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AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 1 - DESCRIPTION FEATURES The A7115B is a 2MHz high-efficiency, PWM step-down converter with integrated main switch and synchronous rectifier that is ideal for powering portable equipment that runs from a single Li-on or Li-Polymer battery. The A7115B can supply up to up to 1.5A load current from a 2.6V to 5.5V input voltage. The output voltage can be as low as 0.6V. The A7115B features include <1uA shutdown current, small external components, such as ceramic input and output caps, as well as small inductors, while still providing low output ripples. This low noise output along with its excellent efficiency achieved by the internal synchronous rectifier, making A7115B an ideal replacement for large power consuming linear regulators. Internal soft- start control circuitry reduces inrush current. Short-circuit and thermal shutdown protection improves design reliability. The A7115B is available in SOT-25 and DFN6 (2x2) packages. High efficiency: up to 97% 2MHz switching frequency Up to 1.5A Load current 2.6V to 5.5V input Voltage Rage Current mode control Low dropout 100% duty operation Internal compensation and soft-start Reference 0.6V Logic control shutdown (I Q<1uA) Thermal shutdown, UVLO Available in SOT-25 and DFN6 (2x2) packages APPLICATION Cellular phones Microprocessors and DSP Core Supplies PDA and Smart Phones MP3 and Portable Media Players Digital Still and Video Cameras Portable Instruments Set Top Box Wireless and DSL modems USB supplied devices in notebooks ORDERING INFORMATION TYPICAL APPLICATION Package Type Part Number SOT-25 SPQ: 3,000pcs/Reel A7115BE5R A7115BE5VR DFN6 SPQ: 3,000pcs/Reel J6 A7115BJ6R A7115BJ6VR Note V: Halogen free Package R: Tape & Reel AiT provides all RoHS products A7115B external Inductor suggest AiT Semi’s PIA2512L-1R0M & PIA2512L-2R2M
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 2 - PIN DESCRIPTION Top View Top View Pin # Symbol Function SOT-25 DFN6 (2x2) 1 2 EN Enable pin for the IC. Drive the pin to high to enable the part , and low to disable 2 5 GND Ground. 3 4 SW Inductor connection. Connect an inductor between SW and the regulator output. 4 3 V IN Supply voltage. 5 6 FB Feedback input. Connect an external resistor divider from the output to FB and GND to set the output to a voltage between 0.6V and V IN - 1 NC No Connection
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 3 - ABSOLUTE MAXIMUM RATINGS Max Input Voltage 8V TJ, Max Operating Junction Temperature 125°C TA, Ambient Temperature -40°C~85°C Maximum Power Dissipation SOT-25 400mW DFN6 (2x2) 600mW TS, Storage Temperature -40°C~150°C Lead Temperature & Time 260°C, 10sec. ESD (HBM) >2kV Stress beyond above listed “Absolut e Maximum Ratings” may lead permanent damage to the device. These are stress ratings only a nd operations of the device at these or any other conditions beyond those indicated in the operati onal sections of the specificat ions are not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 4 -
ELECTRICAL CHARACTERISTICS
VIN=5V, TA=25°C, unless otherwise specified. Parameter Symbol Conditions Min. Typ. Max. Unit Input Voltage Range V IN 2.6 - 5.5 V Input Overvoltage Threshold VOVP - 6.1 - V Feedback Voltage V REF V IN=5V 0.588 0.6 0.612 V Feedback Leakage Current IFB - 0.1 1 μA Quiescent Current I Q Active, VFB=0.65V, No Switching - 80 - μA Shutdown EN=0V - - 1 μA Line Regulation LNR V IN=2.6V to 6V - 0.1 0.2 %/V Load Regulation LDR I OUT=0.01A to 1A - 0.1 0.2 %/A Switching Frequency f SOC 1.6 2 2.4 MHz PMOS RDSON R DSONP - 250 350 mΩ NMOS RDSON R DSONN - 150 250 mΩ Under Voltage Lockout V UVLO 1.9 2.1 2.3 V UVLO Hysteresis V UVLO_HY - 100 - mV Peak Current Limit I LIMIT 1.8 2.3 2.8 A I NOLOAD V IN=5V, VOUT=3.3V, IOUT=0A - 80 - μA SW Leakage Current I SWLK V IN=6V, VSW=0V or 6V, EN=0V - - 1 μA EN Leakage Current I ENLK - - 1 μA EN Input High Voltage V H_EN 1.2 - - V EN Input Low Voltage V L_EN - - 0.5 V Thermal Shutdown Temp TSD - 160 - °C Thermal Shutdown Hysteresis TSH - 1 5 - ° C
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 5 - TYPICAL PERFORMANCE CHARACTERISTICS Tested under TA=25°C, unless otherwise specified 3. Efficiency vs. Output Current (VOUT=3.3V) 4. Output Ripple and SW at 1A load VIN=5V / VOUT=1.8V Ch2—VOUT ripple, Ch3—VSW, Ch4—ISW 5. Load Transient VIN=5V / VOUT=1.2V / IOUT=0.01~1.5A 6. Load Transient VIN=5V / VOUT=3.3V / IOUT=0.01~1.5A Ch2—VOUT ripple, Ch4—IOUT Ch2—VOUT ripple, Ch4—IOUT
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 6 - BLOCK DIAGRAM
