LM3940ISX
The LM3940ISX is an electronic component from Texas Instruments. View the full LM3940ISX datasheet below including electrical characteristics, absolute maximum ratings.
Manufacturer
Texas Instruments
Overview
Part: LM3940 — Texas Instruments
Type: Low-Dropout (LDO) Regulator
Description: A 1-A low-dropout regulator designed to provide 3.3 V from a 5-V supply, suitable for systems with both 5-V and 3.3-V logic.
Operating Conditions:
- Supply voltage: 4.5–5.5 V
- Operating temperature: -40 to 125 °C
- Output current: 5 mA to 1 A
Absolute Maximum Ratings:
- Max supply voltage: 7.5 V
- Max continuous current: 1.7 A (short-circuit current)
- Max storage temperature: 150 °C
Key Specs:
- Output voltage: 3.13–3.47 V (5 mA ≤ I OUT ≤ 1 A, -40°C ≤ T J ≤ 125°C)
- Line regulation: 20 mV (typ), 40 mV (max) (I OUT = 5 mA, 4.5 V ≤ V IN ≤ 5.5 V)
- Load regulation: 35 mV (typ), 80 mV (max) (50 mA ≤ I OUT ≤ 1 A, -40°C ≤ T J ≤ 125°C)
- Quiescent current: 10 mA (typ), 20 mA (max) (I OUT = 5 mA, -40°C ≤ T J ≤ 125°C)
- Dropout voltage: 0.5 V (typ), 1 V (max) (I OUT = 1 A, -40°C ≤ T J ≤ 125°C)
- Output noise voltage: 150 μV (rms) (typ) (ƒ BW = 10 Hz - 100 kHz, I OUT = 5 mA)
- Short-circuit current: 1.2 A (min), 1.7 A (typ) (R L = 0)
Features:
- 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
Applications:
- Laptop and Desktop Computers
- Logic Systems
Package:
- SOT-223 (4 PINS)
- DDPAK/TO-263 (3 PINS)
- TO-220 (3 PINS)
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
Applications
- Laptop and Desktop Computers
- Logic Systems
1
LM3940
SNVS114G -MAY 1999-REVISED FEBRUARY 2015
Pin Configuration
3-Pin TO-220 Package Front View
3-Pin DDPAK/TO-263 Package Front View
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 | 3.2 | 3.3 | 3.4 | 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 |
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 |
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 |
Thermal Information
| LM3940 | LM3940 | LM3940 | ||
|---|---|---|---|---|
| THERMAL METRIC (1) | SOT-223 (DCY) | TO-263 (KTT) | TO-220 (NDE) | |
| 4 PINS | 3 PINS | 3 PINS | ||
| R θ JA | Junction-to-ambient thermal resistance, High-K | 59.3 | 40.9 | 23.3 |
| R θ JC(top) | Junction-to-case (top) thermal resistance | 38.9 | 43.5 | 16.1 |
| R θ JB | Junction-to-board thermal resistance | 8.1 | 23.5 | 4.8 |
| ψ JT | Junction-to-top characterization parameter | 1.7 | 10.3 | 2.7 |
| ψ JB | Junction-to-board characterization parameter | 8.0 | 22.5 | 4.8 |
| R θ JC(bot) | Junction-to-case (bottom) thermal resistance | n/a | 0.8 | 1.1 |
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.
Related Variants
The following components are covered by the same datasheet.
| Part Number | Manufacturer | Package |
|---|---|---|
| LM3940 | Texas Instruments | — |
| LM3940IMP-3.3/NOPB | Texas Instruments | — |
| LM3940IMPX | Texas Instruments | — |
| LM3940IMPX-3.3/NOPB | Texas Instruments | — |
| LM3940IS | Texas Instruments | — |
| LM3940IS-3.3/NOPB | Texas Instruments | — |
| LM3940ISX-3.3/NOPB | Texas Instruments | — |
| LM3940IT | Texas Instruments | — |
| LM3940IT-3.3/NOPB | Texas Instruments | TO-220-3 |
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