Space Grade Voltage Translation Solutions for 1.5V I/O to 1.8V I/O? - Page 1
Forum section: electronics / projects

author: bhj99
author_rank: Contributor
timestamp: April 03, 2022, 12:33:03 am
content: Hello everyone, I am trying to find level shifter solutions that are space-qualified (perhaps parts with Total Ionizing Dose (TID) data or radiation hardening) that can logic level translate from FPGA I/O at 1.5V to and ADC at 1.8V while supporting bidirectional I/O and OE capabilities. This is for high reliability applications. Basically, I am interfacing with SPI data and some status/control discretes from the FPGA 1.5V bank and the transceiver accepts I/O at higher voltages.I've found a part from ST Microelectronics (P/N 5962F1120701VXC) but the voltage does not quite support and there's insufficient data at 1.5V. I also thought about passive voltage dividers or MOSFETs for translation, but those are unidirectional. Would anyone have reference designs at lower voltages? I've mostly seen 1.8V -> 3.3V and 3.3V -> 5V.Does anyone have good solutions that come to mind? I would really appreciate any feedback/suggestions!

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 03, 2022, 01:08:14 am
content: A resistive divider would have a voltage drop going from 1.8V to 1.5V but the drop in the other direction would be only the slight amount caused by loading. That can be offset by having a pullup on the 1.8V side to increase the voltage a little.

author: AndrewBCN
author_rank: Frequent Contributor
timestamp: April 03, 2022, 01:41:41 am
content: https://www.nxp.com/products/peripherals-and-logic/voltage-level-translators/8-bit-dual-supply-translating-transceiver-open-drain-auto-direction-sensing:NTS0308E

author: bhj99
author_rank: Contributor
timestamp: April 03, 2022, 02:06:34 am
content: Quote from: AndrewBCN on April 03, 2022, 01:41:41 amCouldn’t find testing data for TID. Would this be suitable for high reliability applications?

author: bhj99
author_rank: Contributor
timestamp: April 03, 2022, 02:07:42 am
content: Quote from: NiHaoMike on April 03, 2022, 01:08:14 amDo you know of any reference designs for this?

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 03, 2022, 02:15:03 am
content: Quote from: bhj99 on April 03, 2022, 02:07:42 amIt's a voltage divider. In one direction, it divides 1.8V to 1.5V. In the other direction, the 1.5V passes straight through.

author: AndrewBCN
author_rank: Frequent Contributor
timestamp: April 03, 2022, 07:30:22 am
content: Quote from: bhj99 on April 03, 2022, 02:06:34 amContact NXP and ask.

author: amosborne
author_rank: Contributor
timestamp: April 03, 2022, 04:18:02 pm
content: A resistive divider would be a problem if high-speed is required.

author: bhj99
author_rank: Contributor
timestamp: April 03, 2022, 04:54:31 pm
content: Quote from: amosborne on April 03, 2022, 04:18:02 pmQuote from: amosborne on April 03, 2022, 04:18:02 pmYes, I do have some concern here, as the idea would be to support SPI data, which is fairly high speed.

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 03, 2022, 05:20:45 pm
content: The ST rad-hard parts are only spec'ed down to 1.65V I think.If you're looking for level shifters, I suppose you already considered the following and that was not possible, but can you not power one IO bank of the FPGA at 1.8V? Maybe you wouldn't have enough IOs left at 1.5V if you did that?

author: bhj99
author_rank: Contributor
timestamp: April 03, 2022, 07:46:16 pm
content: Quote from: SiliconWizard on April 03, 2022, 05:20:45 pmRight, these dedicated use for the FPGA 2.8V IO bank and so the decision to to utilize the 1.5V IO bank.

author: Sceptre
author_rank: Regular Contributor
timestamp: April 04, 2022, 11:57:30 pm
content: Two other product lines to check:Cobham AES (formerly Aeroflex Microelectronics):https://caes.com/products/radiation-hardened-solutions-high-reliability-components/logicRenesas (formerly Intersil) Rad Hard Digital:https://www.renesas.com/us/en/products/space-harsh-environmentNo experience with using them at 1.5V, don't know if they have the same limitations as the ST parts.