AIC2362 2A 550k/1.1MHz Synchronous PWM/PSM Step-Down Converter with High Light-load Efficiency DESCRIPTION FEATURES 2.5V to 6V Input Voltage Range Adjustable Output Voltage from 0.8V to Vin 2.0A Guaranteed Output Current 93% Efficiency at Heavy Load (Vin=5V, Vout=3.3V, Iout=2.0A) 96% Efficiency at Moderate Load (Vin=5V, Vout=3.3V, Iout=1.0A) 90% Efficiency at Light Load The AIC2362 is a low-noise, pulse-widthmodulated (PWM), DC-DC step-down converter. The device features an internal synchronous rectifier for high efficiency; it requires no external Schottky diode. The AIC2362 is ideally suited for Li-Ion battery applications. Automatic PWM/PSM mode extends battery life and enhance efficiency by switching to a pulse-skippingmodulated mode during light load. Shutdown mode places the device in standby, reducing supply current to under 2µA. Other features of the AIC2362 include high efficiency for all load range, low dropout voltage, short circuit protection, and over temperature protection. (Vin=5V, Vout=3.3V, Iout=20mA) Low RDS(ON) Internal Switches: 110mΩ No Schottky Diode Required 100% Duty Cycle in Low Dropout Operation Fixed 550k/1.1MHz Operating Frequency Optional Soft-Start Internal Fixed 1ms SoftStart APPLICATIONS LCD TV Portable Products Wireless and DSL Modems Solid-State Drives Battery-Operated Devices (1 Li-Ion or 3 NiMH/ NiCd) APPLICATIONS CIRCUIT 8 VIN R1 10Ω 5V 1 ON C1 10uF C2 0.1uF VIN 5 OFF 6 LX VCC FB EN REF PGND AIC2362 GND 7 L1 2.2uH 4 VOUT R2 50kΩ 3.3V 2 3 C4 0.1uF R3 16kΩ C3 22uF Typical Application Circuit Analog Integrations Corporation Si-Soft Research Center DS-2362G-05 20150122 st 3A1, 1 Li-Hsin 1 Rd., Science Park , Hsinchu 300, Taiwan , R.O.C. TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1 AIC2362 ORDERING INFORMATION AIC2362XXXXXX PIN CONFIGURATION PACKING TYPE TR: TAPE & REEL TB: TUBE SOP-8 TOP VIEW PACKAGE TYPE S8: SOP-8 R8: SOP-8 with Exposed Pad VCC 1 REF 8 VIN 2 7 LX 6 PGND GND 3 G: Green Package FB 5 EN 4 A: 1.1MHz B: 550KHz Example: AIC2362AGS8TR Fixed 1.1MHz Operating Frequency With GREEN SOP-8 Package and TAPE & REEL Packing Type SOP-8 with Exposed Pad (Heat Sink) TOP VIEW VCC 1 8 REF 2 7 GND 3 FB 4 (GND) VIN LX 6 PGND 5 EN Note: The exposed pad must be connected with GND pin. ABSOLUTE MAXIMUM RATINGS Supply Input Volatge, VCC, VIN -0.3V to 6.5V LX Pin Switch Voltage -0.3V to 6.5V Other I/O Pin Voltage -0.3V to 6.5V +/-0.3 V PGND to GND -40C to 85C Operating Ambient Temperature Range TA Operating Maximum Junction Temperature TJ 150C -65C to 150C Storage Temperature Range TSTG 260C Lead Temperature (Soldering 10 Sec.) Thermal Resistance Junction to Case SOP-8 40C/W Thermal Resistance Junction to Case SOP-8 (Thermal Pad) * 15C/W Thermal Resistance Junction to Ambient SOP-8 Thermal Resistance Junction to Ambient SOP-8 (Thermal Pad)* Latch-Up HBM (Human Body Mode) 160C/W 60C/W 200mA 4kV (Assume no Ambient Airflow, no Heatsink) Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. 2 AIC2362 ELECTRICAL CHARACTERISTICS (TA=25C, VIN=3.3V, unless otherwise specified.) (Note1) PARAMETER CONDITIONS Input Voltage Range SYMBOL MIN VIN 2.5 TYP MAX UNITS 6 V Under Voltage Lockout Threshold VCC Rising VUVLO(R) 2.3 V VCC Falling VUVLO(F) 2.1 V Output Adjustment Range VOUT 0.8 VIN V Shutdown Current VEN = 0V ISD 1 2 A Quiescent Current IOUT = 0A, VFB = 1V No Switching IQ 200 380 A Standby Current IOUT = 0A, Switching ISB 600 900 A 0.8 0.816 V Feedback Reference Voltage VOUT Line Regulation VOUT Load Regulation VREF VIN = 2.5V to 5.5V, IOUT=0A IOUT = 1mA to 2A, VIN=5V 