IMP525 POWER MANAGEMENT Single Cell Battery Powered Electroluminescent Lamp Driver/Inverter The IMP525 is an Electroluminescent (EL) lamp driver designed for systems that must operate below 1 volt. The input supply voltage range is 0.9V to 2.5V. Typical output lamp drive voltage is 112V. All four EL lampdriving functions are on-chip. These are the switch-mode power supply, its high-frequency oscillator, the high-voltage H-bridge lamp driver and its low-frequency oscillator. EL lamps of up to 6nF capacitance can be driven to high brightness. The circuit requires few external components; one inductor, one diode, one capacitor and two resistors. The resistors set the frequency for the two oscillators. A disable mode puts the chip into a low current-drain state. When disabled, quiescent current drops to 2µA maximum with a VDD of 1.5V. The chip can be disabled by connecting RSW, the oscillator frequency setting resistors, to ground. A disable pad, accessible only on the die, can also be used to disable the driver. An internal circuit shuts down the switching regulator when the lamp drive voltage exceeds 112V peak-to-peak. This conserves power and extends battery life. The IMP525 is available in MicroSO and SO-8 packages and in die form. Block Diagram VDD RSW-OSC GND Key Features ◆ Wide operating voltage range - from 0.9V to 2.5V ◆ Simple design requires few passive components ◆ 112V peak-to-peak typical AC output voltage ◆ Adjustable output frequency controls lamp color and power consumption ◆ Adjustable converter frequency minimizes circuit power consumption ◆ Disable mode extends battery life ◆ Disable current under 2µA ◆ Compact MicroSO package option Applications ◆ ◆ ◆ ◆ ◆ ◆ ◆ Audio/TV remote control units Pagers/Cellular phones PDAs Clocks and radios Portable GPS receivers LCD modules Toys 4 1 2 3 Switch Oscillator LX CS 5 Q + 7 C Regulation Control – VREF VA Q Bridge Output Driver IMP525 Q 6 REL-OSC 8 Lamp Drive Oscillator VB Q 525_01.eps IMP, Inc. San Jose, CA 408-432-9100/www.impweb.com IMP525 Pin Configuration SO/MicroSO VDD 1 IMP525 8 REL-OSC RSW-OSC 2 7 VA CS 3 6 VB LX 4 5 GND 525_02.eps Ordering Information Part Number Input Voltage Regulated Output Voltage Temperature Range Pins-Package IMP525EMA 0.9V to 2.5V YES – 40°C to +85°C 8-MicroSO IMP525ESA IMP525/D 0.9V to 2.5V 0.9V to 2.5V YES YES – 40°C to +85°C 25°C 8-SO Dice Absolute Maximum Ratings Supply Voltage, VDD, VRSW-OSC and VREL-OSC . . – 0.5V to +3.5V Storage Temperature Range . . . . . . . . . . . . . . . . – 65°C to +150°C Power Dissipation (SO package) . . . . . . . . . . . . 400mW Power Dissipation (MicroSO package) . . . . . . . 300mW Note: All voltages are referenced to GND. These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. Electrical Characteristics Unless otherwise noted, VDD = 1.5V, RSW = 1MΩ, REL = 1.0MΩ, and TA = 25°C. Parameter Symbol Conditions ON-resistance of MOS Switch Operating Voltage Output Voltage at CS Output Voltage at CS Output Voltage Peak-to-Peak Quiescent VDD Supply Current, Disabled (Disable pin available on die only) Quiescent VDD Supply Current, Disabled RDS(ON) I = 50mA VCS VCS VA-VB IQDIS VDD = 1.5V, See Figure 1, Table 1 VDD = 0.9V, See Figure 1, Table 2 VDD = 1.5V, See Figure 1 Disable = HIGH IQDIS Input Current at VDD Pin Input Current: IDD Plus Inductor Current VA-B Output Drive Frequency Boost Converter Switching Frequency Switching Duty Cycle Disable Input LOW Voltage (Disable pin available on die only) Disable Input HIGH Voltage (Disable pin available on die only) IDD IIN fEL fSW DSW VDISL RSW-OSC = GND VDD = 1.5V VDD = 0.9V to 1.5V VDD = 1.5V VDD = 1.5V, See Figure 1, Table 1 VDD = 1.5V, See Figure 1, Table 1 VDD = 1.5V, See Figure 1 2 VDISH Min 0.9 52 104 Typ 58 50 112 70 1.0 Max Units 15 2.5 65 Ω V V V VP-P nA 124 2.0 µA 1.5 32 GND 0.2 mA mA Hz kHz % V VDD -0.5V VDD V 23 500 26 87.5 IMP525 Typical Characteristics Boost Converter Switching Frequency EL Lamp Drive Frequency 2400 150 VDD = 1.5V TA = 25°C VDD = 1.5V TA = 25°C 125 Frequency (kHz) Frequency (Hz) 2000 1600 1200 800 400 100 75 50 25 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 REL (MΩ) 0 4.0 0 0.5 1.5 2.0 2.5 RSW (MΩ) 525_08.eps 3.0 525_10.eps Boost Converter Switching Period EL Lamp Drive Period 100 8 VDD = 1.5V TA = 25°C VDD = 1.5V TA = 25°C 7 6 75 5 Period (ms) Period (ms) 1.0 4 3 2 50 25 1 0 0 0 0.5 1.0 1.5 2.0 2.5 REL (MΩ) 3.0 3.5 4.0 525_07.eps 0 0.5 1.0 1.5 RSW (MΩ) 2.0 2.5 3.0 525_09.eps 3 IMP525 Pin Descriptions Pin Number Name 1 VDD 2 RSW-OSC 3 CS Function Positive voltage supply for the IMP525. Inductor L may be connected here or to a separate supply. Switch-mode resistor pin. Switching frequency is determined by external resistor RSW, connected between pin 2 and VDD. Boost converter storage capacitor. The voltage across the EL lamp is equal to twice the voltage at CS. 4 LX 5 GND Connection to flyback inductance, L. 6 VB EL lamp drive. The lamp is connected to a high-voltage bridge circuit with VB providing the complementary connection to VA. 7 VA EL lamp drive. (See above) 8 REL-OSC Disable Pad DIS Ground pin. The EL lamp oscillator frequency-setting pin. The frequency is controlled by resistor REL, connected from pin 8 to VDD. Available only in die form. Setting DIS HIGH disables the chip. External Components External Component Diode Description and Selection Guide A fast reverse recovery diode, with BV > 100, such as a 1N4148. Capacitor CS The high voltage capacitor that stores the inductive energy transferred through the catch diode. A 100 volt capacitor between 10nF and 100nF is recommended. Resistor R EL The EL lamp oscillator frequency-setting resistor. REL is connected between pin 8 and VDD, providing a frequency inversely proportional to REL; as REL increases, the EL lamp frequency decreases along with the current drawn by the lamp. Lamp color is also determined by this frequency. A 1MΩ resistor between the REL-OSC pin and the VDD supply results in a lamp frequency around 500Hz. Resistor RSW Switching Oscillator frequency-setting resistor. RSW is connected between the RSW-OSC pin and the VDD supply. The switching frequency is inversely proportional to the resistor value, dropping as the resistance increases. Capacitor CSW This is an optional noise-suppression capacitor connected from ground to the RSW-OSC pin. A 100pF capacitor is recommended. Inductor L The inductor provides the voltage boost needed by means of inductive “flyback”. The internal MOSFET switch alternately opens and closes the ground connection for the inductor at the LX pin. When the switch opens, the inductor potential will forward-bias the diode and the current will pass through to the storage capacitor CS, charging it to a high voltage. As the value of the inductor is increased, the switching frequency set by RSW should also be increased to prevent saturation. In general, smaller value inductors that can handle more current are more desirable when larger-area EL lamps must be driven. A small electrolytic capacitor (10µF, 16V), normally present across the inductor supply VIN, will likely eliminate the need for CSW. 4 IMP525 Application Information Test Circuit Figure 1 shows the IMP525 configured to drive an EL lamp, represented as a 3nF capacitor. ON = VDD REL OFF = 0V 1 VDD REL-OSC 8 2 RSW-OSC VA 7 3 CS VB 6 4 LX GND 5 RSW L 3nF D 1N4148 + VDD – 0.1µF1 CS 0.1µF 100V IMP525 Note: 1. Larger values may be required depending upon supply impedance. 