AD7151BRMZ-REEL Datasheet AD7151BRMZ, AD7151BRMZ-REEL | P19-P21

AD7151

Rev. 0 | Page 18 of 28

SETUP REGISTER

Address Pointer 0x0B

8 Bits, Read/Write, Factory Preset 0x0B

Table 10. Setup Register Bit Map

Bit Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Mnemonic RngH RngL –

Hyst

ThrSettling (4-Bit Value)

Default 0 0 0 0 0x0B

Table 11. Setup Register Bit Descriptions

Bit Mnemonic Description

Range bits set the CDC input range and determine the step for the AutoDAC function.

RngH RngL Capacitive Input Range (pF) AutoDAC Step (CAPDAC LSB)

0 0 2 4

0 1 0.5 1

1 0 1 2

RngH

RngL

1 1 4 8

5 – This bit should be 0 for the specified operation.

Hyst Hyst = 1 disables hysteresis in adaptive threshold mode. This bit has no effect in fixed threshold mode;

hysteresis is always disabled in the fixed threshold mode.

ThrSettling

Determines the settling time constant of the data average and thus the settling time of the adaptive

thresholds.

The response of the average to an input capacitance step change (that is, response to the change in the CDC

output data) is an exponential settling curve characterized by the following equation:

)1()0()(

/ TimeConstN

eChangeAverageNAverage −+=

where:

Average(N) is the value of average N complete CDC conversion cycles after a step change on the input

Average(0) is the value before the step change

TimeConst can be selected in the range between 2 and 65,536 conversion cycle multiples, in steps of power of

2, by programming the ThrSettling bits.

)1(

gThrSettlin

TimeConst

See

Figure 39.

INPUT CAPACITANCE

(CDC DATA) CHANGE

DATA AVERAGE RESPONSE

TIME

07086-028

Figure 39. Data Average Response to Data Step Change

AD7151

Rev. 0 | Page 19 of 28

CONFIGURATION REGISTER

Address Pointer 0x0F

8 Bits, Read/Write, Factory Preset 0x19

Table 12. Configuration Register Bit Map

Bit Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Mnemonic ThrFixed ThrMD1 ThrMD0 EnConv – MD2 MD1 MD0

Default 0 0 0 1 0 0 0 1

Table 13.Configuration Register Bit Descriptions

Bit Mnemonic Description

7 ThrFixed

ThrFixed = 1 sets the fixed threshold mode. The output reflects comparison of data and a fixed (constant) value

of the threshold register.

ThrFixed = 0 sets the adaptive threshold mode. The output reflects comparison of data to the adaptive

threshold. The adaptive threshold is set dynamically, based on the history of the previous data.

These bits set the output comparator mode.

Output Active When

ThrMD1 ThrMD0 Threshold Mode Adaptive Threshold Mode Fixed Threshold Mode

0 0 Negative data < average – sensitivity Data < Threshold

0 1 Positive data > average + sensitivity Data > Threshold

1 0 In-Window data > average – sensitivity

AND

data < average + sensitivity

ThrMD1

ThrMD0

1 1 Out-Window data < average – sensitivity

data > average + sensitivity

4 EnConv Enables conversion. This bit must be 1 for proper operation.

3 – This bit must be 0 for proper operation.

Converter mode of operation setup.

MD2 MD1 MD0 Mode Description

0 0 0 Idle Part is fully powered up but performing no conversion.

0 0 1

Continuous

Conversion

Part is repeatedly performing conversions, provided the

EnConv bit is set.

0 1 0 Single Conversion

Part performs a single conversion, provided the EnConv bit

is set. After finishing the conversion(s), the part goes to the

idle mode.

0 1 1 Power-Down

Powers down the on-chip circuits, except the digital

interface.

MD2

MD1

MD0

1 X X Reserved Do not use these modes.

AD7151

Rev. 0 | Page 20 of 28

POWER-DOWN TIMER REGISTER

Address Pointer 0x10

8 Bits, Read/Write, Factory Preset 0x00

Table 14. Power-Down Timer Register Bit Map

Bit Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Mnemonic – – Power-Down Timeout (6-Bit Value)

Default 0 0 0x00

Table 15. Power-Down Timer Register Bit Descriptions

Bit Mnemonic Description

[7:6] - These bits must be 0 for proper operation

[5:0]

Power-Down

Timeout

Defines the period duration of the power-down timeout.

If the output comparator output has not been activated during the programmed period, the part enters power-

down mode automatically. The part can be then returned to a normal operational mode either via the serial

interface or by the power supply off/on sequence.

The period is programmable in steps of four hours. For example, setting the value to 0x06 sets the duration to

24 hours. The maximum value of 0x3F corresponds to approximately 10.5 days.

The value of 0x00 disables the power-down timeout, and the part does not enter power-down mode

automatically.

CAPDAC REGISTER

Address Pointer 0x11

8 Bits, Read/Write, Factory Preset 0x00

Table 16. CAPDAC Register Bit Map

Bit Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Mnemonic DacEn DacAuto DacValue (6-Bit Value)

Default 1 1 0x00

Table 17. CAPDAC Register Bit Descriptions

Bit Mnemonic Description

7 DacEn DacEn = 1 enables capacitive DAC.

6 DacAuto DacAuto = 1 enables the AutoDAC function in the adaptive threshold mode.

When the AutoDAC function is enabled, the part dynamically adjusts the CAPDAC to keep the CDC in an

optimal operating capacitive range. The CAPDAC value is automatically incremented when the data average

exceeds ¾ of the CDC full range, and the CAPDAC value is decremented when the data average goes below ¼

of the CDC full range. The AutoDAC increment or decrement step depends on the selected CDC capacitive

input range.

Bit has no effect in fixed threshold mode; the AutoDAC function is always disabled in the fixed threshold mode.

[5:0] DacValue

CAPDAC value, Code 0x00

≈ 0 pF, Code 0x3F ≈ CAPDAC full range.

SERIAL NUMBER REGISTER

Address Pointer 0x13, 0x14, 0x15, 0x16

32 Bits, Read Only, 0xXXXX

This register holds a serial number, unique for each individual part.

CHIP ID REGISTER

Address Pointer 0x17

8 Bits, Read Only, 0xXX

This register holds the chip identification code, used in factory

manufacturing and testing.

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24 P25-P27 P28-P29

AD7151BRMZ-REEL

Mfr. #:

Buy AD7151BRMZ-REEL

Manufacturer:

Analog Devices Inc.

Description:

Data Acquisition ADCs/DACs - Specialized 1-CH Cap Proximity Sensor Inter IC

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AD7151BRMZ-REEL

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