TL331B datasheet(17/27 Pages) TI

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the input voltage range to as high as VCC – 1.5 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:

1. When both IN- and 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

2. When IN- is higher than common mode and IN+ is within common mode, the output is low and the output

transistor is sinking current

3. When IN+ is higher than common mode and IN- is within common mode, the output is high impedance and

the output transistor is not conducting

4. When IN- and IN+ are both higher than common mode, the output is low and the output transistor is sinking

current

8.2.2.2 TL331B-Q1 and TL391B-Q1 ESD Protection

The "B" versions add dedicated ESD protections on all the pins for improved ESD performance as well as

improved negative input voltage handling. Please see Application Note SNOAA35 for more information.

8.2.2.3 Minimum Overdrive Voltage

Overdrive Voltage is the differential voltage produced between the positive and negative inputs of the

comparator over the offset voltage (VIO). In order 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 8-2 and Figure 8-3 show

positive and negative response times with respect to overdrive voltage.

8.2.2.4 Output and Drive Current

Output current is determined by the load/pull-up resistance and logic/pull-up voltage. The output current will

produce a output low voltage (VOL) from the comparator. In which VOL is proportional to the output current. Use

Figure 6-3 to determine VOL based on the output current.

The output current can also effect the transient response. More is explained in the next section.

8.2.2.5 Response Time

Response time is a function of input over drive. See Section 8.2.3 for typical response times. The rise and fall

times can be determined by the load capacitance (CL), load/pullup resistance (RPULLUP), and equivalent

collector-emitter resistance (RCE).

• The rise time (τR) is approximately τR ~ RPULLUP × CL

• The fall time (τF) is approximately τF ~ RCE × CL

– RCE can be determined by taking the slope of Figure 6-3 in its linear region at the desired temperature, or

by dividing the VOL by Iout

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TL331-Q1, TL331B-Q1, TL391B-Q1

SLVS969F – OCTOBER 2009 – REVISED JANUARY 2021

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TL331B Fiches technique(PDF) 17 Page - Texas Instruments