6593x, without the need for external components. The clock frequency of the boost converter is laser-trimmed to ensure good initial accuracy that is relatively insensitive to variations in temperature and supply voltage. The clock frequency of the lamp driver tracks the frequency of the boost converter by a constant scaling factor. Furthermore, the drive architecture of the TK6593x has been designed to limit peak drive current delivered to the lamp. This approach limits the slew rate of the voltage across the lamp and has the potential to improve lamp life and decrease RF interference. The TK6593x is available in a miniature, 6-pin SOT23L-6 surface mount package. TK6593x The proprietary architecture (detailed in the Theory of Operation section) of the TK6593x provides a constant output power to the lamp, independent of variations in the battery voltage. This architecture allows the output voltage to remain relatively constant as battery voltages decay, without the need for directly sensing the high voltage output of the EL driver. ORDERING INFORMATION 20 P EL+ VCC HV GND EL- IND BLOCK DIAGRAM IND VCC HV BOOST CONTROL TK6593 MTL GND Lamp Frequency Code HV OSCILLATOR EL+ H BRIDGE TAPE/REEL CODE LAMP FREQUENCY CODE TK65930 TK65931* TK65932 TK65933* TK65934 175 Hz 200 Hz 225 Hz 250 Hz 275 Hz TK65935* TK65936 TK65937* TK65938 TK65939* May 2000 TOKO, Inc. 300 Hz 325 Hz 350 Hz 375 Hz 400 Hz EL- TL: Tape Left * Consult factory for availability of other frequencies. Page 1 TK6593x ABSOLUTE MAXIMUM RATINGS VCC Pin .................................................................... 6.5 V All Pins Except VCC and GND ............................... VCLAMP Power Dissipation (Note 1) ................................ 600 mW Storage Temperature Range ................... -55 to +150 °C Operating Temperature Range ...................-30 to +80 °C Junction Temperature ........................................... 150 °C TK6593x ELECTRICAL CHARACTERISTICS VCC = 3.6 V, TA = Tj = 25 °C, unless otherwise specified. SYMBOL PARAMETER TEST CONDITIONS MIN TYP MAX UNITS 2.7 3.6 6 V 200 µA 107 mA V CC Input Supply Range IQ Quiescent Current Current into pin 6 IPEAK Peak Current Threshold (Note 4) FLAMP Lamp Frequency See Table 1 Hz FBOOST Boost Frequency See Table 2 kHz V CLAMP Boost Clamp Voltage D(MAX) Maximum Duty Cycle V OUT Peak to Peak Lamp Voltage (Note 3) ICONV Converter Supply Current (Notes 2, 3) 87 Force 100 µA into HV pin 97 90 105 120 V 88 92 96 % 125 140 155 V See Table 3 mA Note 1: Power dissipation is 600 mW when mounted as recommended (200 mW In Free Air). Derate at 4.8 mW/°C for operation above 25 °C. Note 2: Converter supply current is dependent upon the DC resistance of inductor L1. Lower DC resistances will result in lower supply currents. Note 3: When using test circuit below. Note 4: Refer to Page 5 graph of Peak Current Threshold vs. Supply Voltage. Gen. Note: Refer to “INDUCTOR VALUE SELECTION” and “INDUCTOR TYPE SELECTION” of Design Considerations Section for choosing inductor. TEST CIRCUIT EL + VCC HV GND ICONV VCC CEL 20 nF EL - IND L1 330 µH C1 100 nF Page 2 D1 Note: L1 = Toko Low Profile D52FU Series: 875FU-331 M D1 = DIODES INC. DL4148 C1 = AVX 12061C104KAT2A May 2000 TOKO, Inc. TK6593x TK6593x ELECTRICAL CHARACTERISTICS VIN = 3.6 V, TA = Tj = 25 °C, unless otherwise specified. TABLE 1: LAMP FREQUENCY TOKO PART NO. TK65930 TK65931 TK65932 TK65933 TK65934 TK65935 TK65936 TK65937 TK65938 TK65939 MIN. 157 Hz 180 Hz 202 Hz 225 Hz 247 Hz 270 Hz 292 Hz 315 Hz 337 Hz 360 Hz TYP. 175 Hz 200 Hz 225 Hz 250 Hz 275 Hz 300 Hz 325 Hz 