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TK6592x
MEDIUM EL LAMP DRIVER FEATURES
s s s s s s s s s s s s s s High Ratio of Brightness / Input Power Constant Brightness Versus Input Supply Changes Optimized for 9 nf to 27 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) Split Power Supply Application
APPLICATIONS
s s s s s s 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 TK6592x, 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 TK6592x 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 TK6592x is available in a miniature, 6-pin SOT23L-6 surface mount package TK6592x
EL+ VCC GND IND
DESCRIPTION
The TK6592x 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. The proprietary architecture (detailed in the Theory of 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, without the need for directly sensing the high voltage output of the EL driver.
20 P
HV EL-
BLOCK DIAGRAM
IND VCC HV BOOST CONTROL GND
ORDERING INFORMATION
TK6592 MTL
Lamp Frequency Code
OSCILLATOR HV EL+ H BRIDGE EL-
LAMP FREQUENCY CODE
TK65920 TK65921* TK65922 TK65923* TK65924 175 Hz 200 Hz 225 Hz 250 Hz 275 Hz TK65925* TK65926 TK65927* TK65928 TK65929* 300 Hz 325 Hz 350 Hz 375 Hz 400 Hz
TAPE/REEL CODE
TL: Tape Left * Consult factory for availability of other frequencies.
May 2000 TOKO, Inc.
Page 1
TK6592x
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
TK6592x ELECTRICAL CHARACTERISTICS
VCC = 3.6 V, TA = Tj = 25 C, unless otherwise specified.
SYMBOL V CC IQ IPEAK FLAMP FBOOST V CLAMP D(MAX) V OUT ICONV
PARAMETER Input Supply Range Quiescent Current Peak Current Threshold Lamp Frequency Boost Frequency Boost Clamp Voltage Maximum Duty Cycle Peak to Peak Lamp Voltage Converter Supply Current
TEST CONDITIONS
MIN 2.7
TYP 3.6
MAX 6 200
UNITS V A mA Hz kHz
Current into pin 6 44 52 See Table 1 See Table 2 Force 100 A into HV pin 90 88 (Note 3) (Notes 2, 3) 125 105 92 140 See Table 3
60
120 96 155
V % V 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. Gen. Note: Refer to "INDUCTOR VALUE SELECTION" and "INDUCTOR TYPE SELECTION" of Design Considerations Section for choosing inductor.
TEST CIRCUIT
EL + HV EL VCC GND ICONV VCC CEL 12 nF
IND L1 680 H
C1 47 nF
D1
Note: L1 = Toko Low Profile D52FU Series: 875FU-681 M D1 = DIODES INC. DL4148 C1 = AVX 12061C473KAT2A
Page 2
May 2000 TOKO, Inc.
TK6592x
TK6592x ELECTRICAL CHARACTERISTICS
VIN = 3.6 V, TA = Tj = 25 C, unless otherwise specified. TABLE 1: LAMP FREQUENCY
TOKO PART NO. TK65920 TK65921 TK65922 TK65923 TK65924 TK65925 TK65926 TK65927 TK65928 TK65929 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
TABLE 2: OSCILLATOR FREQUENCY
TOKO PART NO. TK65920 TK65921 TK65922 TK65923 TK65924 TK65925 TK65926 TK65927 TK65928 TK65929 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
TABLE 3: CONVERTER SUPPLY CURRENT
TOKO PART NO. TK65920 TK65921 TK65922 TK65923 TK65924 TK65925 TK65926 TK65927 TK65928 TK65929 MIN. TYP. 7.8 mA 9.0 mA 10.1 mA 11.2 mA 12.3 mA 13.4 mA 14.5 mA 15.6 mA 16.8 mA 17.9 mA MAX. 15.6 mA 18.0 mA 20.2 mA 22.4 mA 24.6 mA 26.8 mA 29.0 mA 31.2 mA 33.6 mA 35.8 mA
May 2000 TOKO, Inc.
