PRELIMINARY DATA SHEET SKY87608: 28 V, 3 A Non-Synchronous Step-Down Converter Applications Description The SKY87608 is a step-down DC-DC converter that operates Set-top boxes with a wide 4.5 V to 28 V input voltage range and regulates the Distributed power systems output voltage as low as 0.9 V while supplying up to 3 A to the Industrial applications output. The 450 kHz switching frequency allows for an efficient step-down regulator design. The SKY87608 uses an adjustable output voltage that can be set Features from 12% to 80% of the input voltage by an external resistive 4.5 V to 28 V input voltage voltage divider. Internal soft-start prevents excessive inrush Up to 97% efficiency current without requiring an external capacitor. Internal 180 m high-side N-channel MOSFET The SKY87608 includes input under-voltage and overcurrent protection to prevent damage in the event of a fault condition. Internal 12 refresh MOSFET Thermal overload protection prevents damage to the SKY87608 or Up to 3 A load current circuit board when operating beyond its thermal capability. Adjustable output voltage (0.9 V to 0.8 VIN) The SKY87608 is available in a small Pb-free, 8-pin, Fixed 450 kHz switching frequency SOP-8L-EP package. 4 ms soft-start period A typical application circuit is shown in Figure 1. The pin configuration is shown in Figure 2. Signal pin assignments and External compensation functional pin descriptions are provided in Table 1. Less than 1 A shutdown current Current limit protection Standard 8-pin SOP-8L package (MSL1, 260 C per JEDEC-J- STD-020) with exposed pad Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 201860B Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice May 17, 2013 1 PRELIMINARY DATA SHEET SKY87608 28V, 3A NON-SYNCHRONOUS STEP-DOWN CONVERTER Figure 1. SKY87608 Typical Application Circuit Figure 2. SKY87608 8-Pin SOP-8L (Top View) Table 1. SKY87608 Signal Descriptions Pin Name Description 1 IN Input supply. Connect IN to the input power source. Bypass IN to GND with a 10 F or greater ceramic capacitor. IN connects to the source of the internal high-side N-channel MOSFET and linear regulators powering the controller and drivers. 2 LX Inductor switching. LX is internally connected to the source of the internal high-side N-channel MOS- FET, the high-side driver, and current-sense circuitry. Connect to the power inductor, and the Schottky diode as shown in the Typical Application Circuit diagram. 3 NC Do NOT connect externally. Leave pin floating. 4 GND Ground. GND is internally connected to the analog ground of the control circuitry, and the source of the 12 refresh MOSFET. 5 FB Feedback input. FB senses the output voltage for regulation control. Connect a resistive divider network from the output to FB to GND to set the output voltage accordingly. The FB regulation threshold is 0.9 V for the SKY87608. 6 COMP Compensation pin of the error amplifier. 7 EN Enable input. Logic high enables the regulator. A logic low forces the SKY87608 into shutdown mode, placing the output into a high-impedance state and reducing the quiescent current to less than 1 A. 8 BST Boot-strapped high-side driver supply. Connect a 0.1 F ceramic capacitor between BST and LX as shown in the Typical Application Circuit diagram. EP Exposed paddle. Connect to PCB ground plane. Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 2 May 17, 2013 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice 201860B