Part Number:PGA460
Hello.
We are currently evaluating PGA460 with the following settings:
- Frequency: 249.6 kHz (250 kHz nominal)
- Current limit: variable in 50 - 500 mA range,
- Pulse count: variable in 1 - 25 range,
- Gain: TVG configured for 52 dB initial gain, then +4e-3 dB/uS after initial 100 uS,
- Bandpass: 8 kHz bandwidth, coefficients per table included with PGA460-Q1 EVM software,
- Lowpass: 4 kHz bandwidth,
- Threshold detector: not used, threshold map set to all 0xFF,
- Analog test mux: analog AFE output on TEST pin
- Digital test mux: LPF samples, in full 12-bit resolution.
- Record length: 65.536 ms.
- Maximum object count in Burst and listen command: 8
We are evaluating PGA460 as a replacement for our own discrete solution, and, as such, we already have digital processing implemented for the post-LPF stages, i.e. object separation and classification. Accordingly, we are currently using "Direct Data Burst Through USART Synchronous Mode" exclusively.
However, we have encountered an issue in the configuration listed above: record interval values above 16.384 ms ("3" in P1_REC field) are limited to 16.384 ms. Intervals below - 4.096, 8.192, 16.384, 24.576 - work as expected.
When record length is above 16.384, we receive (at 8 MHz SCLK) a system diagnostics byte, 16384 bytes of data (8192 samples, as expected), and a valid checksum byte.
PGA460 is powered with 12V. VPWR OVP threshold is set at 17.7V. Voltage transient on VPWR during burst does not exceed 50 mV. No errors are reported in the diagnostics byte or DEV_STAT1, 2 registers at any step before or after burst/listen command.
Is this limitation intended or is it caused by a misconfiguration? Can TI propose a fix or workaround?