LM350 Reference Tables, Pins & Specifications

Pin reference

Signal names, electrical functions and connection guidance

TO-220

Physical pin numbers3 pins

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LM350 pin functions and connections
Signal	Type	Function & connection
ADJUST	Floating reference terminal	The loop regulates OUTPUT approximately 1.25 V above ADJUST. Connection guidance Connect the junction of R1 from OUTPUT and R2 to the return. This is not ground; adjustment-pin current contributes IADJ × R2 to output voltage.
OUTPUT	Regulated output and tab	Supplies the external load and feedback divider. The metal tab is electrically connected to OUTPUT. Connection guidance Connect R1 close to this lead and return R2 near the load return. A grounded heatsink needs appropriate electrical insulation from the live output tab.
INPUT	Unregulated input	Powers the series pass stage. Connection guidance Use +9 V in the example, with a local 0.1 µF bypass to the common return. Keep adequate headroom. The 35 V stress limit is input-to-output differential.

Operating reference

Standard LM350 · not LM350A

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Nominal adjustable output	1.2–33 V	With sufficient input headroom and load
Operating junction temperature	0–125°C	This is junction, not ambient temperature
Reference voltage	1.20 / 1.25 / 1.30 V	Minimum / typical / maximum; stated electrical conditions
Adjustment-pin current	50 µA typical; 100 µA maximum	Flows out of ADJUST
Adjustment current change	0.2 µA typical; 5 µA maximum	10 mA–3 A; 3–35 V differential
Input-to-output absolute maximum	35 V	Differential stress limit, not an unconditional input rating

Electrical reference conditions include 3–35 V differential and specified loads; TO-220 dissipation is limited by the source footnote and thermal design.

Regulation and rejection

Manufacturer test conditions retained

Manufacturer-referenced values7 parameters

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Parameter	Value	Conditions / notes
Line regulation at 25°C	0.005%/V typical; 0.03%/V maximum	3–35 V input-output differential
Line regulation over junction range	0.02%/V typical; 0.07%/V maximum	Standard LM350 limits
Load regulation at 25°C	0.1% typical; 0.5% maximum	10 mA–3 A
Load regulation over junction range	0.3% typical; 1.5% maximum	Pulse-tested at constant junction temperature
Thermal regulation	0.002%/W typical; 0.03%/W maximum	20 ms pulse; 25°C
Ripple rejection without CADJ	65 dB typical	10 V output, 120 Hz, 25°C
Ripple rejection with 10 µF CADJ	66 dB minimum; 86 dB typical	10 V output, 120 Hz; applicable full-range limit

Typical figures do not replace guaranteed limits. The LM350A column has tighter accuracy and is not used here.

Minimum load and current limiting

Cooling and differential voltage matter

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Minimum load requirement	3.5 mA typical; 10 mA maximum	At 35 V differential
Current-limit capability at ≤10 V differential	3 A minimum; 4.5 A typical	Within specified power and junction limits
Current limit at 30 V differential	0.25 A minimum; 1 A typical	Safe-area protection reduces available current
Example divider current	1.25 V / 110 Ω ≈11.36 mA	Nominal OUT-to-ADJ branch
Divider worst-case minimum	1.20 V / 111.1 Ω ≈10.80 mA	110 Ω resistor at +1%; above 10 mA
Too little output load	Output can rise above the set value	Do not rely only on typical minimum current

The 3 A label is not a guarantee at every voltage differential or without a heatsink.

Thermal path and protection

LM350T · TO-220 NDE

Manufacturer-referenced values7 parameters

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Parameter	Value	Conditions / notes
Junction-to-case resistance	3°C/W typical; 4°C/W maximum	Manufacturer NDE package reference
Junction-to-ambient reference	50°C/W	No heatsink; actual mounting and airflow matter
Pass-stage estimate	PD ≈ (VIN − VOUT) × IOUT	Include divider current in output current
Example at 100 mA load	(9 − 5) × (0.100 + 0.01136) ≈0.445 W	Nominal estimate; adjustment current term is small
At 3 A and 4 V drop	Approximately 12 W	Requires a carefully designed thermal path
Built-in protections	Current, thermal and safe-area limiting	Protection is not normal operating regulation
Metal tab	Electrically OUTPUT	Insulate from grounded metal when required

Calculate junction temperature with case/interface/heatsink resistances and the actual ambient.

Bypass and discharge paths

Source application guidance

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Input bypass	0.1 µF ceramic or 1 µF solid tantalum	Close to the regulator and return
Output capacitor	1 µF solid tantalum or 25 µF aluminum	Improves transient response; not an arbitrary ceramic substitution
No output capacitor	The regulator can be stable without one	Certain small capacitances can cause ringing
Adjustment bypass	10 µF improves ripple rejection	Optional; evaluate discharge protection
Output discharge protection	Review for large stored output charge	Source states ≤25 µF output capacitors need no diode in its discussed case
Adjustment discharge protection	Depends on CADJ and output voltage	Follow source Figure 17 for larger capacitance / voltage cases

The example uses 0.1 µF input and 1 µF tantalum output, with no ADJ bypass. Review protection if external supplies or stored charge can drive the output.

Nominal 9 V-to-5 V supply

110 Ω / 330 Ω divider · 50 Ω load

Manufacturer-referenced values7 parameters

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Parameter	Value	Conditions / notes
R1; OUT2 to ADJ1	110 Ω, 1%	Dissipates about 14.2 mW at nominal reference
R2; ADJ1 to GND	330 Ω, 1%	Nominal ratio R2/R1 = 3
Ideal output	1.25 × (1 + 330/110) = 5.00 V	Before IADJ and tolerances
Including typical adjustment current	5.0165 V	Adds 50 µA × 330 Ω
Load resistor	50 Ω, at least 1 W	Nominal 100 mA and 0.5 W
Nominal total output current	111.36 mA	Load plus divider; small IADJ contribution omitted
Return connections	Input return, R2, load and capacitor returns	Same GND net; ADJ is not GND

Use adequate resistor/capacitor ratings and verify the actual loaded voltage.

Package and limits

LM350T/NOPB · TO-220

Manufacturer-referenced values6 parameters

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Parameter	Value	Conditions / notes
Front-view leads	1 ADJUST; 2 OUTPUT; 3 INPUT	Marking toward you, leads down
Lead pitch	2.54 mm	Vertical three-lead footprint
Tab connection	OUTPUT	Not ground
Selected package	TO-220 NDE	Original TEP geometry and starting footprint
Other source package	TO-3 is described in the manufacturer sheet	Different physical terminal arrangement; not interchangeable footprint
Storage temperature	−65 to +150°C	Unpowered storage

This page publishes the verified TO-220 variant; no unsupported SMD substitute is implied.