TK6592xM MEDIUM EL LAMP DRIVER FEATURES APPLICATIONS High Ratio of Brightness / Input PowerBattery Powered Systems Constant Brightness Versus Input Supply ChangesCellular Telephones Optimized for 9 nf to 27 nf Panel CapacitancePagers Panel Voltage Slew Rates Controlled for LifeLCD Modules Enhancement Wrist Watches Panel Peak to Peak Voltage Independent of Input Consumer Electronics Voltage and Temperature The oscillator circuits for the boost converter and lampPanel Peak to Peak Frequency Independent of driver are both internally generated in the TK6592x, without Input Voltage and Temperature the need for external components. The clock frequency of Miniature Package (SOT23L-6) the boost converter is laser-trimmed to ensure good initial Operates with Miniature Coil accuracy that is relatively insensitive to variations in Minimum External Components temperature and supply voltage. The clock frequency of the lamp driver tracks the frequency of the boost converterLaser-Trimmed Fixed Frequency Operation by a constant scaling factor. PWM Control Method Adjustable Output Voltage Furthermore, the drive architecture of the TK6592x has Lower Noise (Audio and EMI) been designed to limit peak drive current delivered to the lamp. This approach limits the slew rate of the voltageSplit Power Supply Application across the lamp and has the potential to improve lamp life and decrease RF interference. DESCRIPTION The TK6592x Electroluminescent (EL) Lamp Driver has The TK6592x is available in a miniature, 6-pin been optimized for battery controlled systems where power SOT23L-6 surface mount package consumption and size are primary concerns. The miniature device size (SOT23L-6), together with the miniature Toko TK6592xM EL coils (D32FU, D31FU, D52FU), further helps system designers reduce the space required to drive the small EL + EL V CC panels. HV GND The proprietary architecture (detailed in the Theory of - EL IND Operation section) of the TK6592x 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, BLOCK DIAGRAM without the need for directly sensing the high voltage output of the EL driver. IND HV BOOST VCC ORDERING INFORMATION CONTROL GND TK6592 MTL HV OSCILLATOR Lamp Frequency Code + EL H BRIDGE - EL LAMP FREQUENCY CODE TAPE/REEL CODE TK65920 175 Hz TK65925* 300 Hz TL: Tape Left TK65921* 200 Hz TK65926 325 Hz TK65922 225 Hz TK65927* 350 Hz * Consult factory for availability TK65923* 250 Hz TK65928 375 Hz of other frequencies. TK65924 275 Hz TK65929* 400 Hz February 2001 TOKO, Inc. Page 1 20P TK6592xM ABSOLUTE MAXIMUM RATINGS V Pin .................................................................... 6.5 V Storage Temperature Range .................... -55 to +150 °C CC All Pins Except V and GND ............................... V Operating Temperature Range .................. -30 to +80 °C CC CLAMP Power Dissipation (Note 1) ................................. 600 mW Junction Temperature .......................................... 150 °C TK6592x ELECTRICAL CHARACTERISTICS V = 3.6 V, T = T = 25 °C, unless otherwise specified. CC A j SR YMBOLPS ARAMETE TN EST CONDITION MP I TX YMS A UNIT VI7 nput Supply Range 26 . 36 . V CC IQ6 uiescent CurrentC0 urrent into pin 2Aµ0 Q IP4 eak Current Threshold 42506A m PEAK F Lamp Frequency Sz ee Table 1 H LAMP F Boost Frequency Sz ee Table 2 kH BOOST VBnµoost Clamp VoltageF0 orce 100 A into HV pi 9510 0 1V 2 CLAMP DM8 aximum Duty Cycle 82969% (MAX) VP) eak to Peak Lamp Voltage(5 Note 3 10 2 15 4 1V 5 OUT IC) onverter Supply Current(3 Notes 2, 3 SA ee Table m CONV 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 L . Lower DC resistances will result in lower supply currents. 