AIC1653 Micropower Inverting DC/DC Converter in SOT-23-5 FEATURES DESCRIPTION Low Quiescent Current: The AIC1653 is a micropower inverting DC/DC 15µA in Active Mode converter in 5-lead SOT-23 package. It is designed <1µA in Shutdown Mode for power systems with a 100mA current limit and an input voltage ranging from 1.8V to 10V. Besides, Operates with VIN as Low as 1.8V AIC1653 features a quiescent current of only 15µA Uses Small Surface Mount Components at no load, which further reduces to 0.5µA when High Output Voltage: Up to -28V shutdown. The schemes of current limited and Low profile 5-Lead SOT-23-5 Package fixed off-time control conserve operating current, resulting in high efficiency over a broad range of APPLICATIONS load current. In addition, the 30V switch of LCD Bias AIC1653 allows high voltage outputs up to -28V, Hand-Held Computers which is easily generated without the use of costly Battery Backup transformers. The AIC1653’s low off-time of 400ns Digital Still Cameras permits the use of tiny, low profile inductors and capacitors to minimize footprint and cost in space-conscious portable applications. TYPICAL APPLICATION CIRCUIT C1 4.7µF C3 L1 VIN 2.5V~5V 22µH 5 4 2 VIN SW 0.22µF 1 L2 VOUT -6V/14mA 22µH D1 RB521S-30 SHDN 3 GND NFB R1 150k C2 4.7µF R2 39K AIC1653 L1,L2: TOKO D312F 22µH D1: Rohm RB521S-30 C1,C2,C3: TAIYO YUDEN Ceramic capacitors Analog Integrations Corporation 4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw DS-1653-02 122203 1 AIC1653 ORDERING INFORMATION PIN CONFIGURATION AIC1653CXXX SOT-23-5 (CV) FRONT VIEW 1: SW 2: GND 3: NFB 4. SHDN 5: VIN PACKING TYPE TR: TAPE & REEL BG: BAG PACKAGE TYPE V: SOT-23-5 Example: AIC1653CVTR 5 1 4 2 3 in SOT-23-5 Package & Tape & Reel Packing Type SOT-23-5 Marking Part No. Marking AIC1653 1653 ABSOLUTE MAXIMUM RATINGS (Note 1) VIN, SHDN Voltage 10V SW Voltage 30V NFB Voltage -3V Junction Temperature Operating Temperature Range (Note 2) Storage Temperature Range Lead Temperature (Soldering, 10 sec) 125°C -40°C to 85°C -65°C to 150°C 300°C TEST CIRCUIT Refer to Typical Application Circuit. 2 AIC1653 ELECTRICAL CHARACTERISTICS (TA = 25°C, VIN = 3.6V, V SHDN = 3.6V unless otherwise specified) PARAMETER TEST CONDITIONS MIN. TYP. Minimum Input Voltage Quiescent Current Not Switching 15 VSHDN = 0V FB Comparator Trip Point 3) FB Pin Bias Current (Note 4) -1.205 Switch Off Time Refer to Fig.7 VNFB = –1.23V UNIT 1.8 V 20 1 FB Comparator Hysteresis Output Voltage Line Regulation (Note MAX. 1.3 -1.23 -1.255 µA V 10 mV 0.05 %/V 2 2.7 µA NFB≤-1V 400 nS NFB≥-0.6V 800 nS Inter Switch On-Resistance 0.6 1 1.4 Ω Switch Current Limit 75 100 125 mA SHDN Input Voltage High 0.9 V SHDN Input Voltage Low Switch Leakage Current Switch Off, VSW = 5V 0.01 0.25 V 5 µA Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Specifications over the -40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Output voltage line regulation is guaranteed by design, characterization and correlation with statistical quality controls, not production tested. Note 4: Bias current flows out of the NFB pin. 3 AIC1653 TYPICAL PERFORMANCE CHARACTERISTICS 5 -1.25 VIN=3.6V FB Comparator Trip Point (V) 75 4 -1.24 Efficiency (%) 70 VIN=2.7V VIN =4.2V 60 55 50 45 2 4 6 8 Voltage -1.23 65 10 12 14 16 3 Current -1.22 2 -1.21 1 -1.20 -40 -20 0 20 40 60 80 Load Current (mA) Temperature (°C) Fig. 1 Load Current vs. Efficiency Fig. 2 FB Comparator Trip Point and Pin Bias (Refer to typical application circuit) Current vs. Temperature Bias Current (µA) 80 0 100 1.5 VIN=2.5V VIN =3.6V 120 Switch ON-Resistance (Ω) Switch Current Limit (mA) 140 100 80 VIN=4.2V 60 VIN =8.5V VIN =10V 40 20 0 -40 1.4 VIN=3.6V, 1.3 ISWITCH=50mA 1.2 1.1 1.0 0.9 0.8 -20 0 20 40 60 80 100 0.7 -40 -20 0 20 40 60 80 Temperature (°C) Temperature (°C) Fig. 3 Switch Current Limit vs. Temperature Fig. 4 Switch ON-Resistance vs. Temperature 100 4 AIC1653 TYPICAL PERFORMANCE CHARACTERISTICS (Continued) Temperature (°C) -40 850 Switch Off Time (ns) 700 650 600 550 500 Phase II 450 -20 20 60 40 80 100 20 0 VIN=1.8V to 12V, 22 Phase I 750 400 -40 0 24 VIN=3.6V Supply Current (uA) 800 -20 Temperature = 20°C 20 18 16 Temperature=-40°C to 100°C, 14 VIN =3.6V 12 40 60 80 100 10 2 4 6 8 10 12 Temperature (°C) Supply Voltage (V) Fig. 5 Switch Off Time vs. Temperature Fig. 6 Quiescent Current vs. Temperature and Voltage 7.0 6.8 Output Voltage (V) 6.6 6.4 6.2 6.0 5.8 VOUT = - 6.0V, 5.6 IOUT=2mA 5.4 5.2 5.0 2 3 4 5 6 7 8 9 10 Input Voltage (V) Fig. 7 Line Regulation 5 AIC1653 BLOCK DIAGRAM SW VIN + R1 A2 R2 Bandgap + Q2 100mV Current Limit A1 - Q1 - 400nS/ 800nS One-Shot Logic R3 Drive + R4 NFB - + - A3 -0.6V MODE Control GND SHDN Fig. 8 Block diagram of AIC1653 PIN DESCRIPTIONS PIN 1: SW - Switch Pin. This is the open drain R1 = of the internal N-MOSFET power switch. Minimize the metal trace area connected to this pin to PIN 4: SHDN - Shutdown Pin. Tie this pin to 0.9V or higher to enable the minimize EMI. PIN 2: GND device. Tie below 0.25V to turn - Ground. Tie this pin directly to the off the device. local ground plane. PIN 3: FB - Set the output voltage by values VOUT − 1.23 1.23 + 2 × 10 −6 R2 PIN 5: VIN - Input Supply Pin. Bypass this pin of R1 and R2 (see typical with a capacitor as close to the application circuit): device as possible. 6 AIC1653 APPLICATION INFORMATIONS Principle of Operation AIC1653 uses a constant off-time control scheme, which is represented in Fig. 8, to provide high efficiency over a range of output current. Q1 and Q2 along with R3 and R4 form a bandgap reference used to regulate the output voltage. When the voltage at NFB pin is slightly below -1.23V, comparator A1 disables most of the internal circuitry. Output current is then provided by output capacitor, which slowly discharges until the voltage at the NFB pin goes above the hysteresis point of A1. A1 then enables the internal circuitry to turn power switch NMOS on, and the current in inductor begins ramping up. Once the switch current reaches 100mA, comparator A2 resets one-shot, which turns NMOS off for 400ns. In the meantime, the inductor continues to deliver current to the output. When NMOS turns back on, the inductor current ramps up. And A2 resets one-shot Component Selection Inductor Selection – Inverting Regulator The following formula calculates the appropriate inductor value for an inverting regulator. This value provides a good tradeoff in inductor size and system performance. In any applications, the closest value to the one from the formula needs to be applied to the inductors (both inductors should have the same value). A use of an inductor value up to 22µH can induce a slight increase of output current, but any value beyond that will result in high output ripple voltage with no further output current increase. The size of inductor can be reduced by using a value under 22µH. The formula is shown as below: V OUT + VD L = 2 × t OFF I LIM (1) again when switch current gets to 100mA. This where VD=0.4V (Schottky diode forward voltage), switching action continues until the output voltage ILIM=100mA, and tOFF=400nS. is charged up with NFB pin reaching -1.23V. Then A1 turns the internal circuitry off and the cycle Be aware that, based on formula (1), high output repeats. The AIC1653 contains additional circuitry voltage can raise inductance, which may cause an to provide current-limit protection for start-up as increase of inductor size. well as short-circuit protection. When FB pin voltage is higher than –0.6V, switch off-time is For increased to 800nS. This reduces the average converting from 3.6V to –6V, a 51.2µH inductor is inductor current and helps minimize the power calculated from the above equation. However, a dissipation in AIC1653 power switch, and in the 22µH inductor is recommended instead to prevent external inductor and diode. the loss of output current. a converter (typical application circuit) 7 AIC1653 Inductor Selection – Inverting Charge Pump Multilayer ceramic capacitors are the best choice Regulator as they have a very low ESR and are available in This topology, inverting charge pump regulator, is low-profile packages. Due to the advantage of recommended when internal power switch voltage small size, it makes multilayer ceramic capacitors is over its maximum rating. and AIC1653’s SOT-23 packages good companions for size-concerning applications. As the inverting regulator application above, its internal power switch voltage is 9.6V (the sum of Solid tantalum capacitors are another alternative the absolute value of 3.6V input and –6V output), for output capacitors, but they take more board which is fine as it is under the maximum rating, 30V. area and have larger ESR than ceramics. However, any applications of internal power switch voltage exceeding the maximum rating, topology of Input Capacitors inverting charge pump regulator is recommended Ceramic capacitors also make a good choice for for their system. the input decoupling capacitor, which should be placed as close as possible to AIC1653. A 4.7µF For example, a 12V to -30V converter will generate input capacitor is sufficient for most applications. 