® SP4501 EL Plus Piezo Driver ■ Integrated EL Plus Piezo Driver For Portable Electronic Devices ■ Reduces System Cost, Size & Component Count ■ +2.2V to +6.0V Battery Operation ■ A Single External Coil Drives Both the EL Lamp and Piezotransducer Circuitry ■ Piezotransducer Can Be Driven By an External Clock or Internal Clock ■ A Single Resistor Controls the Internal Oscillator ■ DC-to-AC Inverter Produces Up To 200VP-P to Drive EL Lamps ■ DC-to-AC Inverter Produces Waveform to Drive Piezotransducer ■ Low Current Standby Mode Draws Less than 1µA APPLICATIONS ■ PDA's ■ Pagers ■ GPS ■ Hand Held Medical Devices DESCRIPTION The SP4501 provides designers with both an electroluminescent lamp driver for backlighting and a piezotransducer driver to generate audio alert tones. The integration of an EL lamp driver and a piezotransducer driver in a single cost-effective IC reduces system cost, board space requirements and component count. The SP4501 is ideal for portable applications such as pagers, electronic games, PDAs, medical equipment, and designs with liquid crystal displays, keypads, and backlit readouts. The SP4501 will operate from a +2.2V to +6.0V source. The device features a low power standby mode which draws less than 1µA (typical). The frequency of the internal oscillator is set with a single external resistor. The piezotranducer driver can be driven with the internally generated clock signal or an external clock signal provided by the designer. A single inductor is required to generate the high voltage AC used to drive the EL lamp and the piezotransducer. All input pins are ESD protected with diodes to VDD and VSS. ELEN 1 14 VDD PZEN 2 13 EL2 3 12 EL1 ROSC PZCK 4 SP4501 11-14-00 11 PZ2 10 PZ1 PZCK 5 no connect 6 9 CAP VSS 7 8 COIL SP4501 EL Plus Piezo Driver 1 © Copyright 2000 Sipex Corporation ABSOLUTE MAXIMUM RATINGS STORAGE CONSIDERATIONS Storage in a low humidity environment is preferred. Large high density plastic packages are moisture sensitive and should be stored in Dry Vapor Barrier Bags. Prior to usage, the parts should remain bagged and stored below 40°C and 60%RH. If the parts are removed from the bag, they should be used within 48 hours or stored in an environment at or below 20%RH. If the above conditions cannot be followed, the parts should be baked for four hours at 125°C in order remove moisture prior to soldering. Sipex ships product in Dry Vapor Barrier Bags with a humidity indicator card and desiccant pack. The humidity indicator should be below 30%RH. These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. Power Supply, VDD.................................................7.0V Input Voltages, Logic.....................-0.3V to (VDD+0.3V) Lamp Outputs...................................................220VP-P Operating Temperature.........................-40˚C to +85˚C Storage Temperature..........................-65˚C to +150˚C Power Dissipation Per Package 14-pin SOIC (derate 8.33mW/˚C above +70˚C)....................700mW 14-pin TSSOP (derate 9.96mW/˚C above +70˚C)....................800mW The information furnished by Sipex has been carefully reviewed for accuracy and reliability. Its application or use, however, is solely the responsibility of the user. No responsibility for the use of this information become part of the terms and conditions of any subsequent sales agreement with Sipex. Specifications are subject to change without no responsibility for any infringement of patents or other rights of third parties which may result from its use. No license or other proprietary rights are granted by implication or otherwise under any patent or patent rights of Sipex Corporation. SPECIFICATIONS VDD = +3.0V, L = 470µH, CLAMP = 8nF, CPZ = 16nF, CINT = 1800pF ROSC = 500kΩ, and