350 Hz 375 Hz 400 Hz MAX. 193 Hz 220 Hz 248 Hz 275 Hz 303 Hz 330 Hz 358 Hz 385 Hz 413 Hz 440 Hz MIN. 20.1 kHz 23.0 kHz 25.9 kHz 28.8 kHz 31.6 kHz 34.5 kHz 37.4 kHz 40.3 kHz 43.2 kHz 46.1 kHz TYP. 22.4 kHz 25.6 kHz 28.8 kHz 32.0 kHz 35.2 kHz 38.4 kHz 41.6 kHz 44.8 kHz 48.0 kHz 51.2 kHz MAX. 24.7 kHz 28.2 kHz 31.7 kHz 35.2 kHz 38.8 kHz 42.3 kHz 45.8 kHz 49.3 kHz 52.8 kHz 56.3 kHz TYP. 14.2 mA 16.2 mA 18.3 mA 20.3 mA 22.3 mA 24.3 mA 26.4 mA 28.4 mA 30.4 mA 32.4 mA MAX. 28.4 mA 32.4 mA 36.6 mA 40.6 mA 44.6 mA 48.6 mA 52.8 mA 56.8 mA 60.8 mA 64.8 mA TABLE 2: OSCILLATOR FREQUENCY TOKO PART NO. TK65930 TK65931 TK65932 TK65933 TK65934 TK65935 TK65936 TK65937 TK65938 TK65939 TABLE 3: CONVERTER SUPPLY CURRENT TOKO PART NO. TK65930 TK65931 TK65932 TK65933 TK65934 TK65935 TK65936 TK65937 TK65938 TK65939 May 2000 TOKO, Inc. MIN. - Page 3 TK6593x TYPICAL PERFORMANCE CHARACTERISTICS USING TEST CIRCUIT TK65939 Voltage Waveform TK65931 PEAK TO PEAK LAMP VOLTAGE vs. SUPPLY VOLTAGE TK65939 PEAK TO PEAK LAMP VOLTAGE vs. SUPPLY VOLTAGE L1 = 330 µH 140 VOUT (V) 140 130 VOUT (V) 150 TK65931 Voltage Waveform 130 L1 = 220 µH 120 L1 = 330 µH 120 L1 = 220 µH 110 110 100 2.5 230 3 3.5 4 4.5 5 5.5 100 2.5 6 4.5 5 TK65939 LAMP FREQUENCY vs. SUPPLY VOLTAGE 460 5.5 6 5.5 6 440 FLAMP (Hz) FLAMP (Hz) 4 TK65931 LAMP FREQUENCY vs. SUPPLY VOLTAGE 210 200 190 420 400 380 3 3.5 4 4.5 VCC (V) Page 4 3.5 VCC (V) 220 180 2.5 3 VCC (V) 5 5.5 6 360 2.5 3 3.5 4 4.5 5 VCC (V) May 2000 TOKO, Inc. TK6593x TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT 30 TK65931 AVERAGE CONVERTER SUPPLY CURRENT vs. SUPPLY VOLTAGE 60 50 ICONV (mA) ICONV (mA) 25 20 15 40 30 10 20 5 10 0 0 2.5 110 3 3.5 4 4.5 5 5.5 6 2.5 3 3.5 4.5 5 5.5 VCC (V) TK65931 PEAK CURRENT THRESHOLD vs. SUPPLY VOLTAGE TK65939 PEAK CURRENT THRESHOLD vs. SUPPLY VOLTAGE 110 6 IPEAK (mA) 100 90 80 70 90 80 70 60 60 2.5 3 3.5 4 4.5 5 5.5 6 2.5 3 3.5 VCC (V) 200 TK65931 QUIESCENT CURRENT vs. SUPPLY VOLTAGE 200 4.5 5 5.5 6 5.5 6 TK65939 QUIESCENT CURRENT vs. SUPPLY VOLTAGE IQ (µA) 150 100 50 0 2.5 4 VCC (V) 150 IQ (µA) 4 VCC (V) 100 IPEAK (mA) TK65939 AVERAGE CONVERTER SUPPLY CURRENT vs. SUPPLY VOLTAGE 100 50 3 3.5 4 4.5 VCC (V) May 2000 TOKO, Inc. 5 5.5 6 0 2.5 3 3.5 4 4.5 5 VCC (V) Page 5 TK6593x TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT 160 TK65931 PEAK TO PEAK LAMP VOLTAGE vs. TEMPERATURE 160 TK65939 PEAK TO PEAK LAMP VOLTAGE vs. TEMPERATURE 150 150 VCC = 3.6 V 140 VOUT (V) VOUT (V) 140 130 VCC = 2.7 V 120 VCC = 2.7 V 120 110 110 100 100 90 90 -50 -25 220 0 25 50 75 -50 -25 100 125 50 75 TK65931 LAMP FREQUENCY vs. TEMPERATURE TK65939 LAMP FREQUENCY vs. TEMPERATURE 440 100 125 FLAMP (Hz) 420 200 190 400 380 360 170 -50 -25 0 25 50 75 340 -50 -25 100 125 TEMPERATURE (°C) 0 25 50 75 100 125 TEMPERATURE (°C) TK65931 AVERAGE CONVERTER SUPPLY CURRENT vs. TEMPERATURE TK65939 AVERAGE CONVERTER SUPPLY CURRENT vs. TEMPERATURE 25 45 20 40 ICONV (mA) ICONV (mA) 25 TEMPERATURE (°C) 180 15 10 5 35 30 25 0 -50 -25 0 25 50 75 TEMPERATURE (°C) Page 6 0 TEMPERATURE (°C) 210 FLAMP (Hz) VCC = 3.6 V 130 100 125 20 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) May 2000 TOKO, Inc. TK6593x TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT VCC = 3.6 V 100 IPEAK (mA) 110 90 VCC = 2.7 V 80 70 V CC = 3.6 90 V CC = 2.7 80 70 60 -50 -25 0 25 50 75 60 -50 -25 100 125 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TK65931 QUIESCENT CURRENT vs. TEMPERATURE TK65939 QUIESCENT CURRENT vs. TEMPERATURE 100 120 90 110 IQ (µA) IQ (µA) TK65939 PEAK CURRENT THRESHOLD vs. TEMPERATURE 100 IPEAK (mA) 110 TK65931 PEAK CURRENT THRESHOLD vs. TEMPERATURE 80 100 70 90 60 80 70 50 -50 -25 0 25 50 75 TEMPERATURE (°C) May 2000 TOKO, Inc. 