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BOM, Schematic, and Layout

5.2 Device Operation

Once the analog and digital power sources are applied to the ADS1209EVM, the digital outputs become

active. The ADS1209 is configured to use its onboard oscillator by tying the clock in (CLKIN) and clock

select (CLKSEL) pins to the applied digital power supply. The internal reference of the ADS1209 is used

as the conversion reference inputs by tying the REFOUT pin to both REFIN A and REFIN B.

Additionally, an analog input signal may be applied to the unipolar differential input pair of either channel

at screw terminal J1. See Figure 1 and Table 2 for more details. The analog input range is ±0.92 × V

REF

with a common mode input of +2.5 V. With the nominal internal reference voltage of +2.5 V, the maximum

analog input voltage ranges from +0.125 V to +4.875 V.

As the input voltage approaches the maximum input level of +4.875 V, the 1s density of the modulator

output approaches 92%. Likewise, when the input voltage approaches the lower limit of +0.124 V, the 1s

density is approximately 8%.

6 BOM, Schematic, and Layout

This section contains the complete bill of materials, schematic diagram, and printed circuit board (PCB)

layout for the ADS1209EVM.

NOTE: Board layouts are not to scale. These are intended to show how the board is laid out; they

are not intended to be used for manufacturing ADS1209EVM PCBs.

6.1 Schematic

The ADS1209EVM schematic is appended to this document.

6.2 Printed Circuit Board Layout

Figure 3. ADS1209EVM Silk Screen Drawing

SBAU167–March 2010 ADS1209EVM

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