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UCC28089: VOH/VOL

Brian Wang0928
Genius 14610 points
Part Number: UCC28089


There is a question about the Output Voltage of the UCC28089 OUTA/OUTB. In the below condition, the VOL and VOH level is about 0.5 to 1V at 9Vdd. if this is a case, how does it drive the ext. MOSFET?

In customer condition, the VDD is 15V, what about the output voltage Level? 

application: AC Motor Inverter

Usage: Bias power of the Gate driver

====================================================================================================

TA = --40°C to 105°C for UCC28089, VDD = 9 V (see Note 1), 1 μF capacitor from VDD to GND, RA = 110 kΩ, RB = 182 Ω, CT = 220 pF, TA = TJ,

VOL (OUTA or OUTB) IOUT = 75 mA =>0.5V(typ)1 V(max)

VOH (OUTA or OUTB) IOUT = --35 mA (VDD – VOUT) => 1.0(typ) 1.3(max)

  • 0
    TI__Mastermind 33115 points

    Hi Brian,

    Correct, you cannot drive a MOSFET with 0.5 V<OUTA/B<1 V. Did OUTA/B ever switch correctly and later fail or the customer never saw the output switching? The output stage of UCC28089 should be switching between GND<OUTA/B<VDD. If the OUTA/B is not switching between expected levels then debug is necessary to determine if the fault is in the IC, MOSFET, PCB or combination?

    1. Is VDD>UVLOon (11.5V)?
    2. Remove both MOSFETs and measure VGS, VDS impedance out of the circuit. Compare to VGS, VDS impedance of unused MOSFET?
    3. Does OUTA/B switch correctly with MOSFETs removed - if yes, this indicates a failed MOSFET VGS loading down the OUTA/B? Why di the MOSFET fail - check gate drive circuitry?
    4. Measure OUTA, OUTB and VDD to GND impedance of UCC28089 and compare to unused IC?
    5. Remove IC if necessary and measure OUTA, OUTB, VDD to GND impedance on PCB pads?

    Regards,

    Steve M