+

½ LM2903

Vref

Vin

+

½ LM2903

Vin-

Vin+

LM2903-Q1

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SLCS141E – MAY 2003 – REVISED JULY 2014

9 Application and Implementation

9.1 Application Information

LM2903Q1 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 LM2903Q1 optimal for level

shifting to a higher or lower voltage.

9.2 Typical Application

Figure 5. Single-ended and Differential Comparator Configurations

9.2.1 Design Requirements

For this design example, use the parameters listed in Table 1 as the input parameters.

Table 1. Design 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

1 µA to 20 mA

Input Overdrive Voltage

100 mV

Reference Voltage

2.5 V

15 pF

9.2.2 Detailed Design Procedure

When using LM2903-Q1 in a general comparator application, determine the following:

•

Input Voltage Range

•

Minimum Overdrive Voltage

•

Output & Drive Current

•

Response Time

9.2.2.1 Input Voltage Range

incorrect comparisons.

Below is a list of input voltage situation and their outcomes:

1. When both IN- & IN+ are both within the common mode range:

(a) If IN- is higher than IN+ and the offset voltage, the output is low and the output transistor is sinking

current

(b) If IN- is lower than IN+ and the offset voltage, the output is high impedance and the output transistor is

not conducting

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