Supertex inc. HV860 Initial Release Low Noise Dimmable EL Lamp Driver Features ► ► ► ► ► ► ► The HV860 has two internal oscillators, a switching MOSFET, and a high voltage EL lamp driver H-bridge. 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 REL-OSC pin and VDD pin. An external inductor is connected between the LX and VDD pins or VIN for split supply applications. A 3.0nF capacitor is connected between CS and ground. The EL lamp is connected between VA and VB. Adjustable output regulation for dimming 220VPP output voltage for higher brightness Single cell lithium ion compatible 150nA shutdown current Separately adjustable lamp and converter frequencies 3x3 QFN-12 package Split supply capability Applications ► ► ► ► 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 110V, 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 ±110V across the EL lamp. Mobile cellular phone keypads PDAs Handheld wireless communication products Global Positioning Systems (GPS) General Description EL lamp dimming can be accomplished by changing the input voltage to the VREG pin. The VREG pin allows an external voltage source to control the VCS amplitude. The VCS voltage is approximately 87 times the voltage seen on VREG. The Supertex HV860 is a high voltage driver designed for driving Electroluminescent, (EL), lamps of up to 5 square inches. The input supply voltage range is from 2.5V to 4.5V. The device uses a single inductor and a minimum number of passive components. Using the internal reference voltage, the regulated output voltage is at a nominal voltage of 110V. The EL lamp will therefore see ±110V. An enable pin, (EN), is available to turn the device on and off via a logic signal. Typical Application Circuit VIN CIN LX D RREG 2 10 VDD CDD 1.5V = On 0V = Off RSW VREG 5 VREF LX CS VDD 12 RSW-OSC 1 REL-OSC REL 11 3 EN VA GND VB CS 7 9 8 EL Lamp 4 HV860K7 NR040306 Supertex inc. · 1235 Bordeaux Drive, Sunnyvale, CA 94089 · Tel: (408) 222-8888 · FAX: (408) 222-4895 · www.supertex.com 1 HV860 Ordering Information Device Thermal Resistance Package Option Package θja QFN-12 QFN-12 60 °C/W HV860 HV860K7-G -G indicates package is RoHS compliant (‘Green’) Pin Configuration RSW-OSC EN VDD 12 Absolute Maximum Ratings Parameter Value VDD, Supply Voltage -0.5V to 6.0V Operating Temperature Storage Temperature -40°C to +85°C REL-OSC 1 VREG 2 VREF 3 11 10 HV860K7 9 VA 8 VB 7 CS -65°C to +150°C Power Dissipation QFN-12 VCS, Output Voltage 1.6W 4 -0.5V to +120V VREG External Input Voltage 5 GND LX 1.33V 6 NC QFN-12 Top View 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. Note: Pads are at the bottom of the package. Center heat slug is at ground potential Electrical Characteristics DC Characteristics (Over recommended operating conditions unless otherwise specified TA=25°C) Symbol RDS(ON) VCS VCS Parameter Min Typ Max Units On-resistance of switching transistor - - 6.0 Ω I = 100mA Maximum output regulation voltage - - 120 V VDD = 2.5V to 4.5V - 95 - - 75 - - 55 - 0 - 1.26 V VDD = 2.5V to 4.5V 1.18 1.26 1.33 V VDD = 2.5V to 4.5V Output regulation voltage VREG External input voltage range VREFH VREF output high voltage Conditions VDD = 2.5V to 4.5V, VREG = 1.092V V VDD = 2.5V to 4.5V, VREG = 0.862V VDD = 2.5V to 4.5V, VREG = 0.632V IDDQ Quiescent VDD supply current - - 150 nA EN = low IDD Input current going into the VDD pin - - 200 µA VDD = 2.5V to 4.5V, REL = 2.0MΩ, RSW = 1.0MΩ IIN Input current including inductor current - - 16 mA see Figure 2 fEL EL lamp frequency 160 200 240 Hz REL = 2.0MΩ fSW Switching transistor frequency 76 90 104 kHz RSW = 1.0MΩ D Switching transistor duty cycle - - 88 % --- VIH Enable input logic high voltage 1.5 - VDD V VDD = 2.5V to 4.5V VIL Enable input logic low voltage 0 - 0.2 V VDD = 2.5V to 4.5V IIH Enable input logic high current - - 1.0 µA VIH = VDD = 2.5V to 4.5V NR040306 2 HV860 Electrical Characteristics (cont.) Symbol Parameter Min Typ Max Units Conditions IIL Enable input logic low current - - -1.0 µA VIL = 0V, VDD = 2.5V to 4.5V CIN Enable input capacitance - - 15 pF --- Recommended Operating Conditions Symbol Parameter Min Typ Max Units VDD Supply voltage 2.5 - 4.5 V --- fSW Switching frequency 40 - 200 kHz --- fEL EL output frequency 200 - 500 Hz --- 0 - 20 nF --- -40 - +85 °C --- CLOAD EL lamp capacitance load TA Operating Temperature Conditions Pin Configuration and External Component Description Pin # Name 1 REL-OSC 2 VREG Description External resistor from REL-OSC to VDD sets the EL frequency. The EL frequency is inversely proportional to the external REL resistor value. Reducing the resistor value by a factor of two will result in increasing the EL frequency by two. Input voltage to set VCS regulation voltage. This pin allows an external voltage source to control the VCS amplitude. EL lamp dimming can be accomplished by varying the input voltage to VREG. The VCS voltage is approximately 87 times the voltage seen on VREG. External resistor RREG, connected between VREG and VREF pins controlls the VCS charging rate. The charging rate is inversely proportional to the RREG resistor value. 3 VREF Switched internal reference voltage. 4 GND Device ground. Drain of internal switching MOSFET. Connection for an external inductor. 