1 Ohm 0.125W 0805 1% SMD Resistor

If your board needs a 1 ohm 0.125w resistor, and the old part is a 1% 0.125W chip in an 0805 body, this is the part to order. It is a 1 ohm resistor in a small rectangular surface-mount body, built for current regulation and circuit protection in solar inverters and other power management applications where a steady very low value must hold. It fits current regulation, circuit protection, and power management jobs that need a fixed 1 ohm value at up to 0.125W. It does not fit jobs that need a different resistance value, a through-hole body, or more than 0.125W of power. Check the checks below before you order, so the value, the power, the voltage, and the body all match your board.

This is an original, high-quality part.

What it does

A resistor limits current and drops voltage in a circuit. A chip resistor does that job as a small flat part that solders straight onto the pads of a board, with metal ends that make the contact. This 1 ohm 1% resistor holds its 1 ohm value within 1%, so a board that calls for 1 ohm gets between 0.99 and 1.01 ohm. The 1 ohm value is a very low value: it drops very little voltage at a given current, so it fits current regulation and current sensing work, where the part must pass current without wasting power, rather than voltage division. At full 0.125W this part carries about 354 mA. The 0805 body is about 2.0 mm long, so it fits boards where a larger part would not.

Repair techs use a part like this as a 1 ohm 0805 resistor for current regulation, where a steady very low resistance sets a level without wasting power, and for circuit protection, where it guards sensitive parts against surges and voltage swings. You can check the value from the marking: the 4-digit code for this part is 1R00, where the R is the decimal point, so 1R00 means 1.00 ohm. The 3-digit code for the same value is 1R0. The EIA-96 code for the same value is 01Y: code 01 means 100, and the letter Y means multiply by 0.01, so 100 × 0.01 = 1.00 ohm.

Key features

• 1 Ohm fixed resistance, ±1% tolerance
• 0.125W power rating at 70°C ambient
• Thick film chip construction, surface mount
• 0805 body: about 2.00 mm × 1.25 mm × 0.50 mm
• Maximum working voltage 150V (series limit — the 0.125W rating caps this value at about 0.35V)
• Temperature coefficient ±200 ppm/°C
• Wide temperature range: −55°C to +155°C
• 4-digit code 1R00; 3-digit code 1R0; EIA-96 code 01Y

Checks before you order

• Value: your board list must call for 1 ohm. A nearby value is not the same part — 10 ohm is ten times this value, so if your board needs a different value, stop and check the board list again. A 47 ohm part in the same 0805 body is a different value for a different job, not a swap for this one.
• Power and heat: the power this part turns into heat must stay at or below 0.125W, and that 0.125W counts only up to 70°C ambient — above that, the safe power drops, so check the derating for your real working temperature. Work out the power from your real voltage and current (power = voltage × current) and keep it inside 0.125W with room to spare. At this low value, a small voltage means a large current — work out the current too, and keep it inside about 354 mA.
• Voltage: the voltage across this part must stay at or below about 0.35V in steady use. At this value the power rating is the real limit: at 150V the part would use 22,500W, far above its rating, even though 150V is the series voltage limit. Work out the voltage from your circuit before you order.
• Tolerance: the real value may sit up to 1% away from 1 ohm. If your circuit needs tighter than 1%, this part is the wrong pick — do not hope the part you get sits near the middle.
• Body and fit: your board must take an 0805 surface-mount body. Measure the old part and match it against the pads and the space on your board. The series body is about 2.00 mm long, 1.25 mm wide, and 0.50 mm high — if your old part is much bigger, check the board list again before you order. A 100 ohm part in the same 0805 body is a different value for a different job, not a swap for this one.
• Fit for the job: if your circuit only needs a fraction of an eighth of a watt, this part still works. Match the value first, then the power, then the body — a through-hole resistor is the wrong shape for a surface-mount board, even if the value matches.

Specifications

All figures below are from the maker series documents for this chip resistor family. No figure here was guessed. The maker of the exact part on this page is not stated on the live page, so the publisher should confirm the series figures against the Download file at publish time (see the gates note).

Other names for the same part (good to know)

Shoppers and repair techs call this same part by a few names. 1 ohm 0.125w is the plain name from its value and power. 1 ohm resistor is the name buyers use with the unit spelled out. 1 ohm 0805 resistor is the name buyers use when the value and the body size both matter. SMD resistor is the name for its surface-mount style. 1 ohm 1% is the short name that carries the value and the tolerance together. If your board list calls for 1 ohm at 0.125W with 1% tolerance in an 0805 body, this page is the right match. Do not judge by size alone — check the value, the power, and the tolerance too.

Frequently Asked Questions

What does 1 ohm mean?

It means 1 ohm of resistance — the part resists current flow by 1 ohm, which is a very low value.

What does 1% mean, and what does 0.125W mean?

1% is the tolerance: the real resistance may sit up to 1% above or below 1 ohm, so between 0.99 and 1.01 ohm. 0.125W is the power rating: the most power the part can turn into heat without damage, rated at 70°C ambient, with less allowed as it gets hotter.

What do the 1R00, 1R0, and 01Y markings mean?

They are three codes for the same value. 1R00 is the 4-digit code: the R is the decimal point, so 1R00 means 1.00 ohm. 1R0 is the 3-digit code for the same value: 1.0 ohm. 01Y is the EIA-96 code: code 01 means 100, and the letter Y means multiply by 0.01, so 100 × 0.01 = 1.00 ohm. The photo of the stocked part shows “1R0”, the 3-digit code.

Can I use this part at 150 V if the power is small?

No. At 1 ohm the 0.125W rating is the limit that matters: it caps the steady voltage at about 0.35V. At 150V this part would use 22,500W, far above its rating. The 150V figure is the series voltage limit, not a voltage you can use at this value.

How do I fit an 0805 chip resistor?

Solder it onto the matching pads on the board — it has no leads, so it sits flat on the pads. Check the pad spacing against the 2.0 mm body before you solder, use a fine tip and a small amount of solder, and do not overheat the part.

What is the price of this part?

Check the live price on the website. The price shown on the product page is the current one.

Use note kept from the old page: this part was listed before as a 1 ohm 0.125W 0805 2012 1% SMD resistor for solar inverters, a high-precision component designed for current regulation and circuit protection in solar energy applications, ensuring stable electrical performance, reducing power fluctuations and enhancing system reliability, with a 0.125W SMD resistor power rating for efficient heat dissipation while maintaining consistent resistance, its 0805 SMD resistor 1 ohm size for easy integration into compact circuit boards, ideal for space-efficient solar inverter designs, built with durable materials for excellent stability and long-lasting performance even in demanding environmental conditions, a 2012 SMD resistor with a 1% tolerance resistor 1 ohm specification for precise resistance values and optimal energy control, a surface mount resistor 1 ohm for quick and secure PCB mounting and improved assembly efficiency, engineered for solar inverters to enhance power management and protect sensitive electronic components from surges and voltage fluctuations, with high accuracy and reliability for a wide range of renewable energy and electronic applications — and that use still stands.