Page 3
TK6592x
TYPICAL PERFORMANCE CHARACTERISTICS USING TEST CIRCUIT
TK65921 Voltage Waveform Across 12 nF Lamp
TK65921 PEAK TO PEAK LAMP VOLTAGE vs. SUPPLY VOLTAGE
TK65929 Voltage Waveform Across 12 nF Lamp
TK65929 PEAK TO PEAK LAMP VOLTAGE vs. SUPPLY VOLTAGE
160
160
150
VOUT (V) VOUT (V)
L1 = 680 H
150
L1 = 680 H
140
140
130
L1 = 560 H
130
L1 = 560 H
120 2.5
3
3.5
4
4.5
5
5.5
6
120 2.5
3
3.5
4
4.5
5
5.5
6
VCC (V)
TK65921 LAMP FREQUENCY vs. SUPPLY VOLTAGE
VCC (V)
TK65929 LAMP FREQUENCY vs. SUPPLY VOLTAGE
230 220
460 440
FLAMP (Hz)
FLAMP (Hz)
3 3.5 4 4.5 5 5.5 6
210 200 190 180 2.5
420 400 380 360 2.5
3
3.5
4
4.5
5
5.5
6
VCC (V)
VCC (V)
Page 4
May 2000 TOKO, Inc.
TK6592x
TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT
TK65921 AVERAGE CONVERTER SUPPLY CURRENT vs. SUPPLY VOLTAGE TK65929 AVERAGE CONVERTER SUPPLY CURRENT vs. SUPPLY VOLTAGE
18 16 14 ICONV (mA) 12 10 8 6 4 2 0
26 24 22
ICONV (mA)
20 18 16 14 12 10 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
VCC (V)
VCC (V)
60 55
TK65921 PEAK CURRENT THRESHOLD vs. SUPPLY VOLTAGE
60 55
TK65929 PEAK CURRENT THRESHOLD vs. SUPPLY VOLTAGE
IPEAK (mA)
45 40 35 30 2.5 3 3.5 4 4.5 5 5.5 6 VCC (V)
TK65921 QUIESCENT CURRENT vs. SUPPLY VOLTAGE
IPEAK (mA)
50
50 45 40 35 30 2.5 3 3.5 4 4.5 5 5.5 6 VCC (V)
TK65929 QUIESCENT CURRENT vs. SUPPLY VOLTAGE
200
200
150 IQ (A) IQ (A) 3 3.5 4 4.5 5 5.5 6
150
100
100
50
50
0 2.5
0 2.5
3
3.5
4
4.5
5
5.5
6
VCC (V)
VCC (V)
May 2000 TOKO, Inc.
Page 5
TK6592x
TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT
TK65921 PEAK TO PEAK LAMP VOLTAGE vs. TEMPERATURE TK65929 PEAK TO PEAK VOLTAGE vs. TEMPERATURE
160 150
VOUT (V)
160 150
VOUT (V)
140 130 120 110 -50 -25 0 25
V = 2.7 V
V
CC
= 3.6 V
140 130 120 110
VCC = 3.6 V
CC
VCC = 2.7 V
50
75
100 125
-50 -25
0
25
50
75
100 125
TEMPERATURE (C)
TK65921 LAMP FREQUENCY vs. TEMPERATURE 440 420
TEMPERATURE (C)
TK65929 LAMP FREQUENCY vs. TEMPERATURE
220 210
FLAMP (Hz)
200 190 180 170 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
TK65921 AVERAGE CONVERTER SUPPLY CURRENT vs. TEMPERATURE 14 12
FLAMP (Hz)
400 380 360 340 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
TK65929 AVERAGE CONVERTER SUPPLY CURRENT vs. TEMPERATURE 22 20
ICONV (mA)
ICONV (mA)
10 8
18 16
6 4 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
14 12 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
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May 2000 TOKO, Inc.
TK6592x
TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING TEST CIRCUIT
TK65921 PEAK CURRENT THRESHOLD vs. TEMPERATURE TK65929 PEAK CURRENT THRESHOLD vs. TEMPERATURE
58 56 54
58 56 54
IPEAK (mA)
52 50 48 46 44 42 -50 -25 0 25
VCC = 3.6 V
IPEAK (mA)
52 50 48 46 44
VCC = 2.7 V VCC = 3.6 V
VCC = 2.7 V
50
75
100 125
42 -50 -25
0
25
50
75
100 125
TEMPERATURE (C)
TEMPERATURE (C)
TK65921 QUIESCENT CURRENT vs. TEMPERATURE 100 90
IQ (A)
TK65929 QUIESCENT CURRENT vs. TEMPERATURE 100 90
IQ (A)
80 70 60 50 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
80 70 60 50 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
May 2000 TOKO, Inc.
