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DEM-ADS7843E/45E

INSTALLATION

The DEM-ADS7843E/45E evaluation fixture is designed

for stand-alone evaluation or evaluation using the clocking

network on the board. Stand-alone evaluations imply that

the A/D converter is powered by J4 (power supply connec-

tor) and the user is put to the task to provide analog and

digital input excitation. This is achieved by removing all five

jumper tops of JP4 and using J1 and J2 for direct connec-

tions to the device under test (DUT).

In contrast, the DEM-ADS7843E/45E/45E board has the

appropriate digital interface circuitry to drive the DUT data

clock, chip select, and serial data in which is coordinated

with the BUSY and PENIRQ to provide serial and parallel

output data.

This kit includes the following items:

ADS7843E Evaluation Fixture—A2518

DEM-ADS7843E/45E Documentation (LI-522)

ADS7843E (5 samples)

ADS7845E (5 samples)

The DEM-ADS7843E evaluation fixture has two positions

on the board for the A/D converter to be installed in. The

first position is the socket, DUT1 on the board. This spring-

loaded socket allows the user to quickly swap in or out the

device that is being evaluated. The other option on the board

is the position X1, which is a solder location for the DUT. If

this option is chosen, the user must solder the DUT directly

to the board. This position is only useful for 2 or 3 solder

cycles.

CAUTION: DO NOT connect the a device into the

DUT1 socket and have another device soldered to the

board in position X1 at the same time.

The additional equipment required to do a complete evalu-

ation of the performance of the ADS7843E or ADS7845E

comprises of:

+5VDC power supply

Voltage or current signal source

4-Wire (ADS7843E) or 5-Wire (ADS7845E) Resistive

Touch Screen

To install the DEM-ADS7843E/45E evaluation fixture, con-

nect the appropriate power supply to J4. When power is

applied to the DEM-ADS7843E/45E, the red LED on the

board should light.

USER CONFIGURATIONS

The DEM-ADS7843E/45E evaluation fixture provides the

right combination of jumper options and support circuitry

to allow for a variety of evaluation configurations. Throughout

this data sheet, numerous references are made to the ADS7843

and ADS7845 A/D converters. For more information con-

cerning these devices, refer to the ADS7843 or ADS7845

data sheet. The circuit is laid out with a four-layer board.

The two outside layers are for circuit traces and the inner

layers are the ground and power planes. The analog and

digital planes of the circuit is separated through the middle

of the board all the way to the power supply connector,

where they are joined. The circuit diagram and layout

diagrams for the DEM-ADS7843E/45E is shown in Figure

1 and Figures 4 through 7.

J1

Analog Input Interface. Each connector is labeled.

J2

Digital I/O Interface. Each connector is labeled.

J3

Parallel Output Port.

J4

Power Supply Connector. This connector powers the DUT

and digital network. Refer to the ADS7843 or ADS7845

product data sheet for power supply restrictions. All digital

chips on the DEM-ADS7843E/45E board are capable of

operating with supply voltage from 2.7V to 5.25V.

P1

External DCLK Connector.

TABLE I. Connectors (Jx and P1) Assignments.

JUMPER NUMBER

FACTORY SETTING

DESCRIPTION

JP1

B

Voltage reference. This setting connects A/D converter reference to +VCC.

JP2, JP11, JP10

JP2 = Not Installed

Inverted or non-inverted option for PENIRQ of the ADS7843 or ADS7845 when driving this pin through pin 2.

JP11 = Not Installed

This setting sets this pin HIGH and connects this pin to J2.

JP10 = Not Installed

JP3

D, F, G

Hardwire digital jumpers for DIN serial code. This setting configures the A/D converter for

S = HIGH, A2-A0 = 001, MODE = LOW, SGL/DIF = HIGH, PD1-PD0 = 11.

JP4

A, B, C, D, E

This jumper connects the clocking network to the DUT.

JP5, JP6

JP5 = A

Clock speed options. This configuration sets the board using Y1/10 as the DCLK frequency.

JP6 = B

JP7, JP8

JP7 = B

Optional 16- or 24-bit operation. This configuration sets the board for 16 DCLK per conversion cycle.

JP8 = A

JP9

B

Used to personalize the board for the ADS7843 or ADS7845. Position B = ADS7843 or ADS7845.

TABLE II. Jumper (JPx) Assignments.