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) Page 7 TK6593x TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING D(MAX) TEST CIRCUIT TK65931 MAXIMUM DUTY CYCLE vs. SUPPLY VOLTAGE 95 95 94 D(MAX) (%) D(MAX) (%) 94 93 92 91 93 92 91 90 90 2.5 3 3.5 4 4.5 5 5.5 6 2.5 3 3.5 4 4.5 5 5.5 VCC (V) VCC (V) TK65931 MAXIMUM DUTY CYCLE vs. TEMPERATURE TK65939 MAXIMUM DUTY CYCLE vs. TEMPERATURE 95 95 94 94 D(MAX) (%) D(MAX) (%) TK65939 MAXIMUM DUTY CYCLE vs. SUPPLY VOLTAGE 93 92 91 6 93 92 91 90 90 -50 -25 0 25 50 75 100 125 -50 -25 TEMPERATURE (°C) 0 25 50 75 100 125 TEMPERATURE (°C) D(MAX) TEST CIRCUIT EL + VCC HV GND VCC EL - IND R1 Note: R1 = 470 Ω Page 8 May 2000 TOKO, Inc. TK6593x THEORY OF OPERATION An Electroluminescent (EL) Lamp is a strip of plastic, coated with a phosphorous material that emits light when a high voltage AC signal is applied to the terminals of the device. EL panels have the ability to light the entire panel uniformly. Because of this, they are gradually becoming more popular and widespread than LEDs. The amount of light emitted from an EL Lamp is typically proportional to the magnitude of the voltage applied to the lamp. Furthermore, the color of the light emitted by an EL Lamp is somewhat dependent upon the frequency of the applied drive signal. For most applications, a peak-to-peak voltage of 100 to 170 V, with a drive frequency of 175 to 400 Hz, provides optimal trade-off between lamp intensity and power consumption. The capacitance of the EL Panel is typically proportional to the size of the lamp (a 1 square inch EL Panel typically exhibits approximately 5 nF of capacitance load). The TK6593x series of devices has been optimized to drive EL panels, which are approximately 3-6 square inches in size. The Boost section of the TK6593x consists of a controller for stepping up a relatively low voltage (2.7 to 6 V) to a much higher voltage (50 to 90 V) needed to drive the EL Lamp. The boost section of the TK6593x uses a proprietary architecture which provides a relatively constant output power, independent of the input supply, without the need for sensing the high voltage output of the boost converter. By controlling the peak current through the switching element of the boost converter, the boost section provides a constant output power independent of the input supply. The H-Bridge section of the TK6593x switches the high voltage output of the boost converter to the two terminals of the EL Lamp. By alternately switching the terminals of the lamp between the high voltage supply and ground, the peak-to-peak voltage developed across the lamp is effectively twice the high voltage generated by boost converter. Furthermore, the TK6593x limits the magnitude of the drive currents through the H-Bridge switches in order to minimize the edge rates developed across the EL Lamp. This approach protects the EL Panel from large current spikes and reduces the likelihood of high frequency noise components being injected into neighboring circuitry. The Oscillator section of the TK6593x generates a fixed frequency clock source for the previously described Boost and H-Bridge sections, without the need for external components. The high frequency output of the oscillator is used for driving the boost controller. A lower frequency May 2000 TOKO, Inc. clock is generated by dividing the high frequency clock by 128; this lower frequency clock corresponds to the drive frequency of the EL Lamp. The