DRV8824 High Frequency STEP signal

I am trying to implement a circuit using DRV8824 IC which will drive a bipolar motor in microstep mode. The problem arises when the STEP input signal exceeds 600Hz. The output is highly distorted. But the same works just fine for a 100Hz STEP input signal. However my application requires very small pulse duration and therefore I have to work at a higher frequency.

All the connections are as per the data sheet.

Voltages measured are as follows:

VCP=23.4V

VMA=VMB=12.8V

AVREF=BVREF=V3P3OUT=4.01V

DECAY=OPEN

Here is the Schematic:

The 100Hz output is as follows:

600Hz output is as follows: