Texas Instruments ADS1254, Руководство пользователя

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Analog Inputs
1-3 Introduction
The ADS1254EVM incorporates a PLL-based clock generator which can
synthesize clocks of nearly arbitrary frequency up to the maximum of 8 MHz.
The PLL exhibits increased jitter, so for certain clock frequencies, a direct
divide-down circuit derived from a crystal oscillator is used instead. The
divide-down is selected automatically.
The ADS1254EVM can be powered using an ac power adapter (not included),
a 9-volt battery, or a user-supplied laboratory power supply.
A photograph of the ADS1254EVM with the locations of major components
highlighted is shown in Figure 1−2.
Figure 1−2. ADS1254EVM Component Locations
CHANNEL INPUTS
EXTERNAL
REFERENCE
INPUT
RS-232 PORT
ANALOG
REGULATED
POWER
DIGITAL
REGULATED
POWER
UNREGULATED
POWER
JTAG ADS1254
BATTERY
CONNECTOR
MCU DISABLE VREF DISCONNECT
VREF SOURCE SELECT
DIGITAL VDD SOURCE
ANALOG VDD SOURCE
SRAM
MCU
DSK PERIPHERAL CONNECTOR
DSK MEMORY CONNECTOR
EXT DIGITAL
1.3 Analog Inputs
Analog input is supplied through the eight-way screw terminal block, J2. Each
input is connected to the ADS1254 through a 1-k
Ω
resistor. The inputs are not
protected against overvoltage.
1.4 Prototyping Area
A prototyping area is provided on the ADS1254EVM. This may be used to
incorporate additional circuitry, such as special reference or conditioning
circuits, into the system. Certain holes are connected to convenient circuit
points, such as ground, reference, etc.
1.5 Power Requirements
The ADS1254EVM must be supplied with 5.5 V −15 V for proper operation.
Power can be supplied through barrel jack, J1 (tip positive), screw terminal
blocks J4 and J5, or with a 9-volt battery connected to battery snap BT1.