REF5025ID datasheet(6/48 Pages) TI1

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Power Supplies

4.1

Bipolar Power Options

Power Supplies

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J3 is the power-supply input connector. Table 3 lists the configuration details for J3. Analog inputs to the

ADC can be applied directly to the device (see Section 8.1, Analog Input), bypassing the onboard

amplifiers, and in this case only +5V and +3.3V are required to power the EVM. If the amplifiers are used,

an additional bipolar supply is needed to power them. The EVM includes a switching power supply to

generate a +10V and –10V supply. For optimum noise performance, the external supplies (+VA and –VA)

should be used.

Table 3. J3 Configuration: Power-Supply Input

Pin No.

Pin Name

Function

Required

J3.1

+VA

+10V to +15V

Yes, unless onboard +10V is

used.

J3.2

–VA

–10V to –15V

Yes, unless onboard –10V is

used.

J3.3

+5VA

+5V analog supply

Always

J3.4

–5VA

–5V analog supply

J3.5

DGND

Digital ground input

Yes

J3.6

AGND

Analog ground input

Yes

J3.7

+1.8VD

1.8V digital supply

J3.8

+3.3VD

3.3V digital supply

Always

J3.9

VD1

Not used

J3.10

+5VD

+5V

Used to generate +10V/–10V

The 1.8V for DVDD comes from the voltage regulator U16 using 3.3V as the source voltage input.

All of the power supplies AVDD (+5V), DVDD (1.8V), and IOVDD (3.3V) have corresponding jumpers J10,

J11(AVDD), J13(DVDD) and J14(IOVDD) that can be replaced with a current meter to measure the

respective supply currents.

J15 and J16 require a jumper to select the voltage used by the onboard amplifiers. The external voltages

can range from 10V to 15V. The onboard voltage is always 10V. Table 4 and Table 5 list the options for

J15 and J16, respectively. Figure 3 shows the pinout for connectors J15 and J16.

Table 4. J15 +10V Selection

Jumper

Name

Function

1-2 (OB)

+10V

Select the +10V that is generated on the

EVM

2-3 (EXT)

+VA

Select the external +VA voltage

Table 5. J16 –10V Selection

Jumper

Name

Function

1-2

–10V

Select the –10V that is generated on the

EVM

2-3

–VA

Select the external –VA voltage

ADS1174EVM, ADS1274EVM, ADS1174EVM-PDK, and ADS1274EVM-PDK

SBAU134A – August 2008 – Revised May 2009

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