TAMB = 25˚C unless otherwise noted. PARAMETER MIN. TYP. MAX. Supply Voltage, VDD 2.2 3.0 6.0 V Supply Current, ICOIL+IDD 28 48 90 mA 1.0 0.1 µA 0.25 V Standby Current Input Voltage for ELEN and PZEN, PZCK, PZCK LOW HIGH 2.75 Input Impedance ELEN and PZCK PZEN and PZCK 0 3.0 1 CONDITIONS UNITS MΩ LCOIL = 470µF VELEN = 0V Inductor Drive Coil Frequency, fOSC 37.0 Duty Cycle of fOSC 45.7 54.7 kHz 100 mA 90 % Peak Coil Current EL Lamp/ Piezo Driver Output Piezo Output Voltage, VPZ 25 Lamp Output Voltage, VEL 110 EL Lamp Frequency, fLAMP 289 357 427 Piezo Frequency, fPZ 2.3 2.9 3.4 11-14-00 V fpiezo = 3.1kHz, PZEN = HIGH; TAMB = +25OC TAMB = -40OC to +85OC V TAMB = +25OC TAMB = -40OC to +85OC Hz TAMB = +25OC TAMB = -40OC to +85OC kHz PZEN = HIGH; TAMB = +25OC TAMB = -40OC to +85OC SP4501 EL Plus Piezo Driver 2 © Copyright 2000 Sipex Corporation Electroluminescent Technology The internal diode forward biases when the coil voltage rises above the H-Bridge voltage and the energy enters the EL lamp. Each pulse increases the voltage across the lamp in discrete steps. An EL lamp consists of a thin layer of phosphorous material sandwiched between two strips of plastic which emits light (flouresces) when a high voltage AC signal is applied across it. It behaves primarily as a capacitive load. Long periods of DC voltage applied to the material tend to reduce its lifetime. With these conditions in mind, the ideal signal to drive an EL lamp is a high voltage sine wave. Traditional approaches to achieve this type of waveform include discrete circuits incorporating a transformer, transistors and several resistors and capacitors. This approach is large and bulky and cannot be implemented in most handheld equipment. Sipex offers low power single chip driver circuits specifically designed to drive small to medium sized electroluminescent panels. Sipex EL drivers provide a differential AC voltage without a DC offset to maximize EL lamp lifetime. The only additional components required for the EL driver circuitry are an inductor, resistor and capacitor. As the voltage approaches its maximum, the steps become smaller. (see figure 4). The brightness of the EL lamp output is directly related to energy recovery in the boost converter. There are many variations among coils such as magnetic core differences, winding differences and parasitic capacitances. For suggested coil suppliers refer to page 10. Oscillator The internal oscillator generates a high frequency clock used by the boost converter and H-Bridge. An external resistor from VDD to ROSC sets the oscillator frequency. Typically a 500kΩ resistor sets the frequency to 45.7kHz. The high frequency clock directly controls the coil switch. This high frequency clock is divided by 128 to generate a low frequency clock which controls the EL H-Bridge and sets the EL lamp frequency. The high frequency clock is divided by 16 to create a medium frequency clock to drive the piezo H-Bridge. The oscillator has low sensitivity to temperature and supply voltage variations, increasing the performance of the EL driver over the operating parameters. Electroluminescent backlighting is ideal when used with LCD displays, keypads or other backlit readouts. EL lamps uniformly light an area without creating any undesirable "hot spots" in the display. Also, an EL lamp typically consumes less power that LED's or incandescent bulbs in similar lighting situations. These features make EL ideal for attractive, battery powered products. Dual H-Bridge The H-Bridge consists of two SCR structures and two NPN transistors that control how the lamp is charged. Setting ELEN to HIGH activates the EL H-Bridge. The EL driver illuminates the lamp by applying the high voltage supply of the boost converter to