DC/DC Converter adjustable, wide input range pfm controller features description • • • • • • • • • • • • • Supply voltage range VS 3.0V to 60V Up to 90% efficiency 40µA standby current 180µA circuit operating current 1.5V to 24V or more adjustable output voltage Up to 300kHz switching frequency Improved current-limited PFM control scheme High current driver for external MOSFET Under-voltage lockout and thermal shutdown -40°C to 125°C operating temperature SO8 package 910.26 basis version 910.24 additive with peak current halving for medium loads and extended max. switch-on-time • 910.25 additive with peak current halving for medium loads and extended max. switch-on-time and fault protection applications • • • • 910.24/25/26 Minimum component DC-DC converters 14V, 28V or 42V automotive systems Power conditioning for portable equipment High efficiency on-card switching regulators The family of highly flexible, easy to use PFM controllers is ideal for the use in wide input range switching regulator applications. An advanced PFM control scheme gives these devices the benefits of PWM converters with high efficiency for heavy loads, while using very low operating current for light loads to maintain excellent behaviour with output load variation. The switching circuits are suitable for topologies requiring low side FET, such as boost, flyback, Sepic, etc. Depending on the utilized topology the controllers are capable of producing regulated positive or negative output voltage. Operating from 3V to 60V supply and in temperature ranges from -40°C to 125°C the device is well suited for automotive applications. Requiring a minimum number of external components, these regulators are simple to use and cost-saving. Self-protection features include an overload detection circuit, an overtemperature shutdown under fault conditions and an under-voltage lockout. block diagram VBAT VS VSM int. Supply & References ON On/Off Logic Gain Control (1) Overload Protection (2) PGND 16 | ELMOS Product catalog 10/2004 VSM VOut MDRV DRV PFM Circuit Instr. Ampl. + - ISEN AGND VFB DC/DC Converter adjustable, wide input range pfm controller package SO 8 910.24/25/26 PGND 1 8 MDRV AGND 2 7 VSM ISEN 3 6 VS VFB 4 5 ON pinning Pin Name Description 1 PGND Driver power ground pin. Connect pin to the current sense resistor, the (-) terminal of the input capacitor and the (-) terminal of the output capacitor. Due to high currents, and high frequency operation of the IC, a low impedance circuit ground plane is highly recommended 2 AGND Analog ground pin. This pin provides a clean ground for the controller circuitry: The output voltage sensing resistors should be connected to this ground pin. This pin is connected to the IC substrate. Connect to the (-) terminal of the output capacitor 3 ISEN Current sense input pin. Voltage generated across an external sense resistor is fed into this pin. Filters extensive high-frequency noise 4 VFB Positive feedback pin. Connect to SMPS output via external resistor divider to set output voltage and is referenced to 1.22V. For best stability, keep VFB lead as short as possible and VFB stray capacitance as small as possible 5 ON Switch ON input. Tie this pin to ground to force the IC into idle mode. A voltage of VSM or higher switches the controller in operating mode 6 VS Main supply input. Filters out high-frequency noise with a 100nF ceramic capacitor placed close to the pin to PGND 7 VSM Internal 5V regulator output. The driver and all control circuits are powered from this voltage. Decouple this pin to PGND with a minimum of 4.7µF tantalum and 100nF ceramic capacitors 8 MDRV Drive output. Drives the gate of the external MOSFET between PGND and VSM. Connect the external MOSFET via a damping resistor to this pin Note: ELMOS Semiconductor AG (below ELMOS) reserves the right to make changes to the product contained in this publication without notice. ELMOS assumes no responsibility for the use of any circuits described herein, conveys no licence under any patent or other right, and makes no representation that the circuits are free of patent infringement. While the information in this publication has been checked, no responsibility, however, is assumed for inaccuracies. ELMOS does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of a life-support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications. ELMOS Semiconductor AG Heinrich-Hertz-Str. 1 • 44227 Dortmund • Germany Phone: +49 (0) 231 75 49 0 • Fax: +49 (0) 231 75 49 149 eMail: [email protected] • Internet: www.elmos.de ELMOS France S.A. 29, rue des Peupliers • 92752 Nanterre Cedex • France Phone: +33 (0) 46 52 59 59 • Fax: +33 (0) 42 42 95 54 eMail: [email protected] • Internet: www.elmos.de ELMOS North America, Inc. 2747 Albright • Kokomo, Indiana 46902 • USA Phone: +1 317 491 59 19 • Fax: +1 317 774 89 18 eMail: [email protected] • Internet: www.elmosna.com Copyright © 2004 ELMOS: Reproduction, in part or whole, without the prior written consent of ELMOS, is prohibited. ELMOS Product catalog 10/2004 | 17