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 7 - DETAILED INFORMATION The A7115B high-efficiency switching regulator is a small, simple, DC-to-DC step-down converter capable of delivering up to 1.5A of output current. The device operates in pulse-width modulation (PWM) at 2MHz from a 2.6V to 5.5V input voltage and provides an output voltage from 0.6V to V IN, making the A7115B ideal for on-board post-regulation applications. An internal synchronous rectifier improves efficiency and eliminates the typical Schottky free-wheeling diode. Using the on resistance o f the internal high-side MOSFET to sense switching currents eliminates current-sense resistors, further improving efficiency and cost. Loop Operation A7115B uses a PWM current-mode control scheme. An open-loop com parator compares the integrated voltage-feedback signal against the sum of the amplified curren t-sense signal and the slope compensation ramp. At each rising edge of the internal clock, the internal h igh-side MOSFET turns on until the PWM comparator terminates the on cycle. During this on-time, curren t ramps up through the inductor, sourcing current to the output and storing energy in the inductor. The c urrent mode feedback system regulates the peak inductor current as a func tion of the output voltage error signal. During the off cycle, the internal high-side P-channel MOSFET turns off, and the internal low-side N-channel MOSFET turns on. The inductor (AiT Semi’s PIA2512L-1R0M or PIA2512L-2R2M) releases the stored energy as its current ramps down while still providing current to the output. Current Sense An internal current-sense amplifier senses the current through the high-side MOSFET during on time and produces a proportional current signal, which is used to sum wi th the slope compensation signal. The summed signal then is compared with the error amplifier output by the PWM comparator to terminate the on cycle. Current Limit There is a cycle-by-cycle current limit on the high-side MOSFET of 2.3A (typ). When the current flowing out of SW exceeds this limit, the high-side MOSFET turns off and the synchronous rectifier turns on. A7115B utilizes a frequency fold-back mode to prevent overheating during short- circuit output conditions. The device enters frequency fold-back mode when the FB voltage drops below 100mV, limiting the current to 2.3A (typ) and reducing power dissipation. Normal operation resumes upon removal of the short-circuit condition.
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 8 - Soft-start A7115B has an internal soft-start circuitry to reduce supply inrush current during startup conditions. When the device exits under-voltage lockout (UVLO), shutdown mode, or re starts following a thermal shutdown event, the soft-start circuitry slowly ramps up current available at SW. UVLO If V IN drops below 2.1V, the UVLO circuit inhibits switching. Once VIN rises above 2.2V, the UVLO clears, and the soft-start sequence activates. Thermal Shutdown Thermal shutdown protection limits total power dissipation in t he device. When the junction temperature exceeds T J= +160°C, a thermal sensor forces the device into shutdown, allowing the die to cool. The thermal sensor turns the device on again after the junction temperature cools by 15°C, resulting in a pulsed output during continuous overload conditions. Following a thermal-shut down condition, the soft-start sequence begins. Setting Output Voltages Output voltages are set by external resistors. The FB threshold is 0.6V. R TOP = RBOTTOM [(VOUT / 0.6) - 1] Input Capacitor Selection The input capacitor in a DC-to-DC converter reduces current pea ks drawn from the battery or other input power source and reduces switching noise in the controller. The impedance of the input capacitor at the switching frequency should be less than that of the input sourc e so high-frequency switching currents do not pass through the input source. The output capacitor keeps outpu t ripple small and ensures control-loop stability. The output capacitor mu st also have low impedance at the switching frequency. Ceramic, polymer, and tantalum capacitors are suitable, with ceramic exhibiting the lowest ESR and high-frequency impedance. Output ripple with a ceramic output capacitor is approximately as follows: ΔI L= IN OUTOUT V V1x fs x L V ΔVOUT = IN OUT OUT2 S OUT V V1 x C x L x f x 8 V If the capacitor has significant ESR, the output ripple component due to capacitor ESR is as follows: ΔVOUT = ESR IN OUTOUT Rx V V1x fs x L V
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 9 -
PACKAGE INFORMATION
Dimension in SOT-25 (Unit: mm)
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 10 - Dimension in DFN6(2x2) (Unit: mm) Symbol Min Max A 0.70 0.80 A1 - 0.05 b 0.25 0.35 c 0.18 0.25 D 1.95 2.05 D2 1.00 1.45 e 0.65BSC Nd 1.30BSC E 1.95 2.05 E2 0.50 0.85 L 0.25 0.40 h 0.10 0.20
AiT Semiconductor Inc. A7115B www.ait-ic.com DC-DC CONVERTER BUCK (STEP-DOWN) 1.5A 2MHz SYNCHRONOUS REV1.4 - MAY 2018 RELEASED, SEP 2022 UPDATED - - 11 - IMPORTANT NOTICE AiT Semiconductor Inc. (AiT) reserves the right to make changes to any its product, specifications, to discontinue any integrated circu it product or service without n otice, and advises its customers to obtain the latest version of relevant information to verify, before placin g orders, that the information being relied on is current. AiT Semiconductor Inc.'s integrat ed circuit products are not de signed, intended, authorized, or warranted to be suitable for use in life support applications, devices or sy stems or other critical applications. Use of AiT products in such applications is understood to be fully at the risk of the customer. As used herein may involve potential risks of death, personal injury, or servere property, or environmental damage. In order to minimize risks associated with the custom er's applications, the customer should provide adequate design and operating safeguards. AiT Semiconductor Inc. assumes to no liability to customer prod uct design or application support. AiT warrants the performance of its products of the specifications applicable at the time of sale.