0
\$\begingroup\$

I have a circuit with 3 op amps who require dual +- 5 volt supplies. The datasheets mention their supply currents at 19 mA ,19 mA and ~5 mA. I intend to provide the -5 volts from a charge pump IC . Do the supply currents splits in half for the positive and negative supplies ? What output current the charge pump should be able to provide ?

\$\endgroup\$
2
  • 1
    \$\begingroup\$ Supply currents don't split. The positive supply sources 19mA and the negative supply sinks 19mA (the same current. borns from one and returns to another). ICL7660 (or an equivalent IC) can provide ~10mA if it has a large enough capacitor across its output. \$\endgroup\$ Dec 6, 2018 at 8:12
  • 1
    \$\begingroup\$ Do the supply currents splits in half for the positive and negative supplies ? Do you think that an opamp with a 19 mA supply current uses 9.5 mA from the positive supply and 9.5 mA from the negative supply? That is not the case. The opamp doesn't care/know about the symmetric supply. To an opamp +/- 5V is the same as a 10 V supply. It will consume 19 mA and (most of) that current will flow from the pos. supply pin, through the opamp, to the neg. supply pin. \$\endgroup\$ Dec 6, 2018 at 8:15

1 Answer 1

2
\$\begingroup\$

Supply current flows from the positive supply terminal of the Op-Amp to the negative one. +5V must be able to supply ~43mA and -5V must be able to sink ~43mA, given that this is the peak current draw of the Op-Amps and not just the quiescent current.

\$\endgroup\$
1
  • \$\begingroup\$ Thank you for answering,~43mA is the peak supply current , i have two ADA4817-1 op amps and one TL052 op ampa nd i am searching if i can provide the -5 volts from a TPS60400 charge pump IC.Best regards \$\endgroup\$
    – Chris Sy
    Dec 6, 2018 at 12:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.