SLCS162 June 2017 LM393-MIL
Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.
LM393-MIL will typically be used to compare a single signal to a reference or two signals against each other. Many users take advantage of the open drain output to drive the comparison logic output to a logic voltage level to an MCU or logic device. The wide supply range and high voltage capability makes LM393-MIL optimal for level shifting to a higher or lower voltage.
For this design example, use the parameters listed in Table 1 as the input parameters.
|DESIGN PARAMETER||EXAMPLE VALUE|
|Input Voltage Range||0 V to Vsup-1.5 V|
|Supply Voltage||2 V to 36 V|
|Logic Supply Voltage||2 V to 36 V|
|Output Current (RPULLUP)||1 μA to 20 mA|
|Input Overdrive Voltage||100 mV|
|Reference Voltage||2.5 V|
|Load Capacitance (CL)||15 pF|
When using LM393-MIL in a general comparator application, determine the following:
When choosing the input voltage range, the input common mode voltage range (VICR) must be taken in to account. If temperature operation is above or below 25°C the VICR can range from 0 V to VCC– 2.0 V. This limits the input voltage range to as high as VCC– 2.0 V and as low as 0 V. Operation outside of this range can yield incorrect comparisons.
Below is a list of input voltage situation and their outcomes:
Overdrive Voltage is the differential voltage produced between the positive and negative inputs of the comparator over the offset voltage (VIO). To make an accurate comparison the Overdrive Voltage (VOD) should be higher than the input offset voltage (VIO). Overdrive voltage can also determine the response time of the comparator, with the response time decreasing with increasing overdrive. Figure 8 and Figure 9 show positive and negative response times with respect to overdrive voltage.
Output current is determined by the load/pull-up resistance and logic/pullup voltage. The output current will produce a output low voltage (VOL) from the comparator. In which VOL is proportional to the output current. Use Typical Characteristics to determine VOL based on the output current.
The output current can also effect the transient response. See Response Time for more information.
The transient response can be determined by the load capacitance (CL), load/pullup resistance (RPULLUP) and equivalent collector-emitter resistance (RCE)..
The following curves were generated with 5 V on VCC and VLogic, RPULLUP = 5.1 kΩ, and 50 pF scope probe.