Product Overview
Motorola MC7905CT - Negative 5V 1A Regulator, TO-220
Condition
New. The photo shows a representative unit from our stock.
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Product Overview
The MC7905CT is a fixed negative 5 V regulator in the three-lead TO-220 package, the negative complement to the positive MC7800 parts.
Forty-one are on the shelf, sold each, and they are listed New. The representative unit photographed carries the Motorola batwing beside a round factory stamp, with MC on the first line, 7905CT on the second and QTR417 on the third. Its three leads are full length and straight, with no solder and no bend visible on them in these photos, and the tab is bare metal with a clear mounting hole. QTR417 we quote and do not interpret: no Motorola-published marking guide backs the data we work from, so no date is claimed from that string. A 7905CT ordered from current production ships from onsemi, the successor to Motorola's semiconductor business, which is the whole difference between a new one and a batwing-marked MC 7905CT QTR417 body like this.
Key Features
- Fixed negative 5 V output
- Delivers in excess of 1.0 A with adequate heatsinking (per onsemi's published MC7900 series data)
- Current limiting, thermal shutdown and safe-area compensation (per onsemi)
- Typical dropout 1.3 V at IO = 1.0 A (per onsemi)
- Maximum input voltage -35 V for the -5 V through -18 V devices (per onsemi)
- TO-220 package, CASE 221AB, indicated by the "T" suffix (per onsemi)
- Through-hole mount, three leads, metal tab with mounting hole
- "C" suffix: commercial junction-temperature grade, TJ = 0 degC to +125 degC (per onsemi)
- Verify against onsemi's published MC7900 series data before designing in.
Applications
- Negative half of a plus and minus 5 V split supply
- Analog signal boards needing a regulated -5 V rail
- Repair and restoration of legacy linear power sections
- Bench supply builds paired with a positive 7805
Frequently Asked Questions
How many should I order?
Order what the build needs. We have forty-one of these on the shelf, so a repair, a spare or a whole run of them is no trouble, and a split supply wants one of these for every positive part you are buying alongside it. Shipping is $8 flat rate and free on orders over $28, so small parts like this ship smartest as part of a larger order.
Is the 7905 pinout the same as a 7805?
No, and this is the trap that costs people a part. onsemi's published data gives the TO-220 pinout for the positive MC7800 series as 1 = Input, 2 = Ground, 3 = Output, with the heatsink tab tied to pin 2. For the negative MC7900 series the same published data gives a different TO-220 pinout: 1 = Ground, 2 = Input, 3 = Output, with the tab tied to pin 2. Same package, same look, different wiring. Verify the pin assignment against onsemi's published MC7900 series data before you solder or power it up. The body you get says MC 7905CT, and that 9 is the only thing on the outside telling the two apart once the part is on your bench, so keep it faced where you can read it.
The other half of the split supply, waiting patiently while everyone fusses over the 7805.