42V internal power switch voltage, which exceeds its maximum rating 30V. For such a system, an Be aware that, sufficient voltage rating is required inverting for capacitor selection. charge pump regulator is the recommended topology. Diode Selection Appropriate inductor value for an inverting charge For most AIC1653 applications, Rohm RB521S-30 pump regulator can be calculated by formula (2). surface mount Schottky diode (200mA, 30V) For designs with varying VIN value such as providing the advantage of low forward voltage and battery-powered applications, minimum VIN value fast switching speed is an ideal choice. Note that, is used in formula (2). generally, rating of handling minimum current at 1A L= VOUT − VIN(MIN) + VD t OFF ILIM (2) is required for AIC1653 applications. Reducing Output Ripple Voltage Capacitor Selection Using low ESR capacitors will help reduce the Output Capacitors Low ESR (Equivalent output ripple voltage. In addition, proper selection Series Resistance) capacitors should be used at output terminal to minimize the output ripple voltage. of the inductor and the output capacitor plays an important role in output ripple voltage reduction. The AIC1653 provides energy to the output in 8 AIC1653 bursts by ramping up the inductor current, which is A capacitor at 100pF in parallel to the upper then delivered to load. If either inductor value over feedback resistor is required for a stable feedback. 22µH or capacitor value under 4.7µF is used, output ripple voltage will increase because the PCB Layout capacitor will be slightly overcharged in each burst Proper PCB layout and component placement may cycle. Two methods of helping reduce output ripple enhance the performance of AIC1653 application voltage are recommended. One is to increase the circuit. For a better efficiency, major loop from output 100pF input terminal to output terminal should be as short feedforward capacitor that is parallel with R1 (see as possible. In addition, in a case of a large current Fig.13) is the other. And the addition of the small loop, the track width of each component in the loop capacitor will greatly reduce output ripple voltage. should maintain as wide as possible. In order to get capacitor value. Adding a rid of noise interference, separation of Schottky Output Voltage Programming diode ground and output terminal ground into two A resistive divider, as in formula (3), sets the output independent parts is required. Recommended voltage. layout diagrams and component placement are ( R1 + R1 × 2 × 10 − 6 VOUT = − 1.23V 1 + R2 Fig. 9 Top Layer ) (3) shown as Fig. 9 to Fig. 12. Fig. 10 Bottom Layer 9 AIC1653 Fig. 11 Top Placement Fig. 12 Bottom Placement APPLICATION EXAMPLES C1 4.7µF C3 L1 VIN 3V~5V 22µH 5 4 2 VIN SW 0.22µF 1 L2 VOUT -6V/14mA 22µH D1 RB521S-30 SHDN 3 GND NFB R1 150k C4 100pF C2 4.7µF R2 39k AIC1653 L1,L2: TOKO D312F 22µH D1: Rohm RB521S-30 C1,C2,C3: TAIYO YUDEN Ceramic capacitors Fig. 13 OLED Application for Single Li-Ion Input C1 4.7µF C3 L1 VIN 3V~5V 22µH 5 4 2 VIN SW 0.22µF 1 VOUT -6V/14mA D1 BAT54S SHDN 3 GND NFB AIC1653 R1 150k C4 100pF C2 4.7µF R2 39k L1: TOKO D312F 22µH D1: CHENMKO BAT54S C1,C2,C3: TAIYO YUDEN Ceramic capacitors Fig. 14 Inverting Charge Pump Application 10 AIC1653 PHYSICAL DIMENSIONS (unit: mm) SOT-23-5 (CV) C D L H E e θ1 A A2 SYMBOL MIN MAX A 1.00 1.30 A1 — 0.10 A2 0.70 0.90 b 0.35 0.50 C 0.10 0.25 D 2.70 3.10 E 1.40 1.80 e A1 b 1.90 (TYP) H 2.60 3.00 L 0.37 — θ1 1° 9° Note: Information provided by AIC is believed to be accurate and reliable. However, we cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AIC product; nor for any infringement of patents or other rights of third parties that may result from its use. We reserve the right to change the circuitry and specifications without notice. Life Support Policy: AIC does not authorize any AIC product for use in life support devices and/or systems. Life support devices or systems are devices or systems which, (I) are intended for surgical implant into the body or (ii) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 11