12V Laptop power supply adapter

    This laptop power supply adapter it is build around a TPS40210 boost controller from Texas Instrument. The wide input voltage of this non-synchronous controller and low sale price makes from TPS40210 to be a good option for many applications wich require a boost, flyback or Sepic topologies. A programmable soft start and an overcurrent protection with automatic retry, features are included.
laptop power supply charger circuit

R1 = 220kΩ and C13 = 220pF the switching frequency it is about 350kHz. The soft start time is determined by C5 and for C5 = 470nF it is aprox. 23 ms long enough so that this boost converter can start up without going into an overcurrent state.
    The output voltage value can be calculated by equation:
               where feedback voltage Vfb=0.7V.
               For R4 = 52kΩ and R2 = 1.8kΩ the output voltage Vout = 20.9V. With
R4 = 47kΩ and R2 = 1.8kΩ the output voltage becomes Vout = 19V.

     R6..R8  resistors are used to sense current for the current mode control and for overcurrent protection. To have a  22mΩ resistor value use a 9 pieces bunch of  0.2 Ohmi SMD 1206 resistors in parallel.
   The L1 coil is a high current (min.10A) rated coil type 
74435571100  from Wuerth electronic. Thanks of a spiral winding construction this type of coil has a low internal resistance and losses.
    A S16C40  double schottky diode  
(D2)  parallel mounted  is used to reduce its power dissipation. For output capacitors C 16 and C17 a low ESR capacitors type are a must. The X-ULR series conductive polymer aluminum solid capacitors from X-CON (Man Yue Technology)  meet the required specifications. As result the efficiency is over 90%.
     Led D4 it will lit only when the output voltage applied to D3 & Q3 is more then 16V.

dc/dc boost convertor pcb for laptop adapter
Component placement on SMD side

List of Materials

Reference Description Size Part Number Manufacturer
C1,C2,C3 10uF 1206 16V X7R CL31B106KOHN Samsung Electro-Mechanics
C4 100nF 0603 50V
C5 470nF 0603 50V
C6 2.2nF 0603 50V
C7 1uF 1206 50V
C8,C9,C10,C11 2.2uF 1206 50V X7R CL31B225KBHNNNF Samsung Electro-Mechanics
C12 100pF 0603 50V
C13 220pF 0603 50V X7R CL10C221KBNC Samsung Electro-Mechanics
C14 66pF 0603 50V
C15 0.1uF 0603 50V X7R CL10B104KBNC Samsung Electro-Mechanics
C16,C17 33uF/25V 8x8 ULR336M1EF08 Man Yue Technology
D2 S16C40 TO220 Mospec
L1 10uH / 16.5A 1890 74435571100 Wuerth Electronic
Q2 IRFH5106 PQFN 5X6 mm
Q3 BCR141 SOT23 WDs Infineon
R1 220k 0603
R2 1.8k 0603
R3 22k 0603
R4 52k 0603
R5 1k 1206
R6,R7,R8 R200 - 9pcs. 1206
R9 3.3 1206
R10 15k 0603
U1 TPS40210 DGQ10 TPS40210DGQ TI

Inside of 12V laptop power supply charger

This aluminium case  it is used as a heat sink for D2 diode and L1 coil.

12v powered dc/dc converter with 19V output voltage

The cigarette lighter plug is fitted with an internal 6A line fuse.

Download charger schematics for Orcad here
PCB it is available in pdf format too.

    TPS40210 Datasheet
    IRFH5106 Datasheet

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