Request Datasheet AP64351 3.8V TO 40V INPUT, 3.5A LOW IQ SYNCHRONOUS BUCK WITH PROGRAMMABLE SOFT-START TIME Description Pin Assignments The AP64351 is a 3.5A, synchronous buck converter with a wide input TOP VIEW voltage range of 3.8V to 40V. The device fully integrates a 75m high- side power MOSFET and a 45m low-side power MOSFET to provide high-efficiency step-down DC-DC conversion. BST 1 8 SW The AP64351 device is easily used by minimizing the external component count due to its adoption of peak current mode control. VIN 2 7 GND The AP64351 design is optimized for Electromagnetic Interference EXPOSED PAD (EMI) reduction. The device has a proprietary gate driver scheme to 9 resist switching node ringing without sacrificing MOSFET turn-on and EN 3 6 COMP turn-off times, which reduces high-frequency radiated EMI noise caused by MOSFET switching. AP64351 also features Frequency Spread Spectrum (FSS) with a switching frequency jitter of 6%, which reduces EMI by not allowing emitted energy to stay in any one SS 4 5 FB frequency for a significant period of time. The device is available in an SO-8EP package. SO-8EP Features Typical Application Circuit INPUT VIN 3.8V to 40V VIN BST 3.5A Continuous Output Current C3 L 100nF OUTPUT 5.5H VOUT 0.8V 1% Reference Voltage EN SW 5V C4 R1 22A Low Quiescent Current (Pulse Frequency Modulation) 115k OPEN AP64351 C1 C2 FB 570kHz Switching Frequency 10F 2 x 22F R2 22.1k Programmable Soft-Start Time SS COMP Up to 85% Efficiency at 5mA Light Load Css R5 10nF GND 14k C6 Proprietary Gate Driver Design for Best EMI Reduction 47pF C5 (Optional) 3.3nF Frequency Spread Spectrum (FSS) to Reduce EMI Low-Dropout (LDO) Mode Precision Enable Threshold to Adjust UVLO Protection Circuitry VOUT = 5V, L = 5.5H VOUT = 3.3V, L = 4.7H o Undervoltage Lockout (UVLO) 100 o Output Overvoltage Protection (OVP) 90 o Cycle-by-Cycle Peak Current Limit 80 o Thermal Shutdown 70 Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) 60 Halogen and Antimony Free. Green Device (Note 3) 50 40 30 20 10 0 0.001 0.010 0.100 1.000 10.000 IOUT (A) Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant. 2. See Request Datasheet AP64351 Pin Descriptions Pin Name Pin Number Function High-Side Gate Drive Boost Input. BST supplies the drive for the high-side N-Channel power MOSFET. A 100nF BST 1 capacitor is recommended from BST to SW to power the high-side driver. Power Input. VIN supplies the power to the IC as well as the step-down converter power MOSFETs. Drive VIN with a VIN 2 3.8V to 40V power source. Bypass VIN to GND with a suitably large capacitor to eliminate noise due to the switching of the IC. See Input Capacitor section for more details. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator and low to EN 3 turn it off. Connect to VIN or leave floating for automatic startup. The EN has a precision threshold of 1.18V for programing the UVLO. See Enable section for more details. Soft-start. Place a ceramic capacitor from this pin to ground to program soft-start time. An internal 4A current SS 4 source pulls the SS pin to VCC. See Programming Soft-Start Time section for more details. Feedback sensing terminal for the output voltage. Connect this pin to the resistive divider of the output. FB 5 See Setting the Output Voltage section for more details. Compensation. Connect an external RC network to the COMP pin to adjust the loop response. See External Loop COMP 6 Compensation Design section for more details. GND 7 Power Ground. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter SW 8 from SW to the output load. EXPOSED Heat dissipation path of the die. The exposed thermal pad must be electrically connected to GND and must be 9 PAD connected to the ground plane of the PCB for proper operation and optimized thermal performance. Absolute Maximum Ratings (Note 4) (At T = +25C, unless otherwise specified.) A Symbol Parameter Rating Unit -0.3 to +42.0 (DC) VIN Supply Pin Voltage V -0.3 to +45.0 (400ms) V Bootstrap Pin Voltage V - 0.3 to V + 6.0 V BST SW SW V Enable/UVLO Pin Voltage -0.3 to +42.0 V EN V Soft-Start Pin Voltage -0.3 to +6.0 V SS V Feedback Pin Voltage -0.3 to +6.0 V FB V Compensation Pin Voltage -0.3 to +6.0 V COMP -0.3 to VIN + 0.3 (DC) V Switch Pin Voltage V SW -2.5 to VIN + 2.0 (20ns) T Storage Temperature -65 to +150 C ST T Junction Temperature +160 C J T Lead Temperature +260 C L ESD Susceptibility (Note 5) HBM Human Body Model 2000 V CDM Charged Device Model 500 V Notes: 4. Stresses greater than the Absolute Maximum Ratings specified above may cause permanent damage to the device. These are stress ratings only functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability may be affected by exposure to absolute maximum rating conditions for extended periods of time. 5. Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling and transporting these devices. 2 of 5 October 2019 AP64351 Databrief Diodes Incorporated www.diodes.com