laser-trimmed oscillators are relatively insensitive to variations in temperature and supply voltage. Therefore, they provide good control of the lamp color emitted by the panel. The circuit below illustrates a typical application where the TK6593x is driving a 3-square-inch EL Lamp with a capacitance of approximately 20 nF. EL + VCC HV GND ICONV VCC CEL 20 nF EL - IND L1 330 µH C1 100 nF D1 FIGURE 1: TYPICAL APPLICATION By keeping the ratio of the boost frequency and the HBridge frequency constant, the peak-to-peak output voltage from the TK6593x becomes primarily dependent upon the capacitance of the EL Lamp, the peak current threshold of the boost converter, and the value of the inductive element used in the boost converter. For the TK6593x, the peak current threshold is laser-trimmed to 97 mA. The capacitive load of the EL Lamp is a function of panel size and is typically fixed. Therefore, the high voltage output of the boost converter can be set to a desired voltage by selecting the appropriate value of the inductive element used in the boost converter. IPEAK = Boost Peak Current Threshold (97 mA) CEL = Capacitance of EL Lamp L = Inductance Value VHV = (IPEAK / 2) x (L /CEL) x 128 Page 9 TK6593x THEORY OF OPERATION (CONT.) With properly selected components, the TK6593x will nominally support peak output voltages to 90 V (180 VPK-PK). Should the EL Panel become disconnected from the driver outputs, the removal of the load can cause the output voltage to increase beyond 90 V. To protect against this fault condition, a clamp circuit exists on the high voltage output which nominally limits the output voltage to a typical value of 105 V (210 VPK-PK). DETAILS CONCERNING THE H-BRIDGE SECTION OPERATION HV HVP The FETs are turned off and on in the sequence shown in Figure 3. As is noted in Figure 3, there is a period of time when both of lower N-channel FETs are turned on and both of upper P-channel FETs are turned off. This provides a period of time to discharge the EL panel capacitance completely; before starting to recharge it again with current from HV voltage rail. Therefore, this special sequencing method prevents taking current off the HV voltage rail during the discharge of EL panel capacitance and operates more efficiently. UR HVP EL+ ELEL Panel LL LR Current Source 2 Current Source 1 FIGURE 2: H-BRIDGE SCHEMATIC In an effort to extend EL lamp life, reduce EMI emissions, and reduce the power draw of the IC, current sources to control the charging and discharging of the EL lamp panel and special sequencing control of the H-bridge FETs were added to the H-bridge of TK659xx. Current sources were added between ground and the sources of the low-side N-channel FETs (Figure 2). Therefore, the current into and out of the EL panel is controlled and limited. UL BOTH OFF UL OFF ON OFF OFF UR OFF OFF BOTH ON OFF ON LL ON OFF ON ON LR ON ON ON OFF VEL- VEL+ Discharging EL Panel Capacitance VEL = VEL+ - VEL- FIGURE 3: H-BRIDGE SEQUENCING WAVEFORMS Page 10 May 2000 TOKO, Inc. TK6593x PIN DESCRIPTIONS SUPPLY PIN (VCC) This pin is the positive input supply for the TK6593x. Good design practices dictate capacitive decoupling to the ground pin. GROUND PIN (GND) The pin provides the ground connection for the IC. IND PIN This pin is periodically pulled to ground by a power transistor acting as an internal switch to the TK6593x. Externally, this pin is typically connected to an inductor and a rectifying diode. By modulating the switching action of the internal switch, the TK6593x can boost the relatively low voltage of the battery to the