LM3940
Low-Dropout (LDO) RegulatorThe LM3940 is a low-dropout (ldo) regulator from Texas Instruments. View the full LM3940 datasheet below including key specifications, electrical characteristics, absolute maximum ratings.
Official LM3940 datasheet (PDF) — the source this page was extracted from.
Manufacturer
Texas InstrumentsCategory
Linear Regulators (LDO)LM3940 Key Specifications
| Parameter | Value |
|---|---|
| Protection | Over-temperature, short-circuit |
| Output Current | 1 A |
| Output Voltage | 3.3 V |
| Available Packages | SOT-223 (4), DDPAK/TO-263 (3), TO-220 (3) |
| Input Voltage Range | 4.5 V to 5.5 V |
| Operating Temperature Range | -40°C to 125°C |
| External Components Required | One |
LM3940 Overview
Part: LM3940 — Texas Instruments
Type: Low-Dropout Linear Regulator
Description: 1 A low-dropout linear regulator providing a fixed 3.3 V output from a 4.5 V to 5.5 V input supply with typical 500 mV dropout at full load.
Operating Conditions:
- Supply voltage: 4.5 to 5.5 V
- Operating junction temperature: -40 to 125 °C
- Nominal output voltage: 3.3 V
Absolute Maximum Ratings:
- Max supply voltage: 7.5 V
- Max junction/storage temperature: 150 °C (storage temperature)
Key Specs:
- Output voltage: 3.20 to 3.40 V (5 mA ≤ IOUT ≤ 1 A, TJ = 25 °C)
- Output voltage over temperature: 3.13 to 3.47 V (5 mA ≤ IOUT ≤ 1 A, -40 °C ≤ TJ ≤ 125 °C)
- Line regulation: 20 mV typ, 40 mV max (IOUT = 5 mA, 4.5 V ≤ VIN ≤ 5.5 V)
- Load regulation: 35 mV typ, 50 mV max (50 mA ≤ IOUT ≤ 1 A, TJ = 25 °C)
- Dropout voltage: 0.5 V typ, 0.8 V max (IOUT = 1 A, TJ = 25 °C)
- Dropout voltage over temperature: 1 V max (IOUT = 1 A, -40 °C ≤ TJ ≤ 125 °C)
- Quiescent current: 110 mA typ, 200 mA max (VIN = 5 V, IOUT = 1 A, TJ = 25 °C)
- Short-circuit current: 1.2 A min, 1.7 A typ (RL = 0)
Features:
- Input voltage range: 4.5 V to 5.5 V
- Specified 1 A output current
- Output voltage specified over temperature
- Built-in protection against excess temperature
- Short-circuit protected
- Requires only one external output capacitor for operation
Applications:
- Laptop and desktop computers
- Logic systems (5 V to 3.3 V conversion)
Package:
- SOT-223 (4 pins, 6.50 mm × 3.50 mm)
- DDPAK/TO-263 (3 pins, 10.18 mm × 8.41 mm)
- TO-220 (3 pins, 14.986 mm × 10.16 mm)
LM3940 Features
- 1 · Input Voltage Range: 4.5 V to 5.5 V
- Output Voltage Specified over Temperature
- Excellent Load Regulation
- Specified 1-A Output Current
- Requires only One External Component
- Built-in Protection against Excess Temperature
- Short-Circuit Protected
LM3940 Applications
- Laptop and Desktop Computers
- Logic Systems
1
LM3940
SNVS114G -MAY 1999-REVISED FEBRUARY 2015
LM3940 Pin Configuration
3-Pin TO-220 Package Front View
3-Pin DDPAK/TO-263 Package Front View
LM3940 Electrical Characteristics
Over operating free-air temperature range, VIN = 5 V, IOUT = 1 A, COUT = 33 μ F (unless otherwise noted). Limits apply for T J = 25°C, unless otherwise specified in the Test Conditions column. (1)
| PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |
|---|---|---|---|---|---|---|
| V OUT | Output voltage | 5 mA ≤ I OUT ≤ 1 A, T J = 25°C | 3.20 | 3.3 | 3.40 | V |
| V OUT | Output voltage | 5 mA ≤ I OUT ≤ 1 A, -40°C ≤ T J ≤ 125°C | 3.13 | 3.47 | V | |
| ß V OUT ß V IN | Line regulation | I OUT = 5 mA 4.5 V ≤ V IN ≤ 5.5 V | 20 | 40 | mV | |
| ß V OUT ß I OUT | Load regulation | 50 mA ≤ I OUT ≤ 1 A, T J = 25°C | 35 | 50 | mV | |
| ß V OUT ß I OUT | Load regulation | 50 mA ≤ I OUT ≤ 1 A -40°C ≤ T J ≤ 125°C | 35 | 80 | mV | |
| Z OUT | Output impedance | I OUT (DC) = 100 mA I OUT (AC) = 20 mA (rms) ƒ = 120 Hz | 35 | m Ω | ||