0.784 -2 2 % -1 1 % 0.2 A FB Leakage Current IFB 0.1 EN Supply Current IEN 3.5 A EN Logic High 1.5 VCC V EN Logic Low 0 0.5 V P-Channel On-Resistance VIN = 3.3V RDSH(ON) 110 m N-Channel On-Resistance VIN = 3.3V RDSL(ON) 80 m Switch Leakage Current VEN = 0V, VIN = 5.5V Peak Inductor Current 0.1 1 A IPK 2.6 3.4 A Oscillator Frequency (A Version) fOSCA 920 1100 1280 kHz Oscillator Frequency (B Version) fOSCB 468 550 632 kHz Maximum Duty Cycle DMAX 100 Thermal Shutdown Trip Point TOTP 150 °C Thermal Shutdown Hysteresis TOTP_HYS 25 °C % Soft-Start Charge Current ISS 4 A Note 1: Specifications are production tested at TA=25C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with Statistical Quality Controls (SQC). 3 AIC2362 TYPICAL PERFORMANCE CHARACTERISTICS (C1=10μF,C3=22μF,L1=2.2μH,TA=25℃,unless otherwise noted) y( ) 100.00 95.00 90.00 85.00 80.00 75.00 70.00 65.00 60.00 55.00 50.00 3.3VOUT 1.8VOUT (VCC=VIN=5V) 0 250 500 750 1000 1250 1500 1750 2000 Fig. 1 Efficiency vs load Current Fig. 2 Output Voltage Deviation vs Input Voltage VIN=VCC=3.3V,VOUT=1.8V,ILOAD=1.5A VIN=VCC=3.3V,VOUT=1.8V,ILOAD=1.5A ILX VLX VOUT OUT Ripple VEN Fig. 3 Switching Waveform Fig. 4 Soft Start Waveform VIN=VCC=3.3V,VOUT=0.8V,ILOAD=1.5A VEN VOUT VLX VEN VOUT Fig. 5 Soft Start Waveform Fig. 6 Shoutdown Waveform 4 AIC2362 TYPICAL PERFORMANCE CHARACTERISTICS (Continued) VIN=VCC=5V,VOUT=1.5V,ILOAD=0.5A to 1A VIN=VCC=5V,VOUT=2.5V,ILOAD=0.5A to 1A OUT Ripple OUT Ripple ILOAD ILOAD Fig. 7 Load Transient Response Fig. 8 Load Transient Response Fig. 9 Switching Frequence vs Input Voltage Fig. 10 Output Voltage Deviation vs Load Current 5 AIC2362 BLOCK DIAGRAM Functional Block Diagram of AIC2362 PIN DESCRIPTIONS Pin No. 1 2 3 Pin Name VCC REF GND 4 FB 5 EN 6 7 8 PGND LX VIN Pin Function Signal Input Supply. Decouple this pin to GND with a capacitor. Normally VCC is equal to VIN. Internal Reference Voltage. Decouple this pin to GND with a capacitor. Signal Ground. All small-signal components and compensation components should connect to this ground, which in turn connects to PGND at one point. Feedback Pin. This pin receives the feedback voltage from a resistive divider connect across the output. Enable Pin. Connect to logic high in normal operation. Forcing this pin to GND cause the device to be shutdown. Power Ground. Connect this pin to the negative terminal of CIN and COUT. Internal Power MOSFET Switches Output. Connect this pin to the inductor. Power Input Supply. Decouple this pin to PGND with a capacitor. 6 AIC2362 APPLICATION INFORMATION Operation frequency of AIC2362 will be reduced to one fourth of The AIC2362 is a low-noise step-down DC/DC the normal switching frequency. This lower switching converter control frequency ensures the inductor current has more time architecture. It features an internal synchronous to discharge, thereby preventing inductor current rectifier, which eliminates the external Schottky diode runaway. The switching frequency will automatically and increases efficiency. During normal operation, the return to its designed value while short circuit condition with current-mode PWM/PSM AIC2362 can regulate its output voltage through a is released. feedback control circuit, which is composed of an error Shutdown amplifier; a current comparator and several control By connecting the EN pin to GND, the AIC2362 can be signal generators. By comparing the feedback voltage shut down to reduce the supply current to 2A (typical). to the reference voltage of 0.8V, the error amplifier At this operation mode, the output