LDO selection in four numbers
A low-dropout linear regulator is chosen on four parameters: dropout voltage (how low Vin can fall before regulation is lost), quiescent current Iq (drain on the battery when the load is idle), PSRR (how well it rejects input ripple) and output noise. Everything else — package, thermal, enable pin, fixed vs adjustable — follows from those.
In-stock LDO shortlist
| Part we stock | Vout | Package | Typical use |
|---|---|---|---|
| ams1117-3-3 | 3.3 V | SOT-223 | General 3.3 V rail |
| ams1117-5-0 | 5.0 V | SOT-223 | General 5 V rail |
| lm1117mpx-3-3 | 3.3 V | SOT-223 | MCU / logic rail |
| lm1117mpx-5-0 | 5.0 V | SOT-223 | Sensor / analog rail |
| ht7333-a | 3.3 V | SOT-89 | Low-Iq battery designs |
| xc6206p332mr | 3.3 V | SOT-23 | Space-constrained |
| me6211c33m5g | 3.3 V | SOT-23-5 | Low dropout, low noise |
| mcp1700t-3302e-tt | 3.3 V | SOT-23 | Ultra-low Iq |
| rt9193-33gb | 3.3 V | SOT-23-5 | RF / analog, low noise |
| lm78l05acz | 5.0 V | TO-92 | Legacy through-hole |
| l7805cv | 5.0 V | TO-220 | Higher current 5 V |
| lm317t | Adjustable | TO-220 | Bench / variable rails |
Buck or LDO? A quick rule
Use an LDO when the input-to-output gap is small (roughly <1.5 V) or when you need a quiet rail. When the gap is large and the current is high, the LDO burns the difference as heat — switch to a buck converter. Many designs pair the two: a buck drops 12 V to 5 V, then an LDO cleans 5 V to 3.3 V for the analog section.
Sourcing notes
Fixed 3.3 V SOT-23 LDOs are the most price-sensitive and most counterfeited line, so buy from a source that exposes date code and allows small-quantity sampling. All parts above are in stock with traceable date codes; see the full power management category.
Frequently asked questions
What dropout voltage should I target?
As a rule of thumb keep at least 0.3 V of headroom at your maximum load current. Low-dropout parts such as the ME6211 and MCP1700 hold regulation with under 0.2 V at light loads.
Which LDO is best for battery-powered IoT?
Prioritise quiescent current: parts in the MCP1700 / HT7333 class draw only a few microamps, which preserves runtime between radio bursts.
Can you quote LDOs in reels?
Yes — submit quantities via our BOM upload and we will quote reels or cut tape.
Recommended next steps
If you are sourcing any of the parts mentioned in this guide, we can help you confirm stock, pricing, and lead times quickly.
- Upload your BOM — send your full parts list and receive a consolidated quote within 2 business hours.
- Browse related in-stock lines: Power Management ICs.
- Contact our team for hard-to-find or end-of-life components.
JTDZ Tech is an independent distributor of electronic components. Brand and part numbers are used for identification and cross-reference only; all trademarks belong to their respective owners. Always verify pinout, electrical limits and qualification status against the original device before substituting.