high voltage required to drive the EL Lamp. HV PIN This pin is connected to the filter capacitor and the cathode of the rectifying diode in order to generate a high voltage supply. This high voltage supply is switched to the terminals of the EL Lamp through the H-Bridge. EL+ PIN This pin is connected to one side of the EL Panel. EL- PIN This pin is connected to the other side of the EL Panel. Note: Measuring the voltage across the EL lamp (EL+ pin to EL- pin) should be done with balanced scope probes using differential measurement techniques to obtain a true waveform of the voltage across the EL lamp. May 2000 TOKO, Inc. Page 11 TK6593x DESIGN CONSIDERATIONS INDUCTOR VALUE SELECTION Designing an EL Driver utilizing the TK6593x is a very simple task. The primary component affecting the behavior of the converter is the inductor. Essentially, the entire design task primarily consists of selecting the proper inductor value and type given the operating conditions of the EL Panel (e.g., lamp capacitance, frequency, output voltage, supply range). The following tables and charts are intended to simplify the selection of the inductor. Given the capacitance of the EL Lamp, and the peak output voltage requirements, the following table can be utilized to select the value of the inductive component. TABLE 4: PEAK OUTPUT VOLTAGE VS. INDUCTOR VALUE AND LAMP CAPACITANCE INDUCTOR VALUE 15.0 nF LAMP 20.0 nF LAMP 25.0 nF LAMP 30.0 nF LAMP 35.0 nF LAMP 40.0 nF LAMP 45.0 nF LAMP 100 µH 45 V 39 V 35 V 32 V 29 V 27 V 26 V 120 µH 49 V 43 V 38 V 35 V 32 V 30 V 28 V 150 µH 55 V 48 V 43 V 39 V 36 V 34 V 32 V 180 µH 60 V 52 V 47 V 43 V 39 V 37 V 35 V 220 µH 66 V 58 V 51 V 47 V 44 V 41 V 38 V 270 µH 74 V 64 V 57 V 52 V 48 V 45 V 43 V 330 µH 81 V 70 V 63 V 58 V 53 V 50 V 47 V 390 µH 88 V 77 V 69 V 63 V 58 V 54 V 51 V 84 V 75 V 69 V 64 V 59 V 56 V 82 V 75 V 69 V 65 V 61 V 83 V 76 V 72 V 67 V 84 V 79 V 74 V 87 V 82 V 470 µH 560 µH 680 µH 820 µH 1000 µH Close to 100 V operation check capacitor C1 voltage rating Note: The voltages indicated in the table above may not be achievable under certain circumstances (i.e., low battery or higher drive frequencies). Refer to the charts on page 12 to determine which output voltage/coil combination can be supported by the EL driver. As an example as to how the above table is to be used, assume that we have a 4-square-inch panel (30 nF capacitance) and we would like the peak-to-peak voltage across the lamp to be 140 V. The peak voltage on either terminal would be 70 V (140 V / 2). Referring to the table above, we can see that using a 470 µH coil the peak voltage developed across a 30 nF Lamp would be approximately 69 V. In this particular example, the inductive component should have a value of 470 µH. INDUCTOR TYPE SELECTION After the value of the inductor has been selected, an appropriate coil type needs to be selected taking into account such factors as DC resistance and current capability. The following charts can be utilized for selecting the proper family of Toko Coils. Furthermore, the following charts will also indicate if the TK6593x is the appropriate driver given the frequency and input supply requirements. The following charts will indicate whether or not the TK6593x has sufficient drive capability, Page 12 May 2000 TOKO, Inc. TK6593x DESIGN CONSIDERATIONS (CONT.) given the input supply and frequency requirements. A high-current solution for driving larger panels is currently under development. To utilize the following charts in selecting an appropriate coil, perform the following steps: 1) From the following charts, select the chart that matches the part number of the Toko EL Driver that will be used in the application. The part number of the Toko EL Driver will be dependant upon the desired frequency of the EL panel (e.g., TK65931 = 200Hz). 