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Power Supply

Power supply notes

Due to the various odd voltages required by RF stages, there are no less than 4 rails:

  1. 3.3V for digital/analog wave generation
  2. 5V for RF gain stage
  3. 12V for VCO power
  4. 20-28V for VCO tuning
  5. If you're using the PLL tuning system, there's an additional 2.5V rail (in the PLL section). grr!
  • You should adjust the 24V boost converter to be .5V higher than the Vtune_max of the VCOs you're using to conserve power and reduce the chance of messing up the VCO
  • Winding your own inductors isnt necessary but if you want to save some $ and you have magnet wire hanging around, go for it.
  • Pick R1/R2 to make a voltage divider for your battery input so that the low battery input = 1.1V. You might want to use 1% resistors or measure the 5% ones to get as close as possible.
  • If you're using 5V VCOs, you can power it from the gain stage converter or, alternately, cut the input trace and tie it to the battery input (~3.7V) and tie the select line low. This will change it to a 5V boost.
  • The power supply is rather expensive if you're buying the boost converters. Useful input as to how this can be remedied is appreciated. Currently it seems like some sort of hand-wound multi-tap transformer and a Simple Switcher might be the easiest way.
  • Dont place C20, the datasheet suggests it but it seems to make things worse (?)

Parts List - Power supply

Part no.NameDescriptionDistributorQtyCostTotal
J-188-1SW1Alternate action push button switchDigikey1$0.95$0.95
*TPS79333IC13.3V/200mA LDO regulatorDigikey/Mouser1$0.53$0.53
*LM2733xIC25 (or 7V) DC/DC converter Digikey1$2.58$2.58
*LM2731YIC2 (alt)5 (or 7V) DC/DC converterDigikey1$2.58$2.58
*LT1301CS8IC312V DC/DC converterDigikey/Linear1$4.75$4.75
*LT1173CS8IC425V+ DC/DC converterDigikey/Linear1$4.88$4.88
CDRH6D28NP-150NCL115uH power inductorDigikey1$1.03$1.03
CDRH6D28NP-7R3NCL1 (alt)7.3uH (if IC2 is LM2731Y)Digikey1$1.03$1.03
CDRH6D28NP-330NCL2, L333uH power inductorDigikey2$1.03$2.06
0.1uF 1206 ceramic capacitorC2, C3 C7, C9, C11, C13, C16, C170.1uF ceramic filter capacitorMouser8$0.08$0.64
1.0uF 1206 ceramic capacitorC4, C6, C12, C15, C191.0uF ceramic filter capacitorMouser5$0.18$0.90
UWX0J101MCL1GBC1100uF 6.3V input filter capacitorMouser1$0.17$0.17
UWX0G101MCL1GBC5100uF/4V filter capacitorMouser1$0.17$0.17
TPSC107K010R0100C10100uF/10V low ESR tantalum capacitorDigikey1$1.18$1.18
TPSC686K016R0200C1468uF/16V low ESR tantalum capacitorDigikey1$1.44$1.44
B45197A6226K409C1822uF/35V low ESR tantalum capacitorDigikey1$1.40$1.40
390-550pF 1206 ceramic capacitorC20feed foward capacitor for 5V regulatorDigikey1$0.22$0.22
510K 1206 5% resistorR1Chosen value resistors for low battery detect: R1/(R1+R2)*Vlow = 1.1Digikey/Mouser1$0.08$0.16
220K 1206 5% resistorR2Chosen value resistors for low battery detect: R1/(R1+R2)*Vlow = 1.1Digikey/Mouser1$0.08$0.16
39K 1206 5% resistorR3Boost voltage reference resistor for 5VDigikey/Mouser1$0.08$0.08
12K 1206 5% resistorR4Boost voltage reference resistor for 5VDigikey/Mouser1$0.08$0.08
2K 1206 5% resistor R5LED choke resistorDigikey/Mouser1$0.08$0.08
50K 1206 resistorR6Boost voltage reference resistor for 24VDigikey/Mouser1$0.08$0.08
1M 1206 resistorR7Boost voltage reference resistor for 24VDigikey/Mouser1$0.08$0.08
SS14D1, D2, D3Schottky Diode (at least 1A/20V)Digikey/Mouser3$0.30$0.90

* Can be sampled for free at low quantities

Power supply assembly

coming soon…

/home/ladyada/public_html/wiki/data/pages/wavebubble/power_supply.txt · Last modified: 2016/01/28 18:05 (external edit)