L6726ATR STMicroelectronics

L6726A Single phase PWM controller Feature Flexible power supply from 5 V to 12 V Power conversion input as low as 1.5 V 1% output voltage accuracy High-current integrated drivers Adjustable output voltage SO-8 0.8 V internal reference Sensorless and programmable OCP across Low-side R Description dsON Oscillator internally fixed at 270 kHz L6726A is a single-phase step-down controller Programmable soft-start with integrated high-current drivers that provides complete control logic, protections and reference Ls-less start up voltage to realize in an easy and simple way Disable function general DC-DC converters by using a compact FB disconnection protection SO-8 package. SO-8 package Device flexibility allows managing conversions with power input V as low as 1.5 V and device IN supply voltage ranging from 5 V to 12 V. L6726A provides simple control loop with trans- conductance error amplifier. The integrated 0.8 V Applications reference allows regulating output voltage with 1% accuracy over line and temperature Subsystem power supply (MCH, IOCH, PCI...) variations. Oscillator is internally fixed to 270 kHz. Memory and termination supply L6726A provides programmable over current CPU and DSP power supply protection. Current information is monitored Distributed power supply across the low-side MOSFET R saving the dsON use of expensive and space-consuming sense General DC / DC converters resistors. FB disconnection protection prevents excessive and dangerous output voltages in case of floating FB pin. Table 1. Device summary Order codes Package Packaging L6726A SO-8 Tube L6726ATR SO-8 Tape and reel March 2010 Doc ID 12754 Rev 4 1/35 www.st.com 35Contents L6726A Contents 1 Typical application circuit and block diagram 4 1.1 Application circuit 4 1.2 Block diagram . 4 2 Pins description and connection diagrams 5 2.1 Pin descriptions . 5 2.2 Thermal data . 6 3 Electrical specifications 7 3.1 Absolute maximum ratings . 7 3.2 Electrical characteristics . 7 4 Device description 9 5 Driver section . 10 5.1 Power dissipation . 11 6 Soft start and disable . 12 6.1 Low-side-less start up (LSLess) 12 6.2 Enable / disable 12 7 Protections 13 7.1 Overcurrent protection . 13 7.1.1 Overcurrent threshold setting . 13 7.2 Feedback disconnection protection . 13 7.3 Undervoltage lock out 14 8 Application details . 15 8.1 Output voltage selection 15 8.2 Compensation network 15 8.3 Soft-start time calculation . 18 8.4 Layout guidelines . 18 8.5 Embedding L6726A-based VRs 20 2/35 Doc ID 12754 Rev 4