the lamp terminals through the H-Bridge and then switching the terminal polarity between the high voltage supply and ground at a constant frequency. This applies an AC voltage to the lamp that is twice the peak output voltage of the boost driver. An AC voltage greater than the 40V across the terminals of the lamp is necessary to adequately illuminate the EL lamp. The piezo driver output applies an AC voltage to the piezotransducer in a similar manner. The piezo driver operates in two modes. THEORY OF OPERATION Coil Switch The SP4501 has an inductor-based boost converter to generate the high voltage used to drive the EL lamp. Energy is stored in the inductor according to the equation EL = 1/2 (LIpk2) where Ipk = (tON) (VBATT - VCEsat) /L. An internal oscillator controls the coil switch. During the time the coil switch is on, the coil is connected between VDD and the saturation voltage of the coil switch and a magnetic field develops in the coil. When the coil switch turns off, the switch opens, the magnetic field collapses and the voltage across the coil rises. 11-14-00 SP4501 EL Plus Piezo Driver 3 © Copyright 2000 Sipex Corporation A logic HIGH on pin PZEN will enable the piezo driver and apply a waveform to the piezotransducer until PZEN is released. This waveform will produce a tone that is 1/16 the frequency of the internal oscillator. Alternately, an external clock applied to PZCK or PZCK pins will enable the piezo driver and generate a tone at the applied clock frequency. Larger lamps require more energy to illuminate. Lowering the oscillator frequency allows more energy to be stored in the coil during each coil switch cycle and increases lamp brightness. The oscillator frequency can be lowered to a point where the lamp brightness then begins to drop because the lamp frequency must be above a critical frequency (approx. 100Hz) to light. Lamp color is affected by the switching frequency of the EL driver. Green EL lamps will emit a more blue light as EL lamp frequency increases. The external applied clock frequency should be greater than fosc/64. To put the circuit in an inactive state it is required that PZCK remain at logic LOW and PZCK remain at logic HIGH. The piezo driver and the EL driver may be operated simultaneously but with decreased light output from the EL panel. Noise Decoupling on Logic Inputs If ELEN, PZEN, PZCK or PZCK are connected to traces susceptible to noise, it may be necessary to connect bypass capacitors of approximately 10nF between ELEN and VSS, PZEN and VSS, PZCK and VSS, and PZCK and VDD. If these inputs are driven by a microprocessor which provides a low impedance HIGH and LOW signal, then noise bypassing may not be necessary. If some inputs are unused (as PZCK and PZCK may be) then these inputs should be tied to the power supply that sets the input to an inactive state. DESIGN CONSIDERATIONS Inductor Selection If limiting peak current draw from the power supply is important, small coil values (<1mH) may need a higher oscillator frequency. Inductor current ramps faster in a lower inductance coil than a higher inductance coil for a given coil switch on time period, resulting in higher peak coil currents. Increasing Light Output EL lamp light output can be improved by connecting a fast recovery diode from the COIL pin to the CAP pin. The internal diode is bypassed resulting in an increase in light output at the EL lamp. We suggest a fast recovery diode such as the industry standard 1N4148. It is important to observe the saturation current rating of a coil. When this current is exceeded, the coil is incapable of storing any more energy and then ceases to act as an inductor. Instead, the coil behaves according to its series DC resistance. Since small coils (<1mH) have