Laptop Power Supply in Car

A laptop or notebook computer user while they are away from the home or office knows that sooner or later they will need to plug into a mains outlet to top up the batteries. The car cigarette lighter socket in the car is also an electrical outlet but it can only supply 12 V. That’s no problem for the Laptop Power Supply described here.

(Click This Image to enlarge)

The laptop power supply described here plugs into a car cigarette lighter socket and produces a 19V nominal output voltage adjustable by + - 0.5V. The input voltage range is from 9.2V to 15V and the output voltage shows good regulation even with large fluctuations of the input voltage. The output can supply 5A continuously with brief excursions up to 10A.

The power semiconductor heatsinks of this laptop power supply are dimensioned fo 5A continuous so extended operation up to 10A will increase dissipation in the adapter and in extreme cases will cause the input fuse to complain.

Laptop PSU Adaptor Parts List

• Resistors:

R1 = 5k6
R2 = 51k (51k1)
R3 = 9k1 (9k1)
R4 = 1M
R5 = 4k7
R6,R8 = 15k
R7 = 27k
R9,R10 = 6,8
R11 = 10k
R12 = 100
P1 = 5k preset

• Capacitors:

C1-C4 = 3300µF 16V, radial, low ESR, diam. 12.5 mm, e.g. Panasonic EEUFC1C332 (Farnell)
C5,C10 = 1µF MKT, lead pitch 5mm or 7.5mm (larger version preferred)
C12 = 1µF MKT, lead pitch 5 mm
C6-C9 = 2200µF 25V radial, low ESR, diam. 12.5mm, e.g., EEUFC1E222 (Farnell)
C11 = 22nF, lead pitch 5mm
C13 = 2nF2, lead pitch 5mm
C14,C15 = 100nF ceramic, lead pitch 5mm
C16 = 10µF 63V radial

• Inductors:

L1 = 56µH, 21 turns 10 x 0.5 mm ECW, parallel
1 x ETD 29 coil forner, vertical mounting, Epcos B66359X1014T1 (Schuricht # 331622)
2 x ETD 29 clamp, Epcos B66359-A2000 (Schuricht # 333862)
2 x ETD 29 core half, material # N67, air gap 0.5mm, Epcos B66358-G500-X167 (Schuricht # 333840)

• Semiconductors:

D1 = MBR1645 (International Rectifier) (e.g. Reichelt, Segor)
T1 = IRL2505 (International Rectifier) TO-220AB case, (e.g., RS Components)
T2 = BD139
T3 = BD140
IC1 = UC3843N (Texas Instruments) (e.g. Reichelt, Segor)

• Miscellaneous:

K1-K4 = 2-way spade terminal, vertical, PCB mount
F1 = fuse, 10A/T (slow) 6.3 x 32 mm (¼ x 1¼ inch) + 2 fuse holders for 6.3 mm diameter and PCB mounting
2 x heatsink type SK104-STC (or STS) TO220 38.1mm, 11K/W (Fischer Electronic) Isolating washers for T1 and D1 (TO-220AB) + isolating bushes
PCB

Laptop PSU Adaptor PCB-Layout