LDO Selection
- Kiran Surendran
Some useful references
https://www.taiwansemi.com/assets/uploads/productcategoryfile/AN-1001_A1611.pdf
https://www.allaboutcircuits.com/technical-articles/understanding-noise-and-psrr-in-ldos/
https://www.design-reuse.com/articles/45596/guide-to-choosing-the-best-ldo-for-your-application.html
Requirements for LDO
Must be able to manage an input Voltage = 5V
Output Voltage = 3.3V
Must have a low quiescent current (below at least 250µA at full load)
Must have a low dropout voltage (below at least 500mV at 1A)
Must have a PSRR below 75dB at 120Hz
Preferrably a fixed output regulator
Less components and routing
Must have maximum current output of at least 1A
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Candidates
MPN | Manufacturer | Accuracy (room temp) | Voltage Dropout | Max Current Output | Quiescent Current | PSRR | Additional Notes | Unit Price | Datasheet | Stock (as of Oct 06, 2021) |
|---|---|---|---|---|---|---|---|---|---|---|
ADP3339AKCZ-3.3-R7 | Analog Devices Inc. | 0.9% | 0.23V @ 1.5A | 1.5A | 200µA | 78dB @ 120Hz |  | $6.51 | https://www.analog.com/media/en/technical-documentation/data-sheets/ADP3339.pdf | 6,430 |
TPS76833QDR | Texas Instruments | 2% | 0.35V @ 1A | 1A | 125 µA | 72dB @ 120Hz |  | $5.28 | 5,341 | |
LP38690DT-3.3/NOPB | Texas Instruments | 2.5% | 0.45V @ 1A | 1A | 55µA | 55dB @ 120Hz |  | $3.49 | 5,419 | |
LP38692SD-3.3/NOPB | Texas Instruments | 2.5% | 1V @ 1A | 1A | 55µA | 55dB @ 120Hz |  | $2.58 | 15,268 | |
TPS78533QKVURQ1 | Texas Instruments | 0.5% | 0.425 @ 1A | 1A | 25µA | 70dB @ 120Hz | Internal soft start | $2.73 | 1,751 | |
LP3962EMP-3.3/NOPB | Texas Instruments | 1.5% | 0.380V @ 1.5A | 1.5A | 15µA | 60dB @ 120Hz |  | $4.66 | 1,522 |
We will choose the LP38690DT-3.3/NOPB
Superior Quiescent Current
Superior transients
Excellent Voltage Dropout
Great PSRR
Good price per unit
Good stock
Ease to hand solder https://blog.mbedded.ninja/pcb-design/component-packages/sot-223-component-package/
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