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DRV120: Tolerance on Tpeak & Ipeak

EE User 52
Prodigy 60 points
Part Number: DRV120
Other Parts Discussed in Thread: DRV110

I implemented the DRV120 drivers on my board for driving solenoid valves.  I noticed that there is variation of Tpeak & Ipeak values when I view the current waveforms.  Also the Tpeak values are consistently les than the intended value.  The datasheet only gives Typical values for certain Test Conditions (external component settings).  I'd like to verify if there are any issues w/ my implementation or if the drivers should have this observed tolerance.  Here are the external component values I'm using:

Ckeep = 2.2uF (set for 165mS)

Rpeak = 205KΩ  (set for 81.3mA)

Rhold = 110KΩ (set for 60.6mA)

Rpeak = 196KΩ (set for 20.4KHz)

I use 7 DRV120 drivers on each board.  Here are the parameters I measured on 2 boards:

Bd # 5
Driver # Tpeak(mS) Ipeak(mA) Ihold(mA)
1 149 73.6 56.8
2 124 77.6 60.0
3 146 76.0 60.0
4 119 78.4 60.8
5 139 76.0 60.8
6 128 75.2 59.2
7 146 76.8 60.8
Bd # 6
Driver # Tpeak(mS) Ipeak(mA) Ihold(mA)
1 138 79.2 61.6
2 130 75.2 59.2
3 128 75.2 58.2
4 149 76.0 59.2
5 130 74.4 59.2
6 140 76.0 60.0
7 132 76.8 60.8

Note that I use the same solenoid as the load for each driver's measurement.  The solenoid DCR = 265Ω, L = 0.69H.

Thx for any info.

  • 0
    TI__Expert 6330 points

    Hi,

    I have notified our expert regarding this topic. Please expect a response by 9/11/19.

    Thanks,

    Aaron

  • 0
    TI__Expert 4940 points

    Hi,

    That's no system issue, Ipeak/Ihold and Tkeep measured values are the expected one based on DRV110 tolerances.

     Ipeak, Ihold the tolerances are +/-20% excluding external resistor tolerances. The measured Ipeak is slightly worst than Ihold.

    You can verify if the voltage headroom limits the Ipeak by increasing the supply.

    Tkeep tolerances are <+/-30% excluding capacitor tolerances, the measured time is better than +/-30%.

    Secondly the Ipeak ramp-up/down time reduces Tkeep, should be measured from Ipeak turn on( close to 0mA)

    Regards,

    Costin