Supertex inc. HV857 Low Noise, High Voltage EL Lamp Driver IC Features General Description Patented audible noise reduction Patented lamp aging compensation 190 VPP output voltage for higher brightness Patented output timing for high efficiency Single cell lithium ion compatible 150nA shutdown current Wide input voltage range 1.8 to 5.0V Separately adjustable lamp and converter frequencies Output voltage regulation Split supply capability Available in 8-Lead MSOP and DFN packages The Supertex HV857 is a high voltage driver designed for driving Electroluminescent (EL) lamps of up to 5.0 square inches. The input supply voltage range is from 1.8 to 5.0V. The device uses a single inductor and a minimum number of passive components. The nominal regulated output voltage that is applied to the EL lamp is 95V. The chip can be enabled/disabled by connecting the resistor on RSW-Osc to VDD/GND. The HV857 has two internal oscillators, a switching MOSFET, and a high voltage EL lamp driver. The frequency for the switching MOSFET is set by an external resistor connected between the RSW-Osc pin and the supply pin VDD. The EL lamp driver frequency is set by an external resistor connected between RELOsc pin and VDD pin. An external inductor is connected between the LX and VDD pins or VIN for split supply applications. A 0.0030.1F capacitor is connected between CS and ground. The EL lamp is connected between VA and VB. Applications LCD backlighting Mobile Cellular Phone PDAs Handheld wireless communication products Global Positioning Systems (GPS) The switching MOSFET charges the external inductor and discharges it into the capacitor at CS. The voltage at CS will start to increase. Once the voltage at CS reaches a nominal value of 95V, the switching MOSFET is turned OFF to conserve power. The outputs VA and VB are configured as an H bridge and are switching in opposite states to achieve 95V across the EL lamp. Typical Application Circuit VDD + _ ON = VDD OFF = 0 Enable Signal 1 CDD RSW 2 3 VIN + _ Doc.# DSFP-HV857 A062013 REL CIN 4 VDD HV857 VA RSW-Osc VB REL-Osc CS GND LX 8 EL Lamp 7 6 5 D LX CS Supertex inc. www.supertex.com HV857 Pin Configuration Ordering Information Part Number Package Packing HV857K7-G 8-Lead DFN HV857MG-G 8-Lead MSOP VDD 1 8 VA RSW-Osc 2 7 VB CS REL-Osc 3 6 CS LX GND 4 5 LX VDD 1 8 VA 3000/Reel RSW-Osc 2 7 VB 2500/Reel REL-Osc 3 6 GND 4 5 -G denotes a lead (Pb)-free / RoHS compliant package Pads are at the bottom of the package. Exposed center pad is at ground potential. Value -0.5V to 6.5V Supply voltage, VDD Product Marking -40C to +85C Storage temperature -65C to +150C DFN-8 power dissipation MSOP-8 power dissipation 300mW -0.5 to +120V Output voltage, VCS Package may or may not include the following marks: Si or Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Continuous operation of the device at the absolute rating level may affect device reliability. All voltages are referenced to device ground. 8-Lead DFN Top Marking H857 LLLL Typical Thermal Resistance ja 8-Lead DFN 37OC/W 8-Lead MSOP 171OC/W Y = Last Digit of Year Sealed W = Code for Week Sealed L = Lot Number = "Green" Packaging H857 YWLL 1.6W Package (top view) (top view) Parameter Operating temperature 8-Lead MSOP 8-Lead DFN Absolute Maximum Ratings L = Lot Number YY = Year Sealed WW = Week Sealed = "Green" Packaging Bottom Marking YYWW Mounted on FR4 board, 25mm x 25mm x 1.57mm Package may or may not include the following marks: Si or 8-Lead MSOP Recommended Operating Conditions Sym Parameter Min Typ Max Units VDD Supply voltage 1.8 - 5.0 V --- fEL Operating drive frequency - - 1.0 kHz --- TA Operating temperature -40 - +85 C --- O Conditions Enable/Disable Function Table Sym Parameter Min Typ Max Units EN-L EN-H Conditions Logic input low voltage 0 - 0.2 V VDD = 1.8 to 5.0V Logic input high voltage VDD - 0.2 - VDD V VDD = 1.8 to 5.0V DC Electrical Characteristics (Over recommended operating conditions unless otherwise specified, T = 25C) A Sym RDS(ON) VCS Doc.