2) Determine input supply voltage range (e.g., 4 to 6 V). The x-axis of the following charts represent the minimum expected supply voltage. Below this minimum supply voltage the EL Driver output may begin to droop. On the appropriate chart, draw a vertical line upward from the minimum supply voltage represented on the x-axis (e.g., 4V). 3) Draw a horizontal line passing through the chosen inductor value on the y-axis (e.g., 470 µH). 4) The vertical and horizontal lines drawn in steps 2 and 3 respectively will intersect at a point. This point will lie in one of four regions of the chart (e.g., D52FU). These four regions suggest which family of Toko Coils to use. Of the three coil families suggested in these charts, the D31FU has the smallest physical size but also has higher DC resistance. The D52FU series of coils has the largest physical size and the lowest DC resistance. The D52FU or the D32FU can be used as a reasonable substitute for the D31FU. Similarly, the D52FU can be used as a replacement for the D32FU. Substituting a coil with lower DC resistance will generally result in a system that will consume less power supply current. TK65930, TK65931 1000 D52FU 820 680 560 X 470 390 330 D32FU 270 220 D31FU 180 INDUCTOR VALUE (µH) 1000 3 4 5 470 390 330 D32FU 270 220 D31FU 100 6 3 4 5 6 MINIMUM SUPPLY (V) TK65936, TK65937 TK65938, TK65939 1000 (NOTE 1) D52FU 470 390 330 D32FU 270 220 D31FU (NOTE 1) 820 680 D52FU 560 470 390 330 D32FU 270 220 D31FU 180 MINIMUM SUPPLY (V) 820 680 560 100 3 4 5 3 4 5 MINIMUM SUPPLY (V) May 2000 TOKO, Inc. 6 6 MINIMUM SUPPLY (V) (NOTE 1) 820 680 560 470 D52FU 390 330 D32FU Note 1: A high-current solution for driving larger panels is currently under development. 270 220 D31FU 180 180 100 D52FU 180 INDUCTOR VALUE (µH) 100 1000 (NOTE 1) 820 680 560 INDUCTOR VALUE (µH) (NOTE 1) INDUCTOR VALUE (µH) INDUCTOR VALUE (µH) 1000 TK65934, TK65935 TK65932, TK65933 100 3 4 5 6 MINIMUM SUPPLY (V) Page 13 TK6593x APPLICATION INFORMATION EL LAMP INTENSITY CONTROL APPLICATION In driving EL lamp panels, it is sometimes desirable to be able to adjust the intensity of the EL lamp. The TK6593x can be used in such an application. By reducing the voltage supplied to the VCC pin of the TK6593x, one can reduce the peak current regulation point of the IC. This translates into a reduction in the peak to peak output voltage across the EL panel, which reduces the intensity of the light being emitted from the EL lamp. By decreasing the input voltage to the VCC pin from 2.9 V to 2.1 V, the peak current regulation point will be reduced about 53 mA. This correlates to about a 2/3 reduction in the peak to peak voltage appearing across the EL lamp panel. The VCC pin only takes 200 µA max. when the EL driver is in operation. Therefore, it can normally be controlled by logic power level signals. One way of accomplishing this with two digital logic signals is shown in Figure 4. R1 = 1.5 kΩ R2 = 3.0 kΩ C2 = 10 nF 3 V ~ 1 mA source R1 1.5 k CEL 20 nF EL + VCC HV GND EL - IND C2 10 nF R2 3k 3 V PWM 10% to 90% 200 KHz to 300 KHz ~ 1 mA sink Vpower L1 C1 100 nF 1.8 to 7 V D1 FIGURE 4: INTENSITY CONTROL APPLICATION NOISE CONSIDERATIONS There are two specific noise types relevant to the user when it comes to choosing EL Drivers: the Audio Noise and the Electromagnetic Interference (EMI) Noise. The