inherently low series DC resistance, the current can peak dramatically through a small coil during saturation. This situation results in wasted energy not stored in the magnetics of the coil but expressed as heating which could lead to failure of the coil. The optimal value of CINT will vary depending on the lamp parameters and coil value. Lower CINT values can decrease average supply current but higher CINT values can increase lamp brightness. This is best determined by experimentation. A rule of thumb is larger coils (1mH) are paired with a smaller CINT (680pF) and smaller coils (470µH) are paired with a larger CINT (1800pF). Generally, selecting a coil with lower series DC resistance will result in a system with higher efficiency and lamp brightness. Changing the EL lamp Output Voltage Waveform Designers can alter the sawtooth output voltage waveform to the EL lamp. Increasing the capacitance of the integration capacitor, CINT, will integrate the sawtooth waveform making it Lamp Effects EL lamp parameters vary between manufacturers. Series DC resistance, lighting efficiency and lamp capacitance per area differ the most overall. 11-14-00 SP4501 EL Plus Piezo Driver 4 © Copyright 2000 Sipex Corporation appear more like a square wave. Printed Circuit Board Layout Suggestions The EL driver's high-frequency operation makes PCB layout important for minimizing electrical noise. Keep the IC's GND pin and the ground leads of C1 and CINT less than 0.2in (5mm) apart. Also keep the connections to the COIL pin as short as possible. To maximize output power and efficiency and minimize output ripple voltage, use a ground plane and solder the IC's VSS pin directly to the ground plane. EL Lamp Driver Design Challenges There are many variables which can be optimized for specific applications. The amount of light emitted is a function of the voltage applied to the lamp, the frequency at which is applied, the lamp material, the lamp size, and the inductor used. Sipex supplies characterization charts to aid the designer in selecting the optimum circuit configuration. Sipex will perform customer application evaluations, using the customer's actual EL lamp to determine the optimum operating conditions for specific applications. For customers considering an EL backlighting solution for the first time, Sipex is able to provide retrofits to non-backlit products for a thorough electrical and cosmetic evaluation. Please contact your local Sipex sales Representative or the Sipex factory directly to initiate this valuable service. 11-14-00 SP4501 EL Plus Piezo Driver 5 © Copyright 2000 Sipex Corporation VDD 14 8 9 COIL CAP SP4501 fOSC ROSC SCR2 SCR1 SCR4 SCR3 3 fLAMP FF3 FF4 OSC EN fOSC ELEN fLAMP 1 INT CLOCK PZEN fPZ SELECT SELECTION LOGIC 2 fPZ EXT CLOCK CLOCK SENSORY CIRCUIT 5 1 PZCK 12 7 PZCK VSS 13 EL1 EL2 10 11 PZ1 PZ2 Figure 1: Internal Block Diagram of SP4501 +3V +3V ELEN 500kΩ 14 1 PZEN ROSC VDD 0.1µF EL2 2 13 3 12 EL1 4 11 CEL 2 7.3nF, 2.5in PZ2 10nF PZCK SP4501 10 PZ1 5 PZCK N/C VSS 6 9 7 8 CPZ 16nF 1800pF CAP 1N4148 COIL +3V 820µH* *DC Resistance 13Ω* Figure 2: Test Circuit of the SP4501 11-14-00 SP4501 EL Plus Piezo Driver 6 © Copyright 2000 Sipex Corporation PERFORMANCE CHARACTERISTICS 600 90 550 80 60 50 40 IDD 30 5.5 500 5.0 450 4.5 400 4.0 350 3.5 3.0 300 250 2.5 Lumi. 20 200 2.0 10 150 1.5 0 100 200 400 600 800 1000 1.0 200 400 600 R OSC (kΩ) Figure 4: Lamp Frequency and Luminance vs. Oscillator Frequency. 14.0 120 12.0 100 8.0 60 6.0 4.0 Lumi. 20 IDD (mA), VCAP,pk (V) 10.0 VCAP,pk Luminance (ft-L) IDD (mA), VCAP,pk (V) 140 40 2.0 IDD 0 0.0 2.0 3.0 4.0 1000 R OSC (kΩ) Figure 3: Supply Current and Cap Pin Voltage vs. Oscillator Resistance. 