LM4140_15 Datasheet, PDF (12/23 Pages) Texas Instruments – High Precision Low Noise Low Dropout Voltage Reference

LM4140
SNVS053E – JUNE 2000 – REVISED APRIL 2013
www.ti.com
Figure 27. Typical Thermal Hysteresis
The mechanical stress due to the PCB's mechanical and thermal stress can cause an output voltage shift more
than the true thermal coefficient of the device. References in surface mount packages are more susceptible to
these stresses because of the small amount of plastic molding which support the leads.
Following the recommendations on PCB LAYOUT CONSIDERATION section can minimize the mechanical
stress on the device.
PCB LAYOUT CONSIDERATION
The simplest ways to reduce the stress related shifts are:
1. Mounting the device near the edges or the corners of the board where mechanical stress is at its minimum.
The center of the board generally has the highest mechanical and thermal expansion stress.
2. Mechanical isolation of the device by creating an island by cutting a U shape slot on the PCB for mounting
the device. This approach would also provide some thermal isolation from the rest of the circuit.
Figure 28 is a recommended printed board layout with a slot cut on three sides of the circuit layout to serve as a
strain relief.
12
Submit Documentation Feedback
Product Folder Links: LM4140
Copyright © 2000–2013, Texas Instruments Incorporated