1 Note 3: When using test circuit below. Gen. Note: Refer to “INDUCTOR VALUE SELECTION” and “INDUCTOR TYPE SELECTION” of Design Considerations Section for choosing inductor. TEST CIRCUIT I CONV + V EL CC V CC HV GND C EL 12 nF - IND EL L 1 680 µH D 1 C 1 Note: L = Toko Low Profile D52FU Series: 875FU-681 M 47 nF 1 D = DIODES INC. DL4148 1 C = AVX 12061C473KAT2A 1 Page 2 February 2001 TOKO, Inc. TK6592xM TK6592x ELECTRICAL CHARACTERISTICS V = 3.6 V, T = T = 25 °C, unless otherwise specified. IN A j TABLE 1: LAMP FREQUENCY TOKO PART NO. MIN. TYP. MAX. TK65920 157 Hz 175 Hz 193 Hz TK65921 180 Hz 200 Hz 220 Hz TK65922 202 Hz 225 Hz 248 Hz TK65923 225 Hz 250 Hz 275 Hz TK65924 247 Hz 275 Hz 303 Hz TK65925 270 Hz 300 Hz 330 Hz TK65926 292 Hz 325 Hz 358 Hz TK65927 315 Hz 350 Hz 385 Hz TK65928 337 Hz 375 Hz 413 Hz TK65929 360 Hz 400 Hz 440 Hz TABLE 2: OSCILLATOR FREQUENCY TOKO PART NO. MIN. TYP. MAX. TK65920 20.1 kHz 22.4 kHz 24.7 kHz TK65921 23.0 kHz 25.6 kHz 28.2 kHz TK65922 25.9 kHz 28.8 kHz 31.7 kHz TK65923 28.8 kHz 32.0 kHz 35.2 kHz TK65924 31.6 kHz 35.2 kHz 38.8 kHz TK65925 34.5 kHz 38.4 kHz 42.3 kHz TK65926 37.4 kHz 41.6 kHz 45.8 kHz TK65927 40.3 kHz 44.8 kHz 49.3 kHz TK65928 43.2 kHz 48.0 kHz 52.8 kHz TK65929 46.1 kHz 51.2 kHz 56.3 kHz TABLE 3: CONVERTER SUPPLY CURRENT TOKO PART NO. MIN. TYP. MAX. TK65920 - 7.8 mA 15.6 mA TK65921 - 9.0 mA 18.0 mA TK65922 - 10.1 mA 20.2 mA TK65923 - 11.2 mA 22.4 mA TK65924 - 12.3 mA 24.6 mA TK65925 - 13.4 mA 26.8 mA TK65926 - 14.5 mA 29.0 mA TK65927 - 15.6 mA 31.2 mA TK65928 - 16.8 mA 33.6 mA TK65929 - 17.9 mA 35.8 mA February 2001 TOKO, Inc. Page 3 TK6592xM TYPICAL PERFORMANCE CHARACTERISTICS USING TEST CIRCUIT TK65921 Voltage Waveform Across 12 nF Lamp TK65929 Voltage Waveform Across 12 nF Lamp TK65921 TK65929 PEAK TO PEAK LAMP VOLTAGE PEAK TO PEAK LAMP VOLTAGE vs. SUPPLY VOLTAGE vs. SUPPLY VOLTAGE 160 160 150 150 L = 680 µH 1 L = 680 µH 1 140 140 130 130 L = 560 µH L = 560 µH 1 1 120 120 2.5 3 3.5 4 4.5 5 5.5 6 2.5 3 3.5 4 4.5 5 5.5 6 V (V) V (V) CC CC TK65921 TK65929 LAMP FREQUENCY LAMP FREQUENCY vs. SUPPLY VOLTAGE vs. SUPPLY VOLTAGE 230 460 220 440 420 210 400 200 190 380 180 360 2.5 3 3.5 4 4.5 5 5.5 6 2.5 3 3.5 4 4.5 5 5.5 6 V (V) V (V) CC CC Page 4 February 2001 TOKO, Inc. V (V) F (Hz) OUT LAMP V (V) F (Hz) OUT LAMP TK6592xM TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT TK65921 TK65929 AVERAGE CONVERTER SUPPLY AVERAGE CONVERTER SUPPLY CURRENT vs. SUPPLY VOLTAGE CURRENT vs. SUPPLY VOLTAGE 18 26 16 24 14 22 12 20 10 18 8 16 6 14 4 12 2 10 0 8 2.5 3 3.5 4 4.5 5 5.5 6 2.5 3 3.5 4 4.5 5 5.5 6 V (V) V (V) CC CC TK65921 TK65929 PEAK CURRENT THRESHOLD PEAK CURRENT THRESHOLD vs. SUPPLY VOLTAGE vs. SUPPLY VOLTAGE 60 60 55 55 50 50 45 45 40 40 35 35 30 30 2.5 3 3.5 4 4.5 5 5.5 6 2.5 3 3.5 4 4.5 5 5.5 6 V (V) V (V) CC CC TK65921 TK65929 QUIESCENT CURRENT QUIESCENT CURRENT vs. SUPPLY VOLTAGE vs. SUPPLY VOLTAGE 200 200 150 150 100 100 50 50 0 0 2.5 3 3.5 4 4.5 5 5.5 6 2.5 3 3.5 4 4.5 5 5.5 6 V (V) V (V) CC CC February 2001 TOKO, Inc. Page 5 I (µA) I (mA) Q PEAK I (mA) CONV I (µA) I (mA) Q I (mA) CONV PEAK TK6592xM TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT TK65921 TK65929 PEAK TO PEAK LAMP VOLTAGE PEAK TO PEAK VOLTAGE vs. TEMPERATURE vs. TEMPERATURE 160 160 150 150 V = 3.6 V CC 140 140 V = 3.6 V CC V = 2.7 V 130 130 CC V = 2.7 V CC 120 120 110 110 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TK65921 TK65929 LAMP FREQUENCY LAMP FREQUENCY vs. TEMPERATURE vs. TEMPERATURE 220 440 210 420 200 400 190 380 180 360 