525_03.eps Figure 1. Test Circuit Table 1. VIN = 1.5V Component Connections Value RSW VDD, RSW-OSC 1MΩ REL VDD, REL-OSC 1MΩ 2 330µH Description Boost converter oscillator bias resistor EL lamp driver oscillator bias resistor 2 L VDD, LX CS CS, GND 0.1µF/100V Boost converter inductor D LX, CS 1N4148 Switching diode Value Description Boost converter oscillator bias resistor Boost converter storage capacitor Notes. 2. Murata LQH4N331K04 (8.2Ω max. DCR) Table 2. VIN = 0.9V Component Connections RSW VDD, RSW-OSC 1.0MΩ REL VDD, REL-OSC 2.62MΩ EL lamp driver oscillator bias resistor L VDD, LX3 680µH3 Boost converter inductor CS CS, GND 0.1µF/100V D LX, CS 1N4148 Boost converter storage capacitor Switching diode Notes. 3. Coilcraft DS1608C-684 (2.2Ω max. DCR) 5 IMP525 Enable/Disable Operation Figure 2 shows how the IMP525 can be enabled via a logic gate that connects RSW to VDD, and disabled by connecting it to ground. Enable/Disable Table RSW Connection The IMP525 can also be disabled using a pad on the die. The Disable function pin is not available in packaged parts. IMP525 State Disable PAD Connection (Available only with dice) IMP525 State Enabled Disabled HIGH (VDD) LOW (Ground) Disabled Enabled VDD Ground CMOS Gate ON = VDD REL OFF = 0V 1 VDD REL-OSC 8 2 RSW-OSC VA 7 3 CS VB 6 4 LX GND 5 RSW L1 EL lamp D 1N4148 + VDD – 0.1µF2 15V CS 0.1µF 100V 0.1nF3 IMP525 Note: 1. Murata part # LQH4N561K04 (DC resistance <14.5 Ω) 2. Larger values may be required depending upon supply impedance. 3. Optional noise-suppression capacitor. 525_04.eps Figure 2. Enable/Disable Operation High Voltages Present The IMP525 generates high voltages and caution should be exercised. Inductor Manufacturers Manufacturer Toko Coilcraft River Electronics 6 Series USA Phone Number D52FU (847) 297-0070 DS1608, DO1608, DT1608 (847) 639-6400 FLC32 (310) 320-7488 IMP525 Package Dimensions MicroSO (8-Pin) a Inches Min E1 E + L C A2 D A e b 0.10mm 0.004in A ––––– 0.0433 –––– 1.10 A1 0.0020 0.0059 0.050 0.15 A2 0.0295 0.0374 0.75 0.95 b 0.0098 0.0157 0.25 0.40 C 0.0051 0.0091 0.13 0.23 D 0.1142 0.1220 2.90 e D Millimeters Max Min Max MicroSO (8-Pin) 0.0256 BSC E 3.10 0.65 BSC 0.193 BSC 4.90 BSC E1 0.1142 0.1220 2.90 3.10 L 0.0157 0.0276 0.40 0.70 a 0° 6° 0° 6° SO (8-Pin) MicroSO (8-Pin).eps A1 A 0.053 0.069 1.35 1.75 A1 0.004 0.010 0.10 0.25 B 0.013 0.020 0.33 0.51 C 0.007 0.010 0.19 e SO (8-Pin) 0°– 8° 0.050 0.25 1.27 E 0.150 0.157 3.80 4.00 H 0.228 0.244 5.80 6.20 L 0.016 0.050 0.40 1.27 D 0.189 0.197 4.80 5.00 L N E H C D A e B A1 SO (8-Pin).eps 7 IMP525 IMP, Inc. Corporate Headquarters 2830 N. First Street San Jose, CA 95134-2071 Tel: 408-432-9100 Tel: 800-438-3722 Fax: 408-434-0335 Fax-on-Demand: 1-800-249-1614 (USA) Fax-on-Demand: 1-303-575-6156 (International) e-mail: [email protected] http://www.impweb.com The IMP logo is a registered trademark of IMP, Inc. All other company and product names are trademarks of their respective owners. 8 © 1998 IMP, Inc. Printed in USA Part No.: IMP 525 Preliminary Document Number: IMP525-8-9/98