Datasheet

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2.3 Power Supply Connections
Power is applied through banana connectors J5, J6, J7, J8, J9, and J10. The PGA281 requires three
supply voltages: the high-voltage analog input stage supply, the low-voltage analog output stage supply,
and the digital supply.
2.3.1 Analog Input Stage Power (VSP, VSN)
Power for the analog input stage is applied at J5 (VSP), J10 (GND), and J9 (VSN). The specified range for
these supplies is given in Table 2.
Table 2. Analog Input Stage Power
Name Minimum Maximum Description
VSP +5 V +18 V Positive supply for analog input stage
Ground reference voltage for analog
GND 0 V 0 V
input stage
Negative supply voltage for analog input
VSN –5 V –18 V
stage
2.3.2 Analog Output Stage Power (VSOP, VSON)
Power for the analog output stage is applied at J6 (VSOP) and J7 (VSON). The specified range for these
supplies is given in Table 3. On the PGA281EVM, VSON is always connected to GND.
Table 3. Analog Output Stage Power
NAME MINIMUM Maximum Description
VSOP +2.7 V +5.5 V Positive supply for analog output stage
Negative voltage/ground reference for
VSON 0 V 0 V
analog output stage
2.3.3 Digital Logic Power (VDD)
Power for the digital core is applied at J8 (VDD). The specified range for VDD is the same as VSOP (+2.7
V to +5.5 V). VSON is used as the digital core ground reference.
2.3.4 Onboard LDO Regulator
The PGA281EVM contains an onboard LDO regulator (U2) that is used to generate VSOP and VDD from
VSP. This configuration greatly simplifies the power connections to the PGA281EVM, because then only
VSP, VSN, and GND must be provided. The LDO regulator output voltage can be adjusted by replacing
resistor R20. When using the LDO regulator in this manner, set jumpers JMP1 and JMP2 to INT and
VSOP, respectively.
Table 4. LDO Adjustable Output Voltages
R20 Resistance Output Voltage
33.2 kΩ 5 V
18.2 kΩ 3.3 V
5
dit.SBOU130–May 2013 PGA281EVM
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