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DEVICE PROGRAMMING MODES

USING PARALLEL INTERFACE CONTROL ONLY

USING SERIAL INTERFACE PROGRAMMING ONLY

USING BOTH THE SERIAL INTERFACE AND PARALLEL CONTROLS

ADS5517

SLWS203 – DECEMBER 2007

ADS5517 offers flexibility with several programmable features that are easily configured.

The device can be configured independently using either parallel interface control or serial interface

programming.

In addition, the device supports a third configuration mode, where both the parallel interface and the serial control

registers are used. In this mode, the priority between the parallel and serial interfaces is determined by a priority

table (Table 2). If this additional level of flexibility is not required, the user can select either the serial interface

programming or the parallel interface control.

To control the device using parallel interface, keep RESET tied to high (DRVDD). Pins DFS, MODE, SEN,

SCLK, and SDATA are used to directly control certain modes of the ADC. The device is configured by

connecting the parallel pins to the correct voltage levels (as described in Table 3 to Table 7). There is no need to

apply reset.

In this mode, SEN, SCLK, and SDATA function as parallel interface control pins. Frequently used functions are

controlled in this mode—standby, selection between LVDS/CMOS output format, internal/external reference,

two's complement/straight binary output format, and position of the output clock edge.

Table 1 has a description of the modes controlled by the parallel pins.

Table 1. Parallel Pin Definition

PIN

CONTROL MODES

DFS

DATA FORMAT and the LVDS/CMOS output interface

MODE

Internal or external reference

SEN

CLKOUT edge programmability

SCLK

LOW SPEED mode control for low sampling frequencies (< 50 MSPS)

SDATA

STANDBY mode – Global (ADC, internal references and output buffers are powered down)

To program using the serial interface, the internal registers must first be reset to their default values, and the

RESET pin must be kept low. In this mode, SEN, SDATA, and SCLK function as serial interface pins and are

used to access the internal registers of ADC. The registers are reset either by applying a pulse on the RESET

pin, or by a high setting on the <RST> bit (D1 in register 0x6C). The serial interface section describes the

register programming and register reset in more detail.

Since the parallel pins DFS and MODE are not used in this mode, they must be tied to ground.

For increased flexibility, a combination of serial interface registers and parallel pin controls (DFS, MODE) can

also be used to configure the device.

The serial registers must first be reset to their default values and the RESET pin must be kept low. In this mode,

SEN, SDATA, and SCLK function as serial interface pins and are used to access the internal registers of ADC.

The registers are reset either by applying a pulse on RESET pin or by a high setting on the <RST> bit (D1 in

register 0x6C). The serial interface section describes the register programming and register reset in more detail.

The parallel interface control pins DFS and MODE are used and their function is determined by the appropriate

voltage levels as described in Table 6 and Table 7. The voltage levels are derived by using a resistor string as

illustrated in Figure 4. Since some functions are controlled using both the parallel pins and serial registers, the

priority between the two is determined by a priority table (Table 2).

Copyright © 2007, Texas Instruments Incorporated

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Product Folder Link(s): ADS5517