SNOS455H May   2000  – March 2025 LM4050-N , LM4050-N-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Electrical Characteristics: 2V Option
    6. 5.6  Electrical Characteristics: 2.5V Option
    7. 5.7  Electrical Characteristics: 4.1V Option
    8. 5.8  Electrical Characteristics: 5V Option
    9. 5.9  Electrical Characteristics: 8.2V Option
    10. 5.10 Electrical Characteristics: 10V Option
    11. 5.11 Typical Characteristics
      1. 5.11.1 Start-Up Characteristics
  7. 6 Parameter Measurement Information
    1.     20
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Shunt Regulator
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Precision Reference for an Analog-to-Digital Converter
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
      3. 8.2.3 VOUT Bounded Amplifier
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
      4. 8.2.4 VIN Bounded Amplifier
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
      5. 8.2.5 ±4.096 Precision Reference
        1. 8.2.5.1 Design Requirements
        2. 8.2.5.2 Detailed Design Procedure
      6. 8.2.6 ±1mA Precision Current Sources
        1. 8.2.6.1 Design Requirements
        2. 8.2.6.2 Detailed Design Procedure
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Support Resources
    2. 9.2 Trademarks
    3. 9.3 Electrostatic Discharge Caution
    4. 9.4 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.1 Application Information

The LM4050-N is a precision micropower curvature-corrected bandgap shunt voltage reference. For space critical applications, the LM4050-N is available in the sub-miniature SOT-23 surface-mount package. The LM4050-N has been designed for stable operation without the need of an external capacitor connected between the + pin and the − pin. If, however, a bypass capacitor is used, the LM4050-N remains stable. Reducing design effort is the availability of several fixed reverse breakdown voltages: 2.048V, 2.5V, 4.096V, 5V, 8.192V, and 10V. The minimum operating current increases from 60μA for the LM4050-N-2.0 to 100μA for the LM4050-N-10.0. All versions have a maximum operating current of 15mA.

LM4050-Ns in the SOT-23 packages have a parasitic Schottky diode between pin 2 (−) and pin 3 (Die attach interface contact). Therefore, pin 3 of the SOT-23 package must be left floating or connected to pin 2.

The 4.096V version allows single 5V 12-bit ADCs or DACs to operate with an LSB equal to 1mV. For 12-bit ADCs or DACs that operate on supplies of 10V or greater, the 8.192V version gives 2mV per LSB.

The typical thermal hysteresis specification is defined as the change in 25°C voltage measured after thermal cycling. The device is thermal cycled to temperature –40°C and then measured at 25°C. Next the device is thermal cycled to temperature 125°C and again measured at 25°C. The resulting VOUT delta shift between the 25°C measurements is thermal hysteresis. Thermal hysteresis is common in precision references and is induced by thermal-mechanical package stress. Changes in environmental storage temperature, operating temperature and board mounting temperature are all factors that can contribute to thermal hysteresis.

In a conventional shunt regulator application (Figure 8-1) , an external series resistor (RS) is connected between the supply voltage and the LM4050-N. RS determines the current that flows through the load (IL) and the LM4050-N (IQ). Since load current and supply voltage can vary, RS must be small enough to supply at least the maximum IRMIN (spec. table) to the LM4050-N even when the supply voltage is at the minimum and the load current is at the maximum value. When the supply voltage is at the maximum and IL is at the minimum, RS must be large enough so that the current flowing through the LM4050-N is less than 15mA.

RS is determined by the supply voltage, (VS), the load and operating current, (IL and IQ), and the LM4050-N's reverse breakdown voltage, VR.

Equation 1. LM4050-N LM4050-N-Q1