Hey every one.
MC33063AD is a buck/boost converter. http://www.ti.com/lit/ds/symlink/mc33063a.pdf
Being a noob, I am trying to copy the typical application example for a step-up converter into KiCAD.
In this case I wish to provide an output of 5V, from 1 to 3 AA cells.
There a two ground nets, since as I am trying to layout the thing on a one layer PCB, I discovered I 'd need to ad a jumper wire - symbolized by a 0 ohm resistor (R0).
So, can you confirm that it is correct?
Thanks a lot.
My advice would be ... don't do it.
* The chip needs at least 3V in order to run, therefore you need
at least 3 AA batteries to get it working. 2 rechargeable AA batteries would only give you about 2.5v, 2 alkaline batteries in the best case scenario would give you 3.1..3.2v and quickly drop close to 3v or below 3v. So basically, you
need at least 3 AA batteries to make it work.
* The chip is ancient, has minimal internal protections, runs at low frequencies (<100kHz) , it has high internal power consumption (up to 4mA, datasheet doesn't even specify how much it uses when input voltage is below 5v), and fairly inefficient, your converter would probably be 65-70% efficient.
You'd lose a lot of power just to keep the ancient chip working, then you'd waste power in the inductor, in the shottky diode, electrolytic capacitor etc
Due to being so old and running at such low frequencies, you need big inductors and big electrolytic capacitors - basically the whole circuit would take about as much room on the circuit board as an additional AA battery.
You'd be better off just going with 4 AA batteries, or 4 x AAA batteries if space is an issue. 4 AAA batteries (at around 1100mAh each) would probably behave like 3 AA batteries at 1600-1800mAh used with such inefficient boost converter.
Go with 4 AA or AAA batteries ... rechargeable batteries will have 1.15v .. 1.35v , alkaline batteries will have 1.45v.. 1.65v ... so you have 4.6v to 5.4v for rechargeable batteries and 5.8v to 6.6v for alkaline non-rechargeable batteries.
Whatever you power with 5v , probably works with as little as 4.8v so in reality you're going to use almost all the juice in rechargeable batteries. Don't worry about minimum voltage.
You only need to worry about maximum voltage.
You can basically use a very small, very simple to use LDO (linear regulator with very low dropout voltage) .. you can easily find such chips that have only about 25-50mV dropout voltage (the chip needs a voltage a bit higher than output voltage in order to output a stable set voltage). Also, most LDOs will output a lower voltage just fine, if the input voltage is below the output voltage+dropout voltage, so for example if you configure a LDO to output 5v but your batteries output 4.9v, the LDO will happily output 4.9v - dropout voltage.
Just figure out the maximum current consumption of your circuit and pick a LDO that would be capable of providing that much current, with dropout voltage as low as possible, and which can take up to 7-8v (possible with 4 fresh alkaline batteries)
Most of these LDOs only need a couple of ceramic capacitors which barely take any pcb space, and the adjustable ones only need a couple of resistors to set the output voltage.
If the device uses a lot of current, I would probably use an adjustable LDO and set the voltage to my circuit to about 5.2v (or as much as I'm sure my chips would tolerate, most chips like microcontrollers can go up to 5.5v in perfect safety conditions so 5.2v wouldn't be a big deal... the reason for going above 5.2v would be to lose as little as possible of energy in the LDO.
