HI Kwon,
The PGA281 requires three supply voltages: the high-voltage analog supply, the low-voltage output amplifier supply, and the digital I/O supply.
Input Stage Supplies:
The high-voltage analog supplies, VSP and VSN, power the high-voltage input stage section. The substrate of the device is connected to VSN; therefore, VSN must be connected to the most negative voltage. The PGA281 VSP and VSN input stage supplies, specified minimum is ±5V and maximum range is ±36V as shown on page 5 of the datasheet:
Output Stage Supplies:
The low-voltage analog output supplies, VSOP (positive output supply) and VSON (negative output supply), operate within the high-voltage supply boundary, and have the following limits:
- The usable range for VSON (negative output supply) is a minimum 5 V below VSP(input stage supply) to as low as VSN.
- The common-mode control input, VOCM, requires a voltage at least 2 V less than VSP in order to support internal rail-to-rail performance.
- In most applications VSON is set to GND, and VSOP is set in the range of +2.7V to +5.5V.
Please refer to a more detailed discussion on the "Power Supply" section on page 20 of the PGA281 datasheet.
To answer your question, you could choose to use assymetrical VSP/VSN input stage supplies, for example VSP= +15V, and VSN= -5V, as long all the supplies are within the specified range, as described on the PGA281 datasheet, where VSN is the most negative supply, and has to be in the range from -18V to -5V.
It is also important to consider the input voltage range of the PGA281. The input voltage range of the PGA280 is limited by the input stage supplies (VSP and VSN). Both inputs must always remain within the range (VSN+2.5V) and (VSP-2.5V) or essentially 2.5V away from the VSN and VSP rail supplies as shown on the spec below:
Please let me know if you have additional questions.
Thank you and Regards,
Luis
Hi kwon,
The specified power supply range is between 10V and 36V. That is, 10V <= (VSP - VSN) <= 36V
You may use asymmetrical supply voltages at VSP/VSN with a few considerations.
VSN is connected to the substrate of the device and must be connected to the lowest potential. The output supplies VSOP/VSON and digital supply DVDD must be within the VSP/VSN range with some limitations as specified by the "Power Supply" section of the PGA281 datasheet, see below.
Can ㅣV+ㅣ and ㅣV- ㅣbe different when using general OPAMP full range?
The input common-mode range is defined by the input supplies VSP and VSN. Therefore the input voltage range at INN and INP must be 2.5V less than VSP and 2.5V greater than VSN, as specified in the electrical characteristics section of PGA281 datasheet. You must set the VSP/VSN supplies to accommodate your expected input voltage range.
Regards,
Zach
