DATASHEET ISL6420B FN6901 Rev 1.00 Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller Dec 4, 2009 The ISL6420B simplifies the implementation of a Features complete control and protection scheme for a Operates From: high-performance DC/DC buck converter. It is designed to drive N-Channel MOSFETs in a synchronous rectified - 4.5V to 5.5V Input buck topology. The ISL6420B integrates control, output - 5.5V to 28V Input adjustment, monitoring and protection functions into a 0.6V Internal Reference Voltage single package. Additionally, the IC features an external reference voltage tracking mode for externally - 2.0% Reference Accuracy referenced buck converter applications and DDR Resistor-Selectable Switching Frequency termination supplies, as well as a voltage margining - 100kHz to 1.4MHz mode for system testing in networking DC/DC converter applications. Voltage Margining and External Reference Tracking Modes The ISL6420B provides simple, single feedback loop, voltage mode control with fast transient response. The Output can Sink or Source Current output voltage of the converter can be precisely Lossless, Programmable Overcurrent Protection regulated to as low as 0.6V. - Uses Upper MOSFETs r DS(ON) The operating frequency is fully adjustable from Programmable Soft-Start 100kHz to 1.4MHz. High frequency operation offers Drives N-Channel MOSFETs cost and space savings. Simple Single-Loop Control Design The error amplifier features a 15MHz gain-bandwidth - Voltage-Mode PWM Control product and 6V/s slew rate that enables high converter bandwidth for fast transient response. The Fast Transient Response PWM duty cycle ranges from 0% to 100% in transient - High-Bandwidth Error Amplifier conditions. Selecting the capacitor value from the - Full 0% to 100% Duty Cycle ENSS pin to ground sets a fully adjustable PWM soft-start. Pulling the ENSS pin LOW disables the Extensive Circuit Protection Functions controller. - PGOOD, Overvoltage, Overcurrent, Shutdown The ISL6420B monitors the output voltage and Diode Emulation during Startup for Pre-Biased generates a PGOOD (power good) signal when Load Applications soft-start sequence is complete and the output is Offered in 20 Ld QFN and QSOP Packages within regulation. A built-in overvoltage protection QFN (4x4) Package circuit prevents the output voltage from going above typically 115% of the set point. Protection from - QFN compliant to JEDEC PUB95 MO-220 overcurrent conditions is provided by monitoring the QFN -Quad Flat No Leads - Product Outline r of the upper MOSFET to inhibit the PWM DS(ON) - QFN Near Chip Scale Package Footprint operation appropriately. This approach simplifies the Improves PCB Efficiency, Thinner in Profile implementation and improves efficiency by eliminating Pb-Free (RoHS Compliant) the need for a current sensing resistor. Applications Power Supplies for Microprocessors/ASICs - Embedded Controllers - DSP and Core Processors -DDR SDRAM Bus Termination Ethernet Routers and Switchers High-Power DC/DC Regulators Distributed DC/DC Power Architecture Personal Computer Peripherals Externally Referenced Buck Converters FN6901 Rev 1.00 Page 1 of 21 Dec 4, 2009ISL6420B Ordering Information PART NUMBER PART TEMP. PACKAGE PKG. (Notes 2, 3) MARKING RANGE (C) (Pb-Free) DWG. ISL6420BIAZ 6420B IAZ -40 to +85 20 Ld QSOP M20.15 ISL6420BIAZ-TK (Note 1) 6420B IAZ -40 to +85 20 Ld QSOP (Tape and Reel) M20.15 ISL6420BIRZ 64 20BIRZ -40 to +85 20 Ld 4x4 QFN L20.4x4 ISL6420BIRZ-TK (Note 1) 64 20BIRZ -40 to +85 20 Ld 4x4 QFN (Tape and Reel) L20.4x4 NOTES: 1. Please refer to TB347 for details on reel specifications. 2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. 3. For Moisture Sensitivity Level (MSL), please see device information page for ISL6240B For more information on MSL please see techbrief TB363. Pin Configurations ISL6420B ISL6420B (20 LD QFN) (20 LD QSOP) TOP VIEW TOP VIEW CDEL 1 20 PGOOD PGND 2 19 ENSS 20 19 18 17 16 LGATE 3 18 COMP PVCC 4 17 FB GPIO2 1 15 PGND PHASE 5 16 RT GPIO1/REFIN 2 14 CDEL UGATE 6 15 SGND BOOT 7 14 VIN OCSET 3 13 PGOOD GPIO2 8 13 VCC5 REFOUT 4 12 ENSS GPIO1/REFIN 9 12 VMSET/MODE VMSET/MODE 5 11 COMP OCSET 10 11 REFOUT 678 9 10 FN6901 Rev 1.00 Page 2 of 21 Dec 4, 2009 VCC5 BOOT VIN UGATE SGND PHASE RT PVCC FB LGATE