AD7381 datasheet(20/31 Pages) AD

20 / 31 page

AD7380-4

Data Sheet

Rev. 0 | Page 20 of 31

POWER MODES

The AD7380-4 has two power modes that can be set in the

Configuration 1 register: normal mode and shutdown mode.

These modes of operation provide flexible power management

options, allowing optimization of the power dissipation and

throughput rate ratio for different application requirements.

Program the PMODE bit in the Configuration 1 register to

configure the power modes in the AD7380-4. Set PMODE to

Logic 0 for normal mode and Logic 1 for shutdown mode.

Normal Mode

Keep the AD7380-4 in normal mode to achieve the fastest

throughput rate. All blocks within the AD7380-4 always remain

fully powered and an ADC conversion can be initiated by a

falling edge of CS when required. When the AD7380-4 is not

converting, it is in static mode and power consumption is

automatically reduced. Additional current is required to

perform a conversion. Therefore, power consumption of the

AD7380-4 scales with throughput.

Shutdown Mode

When slower throughput rates and lower power consumption

are required, use shutdown mode by either powering down the

ADC between each conversion or by performing a series of

conversions at a high throughput rate and then powering down

the ADC for a relatively long duration between these burst

conversions. When the AD7380-4 is in shutdown mode, all

analog circuitry powers down. The serial interface remains

active during shutdown mode to allow the AD7380-4 to exit

shutdown mode.

To enter shutdown mode, write to the power mode

configuration bit, PMODE, in the Configuration 1 register.

The AD7380-4 shuts down, and current consumption reduces.

To exit shutdown mode and return to normal mode, set the

PMODE bit in the CONFIGURATION1 register to Logic 0. All

leaving shutdown mode. After exiting shutdown mode, allow

sufficient time for the circuitry to turn on before starting a

conversion.

EXTERNAL REFERENCE

The AD7380-4 core refers to the voltage in the REFIN pin

during ADC conversion. The reference voltage of the

AD7380-4 is driven through the REFIN pin. This pin can be

supplied with a voltage ranging from 2.5 V to 3.3 V. The

external reference voltage must have enough current to drive

the AD7380-4, which is a maximum of 1.2 mA. Connecting a

1 µF capacitor to the REFIN pin is recommended. The

recommended external voltage reference is the ADR4525 for

2.5 V and the ADR4533 for 3.3 V.

SOFTWARE RESET

The AD7380-4 has two reset modes: a soft reset and a hard

reset. A reset is initiated by writing to the reset bits in the

Configuration 2 register.

A soft reset maintains the contents of the configurable registers

but refreshes the interface and the ADC blocks. Any internal

state machines are reinitialized, and the oversampling block

and FIFO are flushed. The alert indication register is cleared.

The reference and LDO regulator remain powered.

A hard reset, in addition to the blocks reset by a soft reset,

resets all user registers to the default status, and resets the

internal oscillator block.

DIAGNOSTIC SELF TEST

The AD7380-4 runs a diagnostic self test after a POR or after a

software hard reset to ensure that the correct configuration is

loaded into the device.

The result of the self test is displayed in the SETUP_F bit in the

alert indication register. If the SETUP_F bit is set to Logic 1, the

diagnostic self test has failed. If the test fails, perform a software

hard reset to reset the AD7380-4 registers to the default status.

tSTARTUP

POWER-DOWN

MODE

NORMAL

MODE

ACCURATE

CONVERSION

SDI

SHUTDOWN

NORMAL

Figure 34. Shutdown Mode Operation

tRESET

SDI

SOFTWARE RESET

Figure 35. Software Reset Operation

AD7381 Datasheet(PDF) 20 Page - Analog Devices

AD7381 Datasheet(HTML) 20 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Datasheet Download

Link URL