80 800 5.0 100 90 80 70 60 50 40 30 20 10 0 Lumi. 5.0 4.0 3.0 2.0 1.0 0.0 IDD 400 6.0 10.0 9.0 8.0 7.0 6.0 VCAP,pk 500 600 700 800 900 Luminance (ft-L) IDD (mA), VCAP,pk (V) Lamp Freq. (Hz) VCAP,pk 70 6.0 Freq. Luminance (ft-L) 100 1000 Inductor Value (µH) VDD (V) Figure 5: Supply Current and Luminance vs. Supply Voltage. Figure 6: Supply Current and Luminance vs. Inductor Value. 70 60 Vpz-pk (V) 50 40 30 20 10 0 0 1000 2000 3000 4000 5000 6000 7000 frequency (Hz) Figure 7: Piezo Output Voltage vs. PZCK Input Frequency. 11-14-00 SP4501 EL Plus Piezo Driver 7 © Copyright 2000 Sipex Corporation VBATT ELEN 1 PZEN 2 VDD ROSC 500kΩ C1 0.1µF ROSC L1 470µH 14 8 SP4501 3 9 CAP *C2 10nF *D1 1N4148 CINT 1800pF 7 EXT CLK COIL PZCK 4 PZCK 5 VHIGH = VDD VLOW = VSS VSS *optional devices 10 11 PZ1 12 13 PZ2 CPZ EL1 EL2 EL Lamp Figure 8: Typical Application Circuit of the SP4501 Figure 9: Typical EL Lamp Voltage Waveform 11-14-00 SP4501 EL Plus Piezo Driver 8 © Copyright 2000 Sipex Corporation PIN ASSIGNMENTS Pin 7 — VSS — Power Supply Ground. Connect to the lowest circuit potential, typically ground Pin 1 — ELEN — Electroluminescent Lamp Enable. When driven HIGH, this input pin enables the EL driver outputs. This pin has an internal pulldown resistor. Pin 8 — COIL — Coil. The inductor for the boost converter is connected from VBATT to this pin. Pin 2 — PZEN — Piezo Enable. When this input pin is driven HIGH, the piezo operates at a frequency fOSC/16. When this input pin is LOW, the clock signals applied to PZCK or PZCK will drive the internal piezo circuitry. This pin has an internal pulldown resistor. Pin 9 — CAP — Integrator Capacitor. An integrator capacitor connected from this pin to ground filters out any coil switching spikes or ripple present in the output waveform to the EL lamp. Connecting a fast recovery diode from COIL to CAP increases the light output of the EL lamp. Pin 3 — ROSC — Oscillator Resistor. Connecting a resistor between this pin and VDD sets the frequency of the internal clock. Pin 10 — PZ1 — Piezotransducer Output. Connect this pin to the piezotransducer. Pin 4 — PZCK — Inverse Piezo Clock. When PZEN is LOW, the internal piezo circuit will operate at the frequency of the clock signal applied to this input pin. For the piezo driver to rest in the inactive mode, it is required that PZCK remains at logic HIGH. This pin has an internal pullup resistor. Pin 11 — PZ2 — Piezotransducer Output. Connect this pin to the piezotransducer. Pin 12 — EL1 — Electroluminescent Lamp Output. Connect this pin to the EL lamp. Pin 13 — EL2 — Electroluminescent Lamp Output. Connect this pin to the EL lamp. Pin 5 — PZCK — Piezo Clock. When PZEN is LOW, the internal piezo circuit will operate at the frequency of the clock signal applied to this input pin. For the piezo driver to rest in the inactive mode, it is required that PZCK remains at logic LOW. This pin has an internal pulldown resistor. Pin 14 — VDD — Positive Power Supply. This pin should be bypassed with a 0.1µF capacitor. Pin 6 — No connect. . 11-14-00 SP4501 EL Plus Piezo Driver 9 © Copyright 2000 Sipex Corporation Coil Manufacturers Hitachi Metals Material Trading Division 2101 S. Arlington Heights Road, Suite 116 Arlington Heights, IL 60005-4142 Phone: 1-800-777-8343 Ext. 12 (847) 364-7200 Ext. 12 Fax: (847) 364-7279 Hitachi Metals Ltd. Europe Immernannstrasse 14-16, 40210 Dusseldorf, Germany Contact: Gary Loos Phone: 49-211-16009-0 Fax: 49-211-16009-29 Hitachi Metals Ltd. Kishimoto Bldg. 2-1, Marunouchi 2-chome, Chiyoda-Ku, Tokyo, Japan Contact: Mr. Noboru Abe Phone: 3-3284-4936 Fax: 3-3287-1945 Hitachi Metals Ltd. Singapore 78 Shenton Way #12-01, Singapore 079120 Contact: Mr. Stan Kaiko Phone: 222-8077 Fax: 222-5232 Murata 2200 Lake Park Drive, Smyrna Georgia 30080 U.S.A. Phone: (770) 436-1300 Fax: (770) 436-3030 Panasonic. 