Page 7
TK6592x
TYPICAL PERFORMANCE CHARACTERISTICS (CONT.) USING D(MAX) TEST CIRCUIT
TK65921 MAXIMUM DUTY CYCLE vs. SUPPLY VOLTAGE TK65929 MAXIMUM DUTY CYCLE vs. SUPPLY VOLTAGE
95 94
95 94
D(MAX) (%)
D(MAX) (%)
93 92 91 90 2.5 3 3.5 4 4.5 5 5.5 6 VCC (V)
93 92 91 90 2.5 3 3.5 4 4.5 5 5.5 6 VCC (V)
TK65929 MAXIMUM DUTY CYCLE vs. TEMPERATURE 95 94
TK65921 MAXIMUM DUTY CYCLE vs. TEMPERATURE 95 94
D(MAX) (%)
D(MAX) (%)
93 92 91 90 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
93 92 91 90 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
D(MAX) TEST CIRCUIT
EL + HV EL VCC VCC GND
IND R1
Note: R1 = 470
Page 8
May 2000 TOKO, Inc.
TK6592x
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 TK6592x series of devices has been optimized to drive EL panels, which are approximately 2-4 square inches in size. 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 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 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 TK6592x 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 TK6592x 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 TK6592x 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 TK6592x is driving a 2-square-inch EL Lamp with a capacitance of approximately 12 nF.
EL + HV EL VCC VIN CEL 12 nF GND
IND L1
C1 47 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 TK6592x 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 TK6592x, the peak current threshold is laser-trimmed to 52 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 (52 mA) CEL = Capacitance of EL Lamp L = Inductance Value VHV = (IPEAK / 2) x (L /CEL) x 128
Page 9
TK6592x
THEORY OF OPERATION (CONT.)
With properly selected components, the TK6592x 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).
HV HVP ELEL Panel LL Current Source 1 LR Current Source 2 HVP EL+
UL
UR
DETAILS CONCERNING THE H-BRIDGE SECTION OPERATION
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. 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.
FIGURE 2: H-BRIDGE SCHEMATIC
BOTH OFF
UL UR LL LR
OFF OFF
ON OFF BOTH ON OFF ON
OFF OFF ON ON
OFF ON ON OFF
ON ON
VEL-
VEL+
Discharging EL Panel Capacitance
VEL = VEL+ - VEL-
FIGURE 3: H-BRIDGE SEQUENCING WAVEFORMS
Page 10
May 2000 TOKO, Inc.
TK6592x
PIN DESCRIPTIONS
SUPPLY PIN (VCC) 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.
May 2000 TOKO, Inc.
Page 11
TK6592x
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 VALUE 180 H 220 H 330 H 390 H 470 H 560 H 680 H 820 H 1000 H 1200 H 1500 H 1800 H 2200 H 9.0 nF LAMP 42 V 46 V 56 V 61 V 67 V 73 V 81 V 89 V 12.0 nF LAMP 36 V 40 V 49 V 53 V 58 V 64 V 70 V 77 V 85 V 15.0 nF LAMP 32 V 36 V 44 V 47 V 52 V 57 V 63 V 69 V 76 V 83 V 18.0 nF LAMP 29 V 33 V 40 V 43 V 48 V 52 V 57 V 63 V 69 V 76 V 85 V 21.0 nF LAMP 27 V 30 V 37 V 40 V 44 V 48 V 53 V 58 V 64 V 70 V 79 V 86 V 24.0 nF LAMP 25 V 28 V 34 V 37 V 41 V 45 V 50 V 54 V 60 V 66 V 74 V 81 V 89 V 27.0 nF LAMP 24 V 27 V 33 V 35 V 39 V 42 V 47 V 51 V 57 V 62 V 69 V 76 V 84 V
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 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 H 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 H. 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 May 2000 TOKO, Inc.
TK6592x
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 H). 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 2200
INDUCTOR VALUE (H)
USE TK6593X D52FU
TK65922, TK65923 2200
USE TK6593X D52FU
TK65924, TK65925 2200 1800 1500 1200 1000 820 680 560 470 390 180
USE TK6593X D52FU
INDUCTOR VALUE (H)
1800 1500 1200 1000 820 680 560 470 390 180 3 4 5 6 MINIMUM SUPPLY (V)
TK65926, TK65927 2200 1800 1500 1200 1000 820 680 560 470 390 180 3 4 5 6 MINIMUM SUPPLY (V)
USE TK6593X
D32FU
1800 1500 1200 1000 820 680 560 470 390 180 3 4
D31FU
D32FU
INDUCTOR VALUE (H)
D32FU
X
D31FU
D31FU
5
6
3
4
5
6
MINIMUM SUPPLY (V)
TK65928, TK65929 2200
INDUCTOR VALUE (H)
USE TK6593X D52FU D32FU
MINIMUM SUPPLY (V)
INDUCTOR VALUE (H)
D52FU
1800 1500 1200 1000 820 680 560 470 390 180 3 4
D32FU
D31FU
D31FU
5
6
MINIMUM SUPPLY (V)
May 2000 TOKO, Inc.
