SNVAA70 june   2023 LM5176 , LM5176-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Principle of the TEC
    2. 1.2 Design Specification and Key Challenge
  5. 2Tec Driver Design Using Buck-Boost Controller
    1. 2.1 System Description
    2. 2.2 Block Diagram of TEC Design With LM5176
    3. 2.3 Output Voltage Control of LM5176
  6. 3Test Result
    1. 3.1 TEC Current Versus Output Voltage
    2. 3.2 Current Ripple Measurement Through TEC Element
    3. 3.3 Start-Up
    4. 3.4 Efficiency
  7. 4Summary
  8. 5References

Abstract

Thermoelectric cooler (TEC) is a heating and cooling device based on the Peltier effect. Due to the advantages of no noise, no vibration, no refrigerant, small size, and light weight, TEC is widely used as the precise temperature control system in industrial areas such as optical communication and medical equipment. In medical in-vitro diagnosis (IVD) equipment such blood gas analyzer, Polymerase Chain Reaction (PCR), and Immuno-analyzer, TEC can keep a stable reaction temperature or accomplish rapid temperature changes. In these applications, bidirectional current control is required to support both heating and cooling and more efficient temperature control. This application note introduces a flexible TEC driver strategy for voltage and current control. To realize the bidirectional current, the TEC is connected between the output (Vout) and input (Vin) of a DC/DC controller (such as the LM5176). The Vout changes from (Vin -10 V) to (Vin +10 V) while Vin is fixed and the maximum current can reach up to ±4 A; therefore, the direction of the current can change to support heating or cooling. Since the current is also effected by the temperature difference of the TEC, a current sense amplifier is implemented for precise temperature control.