DAC161S997

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SNAS621 – JUNE 2013

Figure 17.

ERROR DETECTION AND REPORTING

By default, the DAC161S997 detects and reports several types of errors.

Loop Error

A loop error occurs when the device is unable to sustain the required output current at OUT pin, typically caused

by a drop in loop supply, or an increase in load impedance.

When a loop error occurs, the DAC161S997 changes the OUT-pin current to the value in the ERROR_LOW

register, unless the MASK_LOOP_ERR is set to 1. If the MASK_LOOP_ERR is not set, then the device also

periodically attempts to reassert the OUT current set in DACCODE by default. If the DACCODE-current output is

set, the DAC161S997 then stops reporting a loop error. The interval between reasserts is controlled by the

L_RETRY_TIME field in the ERROR_CONFIG register. If the DIS_RETRY_LOOP field in the ERROR_CONFIG

register is changed to 1, the device does not periodically check the loop and, instead, only checks the loop after

a read of the ERR_STATUS (0x09) register. If the loop error is not resolved, then the loop-error current persists.

When a loop error occurs, the DAC161S997 sets the CURR_LOOP_STATUS and LOOP_STATUS fields in the

STATUS register to 1. The LOOP_STATUS field remains set to 1 until the STATUS register is read or the device

is reset. If the loop error is cleared, either by the device reasserting the loop current or by changing the OUT

current , then the CURR_LOOP_STATUS field clears.

SPI Timeout Error (Channel Error)

The DAC161S997 expects to receive periodic SPI write commands to ensure that the SPI connection is

functioning normally. If no SPI write command occurs within the time indicated by the SPI_TIMEOUT field in the

ERROR_CONFIG register, the device reports a SPI timeout error. Note that the SPI write command must be

properly formatted to avoid SPI Timeout errors (such as a write command that generates a frame error does not

prevent an imminent SPI Timeout error).

SPI Timeout error reporting is inhibited by MASK_SPI_TOUT. SPI Timeout errors are not reported on the loop if

MASK_SPI_ERR is set to 1.

Note that a write command to address 0 is not considered a valid write command and will not prevent a SPI

Timeout error.

Frame Error

If a SPI write command has an incorrect number of SCLK pulses, the device reports a frame error. The number

of SCLK pulses must be an integer and a multiple of 24. A frame error is always reported by ERRB being pulled

low. A frame error does not affect the loop current.

Error Reporting

The DAC161S997 reports errors in 3 different ways, by changing the OUT pin current, pulling the ERRB pin low,

and by updating the read-only register STATUS. The reporting on ERRB and OUT pin is customized by setting

the ERROR_CONFIG register.

The ERRB pin connects to a GPIO pin on the microcontroller to function as an interrupt if an error occurs.

Copyright © 2013, Texas Instruments Incorporated

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Product Folder Links: DAC161S997