AIC1652 MICROPOWER INVERTING DC/DC CONVERTER SPEC NO: DS-1652-02 DEC 27, 00 n FEATURES 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. l l l 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. l Negative Voltage Supply. n TYPICAL APPLICATION CIRCUIT VIN 2.4V ~ 7V 100µF + C1 VIN CL VREF DHI AIC1652 SHDN DLOW FB 0.047µF C4 R2 Q1 9012 D1 RB 1N5819 470~1.8K GND 150µ H *L 100µF C2 VOUT -12V~ -40V -10mA + R1 1M C3 100K * Sumida CD-54 Series VOUT = -1.22V x R1/R2 10nF Negative LCD Contrast Bias Power Supply n ORDERING INFORMATION AIC1652 XX PIN CONFIGURATION ORDER NUMBER PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE AIC1652CN (PLASTIC DIP) TEMPERATURE RANGE C=0 ° C~+70 ° C AIC1652CS (PLASTIC SO) TOP VIEW VIN 1 8 CL VREF 2 7 DHI SHDN 3 6 DLOW 4 5 GND FB ANALOG INTEGRATIONS CORPORATION www.analog.com.tw 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. 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 Operation Temperature Range Storage Temperature Range .................................… … … … ................. -65°C~ 150°C n TEST CIRCUIT Refer to Typical Application Circuit. n ELECTRICAL CHARACTERISTICS (V IN=5V, PARAMETER TEST CONDITIONS VREF Voltage TYP. MAX. UNIT 7 V 80 150 µA 1.22 1.28 V 2.4 Input Voltage Switch Off Current MIN. Ta=25°C, unless otherwise specified.) VFB=-50mV ISOURCE = 250µA 1.16 µA 250 VREF Source Current DLOW “ON Resistance” 5 Ω DHI “ON Resistance” 7 Ω 70 mV CL Threshold 0.8 Shutdown Threshold Shutdown Mode Current VSHDN = 0V 1.5 2.4 V 0.7 2 µA ANALOG INTEGRATIONS CORPORATION www.analog.com.tw 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. 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 Shutdown Current vs VIN 1.5 350 Shutdown Current (µA) Source Current (µA) 300 250 200 150 100 1 0.5 50 0 2 3 4 5 6 7 01 8 2 3 4 Frequency vs VIN Voltage 150 100 130 95 Duty Cycle (%) Frequency (KHz) 5 6 7 8 VIN (V) VIN (V) 110 Ta=0° C 90 Ta=25° C Duty Cycle vs VIN Voltage Ta=0° C Ta=25°C 90 Ta=70 ° C 85 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 VREF SHDN FB V IN CURRENT LIMIT COMPARATOR 1 70mV + 2 3 4 PFM OSCILLATOR CL V IN LATCH 1.22V REFERENCE VOLTAGE OUTPUT DRIVER 7 DHI 6 DLOW + - 8 5 GND ERROR COMPARATOR ANALOG INTEGRATIONS CORPORATION www.analog.com.tw 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. 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: SHDN - Logic input to shutdown the chip. >1.5V = normal operation, GND = shutdown In shutdown mode DLOW and DHI pins are at high level. PIN 4: FB - Feedback signal input to sense ground. Connecting a resistor R1 to VOUT and a resistor R2 to VREF pin yields the output voltage: 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. PIN 8: CL - Current-limit input. This pin clamps the switch peak current to prevent over-current damage to the external switch. VOUT = -(R1/R2 ) x VREF PIN 5: GND - Power ground. n APPLICATION INFORMATIONS Max. Output Power vs VIN 0.8 Typical Application Circuit Max. Output Power (W) 100µH 0.6 120µH 150µH 0.4 180µH 220µH PNP : Inductor Value 0.2 0 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 V CEO > V IN + V OUT IC,MAX ≥ 200 × 2 4 6 8 VIN (V) IOUT VIN V CE < 0. 4 V at I C = 200 × IOUT V IN 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 www.analog.com.tw 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. 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 Efficiency vs Load Current 90 VOUT = -15V L =150µH 85 Efficiency (%) Efficiency (%) V OUT =-15V I OUT =-10mA 88 VIN =7V VIN=5V Efficiency vs VIN 90 VIN=3V 80 75 L=220 µH 86 84 L=150µ H 82 L=100µH 80 70 0 5 10 15 20 25 2 30 3 4 5 Efficiency vs Load Current 7 8 Efficiency vs VIN 90 90 VOUT =- 22V L =120µH VOUT =- 22V IOUT =- 10mA 88 VIN=7V 85 Efficiency (%) VIN=5V Efficiency (%) 6 VIN (V) Load Current (mA) VIN=3V 80 75 L=220 µH 86 L=150µH 84 L=100µH 82 80 70 0 5 10 15 20 25 2 30 3 4 5 Load Current (mA) Efficiency vs Load Current 90 V OUT = -30V L =100µ H 6 7 6 7 8 VIN (V) Efficiency vs V IN 90 VIN=7V VOUT =-30V IOUT =-10mA 88 VIN=5V Efficiency (%) Efficiency (%) 85 80 VIN=3V L=150µH 86 L=120µH 84 75 82 L=100µ H 80 70 0 5 10 15 20 25 30 2 3 Load Current (mA) 4 5 8 VIN (V) ANALOG INTEGRATIONS CORPORATION www.analog.com.tw 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. 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 MIN MAX A 1.35 1.75 A1 0.10 0.25 B 0.33 0.51 C 0.19 0.25 D 4.80 5.00 E 3.80 4.00 H E e e A A1 C B l 1.27(TYP) H 5.80 6.20 L 0.40 1.27 L 8 LEAD PLASTIC DIP (unit: mm) D SYMBOL MIN A1 0.381 — A2 2.92 4.96 b 0.35 0.56 C 0.20 0.36 D 9.01 10.16 E 7.62 8.26 E1 6.09 7.12 E1 E A2 A1 C L e eB b MAX 2.54 (TYP) eB — 10.92 L 2.92 3.81 e UNIT: mm ANALOG INTEGRATIONS CORPORATION www.analog.com.tw 4F, 9 Industry E. 9th Road, Science-based IndustrialPark , Hsinchu, Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510 6