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1.2.1 Supply Voltage
1.2.2 Reference Voltage
Overview
This section gives a general overview of the DAC8555EVM and describes some of the factors that mustbe considered when using this demonstration board.
The DAC8555EVM is a simple evaluation module designed for a quick and easy way to evaluate thefunctionality and performance of the high-resolution, quad-channel, serial input DAC8555 digital-to-analogconverter (DAC). This EVM features a serial interface to communicate with any host microprocessor or TIDSP-based system.
This subsection describes the power requirements for this device.
The DC power supply requirement for the digital section (V
DD
) of this EVM is typically +5V connected tothe 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 forthe analog section of this EVM are: V
CC
and V
SS
range from +15.75V to –15.75V (maximum), connectingthrough J1-3 and J1-1 respectively, or through terminals J3-1 and J3-2. The +5V
A
connects throughterminals J5-3 or J3-3, and the +3.3V
A
connects through terminal J3-8. All of the analog power suppliesare 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 either +5V
A
or +3.3V
A
byselecting the proper position of jumper JMP7. This configuration allows the DAC8555 analog section tooperate 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, thereference chip, U3 and the reference buffer, U4. The negative rail of the output op amp, U2, can beselected between V
SS
and AGND via jumper JMP10. The external op amp is installed as an option toprovide output signal conditioning or to boost capacitive load drive, or for other desired output moderequirements.
CAUTION
To avoid potential damage to the EVM board, be sure that the correct cablesare connected to their respective terminals as labeled on the EVM board.Stresses above the maximum listed voltage ratings may cause permanentdamage to the device.
The +5V precision voltage reference is provided to supply the external voltage reference for the DACthrough the REF02 (U3) via jumper JMP8, by shorting pins 1 and 2. The reference voltage goes throughan adjustable 100k Ωpotentiometer, R15, in series with 20k Ω, R16, to allow the user to adjust thereference voltage to its desired settings. The voltage reference is then buffered through U4A as seen bythe device under test. The test points TP2, TP3 and TP4 are also provided, as well as J4-18 and J4-20, inorder to allow the user to connect another external reference source if the onboard reference circuit is notdesired. The external voltage reference should not exceed +5V DC.
The REF02 precision reference is powered by V
CC
(+15V) through either terminal J1-3 or J3-1.
SLAU204 – December 2006 DAC8555EVM User's Guide 3Submit Documentation Feedback