PM6686TR STMicroelectronics

PM6686 Dual step-down controller with adjustable voltages, adjustable LDO and auxiliary charge pump controller for notebook Features 5.5 V to 28 V input voltage range Dual fixed OUT1 = 1.5 V/5 V and OUT2 = 1.05 V / 3.3 V outputs or adjustable OUT1 = 0.7 V to 5.5 V and OUT2 = 0.7 V to 2.5 V outputs, VFQFPN-32 5 x 5 mm 1.5% accuracy over valley regulation Low-side MOSFETs R current sensing DS(on) and programmable current limit Description Constant ON-time control PM6686 is a dual step-down controller specifically Frequency selectable designed to provide extremely high efficiency Soft-start internally fixed at 2 ms and soft-stop conversion, with lossless current sensing technique. The constant on-time architecture Selectable pulse skipping at light loads assures fast load transient response and the Selectable minimum frequency (33 kHz) in embedded voltage feed-forward provides nearly pulse skip mode constant switching frequency operation. Pulse Independent Power Good and EN signals skipping technique increases efficiency at very light load. Moreover a minimum switching Latched OVP and UVP frequency of 33 kHz is selectable to avoid audio Charge pump feedback noise issues. The PM6686 provides a selectable Fixed 3.3 V/5.0 V, or adjustable output 0.7 V to switching frequency, allowing three different 4.5 V, 1.5% (LDO): 200 mA values of switching frequencies for the two switching sections. The output voltages OUT1 3.3 V reference voltage 2.0%: 5 mA and OUT2 can be programmed to regulate 2.0 V reference voltage 1.0%: 50 A 1.5 V/5 V and 1.05 V/3.3 V outputs respectively or can deliver two adjustable output voltages. An Applications optional external charge pump can be monitored. This device embeds a linear regulator that can Notebook computers provide 3.3 V/5 V or an adjustable voltage from Main (3.3 V/5 V), chipset (1.5 V/1.05 V), 0.7 V to 4.5 V output. The linear regulator DDR1/2/3, graphic cards power supply provides up to 100 mA output current. LDO can be bypassed with the switching regulator outputs PDAs, mobile devices, tablet PC or slates or with an external power supply (switchover 3-4 cells Li+ battery powered devices function). When in switchover, the LDO output can source up to 200 mA. Table 1. Device summary Order codes Package Packaging PM6686 Tray VFQFPN-32L 5 x 5 mm PM6686TR Tape and reel July 2009 Doc ID 15281 Rev 4 1/50 www.st.com 50 Contents PM6686 Contents 1 Simplified application schematic . 6 2 Pin settings 7 2.1 Connections 7 2.2 Pin descriptions . 7 3 Electrical data . 10 3.1 Maximum rating 10 3.2 Thermal data 10 4 Recommended operating conditions 11 5 Electrical characteristics 12 6 Typical operating characteristics . 15 6.1 Screen shots 19 7 Block diagram . 23 8 Device description . 24 8.1 Switching sections 24 8.1.1 Output voltage set up . 24 8.1.2 Constant on time control (COT) . 26 8.1.3 PWM . 28 8.1.4 SKIP 29 8.1.5 Non audible SKIP (NA SKIP) . 29 8.1.6 Gate drivers and logic supply 30 8.1.7 Current sensing and current limit 31 8.1.8 Soft-start and soft-end 32 9 Monitoring and protections 34 9.1 Overvoltage protection . 34 9.2 Undervoltage protection 34 9.3 PVCC monitor . 34 2/50 Doc ID 15281 Rev 4