170 340 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TK65929 TK65921 AVERAGE CONVERTER SUPPLY AVERAGE CONVERTER SUPPLY CURRENT vs. TEMPERATURE CURRENT vs. TEMPERATURE 14 22 12 20 10 18 16 8 6 14 4 12 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) Page 6 February 2001 TOKO, Inc. F (Hz) V (V) I (mA) LAMP OUT CONV F (Hz) V (V) I (mA) LAMP OUT CONV TK6592xM TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT TK65921 TK65929 PEAK CURRENT THRESHOLD PEAK CURRENT THRESHOLD vs. TEMPERATURE vs. TEMPERATURE 58 58 56 56 54 54 V = 3.6 V 52 CC 52 V = 3.6 V CC 50 50 V = 2.7 V CC V = 2.7 V CC 48 48 46 46 44 44 42 42 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TK65921 TK65929 QUIESCENT CURRENT QUIESCENT CURRENT vs. TEMPERATURE vs. TEMPERATURE 100 100 90 90 80 80 µµ 70 70 60 60 50 50 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) February 2001 TOKO, Inc. Page 7 I ( A) I (mA) Q PEAK I (mA) I ( A) PEAK Q TK6592xM TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING D TEST CIRCUIT (MAX) TK65929 TK65921 MAXIMUM DUTY CYCLE MAXIMUM DUTY CYCLE vs. SUPPLY VOLTAGE vs. SUPPLY VOLTAGE 95 95 94 94 93 93 92 92 91 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 6 V (V) V (V) CC CC TK65929 TK65921 MAXIMUM DUTY CYCLE MAXIMUM DUTY CYCLE vs. TEMPERATURE vs. TEMPERATURE 95 95 94 94 93 93 92 92 91 91 90 90 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) D TEST CIRCUIT (MAX) + V EL CC V CC HV GND - IND EL R 1 Note: R = 470 ! 1 Page 8 February 2001 TOKO, Inc. D (%) (MAX) D (%) (MAX) D (%) D (%) (MAX) (MAX) TK6592xM THEORY OF OPERATION An Electroluminescent (EL) Lamp is a strip of plastic, clock is generated by dividing the high frequency clock by coated with a phosphorous material that emits light when 128; this lower frequency clock corresponds to the drive a high voltage AC signal is applied to the terminals of the frequency of the EL Lamp. The laser-trimmed oscillators device. EL panels have the ability to light the entire panel are relatively insensitive to variations in temperature and uniformly. Because of this, they are gradually becoming supply voltage. Therefore, they provide good control of the more popular and widespread than LEDs. The amount of lamp color emitted by the panel. light emitted from an EL Lamp is typically proportional to the magnitude of the voltage applied to the lamp. The circuit below illustrates a typical application where the Furthermore, the color of the light emitted by an EL Lamp TK6592x is driving a 2-square-inch EL Lamp with a is somewhat dependent upon the frequency of the applied capacitance of approximately 12 nF. drive signal. For most applications, a peak-to-peak voltage of 100 to 170 V, with a drive frequency of 175 to 400 Hz, + V EL CC provides optimal trade-off between lamp intensity and V IN power consumption. HV GND C EL 12 nF - IND The capacitance of the EL Panel is typically proportional to EL the size of the lamp (a 1 square inch EL Panel typically L 1 exhibits approximately 5 nF of capacitance load). The TK6592x series of devices has been optimized to drive EL panels, which are approximately 2-4 square inches in size. D 1 C 1 47 nF The Boost section of the TK6592x 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 FIGURE 1: TYPICAL APPLICATION Lamp. The boost section of the TK6592x 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 keeping the ratio of the boost frequency and the H- By controlling the peak current through the switching Bridge frequency constant, the peak-to-peak output voltage element of the boost converter, the boost section provides from the