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LM2904B-Q1: stability with capacitive load

Kavita Rajaram
Prodigy 410 points
Part Number: LM2904B-Q1
Other Parts Discussed in Thread: LM2904B, , ALM2402-Q1, ALM2402F-Q1, ALM2403-Q1

Tool/software:

Hi all,

I've been looking for an opamp to use as a VCOM buffer.

Supply Voltage range:~ +7V/-7V

Output voltage range: -3V to 3V

Stable with capacitive load (~10uF)

Output current ~50mA

AEC-Q100 grade 2

I think the LM2904B matches this, but I'm unsure of the stability.

Can anyone comment on that?

Thanks.

KR

  • 0
    Guru 319180 points

    The LM2904B-Q1 cannot drive 50 mA, and is not stable with capacitive loads.

    Use the ALM2402-Q1 instead, but see section 9.1.1 of its datasheet.

  • 0
    TI__Guru* 77541 points

    Hi KR, 

    LM2904B-Q1's short circuit current is approx. 50mA depending on temperature. The operating current may be able to drive 50-70% of the Isc range depending on the ambient conditions and type of load (see Clemens's comments). For automotive application, Tamb at high side is minimum of 85C. 

    Here is the Isource or sink current vs. temperature. 

    To meet the above driving requirements, you may consider ALM2402-Q1 or ALM2402F-Q1/ ALM2403-Q1 or other automotive grade amplifiers. And it will require some kind of op amp compensation to drive 10uF capacitive load. What is your driving application? What is application's BW requirements?

    If you have other questions, please let me know. 

    Best,

    Raymond