SNOA949 May   2016 LDC1312 , LDC1312-Q1 , LDC1314 , LDC1314-Q1 , LDC1612 , LDC1612-Q1 , LDC1614 , LDC1614-Q1

 

  1.   Power Reduction Techniques for the Multichannel LDCs in Inductive Sensing Applications
    1.     Trademarks
    2. 1 Introduction
    3. 2 Duty Cycling
      1. 2.1 Operational Parameters That Affect Duty Cycling
    4. 3 Clock Gating
    5. 4 Test Setup
    6. 5 Measurement Results
      1. 5.1 Measurements with Internal Clock
      2. 5.2 Current Consumption Measurements vs Data Conversion Time
        1. 5.2.1 Data Readback Overhead
        2. 5.2.2 Comparison of Measured and Estimated Current Consumption
          1. 5.2.2.1 Estimating Current Consumption
        3. 5.2.3 Results
    7. 6 Summary

5.1 Measurements with Internal Clock

The LDC1614 EVM was programmed so that the LDC1614 was forced into the three different power modes: active, sleep, and shutdown. For each state, the current consumption of the device was measured and compared to the expected values given in the data sheet.

Table 2. Current Consumption For Each State: Internal Clock

Measured Current (LDC1614 EVM)
Active Mode (10 MHz) 2.1 mA
Active Mode (43.4 MHz) 3.5 mA
Sleep Mode 35 µA
Shutdown Mode 0.164 µA

These supply current values are taken while using the internal reference clock. When using an external reference clock, it must be gated to achieve the current consumption specifications in the datasheet. If the external clock is not turned off while the LDC is in sleep or shutdown mode, the power consumption in these modes will be significantly higher. The clocking transitions result in an increase of the LDC input pin leakage currents, which is negligible when compared to the normal mode current, but is significant when added onto the lower power mode currents.