TK6592x becomes primarily dependent upon the a constant output power independent of the input supply. capacitance of the EL Lamp, the peak current threshold of the boost converter, and the value of the inductive element The H-Bridge section of the TK6592x switches the high used in the boost converter. For the TK6592x, the peak voltage output of the boost converter to the two terminals current threshold is laser-trimmed to 52 mA. The capacitive of the EL Lamp. By alternately switching the terminals of load of the EL Lamp is a function of panel size and is the lamp between the high voltage supply and ground, the typically fixed. Therefore, the high voltage output of the peak-to-peak voltage developed across the lamp is boost converter can be set to a desired voltage by selecting effectively twice the high voltage generated by boost the appropriate value of the inductive element used in the converter. Furthermore, the TK6592x limits the magnitude boost converter. of the drive currents through the H-Bridge switches in I = Boost Peak Current Threshold (52 mA) order to minimize the edge rates developed across the EL PEAK Lamp. This approach protects the EL Panel from large C = Capacitance of EL Lamp current spikes and reduces the likelihood of high frequency EL noise components being injected into neighboring circuitry. L = Inductance Value The Oscillator section of the TK6592x generates a fixed V = (I / 2) x (L /C ) x 128 frequency clock source for the previously described Boost HV PEAK EL 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 February 2001 TOKO, Inc. Page 9 TK6592xM THEORY OF OPERATION (CONT.) With properly selected components, the TK6592x will HV nominally support peak output voltages to 90 V (180 V ). Should the EL Panel become disconnected PK-PK HVP HVP from the driver outputs, the removal of the load can cause UL UR the output voltage to increase beyond 90 V. To protect - + EL EL against this fault condition, a clamp circuit exists on the EL Panel high voltage output which nominally limits the output LL LR voltage to a typical value of 105 V (210 V ). PK-PK Current Source 1 Current Source 2 DETAILS CONCERNING THE H-BRIDGE SECTION OPERATION In an effort to extend EL lamp life, reduce EMI emissions, FIGURE 2: H-BRIDGE SCHEMATIC 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 BOTH OFF added to the H-bridge of TK659xx. Current sources were added between ground and the UL OFF OFF OFF ON sources of the low-side N-channel FETs (Figure 2). Therefore, the current into and out of the EL panel is UR OFF OFF OFF ON controlled and limited. BOTH ON LL OFF ON ON ON The FETs are turned off and on in the sequence shown in LR ON ON Figure 3. As is noted in Figure 3, there is a period of time ON OFF when both of lower N-channel FETs are turned on and both of upper P-channel FETs are turned off. This provides a - V EL 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 + V EL during the discharge of EL panel capacitance and operates more efficiently. Discharging EL Panel Capacitance + - V = V V - EL EL EL FIGURE 3: H-BRIDGE SEQUENCING WAVEFORMS Page 10 February 2001 TOKO, Inc. TK6592xM PIN DESCRIPTIONS SUPPLY PIN (V ) CC This pin is the positive input supply for the TK6592x. 