L4976 STMicroelectronics

L4976 1A step down switching regulator Features Up to 1A step down converter Operating input voltage from 8v to 55v Precise 5.1V reference voltage DIP8 SO16W Output voltage adjustable from 0.5V to 50V Switching frequency adjustable up to 300kHz Description Voltage feedforward The L4976 is a step down monolithic power Zero load current operation switching regulator delivering 1A at a voltage Internal current limiting (pulse-bypulse between 3.3V and 50V (selected by a simple external divider). Realized in BCD mixed and hiccup mode) technology, the device uses an internal power D- Protection against feedback disconnection MOS transistor (with a typical R of 0.25) to ds(ON) Thermal shutdown obtain very high efficency and high switching speed. A switching frequency up to 300KHz is achievable (the maximum power dissipation of the packages must be observed). A wide input voltage range between 8V to 55V and output voltages regulated from 3.3V to 40V cover the majority of todays applications. Features of this new generations of DC-DC converter include pulse-by-pulse current limit, hiccup mode for short circuit protection, voltage feedforward regulation, protection against feedback loop disconnection and thermal shutdown. The device is available in plastic dual in line, MINIDIP 8 for standard assembly, and SO16W for SMD assembly. Figure 1. Typical application circuit Vi=8V to 55V 5 8 R 1 20K L4976 3 4 C C C 1 7 2 L1 7 1 6 2 V =3.3V/1A 220F 220nF 2.7nF O 260H 63V (77120) C 6 R D1 2 100nF C 9.1K GI 8 330F SB360 C 4 22nF April 2007 Rev 7 1/17 www.st.com 17Contents L4976 Contents 1 Block diagram 3 2 Pin settings 4 2.1 Pin connection 4 2.2 Pin description 4 3 Electrical data 5 3.1 Maximum ratings 5 3.2 Thermal data . 5 3.3 Operating temperature rating . 5 4 Electrical characteristics . 7 5 Typical charcteristics 9 6 Package mechanical data 13 7 Order code 16 8 Revision history . 17 2/17