28119 Parallax Inc, 28119 Datasheet - Page 109

• Manufacturer Part Number: 28119
• Description: KIT UNDERSTANDING SIGNALS
• Manufacturer: Parallax Inc

Specifications of 28119

• Lead Free Status: Contains lead
• Accessory Type: Oscilloscope
• Interface Type: USB
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

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