ICS854110AKI REVISION B JANUARY 27, 2011

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©2011 Integrated Device Technology, Inc.

ICS854110I Data Sheet

2.5V DIFFERENTIAL LVDS CLOCK BUFFER

Power Considerations

This section provides information on power dissipation and junction temperature for the ICS854110I.

Equations and example calculations are also provided.

1.

Power Dissipation.

The total power dissipation for the ICS54110I is the sum of the core power plus the power dissipation in the load(s).

The following is the power dissipation for VDD = 2.5V + 5% = 2.625V, which gives worst case results.

Total power dissipation, includes power dissipation on external components.

•

P_core+load = VDD_MAX * IDD_core+load = 2.625V * 86mA = 225.75mW

Where:

IDD_core+load is the total supply current which includes external components

To calculate the power dissipation on the device alone, Pd_total, and use it for junction temperature calculation, subtract the power dissipation

on the external components.

•

Pd_total = P_core+load – (P_load + P_rset)

Where:

P_load is power dissipation on the output loadings

P_rset is power dissipation on the RSET

The load current per output is:

•Iout = (IDD_core+load – IDD_no_load) / N = (86mA – 18mA) / 10 = 6.8mA

Where:

IDD_no_load is IDD current at no load condition

N is number of outputs

Power Dissipation on output loads

•

P_load = (Iout)^2 * R_load * N = (6.8mA)^2 * 100

Ω * 10 = 46.2mW

Power Dissipation on RSET

•

P_rset = (Vrset)^2 / RSET = (1V)^2 / 4kΩ = 0.25mW

(NOTE: P_rset is small and can be negligible)

Total Power Dissipation on the part excluding the power dissipation on the external components.

Pd_total = P_core+load – (P_load + P_rset)

= 225.75mW – (46.2mW + 0.25mW)

= 179.3mW