FREE VB COURSE - Index of

More documents

Recommendations

Info

HANDS-ON POWER SUPPLIES 95-wat Laptop PSU 12 V in, 19 V at 5 A out! Michael Schön Anyone who regularly uses a laptop or notebook computer 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 PSU Adaptor described here; it can deliver ample voltage and current for today’s portable computers from a car battery. It’s also simple to build and has excellent efficiency. Modellers will also be interested in this design to recharge their battery packs in the field. 42 elektor electronics - 1/2006
Adaptor The laptop adapter described here plugs into a car cigarette lighter socket and produces a 19 V nominal output voltage adjustable by ± 0.5 V. The input voltage range is from 9.2 V to 15 V and the output voltage shows good regulation even with large fluctuations of the input voltage. The output can supply 5 A continuously with brief excursions up to 10 A. The power semiconductor heatsinks are dimensioned for 5 A continuous so extended operation up to 10 A will increase dissipation in the adapter and in extreme cases will cause the input fuse to complain. The high efficiency of this design (typically 95 %) reduces loading on the car battery and also dissipation within the adapter unit. At 60 mm _ 100 mm the PCB outline is not much bigger than the mains adapter unit that was supplied with the laptop or notebook PC. The step-up Converter The majority of laptops require a supply voltage in excess of the 12 V available at the cigarette lighter output socket, even with the engine running the supply will not rise much above 13.8 V and this is still too low for most laptops which typically require 19 V. The 12 V supply can be boosted with the help of a step-up converter design. The basic principle is simple: an inductor is repeatedly ‘charged up’ and ‘dis- Adapter specification • Output current: • Output voltage: 5 A (10 A momentarily) 19 V ± 0.5 V (adjustable) • Input range: • Minimum input voltage: 10 V to 15 V 9.2 V • Switching frequency: • Maximum continuous output power: 42 kHz 95 W • Efficiency: • PCB dimensions: 95 % (typical) 59 mm x 98 mm charged’ and the resultant induced voltage is added to the supply voltage to produce an output voltage higher than the supply. Unlike a standard transformer inverter the basic circuit requires just three components: a coil, a power switch (in this case a MOS- FET) and a diode. All the control functions are performed by IC1, this device produces the pulse width modulated (PWM) switching signal for the power switch. The input and output voltages are smoothed by a series of low-loss capacitors. The principle of the step-up converter operation is shown in Figure 1. When the power switch (MOSFET T) conducts (Figure 1a) current flows through the coil and produces a magnetic field. The anode of the diode (D) will be at ground potential (almost) so it will not be conducting and any a b L D energy previously stored in the capacitor C will be supplied to the load (R L ). The coil core has a 1 mm air gap to ensure that the core material is not driven into saturation during this phase of the cycle. When saturation occurs it is not be possible to store any more energy in the magnetic field and the coil effectively becomes just a low impedance resistor which would shortcircuit the input voltage. When T turns off (Figure 1b) current through the coil no longer has a path to ground through T, the magnetic field starts to collapse inducing a voltage across L of the opposite polarity to the switch-on phase. The induced voltage rises above the supply voltage, forward biasing D and transferring energy to C and R L . Energy stored in C during this phase is transferred to the load during the next switch-on phase. 1/2006 - elektor electronics 43 VIN VIN IIN IIN tON L D t OFF T T C C IOUT V OUT RL 0500029 - 12a IOUT V OUT RL 0500029 - 12b Figure 1. The step-up converter principle: Switch-on phase (a) and Switch-off phase (b).
Page 1 and 2: FREE VB COURSE JANUARY 2006 £3.80
Page 4 and 5: Miscellaneous matters News from www
Page 6 and 7: Volume 32, Number 350, January 2005
Page 8 and 9: INFO & MARKET MAILBOX Rejektor Unde
Page 10 and 11: INFO & MARKET MAILBOX 10 ton), is t
Page 12 and 13: INFO & MARKET NEWS & NEW PRODUCTS 1
Page 14 and 15: INFO & MARKET NEWS & NEW PRODUCTS 1
Page 16 and 17: KNOW-HOW ELECTRONIC ARCHAEOLOGY CMO
Page 18 and 19: KNOW-HOW ELECTRONIC ARCHAEOLOGY 18
Page 20: KNOW-HOW ELECTRONIC ARCHAEOLOGY Jus
Page 23 and 24: Proscribed toxins The following sub
Page 25 and 26: ers and equipment manufacturers mus
Page 27 and 28: Web links [1] Official site for RoH
Page 29 and 30: The designers in the Elektor Electr
Page 31 and 32: About the controller Controlling th
Page 33 and 34: That means we can’t provide insta
Page 35 and 36: manufacturer’s requirements in ac
Page 37 and 38: ily In cooperation with Glyn (www.g
Page 39 and 40: Preliminary exercises The following
Page 41: Order now using the Order Form in t
Page 45 and 46: K1 10...15V 10A T R12 BD139 T2 56µ
Page 47 and 48: Input voltage (V) Input current (A)
Page 49 and 50: Charred PCBs Experimenting with sol
Page 51 and 52: +5V R8 10M IC3.A 1 2 1 X1 C2 100kHz
Page 53 and 54: layout is double sided and componen
Page 55 and 56: The board has a 10/100 Mbps Etherne
Page 57 and 58: and describe the part played by the
Page 59 and 60: As usual we start by defining the i
Page 61 and 62: In all mains-operated equipment cer
Page 63 and 64: Phone Stop! Don’t throw away your
Page 65 and 66: � ��
Page 67 and 68: 230V 10k 470 Ω R3 R18 S1 HOURS K1
Page 69 and 70: COMPONENTS LIST Resistors: R1,R18 =
Page 71 and 72: EMC DIRECTIVE From 1 January 1996,
Page 73 and 74: Step #2: series capacitor To operat
Page 75 and 76: Christmas Tree Lighting with LEDs P
Page 77 and 78: Night of the PROM This issue of Ele
Page 79 and 80: Hexadoku Puzzle with an electronic
Page 81 and 82: products and services directory LON
Page 83 and 84: nline at ectronics.co.uk Due to pra
Page 85 and 86: Order Form Order Form 01-2006 ✁
Page 87 and 88: CD-ROM ECD Edition 3 Now with a new
Page 89 and 90: xHRKCQIy451128zv!:,
Page 91 and 92: Contents by subject Subject Page In
Page 93 and 94:
The Important parts of the Visual B
Page 95 and 96:
• Use a program like Microsoft Pa
Page 97 and 98:
Attaching code to the controls Now
Page 99 and 100:
If there are syntax errors the syst
Page 101 and 102:
Attach the following code to the ap
Page 103 and 104:
Our third program This program will
Page 105 and 106:
2 3 4 5 6 7 8 9 10 11 12 13 14 15 1
Page 107 and 108:
Case 6 lblBand4.BackColor = Color.B
Page 109 and 110:
6 7 8 9 10 11 12 13 14 15 16 17 18
Page 111 and 112:
Control Property Setting Button 2 N
Page 113 and 114:
lblPinouts.Image = My.Resources.SE2
Page 115 and 116:
New Microcontroller Basics Burkhard
show all

FREE VB COURSE - Index of

Create successful ePaper yourself

Delete template?

Save as template?