• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 30 subscribers
  • Views 474 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SA5534A: Can SA5532 be used for PCM1795 as I/V conversion

Koyo Asaishi
Intellectual 1810 points
Part Number: SA5534A
Other Parts Discussed in Thread: PCM1795, SA5534, SA5532A, NE5534, , NE5532

Hi team,

Customer want to use SA5534 or SA5532A as I/V conversion for PCM1795.
PCM1795 recommend NE5534 but they choose SA5534 because wider temperature range is necessary.

Could you comment we can use SA5532A (2ch) instead of SA5534A (1ch)?
SA5532A can achieve smaller PCB area and lower price so I would use this device if possible.

About NE5532, Icc is 8mA (typ) when Vo=0, no load.
Is NE5532 able to output 8mA each channel or both channel?

Best regards,
Koyo 

  • 0
    TI__Guru*** 146106 points

    Hello Koyo-san,

    SA553x can be used in place of NE553x. The dual 5532 is similar to single 5534 so that switch is usually fine.

    Output current and quiescent (ICC) current are two different things. Output current is based of the output drive strength and current limiting. Quiescent (ICC) current always flows from VCC+ to VCC- and is used by the op amp to perform its function.

    NE5532 output current is limited by the 15 ohms resistors in 8.2 Functional Block Diagram. Estimate roughly 0.4V/15 ohms at higher temperature is 26 mA

    The NE5532 Electrical Characteristics tables support a 600 ohm load terminated to effective ground, (VCC+ - VCC-) / 2 

  • 0 in reply to Ron Michallick
    TI__Intellectual 1810 points

    Hi Ronald,

    Thanks for the quick reply.

    My question was wrong about Icc.

    What customer wanted to ask is short circuit current, Ios.
    The Ios current, 38mA(typ), shows each channel spec or both channel spec? 

    I have another question.

    They will use following structure for I/V conversion.
    Rf 700ohm is fixed value, is there possibility to be oscillated when the range of capacitance is 100 to 1000pF?
    They need 100kHz low pass filter.

    Best regards,
    Koyo

  • 0 in reply to Koyo Asaishi
    TI__Guru*** 146106 points

    Koyo,

    700 ohms is rather low. Is the desired VOUT = IIN * -700?

    100pF should be fine. For higher capacitance, consider the input source impedance. If CF and input source is high capacitance then stability may be affected.

    The IOS current is per channel. Be sure to read all of section 7.1 in the data sheet. There is no over temperature protection in the op amp so avoid short circuits if possible.

      

  • 0 in reply to Ron Michallick
    TI__Intellectual 1810 points

    Hi Michallick,

    The output of PCM1795 is 4mApp and their desired swing voltage is 2.8V.
    This is because they choose 700ohm.

    Why do you think 700ohm is rather low?
    For stability?

    Best regards,
    Koyo

  • 0 in reply to Koyo Asaishi
    TI__Guru*** 146106 points

    Koyo,

    Most I to V convertors I have seen have very small input currents. For a (large) 4mA current and 2.8V output range, 700 ohms is perfect.