# DSFP-HV857 A062013 Parameter On-resistance of switching transistor Max. output regulation voltage Min Typ Max Units - - 6.0 I = 100mA 85 95 105 V VDD=1.8 to 5.0V 2 Conditions Supertex inc. www.supertex.com HV857 DC Electrical Characteristics (cont.) Sym Parameter Min Typ Max Units Conditions VA - VB Peak to Peak output voltage 170 190 210 V VDD=1.8 to 5.0V IDDQ Quiescent VDD supply current - - 150 nA RSW-Osc = Low IDD Input current going into the VDD pin - - 150 A VDD= 1.8 to 5.0V. See Figure 1 IIN Input current including inductor current - 20 25 mA See Figure 1* VCS Output voltage on VCS - 84 - V See Figure 1 fEL EL lamp frequency 205 240 275 Hz See Figure 1 fSW Switching transistor frequency - 80 - kHz See Figure 1 D Switching transistor duty cycle - 88 - % See Figure 1 * The inductor used is a 220H Murata inductor, max DC resistance of 8.4, part # LQH32CN221K21. Block Diagram VDD RSW-Osc LX CS Switch Osc Q GND Disable C Q VREF _ High Voltage Level Translator VDD Q EL Osc REL-Osc VA VSENSE + VB Q Figure 1: Typical Application/ Test Circuit ON = VDD Enable Signal OFF = 0V + 1 0.1F 560k VDD 3 - + 2 2.0M 4.7F 4 VDD HV857 VA RSW-Osc VB REL-Osc CS GND LX 8 2.0k Equivalent to 3.0in2 lamp 10nF 7 6 5 HV857 BAS21 220H* 3.3nF 100V VIN - Doc.# DSFP-HV857 A062013 * Murata Inductor LQH32CN221K21 3 Supertex inc. www.supertex.com HV857 Typical Performance Device Lamp Size VDD = VIN IIN VCS fEL Brightness HV857MG-G 3.0in 3.3V 20.0mA 84V 240Hz 6.0ft-lm 2 Typical Performance Curves for Figure 1 (EL Lamp = 3.0in , V 2 VCS vs VIN 95 = 3.0V) IIN vs VIN 25 23 lIN (mA) 85 VCS (V) DD 75 65 21 19 17 15 55 1.5 2.5 3.5 4.5 13 1.5 5.5 2.5 Brightness vs VIN 7 3.5 4.5 5.5 85 95 VIN (V) IIN vs VCS 24 6 22 5 lIN (mA) Brightness (ft-lm) VIN (V) 4 3 20 18 16 2 1 1.5 2.5 3.5 4.5 14 55 5.5 65 VIN (V) 75 VCS (V) IIN, VCS, Brightness vs Inductor Value 100 7 90 6 VCS 80 lIN (mA), VCS (V) Brightness 60 4 50 3 40 30 Brightness (ft-Im) 5 70 2 20 lIN 10 0 100 200 300 1 400 500 600 0 Inductor Value (H) Doc.# DSFP-HV857 A062013 4 Supertex inc. www.supertex.com HV857 External Component Description External Component Diode CS Capacitor Description Fast reverse recovery diode, BAS21 diode or equivalent. 0.003F to 0.1F, 100V capacitor to GND is used to store the energy transferred from the inductor. The EL lamp frequency is controlled via an external REL resistor connected between REL-Osc and VDD of the device. The lamp frequency increases as REL decreases. As the EL lamp frequency increases, the amount of current drawn from the battery will increase and the output voltage VCS will decrease. The color of the EL lamp is dependent upon its frequency. REL Resistor RSW Resistor LX Inductor A 2M resistor would provide lamp frequency of 205 to 275Hz. Decreasing the REL resistor by a factor of 2 will increase the lamp frequency by a factor of 2. (2M)(240Hz) fEL = REL The switching frequency of the converter is controlled via an external resistor, RSW between RSW-Osc and VDD of the device. The switching frequency increases as RSW decreases. With a given inductor, as the switching frequency increases, the amount of current drawn from the battery will decrease and the output voltage, VCS, will also decrease. (560k)(80Hz) fSW = RSW The inductor LX is used to boost the low input voltage by inductive flyback. When the internal switch is on, the inductor is being