UM1557 Datasheet, PDF (1/111 Pages) STMicroelectronics – The aim of this document is to give the design engineer

UM1557
User manual
VIPower MO-5T: high-side switches for 24V systems
Introduction
The aim of this document is to give the design engineer a comprehensive “tool kit” to better
understand the behavior of VIPower high side switches, allowing easier design and saving
time and money.
This document expands on the existing VIPower user manual UM1556 rev.1 covering high
side switches suited to 12 V (passenger car) automotive systems, by focusing on the new
family of VIPower components for 24 V (truck) applications.
The drivers concerned derive from existing state-of-the-art M0-5 technology, but cover the
even harsher environmental conditions found in truck applications.
Not only is the battery voltage doubled (which goes hand in hand with the increased ISO
pulse levels), but the stray inductance of the wire harness is also significantly higher
compared to passenger cars. The temperature range is the same as for passenger cars, but
the required lifetime of the electronics is significantly higher due to the longer average life
time of a truck.
The wires on a truck with a trailer can be as long as 30–40 meters, from the rear lights of the
trailer to the ECU, located at the front of the truck. Due to the larger number of bulbs driven
by the high side switch in a typical truck application, the typical load current is in the same
range or even higher than in 12 V systems, despite the higher battery voltage.
The High Side Drivers in 24 V systems are therefore faced with high currents in combination
with a high level of stray inductance during turn-off, as experienced in short circuit conditions
of the load. This causes a high level of stress at that condition, necessitating new solutions
to achieve short circuit robustness at the same or even higher levels than those achieved for
current 12 V systems.
This document explains the function of the VIPower drivers for 24 V systems that cover the
identified requirement profile.
September 2013
Doc ID 023521 Rev 2
1/111
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