ADC12H034 datasheet(33/53 Pages) TI1

33 / 53 page

ADC12030, ADC12032, ADC12034

ADC12038, ADC12H030, ADC12H032

ADC12H034, ADC12H038

www.ti.com

SNAS080K – JULY 1999 – REVISED MARCH 2013

Hardware power up/down is controlled by the state of the PD pin. Software power-up/down is controlled by the

instruction issued to the ADC. If a software power up instruction is issued to the ADC while a hardware power

down is in effect (PD pin high) the device will remain in the power-down state. If a software power down

instruction is issued to the ADC while a hardware power up is in effect (PD pin low), the device will power down.

When the device is powered down by software, it may be powered up by either issuing a software power up

instruction or by taking PD pin high and then low. If the power down command is issued during a conversion, that

conversion is interrupted, so the data output after power up cannot be relied upon.

Figure 62. Changing the ADC's Conversion Configuration

1.6 User Mode and Test Mode

An instruction may be issued to the ADC to put it into test mode, which is used by the manufacturer to verify

complete functionality of the device. During test mode CH0–CH7 become active outputs. If the device is

inadvertently put into the test mode with CS continuously low, the serial communications may be

desynchronized. Synchronization may be regained by cycling the power supply voltage to the device. Cycling the

power supply voltage will also set the device into user mode. If CS is used in the serial interface, the ADC may

be queried to see what mode it is in. This is done by issuing a “read STATUS register” instruction to the ADC.

When bit 9 of the status register is high, the ADC is in test mode; when bit 9 is low the ADC, is in user mode. As

an alternative to cycling the power supply, an instruction sequence may be used to return the device to user

mode. This instruction sequence must be issued to the ADC using CS. The following table lists the instructions

required to return the device to user mode. Note that this entire sequence, including both Test Mode and User

Mode values, should be sent to recover from the test mode.

DI Data(1)

Instruction

DI0

DI1

DI2

DI3

DI4

DI5

DI6

D17

TEST MODE

Reset

Test Mode

Instructions

USER MODE

Power Up

Set DO with or without Sign

H or L

Set Acquisition Time

H or L

Start a Conversion

H or L

(1)

X = Don't Care

The power up, data with or without sign, and acquisition time instructions should be resent after returning to the

user mode. This is to ensure that the ADC is in the required state before a conversion is started.

1.7 Reading the Data Without Starting a Conversion

The data from a particular conversion may be accessed without starting a new conversion by ensuring that the

CONV line is taken high during the I/O sequence. See Figure 49 and Figure 50. Table 6 describes the operation

of the CONV pin. It is not necessary to read the data as soon as DOR goes low. The data will remain in the

output register ifCS is brought high right after DOR goes high. A single conversion may be read as many times

as desired before CS is brought low.

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Product Folder Links: ADC12030 ADC12032 ADC12034 ADC12038 ADC12H030 ADC12H032 ADC12H034

ADC12H038

ADC12H034 Datasheet(PDF) 33 Page - Texas Instruments

ADC12H034 Datasheet(HTML) 33 Page - Texas Instruments

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