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 TK6592x. Externally, this pin is typically connected to an inductor and a rectifying diode. By modulating the switching action of the internal switch, the TK6592x 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. February 2001 TOKO, Inc. Page 11 TK6592xM DESIGN CONSIDERATIONS INDUCTOR VALUE SELECTION Designing an EL Driver utilizing the TK6592x 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 9.0 nF 12.0 nF 15.0 nF 18.0 nF 21.0 nF 24.0 nF 27.0 nF VALUE LAMP LAMP LAMP LAMP LAMP LAMP LAMP µ1V 80 H 4V 2 3V 6 3V 2 2V 9 2V 7 2V 5 24 µ2V 20 H 4V 6 4V 0 3V 6 3V 3 3V 0 2V 8 27 µ3V 30 H 5V 6 4V 9 4V 4 4V 0 3V 7 3V 4 33 µ3V 90 H 6V 1 5V 3 4V 7 4V 3 4V 0 3V 7 35 µ4V 70 H 6V 7 5V 8 5V 2 4V 8 4V 4 4V 1 39 µ5V 60 H 7V 3 6V 4 5V 7 5V 2 4V 8 4V 5 42 µ6V 80 H 8V 1 7V 0 6V 3 5V 7 5V 3 5V 0 47 µ8V 20 H 8V 9 7V 7 6V 9 6V 3 5V 8 5V 4 51 µ1V 000 H 8V 5 7V 6 6V 9 6V 4 6V 0 57 µ1V 200 H 8V 3 7V 6 7V 0 6V 6 62 µ1V 500 H 8V 5 7V 9 7V 4 69 1800µH 8V 6 V 8V 1 76 Close to 100 V operation check capacitor C voltage rating 2200µH 8V 9 V 84 1 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 2-square-inch panel (12 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 680 µH coil the peak voltage developed across a 12 nF Lamp would be approximately 70 V. In this particular example, the inductive component should have a value of 680 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 TK6592x is the appropriate driver given the frequency and input supply requirements. If the TK6592x does not have sufficient drive capability given the input supply and frequency Page 12 February 2001 TOKO, Inc. TK6592xM DESIGN CONSIDERATIONS (CONT.) requirements, the following charts will suggest the TK6593x family of EL Drivers which have higher drive capabilities. 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., TK65921 = 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., 680 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., D31FU). 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. TK65920, TK65921 TK65924, TK65925 TK65922, TK65923 USE TK6593X USE TK6593X 2200 USE TK6593X 2200 2200 D52FU 1800 1800 1800 D52FU D52FUµµµ 1500 1500 1500 D32FU 1200 D32FU 1200 1200 D32FU 1000 1000 1000 820 820 820 X 680 680 680 560 560 560 470 D31FU 470 D31FU 470 D31FU 390 390 390 180 180 180 3 4 5 6 3 4 5 6 3 4 5 6 MINIMUM SUPPLY (V) MINIMUM SUPPLY (V) MINIMUM SUPPLY (V) TK65926, TK65927 TK65928, TK65929 2200 USE TK6593X 2200 USE TK6593X 1800 1800 D52FU µµD52FU 1500 1500 1200 1200 D32FU D32FU 1000 1000 820 820 680 680 560 560 470 D31FU 470 D31FU 390 390 180 180 3 4 5 6 3 4 5 6 MINIMUM SUPPLY (V) MINIMUM SUPPLY (V) February 2001 TOKO, Inc. Page 13 INDUCTOR VALUE ( H) INDUCTOR VALUE ( H) INDUCTOR VALUE ( H) INDUCTOR VALUE ( H) INDUCTOR VALUE ( H) TK6592xM APPLICATION INFORMATION SPLIT SUPPLY APPLICATION The split power supply application of this EL driver IC is a circuit configuration (see Figure 4) in which the V IC power CC (V ) is separated or split away from the main power input (V ) supplying current to the inductor. control power + V EL CC V control from HV GND 2.7 to 6 V C EL max. 200μA 12 nF - IND EL V power L 1 from 0.9 to 20 V D 1 C 1 47 nF FIGURE 4: SPLIT SUPPLY APPLICATION CIRCUIT The voltage supplied to the V pin of the IC (V ) needs to be maintained in the 2.7 V to 6.0 V range, but the current CC control draw on this power supply rail of the system would be very small (under 200 µA). This V can be used to turn on and control off the EL lamp driver, which permits the V to be connected to the battery or other power source directly with the power least amount of resistance in the power path as possible. Now with the V power for the IC (V ) being supplied from a different source, the main power (V ) can be any CC control power voltage between 0.9 V and 20 V. But it is critical to properly select the inductor such that the proper peak current regulation