DATASHEET ISL78235 FN8713 Rev 8.00 5A Automotive Synchronous Buck Regulator Dec 17, 2021 The ISL78235 is a highly efficient, monolithic, synchronous Features step-down DC/DC converter that can deliver 5A of continuous 2.7V to 5.5V input voltage range output current from a 2.7V to 5.5V input supply. The device uses peak current mode control architecture to achieve very low duty 2MHz default switching frequency cycle operation at high frequency with fast transient response and 100ns guaranteed phase minimum on time for wide output excellent loop stability. regulation The ISL78235 integrates a low ON-resistance P-channel Adjustable switching frequency from 500kHz to 4MHz (35m , typical) high-side FET and N-channel (11m, typical) low-side FET to maximize efficiency and minimize external External synchronization from 1MHz to 4MHz component count. The 100% duty cycle operation allows less Optional PFM mode for light-load efficiency improvement than 250mV dropout voltage at 5A output current. The Very low ON-resistance HS/LS switches: 35m/11m operating frequency of the Pulse-Width Modulator (PWM) is adjustable from 500kHz to 4MHz. The default switching Internal 1ms or adjustable external soft-start frequency of 2MHz is set by connecting the FS pin high. Soft-stop output discharge during disable The ISL78235 can be configured for discontinuous (PFM) or OTP, OCP, output OVP, and input UVLO protections forced continuous (PWM) operation at light load. Forced continuous operation reduces noise and RF interference 1% reference accuracy over-temperature discontinuous mode provides higher efficiency by reducing Up to 95% efficiency switching losses at light loads. AEC-Q100 qualified Fault protection is provided by internal hiccup mode current Common pinout family allows migration from 3A to 5A limiting during short-circuit and overcurrent conditions. The without PCB change: device also integrates output overvoltage and - ISL78233 3A over-temperature protections. A power-good monitor indicates when the output is in regulation. The ISL78235 features a 1ms - ISL78234 4A Power-Good (PG) timer at power-up. - ISL78235 5A When in shutdown, the ISL78235 discharges the output Applications capacitor through an internal 100 soft-stop switch. Other features include internal fixed or adjustable soft-start and DC/DC POL modules internal/external compensation. C/P, FPGA, and DSP power The ISL78235 is available in a 3mmx3mm 16 Ld Thin Quad Flat Video processor/SOC power No-lead (TQFN) Pb-free package and in a 5mmx5mm 16 Ld Automotive infotainment power Wettable Flank Quad Flat No-Lead (WFQFN) package with an exposed pad for improved thermal performance. The ISL78235 is rated to operate across the temperature range of -40C to +105C in the 3mmx3mm package and -40C to +125C in the 5mmx5mm package. L 100 V OUT 5A LOAD DSP, FPGA 2.7V TO 5.5V C 90 OUT C 2.5V IN OUT 80 16 15 14 13 3.3V OUT 1.2V PGND 1.8V OUT VIN 1.5V OUT OUT 1 12 70 PGND VDD 2 11 *ISL78235 SGND PG 60 3 10 FB SYNC 4 9 50 5 6 7 8 T = +25C A *Pin Compatible 40 ISL78233 - 3A BUCK ISL78234 - 4A BUCK 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT LOAD (A) FIGURE 1. TYPICAL APPLICATION: 5A BUCK REGULATOR FIGURE 2. EFFICIENCY vs LOAD (V = 5V f = 2MHz SYNC = GND) IN sw FN8713 Rev 8.00 Page 1 of 23 Dec 17, 2021 2015 Renesas Electronics EN VIN FS PHASE PHASE SS PHASE COMP EFFICIENCY (%)ISL78235 Table of Contents Functional Block Diagram 3 Pin Configuration 4 Pin Descriptions . 4 Ordering Information 5 Typical Application Diagram 6 Absolute Maximum Ratings . 7 Thermal Information . 7 Recommended Operating Conditions 7 Electrical Specifications . 7 Typical Operating Performance 9 Theory of Operation . 16 PWM Control Scheme 16 Skip Mode (PFM) 16 Frequency Adjust 17 Overcurrent Protection . 17 Negative Current Protection . 17 PG 17 UVLO 17 Soft Start-Up 17 Enable . 18 Discharge Mode (Soft-Stop) . 18 Power MOSFETs . 18 100% Duty Cycle 18 Thermal Shutdown 18 Applications Information 18 Output Inductor and Capacitor Selection 18 Output Voltage Selection . 18 Input Capacitor Selection . 19 Loop Compensation Design . 19 PCB Layout Recommendation 20 Revision History 21 Package Outline Drawing 22 FN8713 Rev 8.00 Page 2 of 23 Dec 17, 2021