70009 Parallax Inc, 70009 Datasheet - Page 109

• Manufacturer Part Number: 70009
• Description: BOOK UNDERSTANDING SIGNALS
• Manufacturer: Parallax Inc
• Type: Signal Analysisr

Specifications of 70009

• Style: Book
• Title: Understanding Signals
• Contents: Guide to Generate, View and Measure Wave Forms
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Other names: 70009PAR

Slew Rate
The slew rate refers to how fast the op-amp can change its output voltage. The LM358
has a slew rate of 300 mV per microsecond. For every microsecond, the output can
change as much as 300 mV. Bandwidth refers to the speed of the signal a device can
process, so an op-amp is said to have high bandwidth if it has a high slew rate.
When the slew rate is too slow for the input signal, the op-amp will output a triangle
wave (Figure 8-3). Notice the square wave on the input and the distorted triangle wave on
the output. The op-amp cannot change its output as fast as the input signal. When the
input suddenly changes from low to high, the op-amp can’t keep up. As you can see this
is a function of voltage and time. The larger the output voltage swing, the lower the
bandwidth of the op-amp.
Op-amps can be used for a wide variety of applications. This chapter introduces the two
most popular uses:
•
•
Op-amps used as buffers
Op-amps used as voltage amplifiers
OPAMP OUTPUT
INPUT
Figure 8-3:
Example of op-
amp output with a
slow slew rate