| I Q | Quiescent current | 4.5 V ≤ V IN ≤ 5.5 V, I OUT = 5 mA, T J = 25°C | 10 | 15 | mA | |
| I Q | Quiescent current | 4.5 V ≤ V IN ≤ 5.5 V, I OUT = 5 mA -40°C ≤ T J ≤ 125°C | 10 | 20 | mA | |
| I Q | Quiescent current | V IN = 5 V, I OUT = 1 A, T J = 25°C | 110 | 200 | mA | |
| I Q | Quiescent current | V IN = 5 V, I OUT = 1 A -40°C ≤ T J ≤ 125°C | 110 | 250 | mA | |
| e n | Output noise voltage | ƒ BW = 10 Hz - 100 kHz I OUT = 5 mA | 150 | μ V (rms) | ||
| V DO | Dropout voltage (2) | I OUT = 1 A, T J = 25°C | 0.5 | 0.8 | V | |
| V DO | Dropout voltage (2) | I OUT = 1 A -40°C ≤ T J ≤ 125°C | 0.5 | 1 | V | |
| V DO | Dropout voltage (2) | I OUT = 100 mA, T J = 25°C | 110 | 150 | mV | |
| V DO | Dropout voltage (2) | I OUT = 100 mA -40°C ≤ T J ≤ 125°C | 110 | 200 | mV | |
| I OUT(SC) | Short-circuit current | R L = 0 | 1.2 | 1.7 | A |
LM3940 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
| MIN | MAX | UNIT | |
|---|---|---|---|
| Power dissipation (2) | Internally Limited | ||
| Input supply voltage | -0.3 | 7.5 | V |
| Storage temperature, T stg | - 65 | 150 | °C |
LM3940 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
| MIN | MAX | UNIT | |
|---|---|---|---|
| Junction temperature, T J | -40 | 125 | °C |
| Input supply voltage, V IN | 4.5 | 5.5 | V |
LM3940 Thermal Information
| THERMAL METRIC (1) | LM3940 - SOT-223 (DCY) - 4 PINS | LM3940 - TO-263 (KTT) - 3 PINS | LM3940 - TO-220 (NDE) - 3 PINS | UNIT | |
|---|---|---|---|---|---|
| R θ JA | Junction-to-ambient thermal resistance, High-K | 59.3 | 40.9 | 23.3 | °C/W |
| R θ JC(top) | Junction-to-case (top) thermal resistance | 38.9 | 43.5 | 16.1 | °C/W |
| R θ JB | Junction-to-board thermal resistance | 8.1 | 23.5 | 4.8 | °C/W |
| ψ JT | Junction-to-top characterization parameter | 1.7 | 10.3 | 2.7 | °C/W |
| ψ JB | Junction-to-board characterization parameter | 8.0 | 22.5 | 4.8 | °C/W |
| R θ JC(bot) | Junction-to-case (bottom) thermal resistance | n/a | 0.8 | 1.1 | °C/W |
LM3940 Typical Application
The LM3940 is a linear voltage regulator operating from 5 V on the input and regulates voltage to 3.3V with 1-A maximum output current. This device is suited for system which contain both 5-V and 3.3-V logic, with prime power provided from a 5-V bus.
Variants on the same datasheet
These parts have exact links to the same datasheet. They are candidates to compare, not verified drop-in replacements; check package, pinout and electrical limits.
| Part Number | Manufacturer | Package |
|---|---|---|
| LM3940IMP-3.3/NOPB | Texas Instruments | SOT-223-4 |
| LM3940IMPX | Texas Instruments | SOT-223 |
| LM3940IMPX-3.3/NOPB | Texas Instruments | SOT-223-4 |
| LM3940IS | Texas Instruments | DDPAK/TO-263-3 |
| LM3940IS-3.3/NOPB | Texas Instruments | TO-263-3 |
| LM3940ISX | Texas Instruments | DDPAK/TO-263-3 |
| LM3940ISX-3.3/NOPB | Texas Instruments | DDPAK/TO-263-3 |
| LM3940IT | Texas Instruments | TO-220-3 |
| LM3940IT-3.3/NOPB | Texas Instruments | TO-220-3 |
Other Linear Regulators (LDO)
- LP5907MFX-3.3/NOPB – Texas Instruments, Low-Noise, Low-IQ LDO
- AP7343D-30FS4-7B – Diodes Incorporated, 300mA High PSRR Low-Noise LDO
- MC78M12ACDTRKG – onsemi, Positive Voltage Regulator
- LM317 – Texas Instruments, Adjustable Regulator
- ME6211C33M5G-N – Nanjing Micro One, High PSRR Low-Noise CMOS LDO Regulator
- R1191L – Nisshinbo, LDO Regulator
- RT9080-33GJ5 – Richtek USA Inc., Low-Dropout Linear Regulator
- AAT3221IGV-3.3-T1 – Skyworks Solutions, LDO Linear Regulator
All Linear Regulators (LDO) datasheetsAll Texas Instruments datasheets (2,442)
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