AD5593R datasheet(21/34 Pages) AD

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AD5593R

Data Sheet

Rev. B | Page 20 of 33

GPIO SECTION

Each of the eight I/Ox pins can be configured as a general-

purpose digital input or output pin by programming the GPIO

control register. When an I/Ox pin is configured as an output,

the pin can be set high or low by programming the GPIO write

data register. Logic levels for general-purpose outputs are relative

to VDD and GND. When an I/Ox pin is configured as an input, its

status can be determined by reading the GPIO read configuration

read its status by also setting it as an input pin. When reading

the status of the I/Ox pins set as inputs the status of an I/Ox pin

set as both and input and output pin is also returned.

INTERNAL REFERENCE

The AD5593R contains an on-chip 2.5 V reference. The

reference is powered down by default and is enabled by setting

Bit D9 in the power-down/reference control register to 1. When

the on-chip reference is powered up, the reference voltage

appears on the VREF pin and may be used as a reference source

for other components. When the internal reference is used, it is

recommended to decouple VREF to GND using a 100 nF

capacitor. It is recommended that the internal reference be

buffered before using it elsewhere in the system. When the

reference is powered down, an external reference must be

connected to VREF. Suitable external reference sources for the

AD5593R include the AD780, AD1582, ADR431, REF193, and

ADR391.

RESET FUNCTION

The AD5593R has an asynchronous RESET pin. For normal

operation, RESET is tied high. A falling edge on RESET resets

all registers to their default values and reconfigures the I/O pins

to their default values (85 kΩ pull-down resistor to GND). The

reset function takes 250 μs maximum; do not write new data to

the AD5593R during this time. The AD5593R has a software

reset that performs the same function as the RESET pin. The

reset function is activated by writing 0x0F to the pointer byte

and 0x0D and 0xAC to the most significant and least significant

bytes, respectively.

TEMPERATURE INDICATOR

The AD5593R contains an integrated temperature indicator that

can be read to provide an estimation of the die temperature.

This can be used in fault detection where a sudden rise in die

temperature may indicate a fault condition, such as a shorted

output. Temperature readback is enabled by setting Bit D8 in

the ADC sequence register. The temperature result is then

added to the ADC sequence. The temperature result has an

address of 0b1000 and care must be taken that this result is not

confused with the readback from DAC0. The temperature

conversion takes 5 μs with the ADC buffer enabled and 20 μs

when the buffer is disabled. Calculate the temperature using the

following formulae:

For ADC gain = 1,

Temperature (°C) = 25 +

654

820



Code

ADC

For ADC gain = 2,

Temperature (°C) = 25 +

654

410



Code

ADC

The range of codes returned by the ADC when reading from

the temperature indicator is approximately 645 to 1035,

corresponding to a temperature between −40°C to +105°C. The

accuracy of the temperature indicator is typically 3°C when

averaged over five samples.

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