SBOS392H August   2007  – August 2019 REF3312 , REF3318 , REF3320 , REF3325 , REF3330 , REF3333

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      REF3312 in a Single-Supply Signal Chain
      2.      Dropout Voltage vs Load Current
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and Functions
    1. Table 1. Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Thermal Hysteresis
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Start-Up Time
      2. 9.3.2 Low Temperature Drift
      3. 9.3.3 Power Dissipation
      4. 9.3.4 Noise Performance
    4. 9.4 Device Functional Modes
  10. 10Applications and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Applications
      1. 10.2.1 REF3312 in a Bipolar Signal-Chain Configuration
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
          1. 10.2.1.2.1 Op Amp Level-Shift Design
          2. 10.2.1.2.2 Differential Input Attenuator Design
          3. 10.2.1.2.3 Input Filtering
          4. 10.2.1.2.4 Component Selection
            1. 10.2.1.2.4.1 Voltage References
            2. 10.2.1.2.4.2 Op Amp
          5. 10.2.1.2.5 Input Attenuation and Level Shifting
          6. 10.2.1.2.6 Input Filtering
          7. 10.2.1.2.7 Passive Component Tolerances and Materials
        3. 10.2.1.3 Application Curves
          1. 10.2.1.3.1 DC Performance
          2. 10.2.1.3.2 AC Performance
  11. 11Power-Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Related Links
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Community Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

10.2.1.2.4.1 Voltage References

The REF33xx series of precision low-power voltage references pair well with the low power consumption of the MSP430, while achieving the target accuracy goals. The 16-bit converter in the MSP430F2013 accepts an external reference voltage from 1 V to 1.5 V with a typical reference input of 1.25 V, as shown in Table 2.

Table 2. SD16_A, External Reference Input (MSP430F20x3)(1)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VREF(I) Input voltage range VCC = 3 V, SD16REFON = 0 1 1.25 1.5 V
IREF(I) Input current VCC = 3 V, SD16REFON = 0 50 nA
(1) Over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted).

The REF3312 provides the desired 1.25-V reference voltage for the MSP430 ADC. The accuracy of the REF3312 output, shown in the Electrical Characteristics, directly affects the accuracy of the entire system and must be less than the desired unadjusted error goals. The REF3312 maximum ±0.15% initial accuracy specification is equal to the unadjusted error design goal of 0.15%, indicating that most of the error budget in this design must be devoted to the reference accuracy.

The 3.3-V system supply voltage that powers the MSP430 can also supply other devices, and therefore may have regulation and noise issues. The REF3330 creates an accurate and stable 3.0 V output used by the op amp, REF3312, and other low-power analog circuitry. The REF33xx series has a drop-output voltage of VOUT + 200 mV; therefore, as long as the input supply remains above 3.2 V, the REF3330 produces a regulated 3.0 V output. The output current for the REF33xx series is specified at ±5 mA, as shown in Figure 9, and is sufficient for the REF3312 and a low-power op amp.