About the article

5 V Power Controller

Battery operation from 2 V to 8 V

5 V Power Controller
These days many components and microcontrollers are designed for low-voltage operation and can be powered directly from a battery. For various reasons, however, it is often necessary to power them from a 5 V supply. Designing a high-efficiency supply is time-consuming, and so here we present a universal solution in the form of our 5 V power controller.
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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

• Input voltage range 2 V to 8 V (for example from two AA cells or two lithium-ion or lithium-polymer cells)
• Power a 5 V circuit drawing up to 150 mA using two AA cells
• Especially designed for 5 V microcontroller circuits
• Efficiency: 75 % at 2 V and >76 % from 3 V to 8 V input voltage
• Standard, readily available components
• All connections on 2.54 mm pitch headers
• Soft-off function under processor control
• Power on button can also be used as general input button
• Low current consumption in soft-off standby

(all SMD 0805, 1%)
R1,R2,R4 = 10kOhm
R3 = 10Ohm (see text)
R5 = 100kOhm
R6 = 560kOhm
R7 = 680kOhm
C1,C6,C7 = 100µF 25V SMD (e.g. Farnell # 1735335)
C2,C8 = 100nF 100V SMD (e.g. Reichelt.de # SMD-1812 100N, see text)
C3 = 1µF 25V SMD tantalum 0805 (e.g. Farnell # 1135280)
C4 = 10nF 100V SMD (e.g. Reichelt.de # SMD-1812 10N, see text)
C5 = 220µF 35V SMD (e.g. Farnell # 9695877)
L1,L2 = 33µH, 2A, 0.12Ohm SMD (e.g. Farnell # 1612699, Reichelt.de # L-PISM 33µ)
L3 = 27µH, 0.8A, 0.26Ohm, SMD (e.g. Farnell # 1539570)
(all SMD)
D1,D2 = BAT54S (SOT-23, STMicroelectronics)
D3 = MBRS340 (SMC, ON Semiconductor)
T1 = BSS138N (SOT-23, Infineon)
IC1 = LT1302 (SO-8, Linear Technology)
K1,K2 = 2-pin pinheader
K3 = 5-pin pinheader
PCB # 090719, see Elektor Shop or www.elektor.com/090719
PCB artwork download (free)

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