voltage of step- varies its output voltage. The output voltage of the down converter is equal to 0V. error amplifier is compared with the summing signal of 100% Duty Cycle Operation current sensing signal and slope compensation signal When the input voltage approaches the output voltage, to determine the duty cycle of internal main power the AIC2362 smoothly transits to 100% duty cycle switch (P-channel MOSFET). While the main power operation. This allows AIC2362 to regulate the output switch is turned on, the synchronous power switch (N- voltage until AIC2362 completely enters 100% duty channel MOSFET) will be turned off through anti-short- cycle operation. In 100% duty cycle mode, the output through block. Similarly, when the main power switch voltage is equal to the input voltage minus the voltage, is turned off, the synchronous power switch will be which is the drop across the main power switch. turned on until the inductor current starts to reverse or The AIC2362 achieves 100% duty cycle operation by the beginning of the next switching cycle. In order to extending the turn-on time of the main power switch. If achieve better efficiency and prevent overcharging the the summing signal of current sensing signal and slope output capacitor, AIC2362 will enter pulse-skipping- compensation signal does not reach the output voltage modulated mode (PSM) operation while working at level of the error amplifier at the end of 90% switching light load conditions. period, the main power switch is continuously turned Current Limitation on and the oscillator remains off until the summing The AIC2362 provides current limit function by using signal an internal sensing resistor. When the main power compensation signal reaches the output voltage level switch turns on, current follows through the internal of the error amplifier. After the summing signal of sensing resistor. And current amplifier senses the current sensing signal and slope compensation signal voltage, which crosses the resistor, and amplifies it. reaches the output voltage level of the error amplifier, While the sensed voltage gets higher than reference the main power switch is turned off and the voltage, the current limitation function is activated. synchronous power switch is turned on for a constant While the current limitation function is activated, the off time. At the end of the constant off time, the next duty cycle will be reduced to limit the output power to switching cycle is begun. While the input voltage protect the internal power switches. approaches Short Circuit Protection frequency decreases gradually to smoothly transit to While the output is shorted to ground, the switching 100% duty cycle operation. of current the sensing output signal voltage, and the slope switching 7 AIC2362 If input voltage is very close to output voltage, the VOUT switching mode goes from pure PWM mode to 100% IL ESR IL 8 fOSC COUT duty cycle operation. During this transient state For lower output voltage ripple, the use of low ESR mentioned above, large output ripple voltage may ceramic capacitor is recommended. The tantalum appear on output terminal. capacitor can also be used well, but its ERS is larger Components Selection than that of ceramic capacitor. Inductor When The inductor selection depends on the current ripple of capacitors, X5R and X7R types are recommended inductor, the input voltage and the output voltage. because they retain their capacitance over wider L VOUT 2fOSC IL VOUT 1 VIN choosing the input and output ceramic ranges of voltage