Tl494

Discussion in 'The Projects Forum' started by HelderCC, Feb 13, 2014.

  1. HelderCC

    Thread Starter New Member

    Feb 12, 2014
    3
    0
    Hi guys,

    I'm making an inverter. To gen the PWM pulses to Mosfet drivers i'm using a TL494.

    The IC is generating a internal sawtoth wave @40khz.
    I'm using "Error Amplifier 1" as an Input(sine wave) with unitary gain. And don't using "Error Amplifier 2".
    I grounded the Output Ctrl so there is no flip flop.
    I hope that circuit makes an sawtoth(40khz) that samples sine wave(60hz). Then PWM comparator makes the pulses to Mosfet drivers.

    I'm using orcad capture CIS, the circuit is atached.

    I got that errors:

    "ERROR -- Convergence problem in transient analysis at Time = 749.6E-06"
    These supply currents failed to converge:
    I(X_U1.xinsttl494.Ev103) = -29.80nA \ 0A
    I(X_U1.xinsttl494.X_U3.X2.E1) = 219.09nA \ 218.83nA
    I(X_U1.xinsttl494.X_U3.X2.E2) = 219.09nA \ 218.83nA
    These devices failed to converge:
    X_U1.xinsttl494.X_U3.X1.Q1
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,773
    1,103
    Should you be driving that chip with a sine wave which goes negative? Try adding a DC offset to keep the sine positive.
     
  3. HelderCC

    Thread Starter New Member

    Feb 12, 2014
    3
    0
    Thanks Alec_t for your reply.
    I tried a 2v amplitude sine wave with 2v DC. It did not work...
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,773
    1,103
    Try taking pin 16 to ground instead of 2.5V.
     
  5. Experimentonomen

    Member

    Feb 16, 2011
    331
    46
    Maybe this could help:
    [​IMG]
     
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