charged. When the internal switch is off, the charge stored in the inductor will be transferred to the high voltage capacitor CS. The energy stored in the capacitor is connected to the internal H-bridge, and therefore to the EL lamp. In general, smaller value inductors, which can handle more current, are more suitable to drive larger size lamps. As the inductor value decreases, the switching frequency of the inductor (controlled by RSW) should be increased to avoid saturation. A 220H Murata (LQH32CN221) inductor with 8.4 series DC resistance is typically recommended. For inductors with the same inductance value, but with lower series DC resistance, lower RSW resistor value is needed to prevent high current draw and inductor saturation. Lamp Doc.# DSFP-HV857 A062013 As the EL lamp size increases, more current will be drawn from the battery to maintain high voltage across the EL lamp. The input power, (VIN x IIN), will also increase. If the input power is greater than the power dissipation of the package, an external resistor in series with one side of the lamp is recommended to help reduce the package power dissipation. 5 Supertex inc. www.supertex.com HV857 Split Supply Configuration Enable/Disable Configuration The HV857 can also be used for handheld devices operating from a battery where a regulated voltage is available. This is shown in Figure 2. The regulated voltage can be used to run the internal logic of the HV857. The amount of current necessary to run the internal logic is 150A Max at a VDD of 3.0V. Therefore, the regulated voltage could easily provide the current without being loaded down. The HV857 can be easily enabled and disabled via a logic control signal on the RSW and REL resistors as shown in Figure 2 below. The control signal can be from a microprocessor. The control signal has to track the VDD supply. RSW and REL are typically very high values. Therefore, only 10's of microamperes will be drawn from the logic signal when it is at a logic high (enable) state. When the microprocessor signal is high the device is enabled, and when the signal is low, it is disabled. Figure 2: Split Supply and Enable/Disable Configuration ON = VDD Enable Signal OFF = 0V Regulated Voltage = VDD 1 RSW CDD 2 3 REL 4 VDD VA RSW-Osc VB REL-Osc CS GND LX HV857 8 EL Lamp 7 6 D 5 + VIN - CS LX CIN Audible Noise Reduction This section describes a method (patented) developed at Supertex to reduce the audible noise emitted by the EL lamps used in application sensitive to audible noise. Figure 3 shows a general circuit schematic that uses the resistor, RSER, connected in series with the EL lamp. Figure 3: Typical Application Circuit for Audible Noise Reduction Enable ON = VDD OFF = 0V VDD 1 + RSW CDD - 3 REL VIN Doc.# DSFP-HV857 A062013 2 4 + - VDD HV857 VA RSW-Osc VB REL-Osc CS GND LX RSER 8 7 EL Lamp 6 D 5 LX CIN 6 CS Supertex inc. www.supertex.com HV857 Minimization of EL Lamp Audible Noise Effect of Series Resistor on EL Lamp Audible Noise and Brightness The EL lamp, when lit, emits an audible noise. This is due to EL lamp construction and it creates a major problem for applications where the EL lamp can be close to the ear such as cellular phones. The noisiest waveform is a square wave and the quietest waveform has been assumed to be a sine wave. As EL lamp ages, its brightness is reduced and its capacitance is diminished. By using the RC model to reduce the audible noise emitted by the EL lamp, the voltage across the lamp will increase as its capacitance diminishes. Hence the increase in voltage will compensate for the reduction of the brightness. As a result, it will extend the EL lamp's half-life (half the original brightness). After