??? 09/22/11 04:29 Read: times |
#183844 - looks promising Responding to: ???'s previous message |
Description the datasheet said:
"
The GTL2010 provides ten NMOS pass transistors (Sn and Dn) with a common gate (GREF) and a reference transistor (SREF and DREF). The low ON-state resistance of the switch allows connections to be made with minimal propagation delay. With no direction control pin required, the device allows bidirectional voltage translations any voltage (1 V to 5 V) to any voltage (1 V to 5 V). When the Sn or Dn port is LOW, the clamp is in the ON state and a low-resistance connection exists between the Sn and Dn ports. Assuming the higher voltage is on the Dn port, when the Dn port is HIGH, the voltage on the Sn port is limited to the voltage set by the reference transistor (SREF). When the Sn port is HIGH, the Dn port is pulled to VCC by the pullup resistors. All transistors in the GTL2010 have the same electrical characteristics, and there is minimal deviation from one output to another in voltage or propagation delay. This offers superior matching over discrete transistor voltage-translation solutions where the fabrication of the transistors is not symmetrical. With all transistors being identical, the reference transistor (SREF/DREF) can be located on any of the other ten matched Sn/Dn transistors, allowing for easier board layout. The translator transistors with integrated ESD circuitry provides excellent ESD protection. " This might be exactly what's called-for. I am concerned about the end-effect that causes the MCU to provide the current source/sink with which to drive a cable, though. There's always a "gotcha" isn't there? An individually direction-configurable I/O buffer consisting of a typical CPLD would generally have more drive current than would a typical MCU. Maybe by picking the correct MCU, this problem goes away. RE |