For example, 5.2v in ( 4 x 1.3v = 5.2v) , 5v out .. basically have 96.1% efficiency ... 6.2v in ( 1.55v x 4 for alkaline batteries) and 5.2v out = ~ 84% efficiency .. better than what this mc33063 can do
Here's examples of LDOs that would work here:
TPS77050DBVT Fixed LDO Voltage Regulator, 2.7V to 10V, 35mV Dropout, 5Vout, 50mAout, SOT-23-5 :
http://uk.farnell.com/texas-instruments/tps77050dbvt/ldo-fixed-5v-0-05a-sot-23-5/dp/2382990NCP551SN50T1G Fixed LDO Voltage Regulator, 12V in, 40mV Dropout, 5V/150mA out, TSOP-5 :
http://uk.farnell.com/on-semiconductor/ncp551sn50t1g/ic-ldo-150ma-cmos-low-iq-smd/dp/1468772TEXAS INSTRUMENTS REG101NA-5/250G4 Fixed LDO Voltage Regulator, 1.8V to 10V, 60mV Dropout, 5Vout, 100mAout, SOT-23-5 :
http://uk.farnell.com/texas-instruments/reg101na-5-250g4/v-reg-ldo-0-1a-5-0v-sot-23-5-101/dp/1207241RLTPS76950DBVT Fixed LDO Voltage Regulator, 2.7V to 10V, 71mV Dropout, 5Vout, 100mAout, SOT-23-5:
http://uk.farnell.com/texas-instruments/tps76950dbvt/regulator-ldo-fixed-5v-sot-23/dp/2323601BA050LBSG2-TR Fixed LDO Voltage Regulator, 2.5V to 7V, 90mV Dropout, 5Vout, 150mAout, SMP-5 :
http://uk.farnell.com/rohm/ba050lbsg2-tr/linear-reg-fixed-5v-0-28a-smp/dp/2343139ADP3301ARZ-5 Fixed LDO Voltage Regulator, 3V to 12V, 100mV Dropout, 5Vout, 100mAout, SOIC-8 :
http://uk.farnell.com/analog-devices/adp3301arz-5/ldo-0-8-0-1a-5v-8soic/dp/2094222MC78FC50HT1G LDO VOLTAGE REGULATOR, 5V, 120mA, SOT-89-3 :
http://uk.farnell.com/on-semiconductor/mc78fc50ht1g/ldo-voltage-regulator-5v-120ma/dp/1254286LP2980IM5-5.0 Fixed LDO Voltage Regulator, 2.1V to 16V, 120mV Dropout, 5Vout, 50mAout, SOT-23-5 :
http://uk.farnell.com/texas-instruments/lp2980im5-5-0/v-reg-ldo-5-0v-smd-2980-sot235/dp/9779329... and these are only the "fixed 5v output" ones, there's about 200+ adjustable output LDOs I filtered out before picking those above.
If you insist on having some boost dc-dc converter in your design, pick something more modern.. here's some suggestions:
LT1303CS8-5#PBF Boost (Step Up) Switching Regulator, Fixed, 1.8V-10V In, 5V And 200mA Out, 185 kHz, SOIC
http://uk.farnell.com/linear-technology/lt1303cs8-5-pbf/ic-switching-regulator-155khz/dp/2238166NCP1400ASN50T1G Boost (Step Up) Switching Regulator, Fixed, 800mV-5.5V In, 5V And 0.1A Out, TSOT-23-5 :
http://uk.farnell.com/on-semiconductor/ncp1400asn50t1g/ic-switching-reg-180khz-sot23/dp/1460673NCP1402SN50T1G Boost (Step Up) Switching Regulator, Fixed, 800mV-5.5V In, 5V And 200mA Out, 200 kHz, SOT-23-5 :
http://uk.farnell.com/on-semiconductor/ncp1402sn50t1g/ic-dc-dc-converter-5sot2/dp/1652393ADP3050ARZ-5 Buck, Buck-Boost, SEPIC Switching Regulator, Fixed, 3.6V-30V In, 5V And 1A Out, 240 kHz, NSOIC-8 :
http://uk.farnell.com/analog-devices/adp3050arz-5/buck-5v-1a-8soic/dp/2074857 TPS61032PWPR Synchronous Boost Step Up, Switching Regulator, Fixed, 1.8V-5.5V In, 5V/4A Out, 700 kHz, HTSSOP-16 :
http://uk.farnell.com/texas-instruments/tps61032pwpr/ic-sync-boost-conv-600khz-htssop/dp/1207333again, these only fixed 5v output, plenty more that can be adjusted to 5v output using 2 resistors. Most of the above go from about 200kHz and up, so you can use tiny surface mount inductors and ceramic capacitors , but the higher the frequency the more important it is to do proper routing (very small loops between chip and inductor, thick ground and voltage traces etc etc