AIC1628 3-Cell, High-Efficiency, Step-Up DC/DC Converter FEATURES 4V to 24V Input Voltage Operation. Adjustable Output Voltage. DESCRIPTION The AIC1628 is a high performance step-up DC/DC converter, designed to drive an external power switch to generate programmable positive voltages. In the particularly suitable LCD contrast bias and flash memory programming power supply applications, typical full-load efficiencies are 85% to 95%. 4V to 24V input operation range allows the AIC1628 to be powered directly by the battery pack in the most batteryoperated applications for greater efficiency. 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 100µA and can be reduced to 8µA in shutdown mode. Switching frequency being around 90KHz to 250KHz range, small size switching components are ideal for battery powered portable equipments, like notebook and palmtop computers. Low Quiescent Current at 100µA. Pulse-Skipping and Pulse-Frequency Modulation Maintain High Efficiency (max. 95%). 90KHz to 250KHz Oscillator Frequency. Power-Saving Shutdown Mode (8µA Typical). Push-Pull Driver Output. APPLICATIONS Flash Memory Programming Power Supply. Positive LCD Contrast Bias for Notebook & Palmtop Computers. Step-Up DC/DC Converter Module. Telecom Power Supply. TYPICAL APPLICATION CIRCUIT +5V ~ 24V VIN + *Fuse 60mΩ 0.047µF 5V SHDN **L1 68µH DHI VREF FB VIN=13V CL VIN C2 95 C1 120µF DLOW 1N5819 D1 GND Q1 2SK940 AIC1628 C5 220µF +36V VOUT + C6 >50mA 16.5K 0.033µF C3 90 VIN=5V 85 VOUT=36V 80 470K 0.01µF C4 *Buss Fuse MCR-2A **Sumida CDR105 Color LCD Contrast Bias Supply VIN=18V VIN=9V 0.1µF R1 R2 Efficiency (%) 0 50 100 150 200 Load Current (mA) Efficiency vs. Output Current Analog Integrations Corporation 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC DS-1628-00 TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1 AIC1628 ORDERING INFORMATION AIC1628 XX PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE TEMPERATURE RANGE C=0°C~+70°C VIN Supply Voltage (VIN Pin) TOP VIEW AIC1628CS (PLASTIC SO) VIN 1 8 CL VREF 2 7 DHI SHDN 3 6 DLOW FB 4 5 GND ...........................…………….............................................. 24V .........................................……………................................................15V Operating Temperature Range Storage Temperature Range AIC1628CN (PLASTIC DIP ) ABSOLUTE MAXIMUM RATINGS SHDN Pin Voltage PIN CONFIGURATION ORDER NUMBER .........................…………....................................... 0°C~70°C ..........................………….................................. -65°C~ 150°C TEST CIRCUIT Refer to Typical Application Circuit ELECTRICAL CHARACTERISTICS (VIN= 13V, Ta=25°°C, unless otherwise specified.) PARAMETERS TEST CONDITIONS Input Voltage MIN. TYP. MAX. UNIT 24 V 100 200 µA 8 20 µA 1.22 1.28 V 4 Quiescent Current VFB = 1.5V Shutdown Mode Current V SHDN = 0V VREF Voltage ISOURCE = 250µA VREF Source Current 1.16 250 µA DLOW “ON Resistance” 15 Ω DHI “ON Resistance” 10 Ω CL Threshold VIN - VCL Shutdown Threshold Shutdown Input Leakage Current V SHDN < 15V 45 60 75 mV 0.8 1.5 2.4 V 1 µA 2 AIC1628 TYPICAL PERFORMANCE CHARACTERISTICS Frequency vs VIN Voltage Duty Cycle vs VIN Voltage 100 280 Ta= 25°C 90 230 Duty Cycle (%) Frequency (KHz) Ta= 0°C Ta= 70°C 180 130 80 70 Ta= 0°C 60 Ta= 70°C 50 Ta= 25°C 40 80 4 9 14 19 30 24 4 9 Ta= 0°C 90 80 Ta= 70°C 70 65 14 19 24 VIN = 20V 60 VIN = 13V 55 50 9 VIN (V) 0 20 40 60 80 Temperature (°C) Reference Voltage vs Temperature 1.3 Reference Voltage (V) VIN = 5V 70 CL Threshold (mV) Quiescent Current (µA) Ta= 25°C 4 24 75 100 60 19 Current Limit Threshold vs Temperature Quiescent Current vs VIN Voltage 110 14 VIN (V) VIN (V) VIN = 5V 1.25 1.2 1.15 1.1 0 20 40 60 80 Temperature (°C) 3 AIC1628 BLOCK DIAGRAM VIN VIN CURRENT LIMIT COMPARATOR 1 60mV + 8 CL VREF 2 PFM OSCILLATOR 3 1.22V REFERENCE VOLTAGE SHDN FB 4 + - VIN LATCH 7 DHI OUTPUT DRIVER 6 5 ERROR COMPARATOR DLOW GND PIN DESCRIPTIONS PIN 1: VIN - 4V to 24V input supply voltage. PIN 5: GND - Power ground. 