SBOS196I December 2001 – February 2024 OPA656
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The OPA656 does not require a heat sink or airflow in most applications. The following section describes how the maximum allowed junction temperature sets the maximum allowed internal power dissipation. Do not allow the maximum junction temperature to exceed 150°C.
The operating junction temperature (TJ) is given by TA + PD × RθJA. The total internal power dissipation (PD) is the sum of quiescent power (PDQ), and additional power dissipated in the output stage (PDL) to deliver load power. Quiescent power is the specified no-load supply current times the total supply voltage across the device. The PDL depends on the required output signal and load, but for a grounded resistive load, PDL is at a maximum when the output is fixed at a voltage equal to 1/2 of either supply voltage (for balanced, bipolar supplies). Under this condition, PDL = VS2 / (4 × RL), where RL includes feedback network loading.
Be aware that the power in the output stage, and not into the load, determines internal power dissipation.
As a worst-case example, compute the maximum TJ using an OPA656N (SOT23-5 package) in the circuit of Figure 8-1 operating at the maximum specified ambient temperature of 85°C and driving a grounded 100-Ω load.
All actual applications operate at a lower internal power and junction temperature.