SNAS636C December 2013 – July 2021 LMK00338

PRODUCTION DATA

- 1 Features
- 2 Applications
- 3 Description
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Parameter Measurement Information
- 8 Detailed Description
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support

- RTA|40

- RTA|40

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 V_{CC} core supply current (I_{CC_TOTAL}) can be calculated
using Equation 5:

Equation 5. I_{CC_TOTAL} = I_{CC_CORE} + I_{CC_BANK_A} + I_{CC_BANK_B} + I_{CC_CMOS}

where

- I
_{CC_CORE}is the current for core logic and input blocks and depends on selected input (CLKinX or OSCin). - I
_{CC_BANK_A}is the current for Bank A. - I
_{CC_BANK_B}is the current for Bank B. - I
_{CC_CMOS}is the current for the LVCMOS output (or 0 mA if REFout is disabled).

Because the output supplies (V_{CCOA}, V_{CCOB}, V_{CCOC}) can be powered from 3 independent voltages, the respective output supply currents (I_{CCO_BANK_A}, I_{CCO_BANK_B}, and I_{CCO_CMOS}) should be calculated separately. I_{CCO_BANK} for either Bank A or B can be directly taken from the corresponding output supply current spec (I_{CCO_HCSL}) **provided the output loading matches the specified conditions**. Otherwise, I_{CCO_BANK} should be calculated as follows:

Equation 6. I_{CCO_BANK} = I_{BANK_BIAS} + (N × I_{OUT_LOAD})

where

- I
_{BANK_BIAS}is the output bank bias current (fixed value). - I
_{OUT_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 I_{BANK_BIAS} values and I_{OUT_LOAD} expressions for HCSL.

CURRENT PARAMETER | HCSL |
---|---|

I_{BANK_BIAS} | 4.8 mA |

I_{OUT_LOAD} | V_{OH}/R_{T} |

Once the current consumption is calculated for each supply, the total power dissipation (P_{TOTAL}) can be calculated as:

Equation 7. P_{TOTAL} = (V_{CC} × I_{CC_TOTAL}) + (V_{CCOA} × I_{CCO_BANK_A}) + (V_{CCOB} × I_{CCO_BANK_B}) + (V_{CCOC} × I_{CCO_CMOS})

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

Equation 8. P_{RT_HCSL} (per HCSL pair) = V_{OH}^{2} / R_{T}

Finally, the IC power dissipation (P_{DEVICE}) can be computed by subtracting the external power dissipation values from P_{TOTAL} as follows:

Equation 9. P_{DEVICE} = P_{TOTAL} – N_{} × P_{RT_HCSL}

where

- N
_{2}is the number of HCSL output pairs with termination resistors to GND.