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1
Overview
1.1
Features
1.2
Power Requirements
Overview
This section gives a general overview of the DAC8554EVM and describes some of the factors that must
be considered when using this demonstration board.
The DAC8554EVM is a simple evaluation module designed for a quick and easy way to evaluate the
functionality and performance of the high-resolution, quad-channel, serial input DAC8554 digital-to-analog
converter (DAC). This EVM features a serial interface to communicate with any host microprocessor or TI
DSP-based system.
This subsection describes the power requirements for this device.
1.2.1
Supply Voltage
The DC power supply requirement for the digital section (V
DD
) of this EVM is typ5V connected to
the J5-1 terminal or via the J3-10 terminal (when plugged in with another EVM board or interface card)
and is referenced to ground through the J5-2 and J3-5 terminals. The DC power supply requirements for
the analog section of this EVM are: V
CC
and V
SS
range from +15.75V to –15.75V (maximum), connecting
through J1-3 and J1-1 respectively, or through terminals J3-1 and J3-2. The +5V
A
connects through
terminals J5-3 or J3-3, and the +3.3V
A
connects through terminal J3-8. All of the analog power supplies
are referenced to analog ground through terminals J1-2 and J3-6.
The analog power supply for the device under test, U1, can be powered by 5V
A
or +3.3V
A
by
selecting the proper position of jumper JMP7. This configuration allows the DAC8554 analog section to
operate from either supply power while the I/O and digital section are powered by +5V, V
DD
.
The V
CC
supply source is primarily used to provide the positive rail of the external output op amp, U2, the
reference chip, U3 and the reference buffer, U4. The negative rail of the output op amp, U2, can be
selected between V
SS
and AGND via jumper JMP10. The external op amp is installed as an option to
provide output signal conditioning or to boost capacitive load drive, or for other desired output mode
requirements.
CAUTION
To avoid potential damage to the EVM board, be sure that the correct
cables are connected to their respective terminals as labeled on the EVM
board. Stresses above the maximum listed voltage ratings may cause
permanent damage to the device.
1.2.2
Reference Voltage
The +5V precision voltage reference is provided to supply the external voltage reference for the DAC
through the REF02 (U3) via jumper JMP8, by shorting pins 1 and 2. The reference voltage goes through
an adjustable 100k
Ω
potentiometer, R15, in series with 20k
Ω
, R16, to allow the user to adjust the
reference voltage to its desired settings. The voltage reference is then buffered through U4A as seen by
the device under test. The test points TP2, TP3 and TP4 are also provided, as well as J4-18 and J4-20, in
order to allow the user to connect another external reference source if the onboard reference circuit is not
desired. The external voltage reference should not 5V DC.
The REF02 precision reference is powered by V
CC
(+15V) through either terminal J1-3 or J3-1.
CAUTION
When applying an external voltage reference through TP2 or J4-20, make
sure that it does not 5V maximum. External voltage references in
excess of +5V can permanently damage the DAC8554 being tested (U1).
2
DAC8554EVM User's Guide
SBAU121 – January 2006