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 6: DLOW -Driver sinking output. Connected to gate of the external N-channel MOSFET or base of the NPN bipolar transistor. PIN 3: SHDN - Logical input to shutdown the chip. >1.5V = normal operation, GND = Shutdown, Can not be floating or forced greater than 15V. In shutdown mode DLOW and DHI pins are at low level. PIN 7: DHI - Driver sourcing output. Connected to DLOW when using an external Nchannel MOSFET. When using an external NPN bipolar transistor, connect a base resistance RB from this pin to DLOW. RB value depends on VIN, inductor and NPN current gain. PIN 8: CL - Current-limit input. Threshold voltage is 60mV from VIN. This pin clamps the switch peak current to prevent over-current damage to the external switch, under abnormal conditions. PIN 4: FB- Feedback signal input to sense VREF. Connecting a resistance R1 to VOUT and a resistance R2 to GND yields the output voltage: VOUT = (R1+R2)/R2 x VREF (Refer to typical application circuit) 4 AIC1628 APPLICATION EXAMPLES CL D1 DLOW 1N5819 VOUT GND FB 2SK940 Q1 * ** R2 R1 11.3K 100K +12V >150mA 95 VIN=9V VIN=7V 90 85 VIN=5V 0 50 100 150 + C2 33µF VIN=4V 150µF VIN=3V *L1 47µH DHI D1 DLOW 1N5819 VOUT GND 2SK940 Q1 AIC1628 R2 R1 20K 470K 350 90 CL FB 300 Efficiency vs Load Current Battery Powered +2V~ 5V + SHDN 250 Flash memory programming supply C1 VREF 200 Load Current (mA) 5V VIN + Buss Fuse MCR-2A Sumida RCH108 Fig. 1 0.047µF C3 Efficiency (%) AIC1628 VIN=11V **L1 47µH DHI +12V >50mA + C4 180µF Efficiency(%) VREF Efficiency vs Load Current 100 C1 +5V ~ 11V 120µF C3 SHDN *Fuse 60mΩ 300µF 0.047µF VIN C2 VIN + 85 VIN=2V 80 75 0 50 *Sumida RCH108 100 150 Load Current (mA) Fig. 2 2-cells to +12V Flash memory programmer C1 VIN VREF C2 SHDN 150µF CL DHI DLOW FB RB 910 *L1 150µH D1 Q1 2SC4672 GND AIC1628 1N5819 + C3 220µF C4 VOUT +30V VIN=5V 95 VIN=6V VIN=4V 80 0.1µF R1 R2 17.5K Efficiency vs Load Current 90 Efficiency(%) 0.047µF + VIN +4V~ 6V C6 0.033µF 500K C5 *Sumida CD54 75 0 10 20 30 40 50 Load Current (mA) 0.1µF Fig. 3 4-cells to +30V power supply 5 AIC1628 APPLICATION EXAMPLES (CONTINUED) 1µF C3 C1 ZD1 0.1µF + VIN 12V 0.047µF C4 VIN -48V C5 CL VREF DHI SHDN DLOW FB R5 72K + -48V to +5V VOUT +5V 100mA D1 0.1µF C6 1N3906 Q2 2SK940 20K 80 Efficiency(%) 220µH Sumida CDR105 Q1 2N2907 + 85 C2 300µF R4 100K Efficiency vs Load Current 1N5819 L1 75 70 65 GND R3 20K AIC1628 60 0 50 100 150 Load Current (mA) 1N5819 D3 1N5819 Fig. 4 Telecom +5V supply D2 47µF VIN +5V + C4 CL 100µF 90 DHI SHDN DLOW 33µH D1 GND FB 1µF 2SK1463 Q1 VREF 1N5820 AIC1628 R2 R1 20K 34K Efficiency vs Load Current 95 Efficiency(%) VIN C2 C1 + C5 + 0.04µF 47µF *L1 C3 330µF + VOUT +3.3V 2A 85 80 75 10 *MPP Core Fig. 5 100 1000 Load Current (mA) 5V to 3.3V step-down converter 6 AIC1628 PHYSICAL DIMENSIONS 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 1.27(TYP) H 5.80 6.20 L 0.40 1.27 L 8 LEAD PLASTIC DIP (unit: mm) D E1 E A2 A1 C L eB b e SYMBOL MIN MAX 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 e 2.54 (TYP) eB — 10.92 L 2.92 3.81 7