Where to buy electronic load that works down at uA level - Page 1
Forum section: electronics / testgear

author: Psi
author_rank: Super Contributor
timestamp: July 10, 2020, 01:50:19 am
content: I'm looking for an electronic load that can work down at uA levels. (0.1uA would be ideal but 1uA acceptable)It also needs to have some sort of external control (ethernet/serial/gpib)Anyone know of anything available like that?All the electronics load you normally see are 120V /10Amps max 1mA resolution.The one i'm looking for would be more like 20V /1A max 0.1uA resolution

author: delfinom
author_rank: Regular Contributor
timestamp: July 10, 2020, 01:57:46 am
content: a 0.01% resistor decade box + a good DMM?I would be amazed to see an general purpose electronic load able to regulate at such a low current. There's the Keithly 2380 that can do 0.1mA at best.There's a Instek that claims 0.01mA.

author: jjoonathan
author_rank: Frequent Contributor
timestamp: July 10, 2020, 02:07:32 am
content: A SMU would do... if you can stomach the price tag.

author: Tjuurko
author_rank: Regular Contributor
timestamp: July 10, 2020, 03:54:58 am
content: Maybe Prodigit 3336F will do?http://www.prodigitusa.com/prodigit/3336f/3336fSpecifications.htmhttp://www.prodigit.com/product_c_3.php?button_num=g11&this_cname=DC+Electronic+Load&folder_id=40&cnt_id=20&orderby=1

author: Psi
author_rank: Super Contributor
timestamp: July 10, 2020, 07:58:51 am
content: Quote from: Tjuurko on July 10, 2020, 03:54:58 amSadly it needs to be able to resolve 1uA and it looks like the best that Prodigit 3336F can do is 5uA

author: deadlylover
author_rank: Frequent Contributor
timestamp: July 10, 2020, 12:15:52 pm
content: At what sort of current would you need the 1uA resolution at?The ol' Keithley 2400 can only source/sink that in the 10mA range or lower, it will be similar for most other SMU's out there too. Needing it for 1A is almost insanity and I'm sure there's a 6.5digit SMU out there but it has "ask for quote" pricing.

author: TurboTom
author_rank: Super Contributor
timestamp: July 10, 2020, 01:54:21 pm
content: If you only need to load your DUT with a constant / programmable current, you may want to look at one of the instruments of the Keithley 220 range. The 220 itself may be overkill (max. 100mA, min. resolution 500fA), but the 224 could be okay (max. 100mA, min. resolution 5nA). They are quite old but perform really well and are programmable via GPIB. The voltage compliance is about +-100V. In comparison to a proper DC load, these instruments lack the measurement functions of voltage and actual current. But maybe worth a thought anyway, especially since they can be found at a bargain once in a while.

author: MathWizard
author_rank: Super Contributor
timestamp: July 10, 2020, 03:03:02 pm
content: Quote from: delfinom on July 10, 2020, 01:57:46 amI just made a nice 1% 1W box, with actual 1% resistors (puts my fake ebay ones to shame)What would it cost to make 1 with 0.1% to 0.01% resistors ? What would 56/63/72 of them cost ?

author: Tjuurko
author_rank: Regular Contributor
timestamp: July 14, 2020, 03:29:22 am
content: There is another option.You can take any electronic load and increase the nominal value of the main shunt by 100/1000 times. The current will decrease 100/1000 times.You may still need to leave only one power transistor.

author: Berni
author_rank: Super Contributor
timestamp: July 14, 2020, 05:33:05 am
content: Yep as other said you need a SMUThey are capable of sinking or sourcing currents down into the nA range and often offer measurement resolution down into the pA range.And yes they are very expensive pieces of gear(>1 grand used). Then once you have the gear you might also need expensive triaxial cables and connectors because these low currents require the wires to be wrapped in an extra guard shield to prevent leakage.For a piece of ready made gear the cheapest option is a HP semiconductor analyzer with no front panel. These are used in racks and communicate over GPIB, but since they can only be used via GPIB commands and not with fingers they tend to be pretty unpopular on ebay and sell for cheep here and there. They contain multiple channels of SMUs inside that are sensitive enough to measure leakage currents in diodes and transistors (Used as a test on fab production lines). But for the 1A requirement you will need to find one with high current cards in it as the typical models tend to be only +/-100mA

author: Psi
author_rank: Super Contributor
timestamp: July 14, 2020, 08:42:50 am
content: Quote from: Tjuurko on July 14, 2020, 03:29:22 amThat would be a cool option, and would probably work well, but i suspect it would confuse the hell out of someone when it went out for cal each year

author: Psi
author_rank: Super Contributor
timestamp: July 14, 2020, 08:45:02 am
content: Quote from: Berni on July 14, 2020, 05:33:05 amThanks