Texas Instruments ADS5237 EVM User Manual page 7

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2.2.1 Analog Inputs
The EVM can be configured to provide the ADC with either transformer-coupled or differential amplifier
inputs from a single-ended source. The inputs are provided via SMA connectors J15 and J16 for
transformer-coupled input, and J1, J2, J7, and J9 for differential amplifier input. To set up for one of these
options, the EVM must be configured as follows:
1. For a 1:1 transformer-coupled input to the ADC, a single-ended source is connected to J15 for channel
A and J16 for channel B. R5, R6, R8, and R9 must not be installed. This is the default configuration for
the EVM.
2. For single-ended inputs into the differential amplifiers, sources are connected to J2 for channel A and
J9 for channel B. R5, R6, R8, and R9 must be installed, and R74, R75, R78, and R79 removed.
3. For a differential input into the amplifiers, the positive source of channel A is connected to J2 and the
negative source to J1. The positive source of channel B is connected to J9 and the negative source to
J7. R5, R6, R8, and R9 must be installed, and R74, R75, R78, and R79 removed. R19 and R22 must
be replaced with 383-Ω resistors, and R12 and R14 must be replaced with 54.9-Ω resistors for proper
termination.
2.2.2 Clock Input
To provide a clock to the ADS5231/32/37, apply a 3.3-V, 1.65-V offset, square-wave input to J3. This input
is terminated with a 50-Ω resistor to ground. Caution: the ADS5231/32/37 does not work with a
sinusoidal clock source.
2.2.3 Control Inputs
The EVM has five discrete inputs to control the operation of the device.
2.2.3.1 Output Enable
With jumper W4 installed between pins 2 and 3, channel A of the ADC is enabled. This channel is
disabled with the jumper installed between pins 1 and 2. With jumper W2 installed between pins 2 and 3,
channel B is enabled. Channel B is disabled with the jumper installed between pins 1 and 2.
2.2.3.2 MSB Control
With jumper W9 installed between pins 2 and 3, the outputs of the ADC are straight binary. The outputs
are 2s complement with jumper W9 installed between pins 1 and 2.
2.2.3.3 Power Down
With jumper W3 installed between pins 1 and 2, the ADC is in power-down mode.
2.2.3.4 External Reference
With jumper W1 installed between pins 1 and 2, the ADC is in internal reference mode. The device is in
external reference mode with jumper W1 installed between pins 2 and 3. When using the external
reference mode, install R3 and R4. Use the potentiometers R17 and R18 to adjust the corresponding top
reference and bottom reference. For convenience, two test points, TP6 and TP7, allow monitoring the
voltage while using the external reference mode.
2.2.4 Power
Power is supplied to the EVM via banana jack sockets. Separate connections are provided for a 3.3-V
analog supply (J11 and J10), 3.3-V driver supply, external buffer supply (J17 and J18), and ±5-V amplifier
supply (J14, J13, and J12).
SBAU111B – May 2006 – Revised November 2007
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Circuit Description
ADS5231/32/37 EVM 7