DRV110EVM: DRV110 14 pin

John Mastroianni

Part Number: DRV110EVM
Other Parts Discussed in Thread: DRV120, DRV110

This is a continuation of the DRV120:DRV120 posting. I am using the DRV110EVM and changed Rsense=4ohm. I want to achieve the following setup using a 24 volt power supply:

I Peak = 26 mA

I hold = 15 mA

Ckeep = 100ms

I have these settings on the DRV110EVM using your spreadsheet:

Question: After enable is asserted, the circuit stays at 26 ma and never reduces down to 15mA after the Hold time (100ms). What is wrong? Since I am using 24 volts, do I need to modify the DRV110 Zener external resistor to 7.725Kohm as per the spreadsheet to make this work?

Thanks,

John

over 5 years ago

0 Costin Cazana over 5 years ago

TI__Expert 4940 points

Hi John,

Yes you need to add a current limiting resistor, that's a risk to .damage DRV110 Zener block

What is PWM set to ( Rosc)? Base on issue description the set PWM freq is > 27kHz

If so increase Rosc to be greater than 100kohm.

Regards,

Costin

0 John Mastroianni over 5 years ago in reply to Costin Cazana

Prodigy 90 points

Hi Costin,

I will add the 7.7k ohm resistor to protect the internal Zener. Will this make the circuit work so that I HOLD = 15 mA after 100ms? I have Rosc = 100k ohms.

The data from the spead sheet did not show up. Here it is:

DRV110A Parameters Calculation (14-pin)
T(KEEP) [ms]	100.000
I(PEAK) [A]	0.026
I(HOLD) [A]	0.015
R(SENSE) [Ω]	4
f(PWM) [kHz]	40.000
R(OSC) [kΩ]	100.005
R(PEAK) [kΩ]	576.952
R(HOLD) [kΩ]	166.675
C(KEEP) [μF]	1
Rsens_min (Ipeak) [Ω]	1.154
Rsens_max (Ipeak) [Ω]	34.615
Rsens_min (Ihold) [Ω]	0.333
Rsens_max (Ihold) [Ω]	10.000

I will test it in again in parallel.

Thanks,

John

0 Costin Cazana over 5 years ago in reply to John Mastroianni

TI__Expert 4940 points

Hi John,

Fosc=40kHz may cause the issue, set it <25kHz.

May suggestion is Rosc=160kohm to get Fosc=25kHz

Regards,

Costin

0 John Mastroianni over 5 years ago in reply to Costin Cazana

Prodigy 90 points

Thanks Costin. I will try the new setting and let you know if it works.

-John

0 Costin Cazana over 5 years ago in reply to John Mastroianni

TI__Expert 4940 points

Hi John,

Ok, should work

Regards,

Costin

0 John Mastroianni over 5 years ago in reply to Costin Cazana

Prodigy 90 points

0 John Mastroianni over 5 years ago in reply to John Mastroianni

Prodigy 90 points

Hi, Looks like the circuit is working. The top trace is the OUT pin that is driving the gate of the FET. The bottom trace is the current probe. The solenoid peak current is approximately 27 mA. Then after ~78ms the hold current goes down to ~ 15 mA (average current). This is showing the PWM working.

Additionally, I had to add a .1uF cap to GND on the OUT pin because OUT was oscillating.

Thanks,

John

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DRV110EVM: DRV110 14 pin