1 SS 2 FB 3 COMP 4 ISET 5 AGND 6 MODE 7 PG 8 VIN 9 VIN 10 VIN Buck Converter - High Current, Synchronous NCP3235 The NCP3235 is a high current, high efficiency voltage mode synchronous buck converter which operates from 4.5 V to 23 V input and generates output voltages down to 0.6 V at up to 15 A continuous www.onsemi.com current. It has two operation modes: FCCM and automatic CCM/DCM. In automatic CCM/DCM mode, the controller can switch smoothly between CCM and DCM, where converter runs at reduced MARKING switching frequency to achieve much higher efficiency at light load. DIAGRAM The NCP3235 is available in 6 mm x 6 mm QFN40 pin package. 1 Features 1 40 NCP3235 Wide Input Voltage Range from 4.5 V to 23 V AWLYYWWG QFN40 6x6, 0.5P 0.6 V Internal Reference Voltage CASE 485CM Switching Frequency Option: 550 kHz, 1.1 MHz External Programmable SoftStart A = Assembly Location Lossless Lowside FET Current Sensing WL = Wafer Lot YY = Year Output Overvoltage Protection and Undervoltage Protection WW = Work Week Selective Hiccup/Latch Off Operation for All Faults G = PbFree Package Prebias Startup Adjustable Output Voltage PIN CONNECTIONS Power Good Output Internal Overtemperature Protection Adjustable Input UVLO This is a PbFree Device 11 40 VIN EN 12 39 Typical Application VIN VCC VIN GND 13 38 VIN VB Industry PC Equipment EP42 EP41 14 37 VIN AGND ASIC, FPGA, DSP and CPU Core and I/O Supplies 15 36 VSWH BST Server and Storage System 16 35 PGND VSW Telecom and Network Equipment 17 34 PGND VSWH VSWH 18 33 PGND VSWH EP43 19 32 PGND VSWH 20 31 PGND VSWH (Top View) ORDERING INFORMATION Device Package Shipping NCP3235MNTXG QFN40 2500 / (PbFree) Tape & Reel For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specification Brochure, BRD8011/D. Semiconductor Components Industries, LLC, 2016 1 Publication Order Number: May, 2021 Rev. 2 NCP3235/D 21 PGND 22 PGND 23 PGND 24 PGND 25 PGND 26 PGND 27 PGND 28 PGND 29 VSWH 30 VSWHNCP3235 VB VCC VB LDO VCC VB BST VB OSC VIN COMP VB Control Logic VREF Ramp Generator E/A PWM Logic FB and VSWH UVLO OVP, UVP VSW SS Soft Start Power Good OCP, TSD Protection VCC VB VB 2 A EN Enable Logic PGND 1.2V POR PG Mode MODE Selection AGND ISET Figure 1. NCP3235 Block Diagram Table 1. PIN DESCRIPTION Pin No. Symbol Description 1 SS A capacitor from this pin to GND allows the user to adjust the softstart ramp time. 2 FB Output voltage feedback. 3 COMP Output of the error amplifier. 4 ISET A resistor from this pin to ground sets the overcurrent protection (OCP) threshold. 5, 37 AGND Analog ground. 6 MODE Mode selection for FCCM mode and automatic CCM/DCM mode, switching frequency and hiccup/latch pro- tection mode. See table I in the latter page. 7 PG Power good indicator of the output voltage. Opendrain output. Connect PG to VDD with an external resistor. 814, VIN The VIN pin is connected to the internal power NMOS switch. The VIN pin has high di/dt edges and must be EP42 decoupled to ground close to the pin of the device. 15, 2934, VSWH The VSWH pin is the connection of the drain and source of the internal NMOS switches. At switch off, the EP43 inductor will drive this pin below ground as the body diode and the NMOS conducts with a high dv/dt. 1628 PGND Ground reference and highcurrent return path for the bottom gate driver and low side NMOS. 35 VSW IC connection to the switch node between the top MOSFET and bottom MOSFET. Return path of the high side gate driver. 36 BST Top gate driver input supply, a bootstrap capacitor connection between the switch node and this pin. 38 VB The internal LDO output and supply for the NCP3235. Connect a minimum of 4.7uF ceramic capacitor from this pin to ground. 39 VCC Input Supply for IC. This pin must be connected to VIN. 40 EN Logic control for enabling the switcher. An internal pull up enables the device automatically. The EN pin can also be driven high to turn on the device, or low to turn off the device. A comparator and precision reference allow the user to implement this pin as an adjustable UVLO circuit. EP41 GND Exposed Pad. Connect GND to a large copper plane at ground potential to improve thermal dissipation. www.onsemi.com 2