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TLE2022A-Q1 Operational input/output range

na na78
Guru 16770 points
Other Parts Discussed in Thread: TLE2022A-Q1, TLE2022

Hi

We have questions about TLE2022A-Q1.

1. For input range (VICR)
According to the datasheet, common-mode input voltage range can be shown as 0V to 3.2V (at VCC=5V)
or -15V to 13.2V (at VCC=+/-15V).
It means VICR can support (VCC-) + 0V to (VCC+) -1.8V in full temperature range.

What is the cause of 1.8V drop from VCC+?

We think voltage drop of transistors in the device would cause it.
If so, could you help us to indicate which transistors can cause this voltage drop.
(We can refer the equivalent schematic in page 3 datasheet.)

2. For output swing ragge (VOM+, VOM-)
We could not find VOM+/VOM- at VCC=5V.
Can we refer VOH and VOL?

3. For output swing range (VOM+)
If the answer for question 2 is "yes", positive peak output voltage swing can be
shown as 13.8V (min) at VCC=+/-15V or 3.8V(min) at VCC=5V.

It means VOM+(min) is (Vcc+) - 1.2V in full temperature range.
What is the cause of 1.2V drop from VCC+?

Could you indicate which transistors in the deivce can cause it?

BestRegards

  • 0
    TI__Guru* 93105 points

    Hi,

    See my responses along with your questions:

    1. For input range (VICR)
    According to the datasheet, common-mode input voltage range can be shown as 0V to 3.2V (at VCC=5V) or -15V to 13.2V (at VCC=+/-15V). It means VICR can support (VCC-) + 0V to (VCC+) -1.8V in full temperature range.

    What is the cause of 1.8V drop from VCC+?

    The VICR limitation on the positive end is due to the biasing requirements of the PNP transistors active in that portion of the range. For example, from the Equivalent schematic on Pg. 7, the VBE of Q4 (~0.6 V) + the VBE of Q5 (~0.6 V) + VCE(SAT) of Q7 (~0.2 V) which add up to about 1.4 V. In order to keep these devices active the voltage across them needs somewhere between 1 to 1.5 V below the positive supply rail which sets the positive VICR limit.

    2. For output swing ragge (VOM+, VOM-) We could not find VOM+/VOM- at VCC=5V. Can we refer VOH and VOL?

    Yes, use VOH and VOL for VCC = +5 V. Also see Figures 20 and 22.

    3. For output swing range (VOM+) If the answer for question 2 is "yes", positive peak output voltage swing can be shown as 13.8V (min) at VCC=+/-15V or 3.8V(min) at VCC=5V. It means VOM+(min) is (Vcc+) - 1.2V in full temperature range. What is the cause of 1.2V drop from VCC+? Could you indicate which transistors in the deivce can cause it?

    The TLE2022 uses a classical, push-pull emitter-follower output stage. The output swing limits VOM+ and VOM- are limited by VCE(SAT) of the output driver transistor and the VBE of the output transistor. For the positive swing this would be Q35 and Q39, and for the negative swing Q37 and Q40.

    Regards, Thomas

    PA - Linear Applications Engineering

  • 0 in reply to Thomas Kuehl
    Guru 16770 points
    Hi Thomas

    Thank you for your reply.


    >>2. For output swing ragge (VOM+, VOM-) We could not find VOM+/VOM- at VCC=5V. Can we refer VOH and VOL?
    >Yes, use VOH and VOL for VCC = +5 V. Also see Figures 20 and 22.

    Thank you for advice.

    So, we think negative peak output voltage swing might be shown as -13.6V(min) at VCC=+/-15V or 0.95V(max) at VCC=5V.

    It means negative swing is (VCC-) +0.95V at VCC=5V or (VCC-) +1.4V at VCC=+/-15V.
    That is not like positive output side VOM+, because VOM+ dosn't have dependency for VCC as shown in my question 3.

    What is the cause that VOM- has dependence for VCC?

    Best Regards
  • 0 in reply to na na78
    TI__Guru* 93105 points

    Hi na na 78,

    When the TLE2022 is operated with dual supplies such as +/-15 V and the output load is connected to ground, the output has the ability to sink,or source, current through the load. The upper transistor Q39 sources current, and the lower transistor Q40 sinks current depending on the output swing polarity. The +/-15 V supply table provides the VOM+ and VOM- minimum/ typical levels sourcing and sinking the output current through a 10 k load, respectively. 

    When it is operated with a single +5 V supply it is probable that the 10 k load was still connected to ground. There is nothing in the table to indicate that is was connected to another level such as Vcc/2. Therefore, the output will only be able to source current through the load, and that would only be supplied by the upper transistor Q39. 

    With dual +/-15 V supplies the output current through the 10 k load with a -14.1 V swing will be about 1.4 mA. When a single +5 V supply is used and the negative swing is typically about +0.7 V, the current supplied to the 10 k load is  about 70 uA. The difference in swing range is due to the saturation resistance differences between Q39 and Q40 at their respective current levels.

    The +5 V, LOW-LEVEL OUTPUT VOLTAGE vs LOW-LEVEL OUTPUT CURRENT graph shown in Figure 22 must have been developed with the output sinking current to ground. Therefore, the output load would have to have been connected to a more positive voltage level such that Q40 was sinking current. Despite that, the swing to the negative supply rail, 0 volts, is still about +0.8 to +1 V for the current range of 0 to +2.5 mA.

    Regards, Thomas

    PA - Linear Applications Engineering