and temperature than other types. Output Voltage Programming Accepting a large current ripple of inductor allows the By connecting a resistive divider R2 and R3, the output use of a smaller inductance. However, higher current voltage of AIC2362 step-down converter can be set. ripple of inductor can cause higher output ripple VOUT can be calculated as: current ripple of inductor, a suitable inductance can be R VOUT 0.8 1 2 R3 obtained from above equation. The resistive divider should sit as close to VFB pin as In addition, it is important to ensure the inductor possible. saturation current exceeds the peak value of inductor Layout Consideration current in application to prevent core saturation. The In order to ensure a proper operation of AIC2362, the peak value of inductor current can be calculated following points should be managed comprehensively. according to the following equation. 1. The input capacitor and VIN should be placed as voltage and large core loss. By setting an acceptable IPEAK IOUT max VOUT VOUT 1 2 fOSC L VIN Input Capacitor and Output Capacitor close as possible to each other to reduce the input voltage ripple and noise. 2. The output loop, which is consisted of the inductor, the internal main power switch, the internal To prevent the high input voltage ripple and noise resulted from high frequency switching, the use of low ESR ceramic capacitor for the maximum RMS current is recommended. The approximated RMS current of the input capacitor can be calculated according to the following equation. ICINRMS I 2 OUT ( MAX ) V V V I2 OUT IN 2 OUT L VIN 12 The selection of output capacitor depends on the synchronous power switch and the output capacitor, should be kept as small as possible. 3. The routes with large current should be kept short and wide. 4. Logically the large current on the converter should flow at the same direction. 5. The VFB pin should be connected to the feedback resistors directly and the route should be away from the noise sources. required output voltage ripple. The output voltage ripple can be expressed as: 8 AIC2362 PHYSICAL DIMENSIONS (unit: mm) SOP-8 Package h X 45° A A SEE VIEW B A e H E D WITH PLATING 0.25 C A1 B GAUGE PLANE SEATING PLANE θ L VIEW B BASE METAL SECTION A-A Note: 1. Refer to JEDEC MS-012AA. 2. Dimension "D" does not include mold flash, protrusions or gate burrs. Mold flash, protrusion or gate burrs shall not exceed 6 mil per side . 3. Dimension "E" does not include inter-lead flash or protrusions. 4. Controlling dimension is millimeter, converted inch dimensions are not necessarily exact. S Y M B O L SOP-8 MILLIMETERS 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 e 1.27 BSC H 5.80 6.20 h 0.25 0.50 L 0.40 1.27 θ 0° 8° 9 AIC2362 SOP-8 Exposed Pad(Heat Sink) D D1 EXPOSED THERMAL PAD(Heat Sink) (BOTTOM CENTER OF PACKAGE) h X 45° A A SEE VIEW B A e H E E1 WITH PLATING 0.25 C A1 B GAUGE PLANE SEATING PLANE L VIEW B BASE METAL SECTION A-A Note : 1. Refer to JEDEC MS-012E. 2. Dimension "D" does not include mold flash, protrusions or gate burrs. Mold flash, protrusion or gate burrs shall not exceed 6 mil per side . 3. Dimension "E" does not include inter-lead flash or protrusions. 4. Controlling dimension is millimeter, converted inch dimensions are not necessarily exact. S Y M B O L SOP-8 Exposed Pad(Heat Sink) MILLIMETERS MIN. MAX. A 1.35 1.75 A1 0.00 0.15 B 0.31 0.51 C 0.17 0.25 D 4.80 5.00 D1 1.50 3.50 E 3.80 4.00 E1 1.0 2.55 e 1.27 BSC H 5.80 6.20 h 0.25 0.50 L 0.40 1.27 θ 0° 8° 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. 10