extensive research, Supertex has developed a waveform that is quieter than a sine wave. The waveform takes the shape of approximately 2RC time constants for rising and 2RC time constants for falling, where C is the capacitance of the EL lamp, and R is the external resistor, RSER, connected in series with the EL lamp. This waveform has been proven to generate less noise than a sine wave. Increasing the value of the series resistor with the lamp will reduce the EL lamp audible noise as well as its brightness. This is due to the fact that the output voltage across the lamp will be reduced and the output waveform will have rounder edges. The audible noise from the EL lamp can be set at a desired level based on the series resistor value used with the lamp. It is important to note that use of this resistor will reduce the voltage across the lamp. Reduction of voltage across the lamp will also have another effect on the over all performance of the Supertex EL drivers, age compensation (patented). This addresses a very important issue, EL lamp life that most mobile phone manufacturers are concerned about. Doc.# DSFP-HV857 A062013 7 Supertex inc. www.supertex.com HV857 8-Lead DFN Package Outline (K7) 3.00x3.00mm body, 0.80mm height (max), 0.65mm pitch D2 D 8 8 E E2 Note 1 (Index Area D/2 x E/2) Note 1 (Index Area D/2 x E/2) Top View 1 e b 1 Bottom View View B Note 3 A L Seating Plane A3 A1 L1 Note 2 Side View View B Notes: 1. A Pin 1 identifier must be located in the index area indicated. The Pin 1 identifier can be: a molded mark/identifier; an embedded metal marker; or a printed indicator. 2. Depending on the method of manufacturing, a maximum of 0.15mm pullback (L1) may be present. 3. The inner tip of the lead may be either rounded or square. Symbol Dimension (mm) A A1 MIN 0.70 0.00 NOM 0.75 0.02 MAX 0.80 0.05 A3 0.20 REF b D D2 E E2 0.25 2.85* 1.60 2.85* 1.35 0.30 3.00 - 3.00 - 0.35 3.15* 2.50 3.15* 1.75 e 0.65 BSC L L1 0.30 0.00* 0O 0.40 - - 0.50 0.15 14O JEDEC Registration MO-229, Variation WEEC-2, Issue C, Aug. 2003. * This dimension is not specified in the JEDEC drawing. Drawings not to scale. Supertex Doc. #: DSPD-8DFNK73X3P065, Version C081109. Doc.# DSFP-HV857 A062013 8 Supertex inc. www.supertex.com HV857 8-Lead MSOP Package Outline (MG) 3.00x3.00mm body, 1.10mm height (max), 0.65mm pitch D 1 8 Note 1 (Index Area D/2 x E1/2) E1 E L2 L L1 1 Gauge Plane Seating Plane View B Top View View B A A A2 Seating Plane A1 e b Side View View A-A A Note: 1. A Pin 1 identifier must be located in the index area indicated. The Pin 1 identifier can be: a molded mark/identifier; an embedded metal marker; or a printed indicator. Symbol Dimension (mm) A A1 A2 b D E E1 MIN 0.75* 0.00 0.75 0.22 2.80* 4.65* 2.80* NOM - - 0.85 - 3.00 4.90 3.00 MAX 1.10 0.15 0.95 0.38 3.20* 5.15* 3.20* e 0.65 BSC L 0.40 0.60 0.80 L1 0.95 REF L2 0.25 BSC 1 0O 5O - - 8O 15O JEDEC Registration MO-187, Variation AA, Issue E, Dec. 2004. * This dimension is not specified in the JEDEC drawing. Drawings are not to scale. Supertex Doc. #: DSPD-8MSOPMG, Version H041309. (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to http://www.supertex.com/packaging.html.) Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives an adequate "product liability indemnification insurance agreement." Supertex inc. does not assume responsibility for use of devices described, and limits its liability to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications refer to the Supertex inc. (website: http//www.supertex.com) Supertex inc. (c)2013 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Doc.# DSFP-HV857 A062013 9 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com