L5973AD STMicroelectronics

L5973AD 2 A switch step down switching regulator Features 2 A internal switch Operating input voltage from 4 V to 36 V 3.3 V / (2%) reference voltage HSOP8 exposed pad Output voltage adjustable from 1.235 V to 35 V Low dropout operation: 100% duty cycle Description 500 kHz Internally fixed frequency The L5973AD is a step down monolithic power Voltage feedforward switching regulator with a switch current limit of Zero load current operation 2 A so it is able to deliver more than 1.5 A DC Internal current limiting current to the load depending on the application conditions. Inhibit for zero current consumption The output voltage can be set from 1.235 V Synchronization to 35 V. The high current level is also achieved Protection against feedback disconnection thanks to an SO8 package with exposed frame, that allows to reduce the R down to Thermal shutdown thJA approximately 40 C/W. The device uses an internal P-Channel D-MOS Applications transistor (with a typical of 200 m) as switching element to avoid the use of bootstrap capacitor Consumer: STB, DVD, TV, VCR, car radio, and guarantee high efficiency. LCD monitors An internal oscillator fixes the switching frequency Networking: XDSL, modems, DC-DC modules at 500 kHz to minimize the size of external Computer: printers, audio/graphic cards, components. optical storage, hard disk drive Having a minimum input voltage of 4 V only, it is particularly suitable for 5 V bus, available in all Industrial: chargers, car battery, DC-DC computer related applications. converters Pulse by pulse current limit with the internal frequency modulation offers an effective constant current short circuit protection. Figure 1. Test application circuit VREF 3.3V L1 15H VOUT=3.3V 6 OUT 1 VIN = 4V to 35V VCC D1 8 L5973AD R1 STPS340U SYNC. 2 5.6K C2 5 COMP 330F C1 4 3 7 FB 10V C4 10F INH GND 22nF 35V R2 CERAMIC 3.3K C3 R3 220pF 4.7K D03IN1453 November 2009 Doc ID 9552 Rev 9 1/22 www.st.com 22Contents L5973AD Contents 1 Pin settings 3 1.1 Pin connection 3 1.2 Pin description 3 2 Electrical data 4 2.1 Maximum ratings 4 2.2 Thermal data . 4 3 Electrical characteristics . 5 4 Functional description . 7 4.1 Power supply and voltage reference . 8 4.2 Voltages monitor . 8 4.3 Oscillator and synchronization 8 4.4 Current protection 9 4.5 Error amplifier 10 4.6 PWM comparator and power stage . 11 4.7 Inhibit function . 12 4.8 Thermal shutdown 12 5 Additional features and protections . 13 5.1 Feedback disconnection 13 5.2 Output overvoltage protection . 13 5.3 Zero load . 13 5.4 Application circuit . 13 6 Application ideas . 16 7 Package mechanical data 18 8 Order code 20 9 Revision history . 21 2/22 Doc ID 9552 Rev 9