EMI Noise would most likely come from the boost converter section of the EL Driver circuit. The Toko EL Driver has specifically been designed to address this issue. The device runs at a fixed frequency and the frequency is controlled tightly in order to avoid interference. Furthermore, the panel frequency is forced to be a 128 submultiple of the boost frequency avoiding any type of beating frequencies. By choosing shielded coils, the EMI noise problem can further be reduced. The Audio Noise can come from several components which make up the system. The coil, if operated in the audio range would be a source of noise. The Toko EL Driver was carefully designed to give the user the choice of 10 frequencies such that the coil frequency will always be above audio range. Since the device operates at a fixed frequency in discontinuous conduction mode, there are no possible submultiples which would cause audible noise. The filter capacitor can be a source of audio noise. Furthermore, depending on how this cap is mounted, the mounting can act as an amplifier (as a speaker box). Certain ceramic caps driven from a high voltage source as in the EL Driver case, demonstrate a PIEZOELECTRIC effect which is distinguishable in the Audio Range. Other types of caps, such as film type do not denote an audio noise. The panel itself, being operated well into the Audio Range (175 Hz to 400 Hz) and of a capacitive nature driven from high voltage may also display Audible Noise. Mounting of this panel can enhance or diminish this natural effect of the panel. Page 14 May 2000 TOKO, Inc. TK6593x LAYOUT Actual Size 2x SPLIT SUPPLY LAYOUT Actual Size 2x May 2000 TOKO, Inc. Page 15 TK6593x PACKAGE OUTLINE Marking Information SOT23L-6 +0.15 TK65930 TK65931 TK65932 TK65933 TK65934 TK65935 TK65936 TK65937 TK65938 TK65939 0.4 - 0.05 0.1 M 0.6 6 e1 3.0 1.0 Marking 1 2 3 0.32 e 5 PL e 3.5 +0.15 - 0.05 0.1 e 0.95 M 0.95 0.95 Marking C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 e 0.95 Recommended Mount Pad +0.3 - 0.1 2.2 max 15 1.2 0.15 Dimensions are shown in millimeters Tolerance: x.x = ± 0.2 mm (unless otherwise specified) +0.15 - 0.05 0 - 0.1 1.4 max 0.3 (3.4) 0.4 + 0.3 3.3 Toko America, Inc. Headquarters 1250 Feehanville Drive, Mount Prospect, Illinois 60056 Tel: (847) 297-0070 Fax: (847) 699-7864 TOKO AMERICA REGIONAL OFFICES Midwest Regional Office Toko America, Inc. 1250 Feehanville Drive Mount Prospect, IL 60056 Tel: (847) 297-0070 Fax: (847) 699-7864 Western Regional Office Toko America, Inc. 2480 North First Street , Suite 260 San Jose, CA 95131 Tel: (408) 432-8281 Fax: (408) 943-9790 Eastern Regional Office Toko America, Inc. 107 Mill Plain Road Danbury, CT 06811 Tel: (203) 748-6871 Fax: (203) 797-1223 Semiconductor Technical Support Toko Design Center 4755 Forge Road Colorado Springs, CO 80907 Tel: (719) 528-2200 Fax: (719) 528-2375 Visit our Internet site at http://www.tokoam.com The information furnished by TOKO, Inc. is believed to be accurate and reliable. However, TOKO reserves the right to make changes or improvements in the design, specification or manufacture of its products without further notice. TOKO does not assume any liability arising from the application or use of any product or circuit described herein, nor for any infringements of patents or other rights of third parties which may result from the use of its products. No license is granted by implication or otherwise under any patent or patent rights of TOKO, Inc. Page 16 © 1999 Toko, Inc. All Rights Reserved May 2000 TOKO, Inc. IC-xxx-TK6593x 0798O0.0K Printed in the USA