DATASHEET ISL8025, ISL8025A FN8357 Rev 1.00 Compact Synchronous Buck Regulators December 19, 2013 The ISL8025, ISL8025A are highly efficient, monolithic, Features synchronous step-down DC/DC converters that can deliver 5A of 2.7V to 5.5V input voltage range continuous output current from a 2.7V to 5.5V input supply. The devices use current mode control architecture to deliver a very low Very low ON-resistance FETs - P-channel 36m and duty cycle operation at high frequency with fast transient N-channel 13m typical values response and excellent loop stability. High efficiency synchronous buck regulator with up to 95% efficiency The ISL8025, ISL8025A integrates a very low ON-resistance Pin-to-pin compatible with ISL8023 and ISL8024 P-Channel (36m ) high-side FET and N-Channel (13m) low-side FET to maximize efficiency and minimize external 0.8% reference accuracy over-temperature/load/line component count. The 100% duty-cycle operation allows less Internal soft-start: 1ms or adjustable than 180mV dropout voltage at 5A output current. The Soft-stop output discharge during disable operation frequency of the pulse-width modulator (PWM) is Adjustable frequency from 500kHz to 4MHz - default at adjustable from 500kHz to 4MHz. The default switching 1MHz (ISL8025), 2MHz (ISL8025A) frequency, which is set by connecting the FS pin high, is 1MHz External synchronization up to 4MHz for the ISL8025 and 2MHz for the ISL8025A. Over-temperature, overcurrent, overvoltage and negative The ISL8025, ISL8025A can be configured for discontinuous or overcurrent protection forced continuous operation at light load. Forced continuous operation reduces noise and RF interference, while Applications discontinuous mode provides higher efficiency by reducing DC/DC POL modules switching losses at light loads. C/P, FPGA and DSP power Fault protection is provided by internal hiccup mode current Plug-in DC/DC modules for routers and switchers limiting during short circuit and overcurrent conditions. Other Portable instruments protection, such as overvoltage and over-temperature, are also Test and measurement systems integrated into the device. A power-good output voltage monitor indicates when the output is in regulation. Li-ion battery powered devices The ISL8025, ISL8025A offers a 1ms Power-good (PG) timer Related Literature at power-up. When in shutdown, the ISL8025, ISL8025A See AN1806, 5A Low Quiescent Current High Efficiency discharges the output capacitor through an internal soft-stop Synchronous Buck Regulator switch. Other features include internal fixed or adjustable soft-start and internal/external compensation. The ISL8025, ISL8025A are offered in a space saving 16 Ld 3x3 Pb-free QFN package with an exposed pad for improved thermal performance and 1mm maximum height. The 2 complete converter occupies less than 0.22 in area. L1 +1.8V/5A VOUT 100 1.0H C2 2 x 22F GND +2.7V +5.5V 1 12 90 VIN PGND VIN ISL8025, ISL8025A R2 C1 C3* 2 x 22F 200k 22pF GND 2 11 R1 VDD PGND 100k 80 R3 3 10 PG SGND PG 100k 70 4 +0.6V 9 SYNC FB 3.3V 60 OUT *C3 IS OPTIONAL. IT IS 2.5V OUT RECOMMENDED TO PUT A PLACEHOLDER FOR IT AND CHECK 1.8V OUT LOOP ANALYSIS BEFORE USE. 50 1.5V OUT 1.2V OUT V 40 O ------------ 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 R = R 1 (EQ. 1) 2 3 VFB OUTPUT LOAD (A) FIGURE 1. TYPICAL APPLICATION CIRCUIT CONFIGURATION FIGURE 2. EFFICIENCY vs LOAD (INTERNAL COMPENSATION OPTION) F = 1MHz, V = 5V, MODE = PFM, T = +25C SW IN A FN8357 Rev 1.00 Page 1 of 22 December 19, 2013 5 16 EN EN VIN 6 15 FS PHASE 7 14 SS PHASE 8 13 COMP PHASE PAD 17 EFFICIENCY (%)ISL8025, ISL8025A Table of Contents Pin Configuration 3 Pin Descriptions . 3 Ordering Information 4 Absolute Maximum Ratings . 6 Thermal Information . 6 Recommended Operating Conditions 6 Electrical Specifications . 6 Typical Operating Performance 8 Typical Operating Performance . 11 Theory of Operation . 16 PWM Control Scheme 16 SKIP Mode . 16 Frequency Adjust 17 Overcurrent Protection . 17 Negative Current Protection . 17 PG 17 UVLO 17 Soft Start-Up 17 Enable . 17 Discharge Mode (Soft-Stop) . 18 Power MOSFETs . 18 100% Duty Cycle 18 Thermal Shut-Down 18 Application Information . 18 Output Inductor and Capacitor Selection 18 Output Voltage Selection . 18 Input Capacitor Selection . 18 Loop Compensation Design . 18 PCB Layout Recommendation 20 Revision History 21 About Intersil 21 Package Outline Drawing 22 FN8357 Rev 1.00 Page 2 of 22 December 19, 2013