SNVS429C October   2006  – December 2016 LM3405

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Boost Function
      2. 7.3.2 Setting the LED Current
      3. 7.3.3 Output Voltage
      4. 7.3.4 Enable Mode or Shutdown Mode
      5. 7.3.5 LED PWM Dimming
      6. 7.3.6 Undervoltage Lockout
      7. 7.3.7 Current Limit
      8. 7.3.8 Overcurrent Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Thermal Shutdown
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Inductor (L1)
      2. 8.1.2 Input Capacitor (C1)
      3. 8.1.3 Output Capacitor (C2)
      4. 8.1.4 Feed-Forward Capacitor (C4)
      5. 8.1.5 Catch Diode (D1)
      6. 8.1.6 Boost Diode (D2)
      7. 8.1.7 Boost Capacitor (C3)
      8. 8.1.8 Power Loss Estimation
    2. 8.2 Typical Applications
      1. 8.2.1 VBOOST Derived from VIN (VIN = 5 V, IF = 1 A)
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Calculate Duty Cycle (D)
          2. 8.2.1.2.2 Choose Capacitor Values (C1, C2, C3, and C4)
          3. 8.2.1.2.3 Set the Nominal LED Current (R1)
          4. 8.2.1.2.4 Choose Diodes (D1 and D2)
          5. 8.2.1.2.5 Calculate the Inductor Value (L1)
        3. 8.2.1.3 Application Curve
    3. 8.3 System Examples
      1. 8.3.1 VBOOST Derived From VOUT (VIN = 12 V, IF = 1 A)
        1. 8.3.1.1 Bill of Materials
      2. 8.3.2 VBOOST Derived From VIN Through a Series Zener Diode, D3 (VIN = 15 V, IF = 1 A)
        1. 8.3.2.1 Bill of Materials
      3. 8.3.3 VBOOST Derived From VIN Through a Shunt Zener Diode, D3 (VIN = 15 V, IF = 1 A)
        1. 8.3.3.1 Bill of Materials
      4. 8.3.4 VBOOST Derived from VOUT Through a Series Zener Diode, D3 (VIN = 15 V, IF = 1 A)
        1. 8.3.4.1 Bill of Materials
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resource
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)
MIN MAX UNIT
Input voltage, VIN –0.5 20 V
SW voltage –0.5 20 V
Boost voltage –0.5 26 V
Boost to SW voltage –0.5 6 V
FB voltage –0.5 3 V
EN/DIM voltage –0.5 (VIN + 0.3) V
Junction temperature, TJ 150 °C
Storage temperature, Tstg –65 150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

6.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±1000
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

MIN MAX UNIT
Input voltage, VIN 3 15 V
EN/DIM voltage 0 (VIN + 0.3) V
Boost to SW voltage 2.5 5.5 V
Junction temperature, TJ –40 125 °C

6.4 Thermal Information

THERMAL METRIC(1) LM3405 UNIT
DDC
(SOT)
6 PINS
RθJA Junction-to-ambient thermal resistance 182.9 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 53.4 °C/W
RθJB Junction-to-board thermal resistance 28.1 °C/W
ψJT Junction-to-top characterization parameter 1.2 °C/W
ψJB Junction-to-board characterization parameter 27.7 °C/W
RθJC(bot) Junction-to-case (bottom) thermal resistance — °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.

6.5 Electrical Characteristics

VIN = 12 V, typical values are for TJ = 25°C only; minimum and maximum limits apply over the junction temperature (TJ) range of –40°C to 125°C (unless otherwise noted). Typical values represent the most likely parametric norm, and are provided for reference purposes only.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VFB Feedback voltage 0.188 0.205 0.22 V
ΔVFB/(ΔVIN×VFB) Feedback voltage line regulation VIN = 3 V to 15 V 0.01% V
IFB Feedback input bias current Sink or source 10 250 nA
UVLO Undervoltage lockout VIN rising 2.74 2.95 V
VIN falling 1.9 2.3
UVLO hysteresis 0.44 V
fSW Switching frequency 1.2 1.6 1.9 MHz
DMAX Maximum duty cycle VFB = 0 V 85% 94%
RDS(ON) Switch ON resistance VBOOST – VSW = 3 V 300 600 mΩ
ICL Switch current limit VBOOST – VSW = 3 V, VIN = 3 V 1.2 2 2.8 A
IQ Quiescent current Switching, VFB = 0.195 V 1.8 2.8 mA
Quiescent current (shutdown) VEN/DIM = 0 V 0.3 µA
VEN/DIM_TH Enable threshold voltage VEN/DIM rising 1.8 V
Shutdown threshold voltage VEN/DIM falling 0.4 V
IEN/DIM EN/DIM pin current Sink or source 0.01 µA
ISW Switch leakage VIN = 15 V 0.1 µA

6.6 Typical Characteristics

VIN = 12 V, VBOOST – VSW = 5 V, and TA = 25°C (unless otherwise noted).
LM3405 20178973.png
Figure 1. Efficiency vs LED Current
LM3405 20178932.png
IF = 0.7 A
Figure 3. Efficiency vs Input Voltage
LM3405 20178927.png
Figure 5. VFB vs Temperature
LM3405 20178972.png
Figure 7. Current Limit vs Temperature
LM3405 20178934.png
Figure 9. Quiescent Current vs Temperature
LM3405 20178931.png
IF = 1 A
Figure 2. Efficiency vs Input Voltage
LM3405 20178933.png
IF = 0.35 A
Figure 4. Efficiency vs Input Voltage
LM3405 20178936.png
Figure 6. Oscillator Frequency vs Temperature
LM3405 20178930.png
VBOOST – VSW = 3 V
Figure 8. SOT RDS(ON) vs Temperature
LM3405 20178968.png
VIN = 15 V IF = 0.2 A
Figure 10. Start-Up Response to EN/DIM Signal