Product category:
Power Supply ICs and Controllers
News Release from: STMicroelectronics | Subject: STHS4257 and STHS237x
Edited by the Electronicstalk Editorial
Team on 01 October 2007
Power controllers are ready for PoE
expansion
Power-over-Ethernet interface controllers are fully compliant with the IEEE802.3af specification for powered devices
STMicroelectronics has developed two new families of power-over-Ethernet (PoE) interface controllers All devices in the families are fully compliant with the IEEE802.3af specification for powered devices (PD), which provide all the control functions needed to enable a PD to request and draw power from an Ethernet network via a power source
This article was originally published on Electronicstalk on 8 Nov 2004 at 8.00am (UK)
Related stories
Driver drives LED efficiency
STMicroelectronics has introduced a new white LED driver with specific features for small LCD module backlight and high efficiency white LED power supply for portable applications.
Single-chip tuner cuts set-top box parts count
The STB6000 single-chip silicon tuner is designed to replace complex discrete component tuners in set-top boxes used for receiving digital TV or web-based material via satellite.
By using these new controllers, designers will be able to eliminate the 110/220V AC power lines to many wired LAN devices such as VoIP phones and security cameras.
Other applications benefiting from PoE include webcams, wireless LAN access points, point of sale terminals and RFID readers.
The STHS4257 and STHS237x PoE powered device interface controllers enable greater flexibility in installation locations, and lower overall product cost, by removing the external power supplies; the standard Cat5 Ethernet cabling can now carry power and data to devices on the network.
Further reading
Single-chip Bluetooth comes in under $3
The STLC2500 is a single-chip product for handheld terminal applications that adds full Bluetooth v1.2 function and capability with superior radio performance and very low power consumption.
Driver houses complete automotive H bridge
STMicroelectronics has produced a complete H bridge in a single package for high-power automotive applications such as driving window lifts, seat positioners and for DC motor control.
The controllers are drop-in replacements for competitors' products.
Each device consists of two main sections: the IEEE802.3af-compliant interface to the PoE-powered RJ45 wall socket, which includes basic PD detection and classification functions; and the hot swap controller (HSC), which protects the PD during insertion, operation and power withdrawal.
The controllers integrate a high-voltage power MOSFET (low-side switch), with low on-resistance, and with the capability to accept transients as high as 100V.
The hot-swap features include functions such as inrush current limiting, undervoltage lockout (UVLO) and thermal overload protection.
All the devices include an open drain power-good signal to indicate normal operation, and a 1.5V voltage offset to accommodate the input-diode bridge which is used to make the PD polarity insensitive.
The basic parts - the STHS2375, STHS2376, STHS2377, STHS4257A/L and STHS4257A1/L1 - are available with either latched operation (L) or automatic retry (A), after fault conditions.
The STHS4257 part integrates a 25kohm signature resistor, with signature disable function.
The STHS237x requires an external signature resistor.
The STHS237x family consists of devices for all the UVLO limits configurations: IEEE compliant (STHS2375), programmable (STHS2376), and for legacy systems (STHS2377).
The STHS4257A1/L1 includes a dual-level current-limit circuit, which allows it to interface with legacy PoE systems while maintaining compatibility with the current IEEE802.3af specification.
Both families are available in volume now, the STHS4257 in an SO8 package (DFN8 available on request), priced at US $1.35 in 1000-unit quantities and the STHS237x in SO8 package (TSSOP8 available on request), priced at US $1.01 in 1000-unit quantities.
• STMicroelectronics: contact details and other news
• Email this article to a colleague
• Register for the free Electronicstalk email newsletter
• Electronicstalk Home Page
Search the Pro-Talk network of sites
