ISL8088EVAL2Z Renesas

DATASHEET ISL8088 FN6858 Rev 2.00 Dual 800mA Low Quiescent Current 2.25MHz High Efficiency Synchronous Buck May 26, 2011 Regulator The ISL8088 is a high efficiency, dual synchronous step-down Features DC/DC regulator that can deliver up to 800mA continuous Internal Current Mode Compensation output current per channel. The supply voltage range of 2.75V to 5.5V allows the use of a single Li+ cell, three NiMH cells or a 100% Maximum Duty Cycle for Lowest Dropout regulated 5V input. The current mode control architecture Selectable Forced PWM Mode and PFM Mode enables very low duty cycle operation at high frequency with fast transient response and excellent loop stability. The External Synchronization up to 4MHz ISL8088 operates at 2.25MHz switching frequency allowing Start-up with Pre-biased Output the use of small, low cost inductors and capacitors. Each channel is optimized for generating an output voltage as low Soft-Stop Output Discharge During Disabled as 0.6V. Internal Digital Soft-Start - 2ms The ISL8088 has a user configurable mode of operation-forced Power-Good (PG) Output with 1ms Delay PWM mode and PFM/PWM mode. The forced PWM mode operation reduces noise and RF interference while the PFM Applications mode operation provides high efficiency by reducing switching DC/DC POL Modules losses at light loads. In PFM mode of operation, both channels draw a total quiescent current of only 30A hence enabling C/P, FPGA and DSP Power high light load efficiency in order to maximize battery life. Plug-in DC/DC Modules for Routers and Switchers The ISL8088 offers a 1ms Power-Good (PG) to monitor both Test and Measurement Systems output at power-up. When shutdown, ISL8088 discharges the outputs capacitor. Other features include internal digital soft- Li-ion Battery Power Devices start, enable for power sequence, overcurrent protection, and Bar Code Readers thermal shutdown. The ISL8088 is offered in a 3mmx3mm 10 Ld DFN package with 1mm maximum height. The complete 2 converter occupies less than 1.8cm area. 100 90 80 2.5V -PFM OUT 1.8V -PFM OUT 70 2.5V -PWM OUT 60 1.8V -PWM OUT 50 VIN = 5V 40 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 OUTPUT LOAD (A) FIGURE 1. EFFICIENCY CHARACTERISTICS CURVE FN6858 Rev 2.00 Page 1 of 18 May 26, 2011 EFFICIENCY (%)ISL8088 Typical Application L1 OUTPUT1 2.2H 2.5V/800mA LX1 C2 10F C3 10pF PGND R2 316k INPUT 2.75V TO 5.5V FB1 VIN R3 EN1 C1 100k 10F ISL8088 EN2 L2 OUTPUT2 2.2H 1.8V/800mA LX2 PG C4 10F C5 10pF PGND R5 SYNC 200k FB2 R6 100k PGND FN6858 Rev 2.00 Page 2 of 18 May 26, 2011