SNAS636C December   2013  – July 2021 LMK00338

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 Parameter Measurement Information
    1. 7.1 Differential Voltage Measurement Terminology
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Crystal Power Dissipation vs. RLIM
      2. 8.3.2 Clock Inputs
      3. 8.3.3 Clock Outputs
        1. 8.3.3.1 Reference Output
    4. 8.4 Device Functional Modes
      1. 8.4.1 VCC and VCCO Power Supplies
  9. 9 Power Supply Recommendations
    1. 9.1 Current Consumption and Power Dissipation Calculations
      1. 9.1.1 Power Dissipation Example: Worst-Case Dissipation
    2. 9.2 Power Supply Bypassing
      1. 9.2.1 Power Supply Ripple Rejection
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Management
  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 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary

Package Options

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

9.1 Current Consumption and Power Dissipation Calculations

The current consumption values specified in the Electrical Characteristics table can be used to calculate the total power dissipation and IC power dissipation for any device configuration. The total VCC core supply current (ICC_TOTAL) can be calculated using Equation 5:

Equation 5. ICC_TOTAL = ICC_CORE + ICC_BANK_A + ICC_BANK_B + ICC_CMOS

where

  • ICC_CORE is the current for core logic and input blocks and depends on selected input (CLKinX or OSCin).
  • ICC_BANK_A is the current for Bank A.
  • ICC_BANK_B is the current for Bank B.
  • ICC_CMOS is the current for the LVCMOS output (or 0 mA if REFout is disabled).

Because the output supplies (VCCOA, VCCOB, VCCOC) can be powered from 3 independent voltages, the respective output supply currents (ICCO_BANK_A, ICCO_BANK_B, and ICCO_CMOS) should be calculated separately. ICCO_BANK for either Bank A or B can be directly taken from the corresponding output supply current spec (ICCO_HCSL) provided the output loading matches the specified conditions. Otherwise, ICCO_BANK should be calculated as follows:

Equation 6. ICCO_BANK = IBANK_BIAS + (N × IOUT_LOAD)

where

  • IBANK_BIAS is the output bank bias current (fixed value).
  • IOUT_LOAD is the DC load current per loaded output pair.
  • N is the number of loaded output pairs per bank (N = 0 to 4).

Table 9-1 shows the typical IBANK_BIAS values and IOUT_LOAD expressions for HCSL.

Table 9-1 Typical Output Bank Bias and Load Currents
CURRENT PARAMETERHCSL
IBANK_BIAS4.8 mA
IOUT_LOADVOH/RT

Once the current consumption is calculated for each supply, the total power dissipation (PTOTAL) can be calculated as:

Equation 7. PTOTAL = (VCC × ICC_TOTAL) + (VCCOA × ICCO_BANK_A) + (VCCOB × ICCO_BANK_B) + (VCCOC × ICCO_CMOS)

If the device configuration is configured with HCSL outputs, then it is also necessary to calculate the power dissipated in any termination resistors (PRT_HCSL). The external power dissipation values can be calculated as follows:

Equation 8. PRT_HCSL (per HCSL pair) = VOH2 / RT

Finally, the IC power dissipation (PDEVICE) can be computed by subtracting the external power dissipation values from PTOTAL as follows:

Equation 9. PDEVICE = PTOTAL – N × PRT_HCSL

where

  • N2 is the number of HCSL output pairs with termination resistors to GND.