PGA460: What is the correct waveform from outA and outB?

Hi magic Gao,

How are you driving the transducer? Are you using a transformer or direct-drive configuration? How many pulses are a you transmitting? What is your drive/receive frequency set to?

OUTA/B should appear as a sinusoidal waveform (CH3=purple=IN2) when connected to a transformer (this example uses a center-tap voltage of 9V):

OUTA/B should appear as a square waveform (CH2=blue=XDCR+) when connected to a half-bridge direct-driver (this example uses a high side voltage reference of 7.2V):

It almost appears as if no load is connected to the OUTA/B pin you are probing. Can you ensure you have continuity?

Thanks for your reply.
we use direct-drive configuration , 16 pulses transmitting and drive frequency set to 40Khz.
My program flow looks like this:
1.Threshold bulk write.(send data:55 10 88 88 88 88 88 88 84 21 42 10 10 80 80 80 80 00 88 88 88 88 88 88 84 21 42 10 10 80 80 80 80 00 75)
2.bulk user EEPROM write.(send data:55 0C 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 32 A0 20 20 40 40 19
33 11 7C 4F 00 00 09 09 C5)
3.bulk TVG write.(send data:55 0A 26 4F 80;55 0E 88 88 88 82 08 20 80 2D 4C 68 4B)
4.ultrasonicCmd (0x55,0x01,0x01,calcChecksum(0x01),start burst.

we can read the value of the register and the same as we wrote it.We connected load to the OUTA and OUTB.
No matter how I configure the value of the register, the output waveform is the one above.
I really don't know what wrong with my program?Is there a problem with my program?
I really need your help!

Hi magic Gao,

Can you read back the value of DEV_STAT0 to ensure the THR_CRC_ERR bit is cleared to a value of '0' after you write the threshold?

What is your supply voltage set to? If the supply voltage is less than the value of VPWR_OV_TH, then the PGA460 will not allow the driver to burst. The VPWR_OV_TH bits represent the following VPWR limits:
00b = 12.3 V
01b = 17.7 V
10b = 22.8 V
11b = 28.3 V