Ads5231/32/37 Evm Operational Procedure; Circuit Description; Schematic Diagram; Circuit Function - Texas Instruments ADS5237 EVM User Manual

Circuit Description

1.4

ADS5231/32/37 EVM Operational Procedure

The ADS5231/32/37 EVM provides a flexible means of evaluating the ADS5231/32/37 in a number of
modes of operation. A basic setup procedure that can be used as a board confidence check is as follows:
1. Verify all jumper settings against the schematic jumper list in
2. Connect supplies to the EVM as follows:
•
3.3-V ADC output buffer supply to J17 and return to J18.
•
3.3-V ADC analog supply to J11 and return to J10.
3. Switch power supplies on
4. Use a function generator with 50-Ω output to input a 45-MHz, 1.5-V offset, 3-V square-wave signal into
J3. The frequency of the clock must be within the specification for the device speed grade. Caution:
the ADS5231/32/37 does not work with a sinusoidal clock source.
5. Use frequency generators with a 50-Ω output to provide a 10.1-MHz, 0-V offset, –1-dBFS amplitude,
sine-wave signal into J15 and J16. This provides a transformer-coupled differential input signal to both
channels of the ADC. A full-scale input tone into channel A or channel B can be calculated by using
the following formula:
* dBFS + 20 log
6. The digital patterns on output connectors J8 and J21 should now represent a sine wave and can be
monitored using a logic analyzer or TSW1100.
Jumper
W1 Reference select
W2 Channel B output enable
W3 Power down select
W4 Channel A output enable
SJP1 Common-mode voltage-path provider
W9 Invert most significant bit
SJP3 Common-mode voltage path
2 Circuit Description
2.1

Schematic Diagram

The schematic diagram for the EVM is attached to the end of this document.
2.2

Circuit Function

The following paragraphs describe the function of individual circuits. See the ADS5232 Dual, 12-Bit,
65MSPS, +3.3V Analog-to-Digital Converter data sheet (SBAS294), the ADS5231 Dual, 12-Bit, 40MSPS,
+3.3V Analog-to-Digital Converter data sheet (SBAS295), or the ADS5237 Dual, 10-Bit, 65MSPS, +3.3V
Analog-to-Digital Converter data sheet (SBAS420) for device operating characteristics.
6 ADS5231/32/37 EVM
captured max code * captured min code
2 N
Table 1. Three-Pin Jumper List
Function
Internal reference
Output disabled
Power-down mode
Output disabled
Common-mode voltage to CHA
differential amplifier
2s complement
Provide common-mode voltage
to CHB differential amplifier
Table 1:
, N is the number of bits
Location: Pins 1- 2
External reference
Output enabled
Operate mode
Output enabled
Provide common-mode voltage
to transformer T1
Offset binary
Provide common-mode voltage
to transformer T2
SBAU111B – May 2006 – Revised November 2007
www.ti.com
Location: Pins 2-3 Default
1-2
2-3
2-3
2-3
2-3
2-3
2-3
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