Product category:
Power Supply ICs and Controllers
News Release from: Fairchild Semiconductor | Subject: FSTD bus switch family
Edited by the Electronicstalk Editorial
Team on 23 November 2001
Bus switches to a smoother voltage
change
Fairchild Semiconductor has released eight high-bit-count FST bus switches with TruTranslation circuitry for interfacing 5.0V inputs to 3.3V outputs.
Fairchild Semiconductor has released eight high-bit-count FST bus switches with TruTranslation circuitry for interfacing 5.0V inputs to 3.3V outputs Using the TruTranslation circuitry eliminates charge build-up during high-impedance, high-frequency, fast edge-rate switching and protects CPU buses, memory modules and ASICs from overvoltage failures
This article was originally published on Electronicstalk on 28 Feb 2001 at 8.00am (UK)
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"IC reliability is compromised whenever the gate oxide on a 3.3V device on the switch output is stressed by a higher than expected voltage", says Rick Whitcomb, product marketing manager for bus switches, Fairchild Semiconductor.
"Output overvoltage stress could lead to immediate, random device failures, or - depending on gate-oxide thickness - failures could occur one to two years later".
TruTranslation incorporates a voltage reference and a current amplifier into a comparator circuit that monitors charge buildup during voltage translation.
When this charge climbs above a referenced voltage, the comparator turns on the current amplifier to create a discharge path to ground for the trapped charge.
In previous applications, voltage-level shifting bus-switch ICs used a diode to translate 5.0V to 3.3V.
However, with input-edge rates faster than 1.0V/ns or input frequencies greater than 10MHz, such a translating diode prevents this trapped charge from dissipating.
This accumulated charge then raises the switch output voltage level up to 5V on a 3.3V bus, which can corrupt data, shorten component lifetime, or result in damaged circuits.
TruTranslation solves that problem for designers and prevents charge build-up, protecting the circuit from overvoltage.
TruTranslation circuitry available today begins with 4 to 20bit and configurable devices, including FSTD16450, FSTD16861, FSTUD16450, FSTD3125 and FSTUD32450.
Fairchild plans to extend TruTranslation to the entire FSTD bus switch family, starting with five bus switches in the next six months.
Devices are packaged in SOIC, SSOP, QSOP, TSSOP and BGA.
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