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

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ELMOS North America, Inc.

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Copyright © 2004 ELMOS: Reproduction, in part or whole, without the prior written consent of ELMOS, is prohibited.

ELMOS Product catalog 10/2004 | 17

DC/DC Converter

package

SO 8

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

1

2

3

4

8

7

6

5

PGND

AGND

ISEN

VFB

MDRV

VSM

VS

ON

adjustable, wide input range

910.24/25/26

pfm controller