LM6132

www.ti.com

SNOS751D – APRIL 2000 – REVISED FEBRUARY 2013

LM6132/34 APPLICATION INFORMATION

The LM6132 brings a new level of ease of use to op amp system design.

With greater than rail-to-rail input voltage range concern over exceeding the common-mode voltage range is

eliminated.

Rail-to-rail output swing provides the maximum possible dynamic range at the output. This is particularly

important when operating on low supply voltages.

The high gain-bandwidth with low supply current opens new battery powered applications, where high power

consumption, previously reduced battery life to unacceptable levels.

To take advantage of these features, some ideas should be kept in mind.

ENHANCED SLEW RATE

Unlike most bipolar op amps, the unique phase reversal prevention/speed-up circuit in the input stage eliminates

phase reversal and allows the slew rate to be very much a function of the input signal amplitude.

Figure 32 shows how excess input signal is routed around the input collector-base junctions directly to the

current mirrors.

The LM6132/34 input stage converts the input voltage change to a current change. This current change drives

the current mirrors through the collectors of Q1–Q2, Q3–Q4 when the input levels are normal.

If the input signal exceeds the slew rate of the input stage and the differential input voltage rises above a diode

drop, the excess signal bypasses the normal input transistors, (Q1–Q4), and is routed in correct phase through

the two additional transistors, (Q5, Q6), directly into the current mirrors.

This rerouting of excess signal allows the slew-rate to increase by a factor of 10 to 1 or more. (See Figure 31).

As the overdrive increases, the op amp reacts better than a conventional op amp. Large fast pulses will raise the

slew- rate to around 25V to 30 V/

μs.

Figure 31.

This effect is most noticeable at higher supply voltages and lower gains where incoming signals are likely to be

large.

This speed-up action adds stability to the system when driving large capacitive loads.

Copyright © 2000–2013, Texas Instruments Incorporated

Submit Documentation Feedback

11

Product Folder Links: LM6132