6550 Katella Ave Cypress, CA 90630-5102 Phone: (714) 373-7366 Fax: (714) 373-7323 Murata European Holbeinstrasse 21-23, 90441 Numberg, Postfachanschrift 90015 Phone: 011-4991166870 Fax: 011-49116687225 Sumida Electric Co., LTD. 5999, New Wilke Road, Suite #110 Rolling Meadows, IL,60008 U.S.A. Phone: (847) 956-0666 Fax: (847) 956-0702 Murata Taiwan Electronics 225 Chung-Chin Road, Taichung, Taiwan, R.O.C. Phone: 011 88642914151 Fax: 011 88644252929 Murata Electronics Singapore 200 Yishun Ave. 7, Singapore 2776, Republic of Singapore Phone: 011 657584233 Fax: 011 657536181 Murata Hong Kong Room 709-712 Miramar Tower, 1 Kimberly Road, Tsimshatsui, Kowloon, Hong Kong Phone: 011-85223763898 Fax: 011-85223755655 Hitachi Metals Ltd. Hong Kong Room 1107, 11/F., West Wing, Tsim Sha. Tsui Center 66 Mody Road,Tsimshatsui East, Kowloon, Hong Kong Phone: 2724-4188 Fax: 2311-2095 Polarizers/transflector Mnfg. EL Lamp Manufacturers Nitto Denko Yoshi Shinozuka Bayside Business Park 48500 Fremont, CA. 94538 Phone: 510 445 5400 Fax: 510 445-5480 Leading Edge Ind. Inc. 11578 Encore Circle Minnetonka, MN 55343 Phone 1-800-845-6992 Top Polarizer- NPF F1205DU Bottom - NPF F4225 or (F4205) P3 w/transflector Transflector Material Astra Products Mark Bogin P.O. Box 479 Baldwin, NJ 11510 Phone (516)-223-7500 Fax (516)-868-2371 11-14-00 Midori Mark Ltd. 1-5 Komagata 2-Chome Taita-Ku 111-0043 Japan Phone: 81-03-3848-2011 Luminescent Systems inc. (LSI) 4 Lucent Dr. Lebanon, NH. 03766 Phone: (603) 643-7766 Fax: (603) 643-5947 SP4501 EL Plus Piezo Driver 10 Sumida Electric Co., LTD. 4-8, Kanamachi 2-Chrome, Katsushika-ku, Tokyo 125 Japan Phone: 03-3607-5111 Fax: 03-3607-5144 Sumida Electric Co., LTD. Block 15, 996, Bendemeer Road #04-05 to 06, Singapore 339944 Republic of Singapore Phone: 2963388 Fax: 2963390 Sumida Electric Co., LTD. 14 Floor, Eastern Center, 1065 King's Road, Quarry Bay, Hong Kong Phone: 28806688 Fax: 25659600 NEC Corporation Yumi Saskai 7-1, Shiba 5 Chome, Minato-ku, Tokyo 108-01, Japan Phone: (03) 3798-9572 Fax: (03) 3798-6134 Seiko Precision Shuzo Abe 1-1, Taihei 4-Chome, Sumida-ku, Tokyo, 139 Japan Phone: (03) 5610-7089 Fax: (03) 5610-7177 Gunze Electronics 2113 Wells Branch Parkway Austin, TX 78728 Phone: (512) 752-1299 Fax: (512) 252-1181 © Copyright 2000 Sipex Corporation PACKAGE: PLASTIC NARROW SMALL OUTLINE (NSOIC) E H D A Ø e 11-14-00 B A1 L DIMENSIONS in. (mm) Minimum/Maximum 14–PIN A 0.053/0.069 (1.346/1.748) A1 0.004/0.010 (0.102/0.249) B 0.014/0.018 (0.360/0.460) D 0.337/0.344 (8.552/8.748) E 0.150/0.157 (3.802/3.988) e 0.050 BSC (1.270 BSC) H 0.228/0.244 (5.801/6.198) L 0.016/0.050 (0.406/1.270) Ø 0°/8° (0°/8°) SP4501 EL Plus Piezo Driver 11 © Copyright 2000 Sipex Corporation PACKAGE: PLASTIC THIN SMALL OUTLINE (TSSOP) E2 E1 D A Ø e B A1 L DIMENSIONS in inches (mm) Minimum/Maximum 14–PIN A - /0.043 ( /1.10) A1 0.002/0.006 (0.05/0.15) B 0.007/0.012 (0.19/0.30) D 0.193/0.201 (4.90/5.10) E1 0.169/0.177 (4.30/4.50) e 0.026 BSC (0.65 BSC) E2 0.126 BSC (3.20 BSC) L 0.020/0.030 (0.50/0.75) Ø 0°/8° ORDERING INFORMATION Model Temperature Range Package Type SP4501EN .............................................. -40˚C to +85˚C ....................................... 14-Pin NSOIC SP4501EY .............................................. -40˚C to +85˚C ...................................... 14-Pin TSSOP SP4501NEB ............................................................................................ NSOIC Evaluation Board Corporation SIGNAL PROCESSING EXCELLENCE Sipex Corporation Headquarters and Main Offices 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: [email protected] 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600 Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.