High Speed, Bidirectional Level Shifter for Networks and Servers
Diodes Incorporated added to its family of low voltage level translators, offering simple and autonomous bidirectional operation. The PI4GTL2002 is a 2-bit level shifter that the company designed to translate signals conditioned for one voltage level to signals at a higher or lower voltage, including gunner transceiver logic (GTL) or GTL+ to LVTTL/TTL.
The company points out that as leading processor makers continue to include GTL+ interfaces in their products, the need for high-performance level translators is increasing in applications such as server/data centers and networking. The PI4GTL2002 meets that demand while eliminating the need for directional control.
The open-drain design of the PI4GTL2002 allows the device to translate voltage levels in either direction without producing the design complexity or performance penalty of a dedicated direction control signal. The voltage level translator operates in either direction, shifting between 0.8V and 5V (CMOS), with less than 1.5ns propagation delay between inputs and outputs. This flexibility allows the PI4GTL2002 to support several use cases, including standard and fast mode I2C.
The design's NMOS-based pass transistors use a common gate to enable bidirectional operation, with reference voltages for each of the two signals. This allows the application of a different voltage to either side of the device, enabling voltage translation between signals ranging from 0.8V to 5V.
The pin-out of the PI4GTL2002 follows a flow-through arrangement, making PCB layout simpler. A low input and output capacitance keep the propagation delay low, and the device also features an on-resistance of just 3.5Ω to minimize signal distortion.
The Gunning Transceiver Logic - Transceiver Voltage Clamps (GTL-TVC) offer high-speed voltage translation with low ON-state resistance and minimal propagation delay. The GTL2002 has 2 NMOS pass transistors (Sn and Dn) with a common gate (GREF) and a reference transistor (SREF and DREF).
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 pull-up resistors. This functionality allows a seamless translation between higher and lower voltages selected by the user, without the need for directional control.
All transistors within the device have the same electrical characteristics and there is minimal deviation from one output to another in voltage or propagation delay. Because all transistors in the device are identical, SREF and DREF can be positioned on any of the other two matched Sn/Dn transistors, allowing easier board layout.
The translator's transistors offer excellent ESD protection to lower voltage devices while protecting less ESD-resistant devices.
Features
- 2-bit bidirectional translator
- Less than 1.5ns maximum propagation delay to accommodate Standard mode and Fast mode I2Cbus devices and multiple masters
- Allows voltage level translation between 0.8V, 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, and 5V buses, which allows direct interface with GTL, GTL+, LVTTL/TTL and 5V CMOS levels
- Provides bidirectional voltage translation with no direction pin
- Low 3.5Ω state connection between input and output ports provides less signal distortion
- Supports hot insertion
- 5V tolerant inputs
- Flow through pin-out for ease of printed-circuit board trace routing
- ESD protection exceeds 4KV HBM per JESD22- A114
- Package: UQFN1.6*1.6-8L, MSOP-8L,SOIC-8L
The PI4GTL2002UEX is available in the U-QFN package for $0.41 each in 3000 piece quantities. The PI4GTL2002 is also available in the W-QFN package (PI4GTL2002WEX) and the XT-QFN (PI4GTL2002XTEX) package.
