AN1882 Datasheet, PDF (1/30 Pages) STMicroelectronics – This application note details the main features

AN1882
Application note
Designing with the L6926, high efficiency monolithic
synchronous step-down regulator
Introduction
This application note details the main features and application advantages of this new
synchronous step-down regulator. After describing how the device works and the main
features, a step-by-step design section is provided in order to aid in the selection of the
external components and in the evaluation of the losses. The device performances are
shown in terms of efficiency and thermal results. At the end, some application ideas are
proposed. This new product, designed using BCDV technology, is a high efficiency
monolithic synchronous step-down regulator capable of delivering up to 800 mA of
continuous output current and to regulate the output voltage from 0.6 V up to V_IN thanks to
the 100% duty cycle operation capability. The input voltage ranges from 2 V to 5.5 V. The
control loop architecture is based on a constant frequency peak current mode, while high
efficiency at light loads is achieved by a low consumption functionality. The very low
quiescent current (25 µA) and shutdown current (0.2 µA) make the device very suitable to
supply battery-powered equipment like PDAs and hand-held terminals, DSCs (digital still
cameras) and cellular phones. The switching frequency is internally set at 600 kHz, but the
device can be externally synchronized up to 1.4 MHz. An internal reference voltage of 0.6 V
(typ) allows the device to regulate a minimum output voltage of the same low value. The low
MOSFETs R_DS(on) ensures high efficiency at high output current. Additional beneficial
features are: hysteretic UVLO, OVP, constant current short-circuit protection, Power Good
and thermal shutdown. The MSOP8 package allows significant space savings on the board.
Figure 1. Application test circuit
April 2012
Doc ID 10209 Rev 4
1/30
www.st.com