MICROPOWER INVERTING DC/DC CONVERTER

AIC1652 MICROPOWER INVERTING DC/DC CONVERTER SPEC NO: DS-1652-02 DEC 27, 00 n FEATURES l l l l l l l n DESCRIPTION The AIC1652 is a high performance inverting DC/DC converter, designed to drive an external power switch to generate programmable negative voltages. In the particularly suitable LCD bias contrast application, efficiency of 87% can be achieved with low cost PNP bipolar transistor drivers. Output voltage can be scaled to -40V or greater by two external resistors. A pulse frequency modulation scheme is employed to maintain high efficiency conversion under wide input voltage range. Quiescent current is about 80µA and can be reduced to 0.7µA in shutdown mode. Switching frequency being around 70KHz to 160KHz range, small size switching components are ideal for battery powered portable equipments, like notebook and palmtop computers. 2.4V to 7V Input Voltage Operation. Adjustable Output Voltage up to -40V. Low Quiescent Current at 80µA. Pulse Frequency Modulation Maintains High Efficiency (87%). 70KHz to 160KHz Switching Frequency. Power-Saving Shutdown Mode (0.7µA Typical). High Efficiency with Low Cost External PNP Bipolar Transistor. n APPLICATIONS l Negative LCD Contrast Bias for 1. Notebook & Palmtop Computers. 2. Pen-Based Data System. 3. Portable Data Collection Terminals. 4. Personal Digital Assistants. Negative Voltage Supply. l n TYPICAL APPLICATION CIRCUIT VIN 2.4V ~ 7V 100µF + C1 VIN VREF CL DHI RB 470~1.8K 150µ H *L 100µF C2 + Q1 9012 D1 AIC1652 SHDN DLOW FB GND 1N5819 VOUT -12V~ -40V -10mA 0.047µF C4 R2 100K R1 1M C3 10nF * Sumida CD-54 Series VOUT = -1.22V x R1/R2 Negative LCD Contrast Bias Power Supply n ORDERING INFORMATION AIC1652 XX PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE TEMPERATURE RANGE C=0 ° C~+70 ° C ORDER NUMBER AIC1652CN (PLASTIC DIP) AIC1652CS (PLASTIC SO) PIN CONFIGURATION TOP VIEW VIN VREF SHDN FB 1 2 3 4 8 7 6 5 CL DHI DLOW GND ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 1 AIC1652 MICROPOWER INVERTING DC/DC CONVERTER SPEC NO: DS-1652-02 DEC 27, 00 n ABSOLUTE MAXIMUM RATINGS Supply Voltage ..................................................................… … … … … … … ............ 7V SHDN Voltage ...............................................… … … … … ..................................... 7V ................................… … … .......................... 0°C~70°C .................................… … … … ................. -65°C~ 150°C Operation Temperature Range Storage Temperature Range n TEST CIRCUIT Refer to Typical Application Circuit. n ELECTRICAL CHARACTERISTICS (V PARAMETER Input Voltage Switch Off Current VREF Voltage VREF Source Current DLOW “ON Resistance” DHI “ON Resistance” CL Threshold Shutdown Threshold Shutdown Mode Current VFB=-50mV ISOURCE = 250µA IN=5V, Ta=25°C, unless otherwise specified.) TYP. MAX. 7 80 150 1.28 TEST CONDITIONS MIN. 2.4 UNIT V µA V µA 1.16 250 1.22 5 7 70 0.8 1.5 0.7 2.4 2 Ω Ω mV V µA VSHDN = 0V ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 2 AIC1652 MICROPOWER INVERTING DC/DC CONVERTER SPEC NO: DS-1652-02 DEC 27, 00 n TYPICAL PERFORMANCE CHARACTERISTICS V REF Source Current vs VIN 350 300 1.5 Shutdown Current vs VIN 250 200 Shutdown Current (µA) Source Current (µA) 1 150 100 0.5 50 0 2 3 4 5 6 7 8 01 2 3 4 5 6 7 8 VIN (V) VIN (V) Frequency vs VIN Voltage 150 100 Duty Cycle vs VIN Voltage Frequency (KHz) 130 95 110 Duty Cycle (%) Ta=0° C Ta=25°C 90 Ta=0° C 90 Ta=70 ° C 85 Ta=25° C 70 Ta=70 ° C 50 80 2 3 4 VIN (V) 5 6 7 2 3 4 5 6 7 V IN (V) n BLOCK DIAGRAM VIN 1 CURRENT LIMIT COMPARATOR + PFM OSCILLATOR 1.22V REFERENCE VOLTAGE + V IN 70mV 8 CL V IN LATCH 7 DHI VREF 2 SHDN 3 OUTPUT DRIVER 6 DLOW 5 FB 4 - GND ERROR COMPARATOR ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 3 AIC1652 MICROPOWER INVERTING DC/DC CONVERTER SPEC NO: DS-1652-02 DEC 27, 00 n PIN DESCRIPTIONS PIN 1: VIN - 2.4V to 7V input supply voltage. PIN 2: VREF - 1.22V reference output. Bypass with a 0.047µF capacitor to GND. Sourcing capability is guaranteed to be greater than 250µA. PIN 3: PIN 6: DLOW - Driver sinking output. Connected to DHI when using an external Pchannel MOSFET. When using an external PNP bipolar transistor, connect a resistor RB from this pin to DHI. RB value depends on VIN, inductor and PNP bipolar transistor. By adjusting the RB value, efficiency can be optimized. PIN 7: DHI - Driver sourcing output. Connect to gate of the external P-channel MOSFET or base of the PNP bipolar transistor. - Current-limit input. This pin clamps the switch peak current to prevent over-current damage to the external switch. SHDN - Logic input to shutdown the chip. >1.5V = normal operation, GND = shutdown In shutdown mode DLOW and DHI pins are at high level. - Feedback signal input to sense ground. Connecting a resistor R1 to VOUT and a resistor R2 to VREF pin yields the output voltage: VOUT = -(R1/R2 ) x VREF PIN 4: FB PIN 8: CL PIN 5: GND - Power ground. n APPLICATION INFORMATIONS 0.8 Max. Output Power vs VIN Typical Application Circuit 100µH Max. Output Power (W) 0.6 120µH 150µH 0.4 180µH 220µH Inductor Value The typical application circuit generates an adjustable negative voltage for contrast bias of LCD displays. Efficiency and output power can be optimized by using appropriate inductor and switch. The following formulas provide a guideline for determining the optimal component values: V IN L = (11.1 − 0.15 × V IN ) × IOUT × V OUT PNP : V CEO > V IN + V OUT IC,MAX ≥ 200 × IOUT VIN IOUT V IN 0.2 0 2 4 6 8 V CE < 0. 4 V at I C = 200 × VIN (V) and β = 10 RB ≅ 3 x L x (V IN - 0.8) where, units: VIN & VOUT in V, IOUT in A, L in µH, RB in Ω ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 4 AIC1652 MICROPOWER INVERTING DC/DC CONVERTER SPEC NO: DS-1652-02 DEC 27, 00 n APPLICATION EXAMPLES 90 Efficiency vs Load Current VOUT = -15V L =150µH 90 Efficiency vs VIN V OUT =-15V I OUT =-10mA L=220 µH 85 VIN=5V VIN=3V VIN =7V 88 Efficiency (%) Efficiency (%) 86 80 84 L=150µ H 75 82 L=100µH 70 0 5 10 15 20 25 30 80 2 3 4 5 6 7 8 Load Current (mA) VIN (V) Efficiency vs VIN VOUT =- 22V IOUT =- 10mA L=220 µH 86 Efficiency vs Load Current 90 90 VOUT =- 22V L =120µH 85 88 VIN=7V Efficiency (%) Efficiency (%) VIN=5V VIN=3V 80 L=150µH 84 75 82 L=100µH 70 0 5 10 15 20 25 30 80 2 3 4 5 6 7 8 Load Current (mA) VIN (V) 90 Efficiency vs Load Current V OUT = -30V L =100µ H 90 Efficiency vs V IN VOUT =-30V IOUT =-10mA L=150µH L=120µH VIN=7V 88 85 Efficiency (%) Efficiency (%) VIN=5V 80 86 VIN=3V 84 75 82 L=100µ H 70 0 5 10 15 20 25 30 80 2 3 4 5 6 7 8 Load Current (mA) VIN (V) ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 5 AIC1652 MICROPOWER INVERTING DC/DC CONVERTER SPEC NO: DS-1652-02 DEC 27, 00 n PHYSICAL DIMENSIONS l 8 LEAD PLASTIC SO (unit: mm) D SYMBOL A A1 H E MIN 1.35 0.10 0.33 0.19 4.80 3.80 MAX 1.75 0.25 0.51 0.25 5.00 4.00 1.27(TYP) 6.20 1.27 B C D E e e A C A1 H L L 5.80 0.40 B l 8 LEAD PLASTIC DIP (unit: mm) D SYMBOL A1 E1 MIN 0.381 2.92 0.35 0.20 9.01 7.62 6.09 — 2.92 MAX — 4.96 0.56 0.36 10.16 8.26 7.12 10.92 3.81 A2 b C E D E E1 C A2 A1 L e eB L UNIT: mm 2.54 (TYP) eB b e ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 6