Wafer scale packaging for 4A FET

March 08, 2017 // By Graham Prophet
Silego Technology has developed a series of integrated power switches for use in mobile and battery powered products, to carry out power gating of functional blocks within a design; the devices come in sub-mm-size chip scale packages, handle currents from 1 to 4 A, and integrate functions such as in-rush current limiting and over-current or thermal protection.

Employing its own FET IP, the company has released three low-RDS ON switches. These are the first products that Silego has issued in chip-scale packaging; the company hints that other devices from its range, such as the configurable-function PAC devices, may appear in similar outlines in the future. In the GFET3 Integrated Power Switch (IPS) portfolio, the three new switches are aimed at extremely PCB-space-constrained, high-performance applications in tablet PC, smartphones and fitness band markets, and offer high-side power control.

For smartphone and fitness band applications, the 0.64 mm ² (0.8 x 0.8 mm) SLG59M1730C (33 mΩ/1A) and the SLG59M1736C (33 mΩ/2.2A) are low-leakage, self-powered p-FET IPSs that can operate from 2.5 V to 5.5 V supply voltages and draw very little supply current. Both products offer low-threshold ON/OFF control, fast output voltage discharge, and a controlled input current profile on startup. This can, Silego says, avoid battery-voltage ‘sag’ when powering from small, high-internal-resistance cells, which may cause an associated MCU to re-boot. The SLG59M1730C/SLG59M1736C offer a controlled 16.5 mA inrush current profile on startup. Other 4-ball WLCSPs in the market typically offer fast, fixed output voltage rise times allowing large inrush currents.

For higher-power tablet pc applications, the SLG59M1735C is a 10.5 mΩ/4A n-FET IPS with a full suite of protection features. Powered from 2.5V to 5.5V supplies, the input voltage range extends down to 0.9V to accommodate 1.0V high-current rails found in FPGA, ASIC, and processor power sequencing applications. The SLG59M1735C feature set includes: ON/OFF control, soft-start control, undervoltage detection, and two-level current-limit protection. When compared to other packaged products in Silego’s GFET3 portfolio with similar features, the 1.5 mm ² SLG59M1735C is a 50% smaller footprint. When compared to other 4A WLCSP/DFN products in the market with similar protection features, the SLG59M1735C is a 14% to 32% smaller footprint.



Switch Type


Continuous Operating Current

Supply Voltage Range, V DD

Input Voltage Range, V