Product Overview
Four Low-Bias JFET Inputs in a 14-Lead SOIC
Condition
Condition is New. The photos show a 14-lead surface-mount device with the top surface marked with National Semiconductor's script N logo, the code HM85AF, and LF444CM directly below it. Leads are bright and evenly formed, seven per side, with no solder, flux, or board residue visible in these photos. The underside is plain black with two round mold marks and no markings visible on that face. Stock is deep, so treat the photographed device as representative of the stock rather than as the individual piece that ships. HM85AF reads as a date and lot code, not as an orderable part number.
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Product Overview
The LF444CM is National Semiconductor's quad low power JFET-input operational amplifier in a 14-lead small-outline package, the M suffix that puts four independent amplifiers on a surface-mount footprint instead of a DIP. JFET inputs are the reason a designer reaches for this part: input bias current is specified at 50 pA maximum, low enough that a high-impedance source such as a photodiode, a piezo element, or a glass electrode is not meaningfully loaded by the amplifier reading it. The manufacturer's published figures for the family also include a 1 MHz gain bandwidth product, a 1 V per microsecond slew rate, equivalent input noise voltage of 35 nV per root Hz, and large signal voltage gain of 50k minimum. Supply voltage range, quiescent current, offset voltage, and pin assignments are not confirmed here - verify them against the LF444 datasheet before use. This is a device that shows up in analog front ends, instrumentation boards, and multi-channel signal conditioning where four channels of low-bias amplification need to share one small package.
Key Features
- Quad operational amplifier - four independent JFET-input amplifiers in one package
- 14-lead SOIC, gull-wing leads, seven per side, surface mount
- Input bias current 50 pA maximum (manufacturer published)
- Gain bandwidth product 1 MHz
- Slew rate 1 V per microsecond
- Equivalent input noise voltage 35 nV per root Hz
- Large signal voltage gain 50k minimum
- Photographed piece is top marked with National Semiconductor's script N logo and LF444CM, with a HM85AF date and lot code line on that unit
Applications
- A repair tech working a 1980s or 1990s instrument board that used the LF444 in its analog front end and wants a replacement carrying the same maker and the same part marking.
- A sensor designer buffering a high-impedance source, where 50 pA of bias current keeps the amplifier from pulling the signal it is supposed to be reading.
- A four-channel signal conditioning build - thermocouple buffers, active filters, integrators - where one 14-lead package replaces four singles and saves the board space.
- A prototyper laying out a SOIC-14 footprint who needs three or four devices for a first article run, not a factory reel.
Frequently Asked Questions
What is actually marked on the part?
Two of the photos show the top face carrying National Semiconductor's script N logo, HM85AF on the first line, and LF444CM on the second. We read HM85AF as a date and lot code and did not treat it as a part number. The opposite face is plain black with two round mold marks and no markings visible in these photos.
What package is this, and what is the pinout?
It is the 14-lead small-outline surface-mount package, the M suffix in LF444CM, with seven gull-wing leads per side. Pin assignments are not confirmed here - verify against the LF444 datasheet before you commit a layout.
What supply voltage will it run on?
Not confirmed - verify against the datasheet before use. The figures we do publish for this family are the ones listed above: 50 pA maximum bias current, 1 MHz gain bandwidth, 1 V per microsecond slew rate, 35 nV per root Hz noise voltage, and 50k minimum gain.
Do I get the exact device shown in the photos?
No. Stock here is deep, and the device in the photos is representative of that stock. We photograph one piece so you can see the marking and the package style you are ordering against, but the specific piece that ships is another one from the same stock.
Why buy four of these here instead of a full reel somewhere else?
Because a four-channel front end needs four devices, not two thousand five hundred. This is priced and stocked so you can count out exactly what the board calls for, add a spare for the one that ends up under a heat gun, and be done - no minimum order quantity, no reel fee, no drawer full of leftovers waiting for a project that never arrives. Shipping is $8 flat rate and goes free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
Fifty picoamps of input bias current is the kind of number that lets a sensor forget it is being measured. Four of those amplifiers ride on one small black body, waiting on whatever high-impedance signal you put in front of them.
