ASD1194 datasheet(33/76 Pages) TI

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START

DRDY

SCLK

DIN

DOUT

ADS1198

(Device0)

START

DRDY

SCLK

DIN

DOUT

ADS1194

(Device1)

START

(1)

a)StandardConfiguration

CLK

INT

GPO0

GPO1

SCLK

MOSI

HostProcessor

MISO

CLK

START

DRDY

SCLK

DIN

DOUT

ADS1198

(Device0)

START

DRDY

SCLK

DIN

DAISY_IN

ADS1194

(Device1)

START

(1)

b)Daisy-ChainConfiguration

CLK

INT

GPO

SCLK

MOSI

HostProcessor

MISO

CLK

DOUT

DAISY_IN

ADS1194, ADS1196

ADS1198

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SBAS471C

– APRIL 2010 – REVISED NOVEMBER 2011

Standard Mode

Figure 36a shows a configuration with two devices cascaded together. One of the devices is an ADS1198

(eight-channel) and the other is an ADS1194 (four-channel). Together, they create a system with 12 channels.

DOUT, SCLK, and DIN are shared. Each device has its own chip select. When a device is not selected by the

corresponding CS being driven to logic 1, the DOUT of this device is high-impedance. This structure allows the

other device to take control of the DOUT bus. This configuration method is suitable for the majority of

applications.

DAISY-CHAIN MODE

Daisy-chain mode is enabled by setting the DAISY_EN bit in the CONFIG1 register. Figure 36b shows the

daisy-chain configuration. In this mode SCLK, DIN, and CS are shared across multiple devices. The DOUT of

one device is hooked up to the DAISY_IN of the other device, thereby creating a chain. One extra SCLK must be

issued in between each data set. Also, when using daisy-chain mode the multiple readback feature is not

available. Short the DAISY_IN pin to digital ground if not used. Figure 2 (Daisy-Chain Interface Timing) describes

the required timing for the ADS1198 shown in Figure 36. Data from the ADS1198 appear first on DOUT, followed

by a don

’t care bit, and finally by the status and data words from the ADS1194.

(1) To reduce pin count, set the START pin low and use the START serial command to synchronize and start conversions.

Figure 36. Multiple Device Configurations

In a case where all devices in the chain operate in the same register setting, DIN can be shared as well and

thereby reduce the SPI communication signals to four, regardless of the number of devices. However, because

the individual devices cannot be programmed, the RLD driver cannot be shared among the multiple devices.

Furthermore, an external clock must be used.

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Product Folder Link(s): ADS1194 ADS1196 ADS1198

ASD1194 Datasheet(PDF) 33 Page - Texas Instruments

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