Page 13
TK6592x
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 VCC IC power (Vcontrol) is separated or split away from the main power input (Vpower) supplying current to the inductor.
EL + HV EL -
VCC GND Vcontrol from 2.7 to 6 V max. 200 A Vpower from 0.9 to 20 V
CEL 5 nF
IND L1
C1 22 nF
D1
FIGURE 4: SPLIT SUPPLY APPLICATION CIRCUIT
The voltage supplied to the VCC pin of the IC (Vcontrol) needs to be maintained in the 2.7 V to 6.0 V range, but the current draw on this power supply rail of the system would be very small (under 200 A). This Vcontrol can be used to turn on and off the EL lamp driver, which permits the Vpower to be connected to the battery or other power source directly with the least amount of resistance in the power path as possible. Now with the VCC power for the IC (Vcontrol) being supplied from a different source, the main power (Vpower) can be any 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 H) corresponds to each type of specialized Toko EL driver inductors (D31FU, D32FU, and D52FU types of Toko inductors).
Page 14
May 2000 TOKO, Inc.
TK6592x
APPLICATION INFORMATION (CONT.)
TABLE 5: DUAL CELL ALKALINE AND DUAL CELL LI-ION INDUCTANCE SELECTION TABLE
PART NO. TK65920 f lamp 175 Hz f converter 22.4 kHz min.Vp L type 1.8V D31FU D32FU D52FU D31FU D32FU D52FU 390 H 560 H 680 H 1000 H 1200 H 2700 H
TK65921 TK65922 200 Hz 225 Hz 25.6 kHz 28.8 kHz 390 H 560 H 680 H 1000 H 1200 H 2200 H 390 H 470 H 560 H 1000 H 1200 H 2200 H
TK65923 TK65924 TK65925 250 Hz 275 Hz 300 Hz 32.0 kHz 35.2 kHz 38.4 kHz 390 H 470 H 560 H 1000 H 1200 H 1800 H 390 H 470 H 560 H 1000 H 1200 H 1800 H 390 H 470 H 470 H 1000 H 1200 H 1800 H
TK65926 TK65927 325 Hz 350 Hz 41.6 kHz 44.8 kHz 390 H 390 H 470 H 1000 H 1200 H 1500 H 330 H 390 H 470 H 1000 H 1200 H 1500 H
TK65928 375 Hz 48.0 kHz 330 H 390 H 390 H 1000 H 1200 H 1500 H
TK65929 400 Hz 51.2 kHz 330 H 330 H 390 H 1000 H 1200 H 1200 H
5.4V
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. May 2000 TOKO, Inc. Page 15
TK6592x
LAYOUT
Actual Size
2x
SPLIT SUPPLY LAYOUT
Actual Size
2x
Page 16
May 2000 TOKO, Inc.
TK6592x
NOTES
May 2000 TOKO, Inc.
Page 17
TK6592x
NOTES
Page 18
May 2000 TOKO, Inc.
TK6592x
NOTES
May 2000 TOKO, Inc.
Page 19
TK6592x
PACKAGE OUTLINE
Marking Information
Marking B0 B1 B2 B3 B4 B5 B6 B7 B8 B9
SOT23L-6
+0.15 0.4 - 0.05
0.1 6
M
0.6
1.0
Marking
TK65920 TK65921 TK65922 TK65923 TK65924 TK65925 TK65926 TK65927 TK65928 TK65929
1 e
2 e 0.95
3 0.32 5 PL 0.95
+0.15 - 0.05
0.1
M
e 0.95
e 0.95
Recommended Mount Pad
3.5
+0.3 - 0.1
2.2 0.3
(3.4)
1.4 max
e1 3.0 1.2
+0.15 - 0.05
15 0 - 0.1 0.4
+ 0.3
0.15
Dimensions are shown in millimeters Tolerance: x.x = 0.2 mm (unless otherwise specified)
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 20
(c) 1999 Toko, Inc. All Rights Reserved IC-xxx-TK6592x 0798O0.0K
max
May 2000 TOKO, Inc.
Printed in the USA

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