is maintained over the input voltage operating range of the converter. If the inductor value is too large the current will rise too slowly and not have time to reach its set peak current trip point at low input voltages, but at high input voltage the current might rise too quickly and overshoot the set peak current trip point. The primary battery applications for this part are in a dual cell alkaline or dual cell Li-Ion system (such as a GPS or smart cell phones). These systems are assumed to have a minimum useable input voltage of 1.8 V for the dual cell alkaline system and 5.4 V for the dual cell Li-Ion system. For low converter input voltages (1.8 V and 5.4 V minimum input voltages), Table 5 shows the recommended maximum inductance value for a given device part number (therefore a given frequency of operation) and a minimum input voltage. Each cell in the table gives three inductance values; each value (in µH) corresponds to each type of specialized Toko EL driver inductors (D31FU, D32FU, and D52FU types of Toko inductors). Page 14 February 2001 TOKO, Inc. TK6592xM APPLICATION INFORMATION (CONT.) TABLE 5: DUAL CELL ALKALINE AND DUAL CELL LI-ION INDUCTANCE SELECTION TABLE PART NO. TK65920 TK65921 TK65922 TK65923 TK65924 TK65925 TK65926 TK65927 TK65928 TK65929 f lamp 175 Hz 200 Hz 225 Hz 250 Hz 275 Hz 300 Hz 325 Hz 350 Hz 375 Hz 400 Hz f converter 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 min.Vp L type D31FU 390µH 390µH 390µH 390µH 390µH 390µH 390µH 330µH 330µH 330µH 1.8V D32FU 560µH 560µH 470µH 470µH 470µH 470µH 390µH 390µH 390µH 330µH D52FU 680µH 680µH 560µH 560µH 560µH 470µH 470µH 470µH 390µH 390µH D31FU1Hµ000 1000µH 1000µH 1000µH 1000µH 1000µH 1000µH 1000µH 1000µH 1000µH 5.4V D32FU 1Hµ200 1200µH 1200µH 1200µH 1200µH 1200µH 1200µH 1200µH 1200µH 1200µH D52FU2Hµ700 2200µH 2200µH 1800µH 1800µH 1800µH 1500µH 1500µH 1500µH 1200µH After selecting the inductor type and value, Table 4 of the TK6592X data sheet can be used to determine the typical output voltage for a given loading of EL lamp capacitance. If you wish to reduce this output voltage, just reduce the inductor’s inductance value. 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/coil section. 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. February 2001 TOKO, Inc. Page 15 TK6592xM LAYOUT Actual Size 2x SPLIT SUPPLY LAYOUT Actual Size 2x Page 16 February 2001 TOKO, Inc. TK6592xM NOTES February 2001 TOKO, Inc. Page 17 TK6592xM NOTES Page 18 February 2001 TOKO, Inc. TK6592xM NOTES February 2001 TOKO, Inc. Page 19 TK6592xM PACKAGE OUTLINE Marking Information SOT23L-6 Marking TK65920 B0 +0.15 0.4 - 0.05 TK65921 B1 0.1 M 0.6 TK65922 B2 6 TK65923 B3 Marking TK65924 B4 TK65925 B5 TK65926 B6 TK65927 B7 TK65928 B8 TK65929 B9 +0.15 123 - 0.05 0.32 e e 0.1 0.95 0.95 M 5 PL e e 0.95 0.95 Recommended Mount Pad +0.3 - 0.1 3.5 2.2 (3.4) 0.4 + 0.3 3.3 Dimensions are shown in millimeters Tolerance: x.x = ± 0.2 mm (unless otherwise specified) 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 Western Regional Office Semiconductor Technical Support Toko America, Inc. Toko America, Inc. Toko Design Center 1250 Feehanville Drive 2480 North First Street , Suite 260 4755 Forge Road Mount Prospect, IL 60056 San Jose, CA 95131 Colorado Springs, CO 80907 Tel: (847) 297-0070 Tel: (408) 432-8281 Tel: (719) 528-2200 Fax: (847) 699-7864 Fax: (408) 943-9790 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 20 February 2001 TOKO, Inc. © 1999 Toko, Inc. IC-xxx-TK6592x Printed in the USA All Rights Reserved 0798O0.0K 1.4 max 0 - 0.1 1.2 +0.15 - 0.05 0.3 0.15 1.0 e1 3.0 15 max