Evm Overview - Texas Instruments AMC7823 EVM User Manual

EVM Overview

The SPI™ serial interface of the AMC7823 can communicate with any host microprocessor capable of the
SPI protocol and most TI DSP based systems.
A socket (Samtec, P/N SS-101-T-1C) for a through-hole resistor, R14, is also provided so that the load
current can be precisely set to the desired value required to bias any external component connected to pin
5 (THERM_I_OUTPUT) of the AMC7823.
1.2 Power Requirements
The following sections describe the power requirements of this EVM.
1.2.1 Supply Voltage
The dc analog power supply requirement for the AMC7823 EVM (AV
and +5 VA via jumper headers, W3. The +3.3 VA comes from J6-8 or J11-1 (if installed), and the +5 VA
comes from the J6-3 or J11-3 (if installed) terminals. These power supply voltages are referenced to
ground through the J6-6 or J11-2 (if installed) terminals. All of the analog power supplies are referenced to
analog ground through the J11-2 and J6-6 terminals.
On the other hand, the dc digital power supply requirement for DV
between +3.3 VD and +5 VD via jumper headers, W4 and W2, respectively. The +3.3 VD comes from the
J6-9 or J12-3 (if installed) terminals, and the +5 VD comes from the J6-10 or J12-1 (if installed) terminals.
All of the digital power supplies are referenced to digital ground through the J6-5 and J12-2 terminals.
Green LED indicators, D1 and D5 for AV
applied on the EVM board.
To avoid potential damage to the EVM board, make 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 AMC7823 comes with an internal bandgap reference that is software selectable between 1.25 V and
2.5 V, where the default on power up is 1.25 V. Although the internal reference is included on the DUT, an
external reference circuit is still provided onboard the EVM, as well as the option of providing the user
supplied reference voltage via terminal pin, TP1.
The REF3125 (REF2) and REF3112 (REF1) precision voltage references are provided to supply the
onboard external voltage reference and set the voltage output range of the ADC and DAC of the
AMC7823 device. The 1.25-V or 2.5-V reference voltage can be selected via the W7 jumper. The onboard
external reference or the user supplied reference can also be selected via W1 jumper. The user supplied
reference can be applied to the TP1 test point or J1-20 terminal pins, which are also provided to allow the
user to connect to another external reference source if the onboard reference circuit is not desired. The
external voltage reference should not exceed the specified voltages listed in the data sheet.
The REF3125 and REF3112 precision references are powered by +5 VA or +3.3 VA, selectable through
the W3 jumper.
When applying an external voltage reference through TP1 or J1-20, make
sure that it does not exceed the maximum specified voltage listed in the
data sheet. Otherwise, this can permanently damage the AMC7823, U1,
device under test.
2 AMC7823 Evaluation Module
and DV respectively, are included to show that power is
DD DD
CAUTION
CAUTION
) is selectable between +3.3 VA
DD
and IOV are also selectable
DD DD
SLAU171 – November 2005
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