MCP37231 datasheet(75/144 Pages) MICROCHIP

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 2014-2016 Microchip Technology Inc.

DS20005322D-page 75

MCP37231/21-200 AND MCP37D31/21-200

4.13.1.1

Hardware Reset

A hard reset is triggered by toggling the RESET pin. On

the rising edge, all internal calibration registers and

user registers are initialized to their default states and

recalibration of the ADC begins. The recalibration time

is the same as the power-up calibration time. See

Figure 2-8 for the timing details of the hardware

RESET pin.

4.13.1.2

Soft Reset

The user can issue a Soft Reset command for a fast

recalibration of the ADC by setting the SOFT_RESET

bit to ‘0’ in Address 0x00 (Register 5-1). During Soft

Reset, all internal calibration registers are initialized to

their initial default states. User registers are unaffected.

When exiting the Soft Reset (changing from ‘0’ to ‘1’),

an automatic device calibration takes place.

4.14

Power Dissipation and Power

Savings

The power dissipation of the ADC core is proportional

to the sample rate (fS). The digital power dissipation of

the CMOS outputs are determined primarily by the

strength of the digital drivers and the load condition on

each output pin. The maximum digital load current

(ILOAD) can be calculated as:

EQUATION 4-10:

CMOS OUTPUT LOAD

CURRENT

The capacitive load presented at the output pins needs

to be minimized to minimize digital power consumption.

The output load current of the LVDS output is constant,

since it is set by LVDS_IMODE<2:0> in Address 0x63

(Register 5-21).

4.14.1

POWER-SAVING MODES

This device has two power-saving modes:

• Shutdown

• Standby

They are set by the SHUTDOWN and STANDBY bits in

Address 0x00 (Register 5-1).

In Shutdown mode, most of the internal circuitry,

including the reference and clock, are turned off with

the exception of the SPI interface. During Shutdown,

the device consumes 23 mA (typical), primarily due to

digital leakage. When exiting from Shutdown, issuing a

Soft Reset at the same time is highly recommended.

This will perform a fast recalibration of the ADC. The

contents of the internal registers are not affected by the

Soft Reset.

In Standby mode, most of the internal circuitry is

disabled except for the reference, clock and SPI

interface. If the device has been in standby for an

extended period of time, the current calibration value

may not be accurate. Therefore, when exiting from

Standby mode, executing the device Soft Reset at the

same time is highly recommended.

LOAD

DD1.8

DCLK

LOAD



Where:

N = Number of bits

CLOAD = Capacitive load of output pin

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