0

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0

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Time (seconds)

C01

Figure 7-10. Reflow Profile

The reference output voltage is measured before and after the reflow process. Solder shift depends on the

size, thickness, and material of the printed circuit board. An important note is that the Figure 7-11 displays the

typical shift for exposure to a single reflow profile. Exposure to multiple reflows, as is common on PCBs with

surface-mount components on both sides, causes additional shifts in the output voltage. If the PCB is exposed to

multiple reflows, the device must be soldered in the last pass to minimize the exposure to thermal stress.

Figure 7-11. Solder Shift

7.6 Power Dissipation

The REF54 voltage references are capable of source and sink up to 10 mA of load current across the rated input

voltage range. However, when used in applications subject to high ambient temperatures, the input voltage and

load current must be carefully monitored to make sure that the device does not exceed the maximum power

dissipation rating. The maximum power dissipation of the device can be calculated with Equation 3:

J

A

D

JA

T

T

P

R

T

u

(3)

where

• PD is the device power dissipation

• TJ is the device junction temperature

• TA is the ambient temperature

• RθJA is the package (junction-to-air) thermal resistance

Because of this relationship, acceptable load current in high temperature conditions can be less than the

maximum current-sourcing capability of the device. Do not operate the device outside of the maximum power

rating because doing so can result in premature failure or permanent damage to the device.

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REF54

SNVSCN7 – NOVEMBER 2023

Copyright © 2023 Texas Instruments Incorporated

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