5 LX 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 220µH Cooper (SD3814-221) inductor with 5.5Ω 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. 6 NC No internal connections to the device. 7 CS High voltage regulated output. Connection for an external high voltage capacitor to ground 8 VB VB side of the EL lamp driver H-bridge. Connection for one of the EL lamp terminals. 9 VA VA side of the EL lamp driver H-bridge. Connection for one of the EL lamp terminals. 10 VDD Low voltage input supply pin. 11 EN Logic input pin. Logic high will enable the device. 12 RSW-OSC External resistor from RSW-OSC to VDD sets the switch converter frequency. The switch converter frequency is inversely proportional to the external RSW resistor value. Reducing the resistor value by a factor of two will result in increasing the switch converter frequency by two. NR040306 3 HV860 Figure 1: Block Diagram VDD EN CS LX Device Enable PWM Switch Oscillator 0 to 88% RSW-OSC VA + 1.26V VREF 60pF VREF Output Drivers - C VREG VSENSE VCS 2x EL Freq. REL-OSC VB EL Frequency GND Figure 2: Typical Application / Test Circuit + - 4.7μF VIN 220μH (Cooper Inductor SD3814-221) 3.3MΩ 2 10 VDD 1.0MΩ 12 0.1μF VREG 0V = Off 5 BAS21 VREF LX CS 7 VDD RSW-OSC 2.0MΩ 1 REL-OSC 11 EN 1.5V = ON 3 VA VB GND 4 3.3nF 200V 9 8 3.0in2 EL Lamp HV860K7 Typical Performance VDD 3.0V Lamp Size 3.0in2 VIN IIN 3.0V 16.17mA 3.5V 14.18mA 4.2V 12.13mA VCS fEL Brightness 18.2cd/m2 100V (peak) 196Hz 19.3cd/m2 19.9cd/m2 NR040306 4 HV860 Figure 3: Typical Waveform on VA, VB, and Differential Waveform VA - VB Split Supply Configuration The HV860 can also be used for handheld devices operating from a battery where a regulated voltage is available. This is shown in the Figure 4. The regulated voltage can be used to run the internal logic of the HV860. The amount of current necessary to run the internal logic is 200µA max. Therefore, the regulated voltage could easily provide the current without being loaded down. Enable/Disable Configuration microprocessor signal is high the device is enabled, and when the signal is low, it is disabled. The HV860 can be easily enabled and disabled via a logic control signal on the EN pin as shown in the Figure 4. The control signal can be from a microprocessor. When the Figure 4: Split Supply and Enable/Disable Configuration + - CIN VIN LX D RREG 2 10 Regulated Voltage = VDD CDD RSW 12 1 On = 1.5V REL 11 Off = 0V 3 VREG 5 VREF VDD LX CS RSW-OSC VA REL-OSC EN GND VB CS 7 9 8 EL Lamp 4 HV860K7 NR040306 5 HV860 Audible Noise Reduction The EL lamp, when lit, emits an audible noise. This is due to EL lamp construction. The audible noise generated by the EL lamp can be a major problem for applications where the EL lamp is held close to the ear, such as cellular phones. The HV860 employs a proprietary circuit to help minimize the EL lamp’s audible noise by using a single resistor, RREG, as shown in Figure 5. Figure 5: Typical Application Circuit for Audible Noise Reduction VIN CIN LX D RREG 2 10 VDD CDD RSW 12 1 1.5V = On 0V = Off REL 11 3 VREG 5 VREF LX CS VDD RSW-OSC VA REL-OSC EN VB GND CS 7 9 EL Lamp 8 4 HV860K7 How to Minimize EL Lamp Audible Noise The audible noise from the EL lamp can be minimized with the proper selection of RREG. RREG is connected between the VREF and VREG pins. VREG has an internal 60pF capacitor to ground. EL lamp noise can be minimized without much loss in brightness by setting the RC time constant to be approximately 1/12TH of the EL frequency’s period. EL Lamp Dimming using PWM This section describes the method of dimming the EL lamp. Reducing the voltage amplitude at the VREG pin will reduce the voltage on the VCS pin, which will effectively reduce the peak the peak voltage the EL lamp sees. Figure 5 shows a circuit to dim the lamp by changing the duty cycle of a PWM signal. A 10kΩ resistor is connected in series with a 3.3MΩ resistor. An n-channel open drain PWM signal is used to pull the 10kΩ resistor to ground. The effective voltage on the VREG pin will be proportional to the duty cycle of the PWM signal. The PWM operating frequency can be anywhere between 20kHz to 100kHz. Figure 6: PWM Dimming Circuit + - VIN 4.7μF 220μH (Cooper Inductor SD3814-221) Open Drain n-channel PWM Signal 3.3MΩ 10kΩ 10 + - VDD On = 1.5V 0.1μF 2 VREG VDD 1.0MΩ 12 RSW-OSC 2.0MΩ 1 REL-OSC 11 EN Off = 0V 3 5 VREF LX CS VA GND 4 VB BAS21 7 3.3nF 200V 9 8 EL Lamp HV860K7 NR040306 6 HV860 12-Lead QFN Package Outline (K7) 0.73 0.85 1.25 1.65 All dimensions are in millimeters Legend: min max 0.73 0.85 Pin #1 1.25 1.65 3.00 1.55 2.40 0.18 0.30 0.30 0.50 0.5 3.00 Top View θ ~ 14O 0.70 0.80 0.20 Side View (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 its products for use in such applications, unless it receives an adequate "product liability indemnification insurance agreement". Supertex 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 or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the Supertex website: http//www.supertex.com. ©2006 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Supertex inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 TEL: (408) 222-8888 / FAX: (408) 222-4895 Doc.# DSFP - HV860 NR040306 www.supertex.com 7