BETAFixed output3.3 V · C grade, ±1% at 25°C
100 mA low-dropout fixed regulator
LP2950-3.3 Specifications
Review LP2950-3.3 electrical specifications, operating conditions and package details.
Package view
Key specifications
An internal reference and feedback divider control a series-pass stage. Output capacitance, headroom and ground current remain part of the design.
Output class100 mA · thermally limited
Light-load ground current75 µA typical at 100 µA load
Junction range−40–125 °C recommended
Package details
LP2950CZ-3.3/NOPB · TO-92
| Property | Details |
|---|---|
| Manufacturer | Texas Instruments |
| Part number | LP2950CZ-3.3/NOPB |
| Package | TO-92 |
| Connections | 3 pins |
| Mounting | Through-hole |
| Lead pitch | 1.27 mm · straight leads |
| Package code | LP |
| Thermal reference | θJA 157.4°C/W under TI board conditions; actual mounting changes temperature rise |
Device and package identity
C-grade fixed 3.3 V parts
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Through-hole order | LP2950CZ-3.3/NOPB | TO-92 LP; straight-lead bulk footprint |
| SMD order | LP2950CDT-3.3/NOPB | TO-252 NDP; formed outer leads and grounded tab |
| TO-92 physical pins | OUT1 · GND2 · IN3 | Flat face toward viewer, leads down |
| TO-252 physical pins | IN1 · GND2 · OUT3 | Front face, leads down; tab is GND |
| Accuracy grade | C: ±1% initial | AC-grade values are not substituted |
| Extra controls | No shutdown or error-output lead | These belong to the related LP2951 |
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Verify order suffix and lead form before fabrication.
Operating ranges and stress limits
Temperature and headroom remain essential
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Nominal output | 3.3 V | Fixed internally; no external divider |
| Recommended input range | 2.3–30 V family range | 3.3 V regulation additionally needs dropout headroom |
| Maximum input stress | 30 V | Do not design at the stress limit |
| Output-current class | 100 mA | Adequate voltage headroom and cooling required |
| Junction operating temperature | −40–125°C | Device junction, not ambient |
| Minimum external load | Not required for LP2950 regulation | Capacitor stability requirements still apply |
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A 2.3 V input cannot produce a regulated 3.3 V output.
C-grade output accuracy
3.3 V option; source conditions retained
Manufacturer specifications 7 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Output at 25°C | 3.267–3.333 V | Nominal 3.3 V |
| Output at −25 to 85°C | 3.251–3.350 V | Manufacturer specified range |
| Output over full temperature | 3.234–3.366 V | −40 to 125°C |
| Across 100 µA–100 mA load | 3.221–3.379 V | Full-temperature limit |
| Temperature coefficient | 50 ppm/°C typical; 150 max. | Output-voltage drift |
| Line regulation at 25°C | 0.04% typical; 0.2% max. | Input from VOUT(nom)+1 V to 30 V |
| Load regulation at 25°C | 0.1% typical; 0.2% max. | Load from 100 µA to 100 mA |
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AC-grade limits are tighter; this page deliberately uses the selected C-grade specification.
Dropout and ground current
Load and temperature change both
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Dropout at 100 µA load, 25°C | 50 mV typical; 80 mV max. | 150 mV maximum over full temperature |
| Dropout at 100 mA load, 25°C | 380 mV typical; 450 mV max. | 600 mV maximum over full temperature |
| Ground current at 100 µA load | 75 µA typical; 120 µA max. at 25°C | 140 µA maximum over full temperature |
| Ground current at 100 mA load | 8 mA typical; 12 mA max. at 25°C | 14 mA maximum over full temperature |
| Short-circuit current | 160 mA typical; 200 mA max. at 25°C | 220 mA maximum over full temperature; not a load rating |
| Full-load example headroom | At least 0.6 V for the full-temperature dropout limit | Allow additional tolerance and ripple margin |
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Dropout is measured when output falls 100 mV below its nominal operating value.
Capacitors and stability
Capacitance alone is not enough
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| 3.3 V minimum output capacitor | 2.2 µF | Observe the stability-versus-ESR curves |
| Illustrated output capacitor | 10 µF tantalum, ≥10 V | Choose ESR in the recommended stable region across temperature |
| ESR guidance for 2.2 µF | Approximately 0.05–5 Ω | TI application guidance; larger capacitors have their own curves |
| Ceramic output capacitor | May need 0.1–2 Ω series resistance | Use X5R/X7R and check effective capacitance after DC bias |
| Local input bypass | 1 µF | Particularly for batteries or long supply wiring |
| Example COUT polarity | Positive to OUT; negative to GND | Check voltage rating and startup behavior |
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10 µF helps mitigate some startup/short-recovery overshoot. It is not a guarantee for arbitrary source impedance or capacitor ESR.
Thermal design and losses
Manufacturer thermal-board conditions
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| TO-92 θJA | 157.4°C/W | TI reference board; actual assembly varies |
| TO-252 θJA | 51.3°C/W | High-K board with 12 thermal vias |
| TO-252 θJC(bottom) | 2.2°C/W | Grounded exposed tab |
| Total regulator dissipation | (VIN−VOUT)×ILOAD + VIN×IGND | Ground current cannot always be ignored |
| Example 10 mA pass loss | (5−3.3)×0.010 = 17 mW | Add 5×IGND at the actual load |
| Illustrative full-load total | 170 mW + 40 mW = 210 mW | 5 V input, 100 mA load, typical 8 mA ground current |
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Thermal resistance is not an intrinsic promise of available output current.
5 V to 3.3 V working example
A modest test load with clear returns
Manufacturer specifications 6 parameters
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| Parameter | Value | Conditions / notes |
|---|---|---|
| Supply / input bypass | 5 V / 1 µF | Common GND return |
| Nominal output | 3.3 V | Actual output follows the C-grade limits |
| Test load | 330 Ω, ≥0.25 W | 3.3/330 = 10 mA |
| Load dissipation | 3.3²/330 = 33 mW | Nominal calculation |
| Output capacitor | 10 µF, ≥10 V, ESR verified | Local placement between OUT and GND |
| Pass-stage loss | 17 mW | Does not include load-dependent ground current |
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Calculated illustration; not measured waveforms or an executable simulation.
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