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Farewell 7805 & 7905

Switch-mode replacements do a much better job

Based on a Labs project | January 2012 | Find it here
Farewell 7805 & 7905
Classic devices such as the positive-output 7805 and the negative-output 7905 are not exactly champions in energy efficiency, due to their linear mode of operation. All superfluous power between the input and output pins of these regulators is simply converted into heat. Surely we can do better nowadays — more energy efficient and greener? That’s what this article is about.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.

Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Extra info / Update
Positive voltage regulator
- Output voltage +5 V (adjustable with two resistors)
- Input voltage range 6 to 17 V
- Maximum output current 1 A
- Maximum output ripple 80 mVpp at 17 V in and 1 A out
- Dimensions and pinout identical to standard 7805
Negative voltage regulator
- Output voltage –5 V
- Input voltage range –6 to –17 V
- Maximum output current 0.85 A
- Maximum output ripple 36 mVpp at –17 V in and 0.85 A out
- Dimensions and pinout identical to standard 7905
Download the BOM list
The BOM (Bill of Materials) is the technically exhaustive listing of parts and other hardware items used to produce the working and tested prototype of any Elektor Labs project. The BOM file contains deeper information than the Component List published for the same project in Elektor Magazine. If required the BOM gets updated directly by our lab engineers. As a reader, you can download the list here.
Want to learn more about our BOM list? Read the BOM list article for extra information.
Component list
positive voltage regulator
R1 = 430kOhm 1%/0.1 W, SMD 0402
R2 = 82kOhm 1%/0.1 W, SMD 0402
R3 = 0.1Ohm 1%/0.1 W, SMD 0402
C1 = 10µF 25 V, X5R, SMD 0805 (e.g. TMK212BBJ106KG-T)
C2 = 22µF 6.3 V, X5R, SMD 0805 (e.g. JMK212BJ226MG-T)
C3 = 3.3nF 25V, X7R, SMD 0402
C4 = 100nF 25V, X5R, SMD 0402
L1 = 100nH, SMD 0805 (e.g. MLZ2012DR10D)
L2 = 3.3µH, 4x4 mm (e.g. NRS4018T3R3MDGJ)

negative voltage regulator
R1 = 15 Ohm 1%/0.1 W, SMD 0402
R2 = 1k24 1%/0.1 W, SMD 0402
R3 = 4k99 1%/0.1 W, SMD 0402
C1 = 10µF 25V, X5R, SMD 0805 e.g. TMK212BBJ106KG-T
C2 = 22µF 6.3V, X5R, SMD 0805 e.g. JMK212BJ226MG-T
C3 = 10nF 25V, X5R, SMD 0402
C4 = 100nF 25V, X5R, SMD 0402
L1 = 100nH, SMD 0805, e.g. MLZ2012DR10D
L2 = 3.3µH, 4x4 mm, e.g. NRS4018T3R3MDGJ
IC1 = TPS61170DRVR boost-converter, 6-SON
IC2 = MAX4073TAXK+T current-sense amplifier, SC-70-5
D1 = PD3S230H-7 Schottky-diode, PowerDI323
K1 = 3-pin pinheader, right angled, 0.1’’ pitch (2.54mm)
PCB # 120212-2

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