PGA308-W: Data wrote times

Hi Tom,

The PGA308 memory structure is divided into two separate regions: the one time programmable (OTP) memory, and the random access memory (RAM). The RAM is volatile and may be programmed many times during the calibration process, or while evaluating the device. The OTP memory is non-volatile and as indicated by the name, each OTP register can only be programmed a single time.

See my responses to your questions below.

1.) This chip has 7 "OTP" memory banks. It means we can write a set of gain and offset only one time in a bank ?

Yes, each OTP register may be programmed only once. During your factory calibration procedure, the gain and offset settings may be written to the RAM many times until the desired register values are confirmed. Once the desired gain and offset settings are determined in RAM, these values will be written to the non-volatile OTP register. The seven possible OTP user memory banks allow an end product with a microcontroller interface between the end user and the PGA308 to select from up to seven factory pre-programmed configurations.

2.) This chip has 4 "OTP" bank select registers, and the largest number register is enabled. It means we can use only one bank on "POR" ?                                                          And also we can change the bank only 3 times, excluding the first one ?

Yes, by programming the BANK_SELx register in order from BANK_SEL1 to BANK_SEL4, you may change the default pointer up to three times after the original pointer is set. 

This programmability allows for situations where a calibration may be conducted on a given module before discovery that the calibration system was not configured correctly or was out of calibration. This four-time re-programmability for OTP user bank selection allows for recalibration rather than discarding the final sensor module.

3.) After running out the 4 bank select registers, we can still exchange banks by 1 wire ?

Yes, the One-Wire Interface can always communicate with the PGA308 and override the contents of the current OTP bank in use, unless this function is disabled by the OWD bit in the CFG2 Register (Configuration Register 2). Overriding the contents of the current OTP bank is accomplished by setting the appropriate SWL[2:0] bits in the SFTC Register (Software Control Register). This is described in detail in the PGA308 User's Guide section 5.8: "Software Lock Mode". When operating in Software Lock Mode, preprogrammed contents from any of the seven OTP memory banks may be loaded into the RAM. Or the RAM may be programmed with new values directly through the one-wire.

4.) After running out the 7 banks, we can still change offsets and gain by 1 wire ?

Yes, see above.

Thanks,

Zach