ADC128D818CIMTX/NOPB - NATIONAL SEMICONDUCTOR

ADC128D818

ADC128D818 12-Bit, 8-Channel, ADC System Monitor with Temperature Sensor,

Internal/External Reference, and I 2 C Interface

Literature Number: SNAS483D

ADC128D818

January 10, 2011

12-Bit, 8-Channel, ADC System Monitor with Temperature

Sensor, Internal/External Reference, and I2C Interface

1.0 General Description

The ADC128D818 I2C™ system monitor is designed for max-

imum flexibility. The system monitor can be configured for

single-ended and/or pseudo-differential inputs. An on-board

temperature sensor, combined with WATCHDOG window

comparators, and an interrupt output pin, INT, allow easy

monitoring and out-of-range alarms for every channel. A high

performance internal reference is also available to provide for

a complete solution in the most difficult operating conditions.

The ADC128D818’s 12-bit delta-sigma ADC supports Stan-

dard Mode (Sm, 100 kbits/s) and Fast Mode (Fm, 400kbits/s)

I2C interfaces. The ADC128D818 includes a sequencer to

control channel conversions and stores all converted results

in independent registers for easy microprocessor retrieval.

Unused channels can be shut down independently to con-

serve power.

The ADC can use either an internal 2.56V reference or a vari-

able external reference. An analog filter is included on the

I2C digital control lines to provide improved noise immunity.

The device also includes a TIMEOUT reset function on SDA

and SCL to prevent I2C bus lock-up.

The ADC128D818 operates from +3.0 to +5.5V power supply

voltage range, –40°C to 125°C temperature range, and the

device is available in a 16-pin TSSOP package.

2.0 Applications

■Communications Infrastructure

■Thermal / Hardware Server Monitors

■System Monitors

■Industrial and Medical Systems

■Electronic Test Equipment and Instrumentation

■Power Supply Monitoring / Supervision

3.0 Features

■12-bit Resolution Delta-Sigma ADC

■Local Temperature Sensing

■Configurable Single-Ended and/or Pseudo-Diff. Inputs

■+2.56V Internal VREF or Variable External VREF

■WATCHDOG Window Comparators with Status and Mask

Registers of All Measured Values

■Independent Registers for Storing Measured Values

■INT Output Notifies Microprocessor of Error Event

■I2C Serial Bus Interface Compatibility

■9 Selectable Addresses

■TIMEOUT Reset Function to Prevent I2C Bus Lock-Up

■Individual Channel Shutdown to Limit Power Consumption

■Deep Shutdown Mode to Minimize Power Consumption

■TSSOP 16-Lead Package

4.0 Key Specifications

■ ADC Resolution 12-bit

■ Supply Voltage Range +3.0V to +5.5V

■ Total Unadjusted Error –0.45/+0.2%

■ Integral Non-Linearity ±1LSb

■ Differential Non-Linearity ±1LSb

■ Operating Current 0.56 mA

■ Deep Shutdown Current 10 µA

■ Temperature Resolution 0.5°C/LSb

■ Temp. Accuracy (–40°C to 125°C) ± 3°C

■ Temp. Accuracy (–25°C to 100°C) ± 2°C

5.0 Typical Application

30096301

I2C® is a registered trademark of the Philips Corporation.

ADC128D818 12-Bit, 8-Channel, ADC System Monitor with Temperature Sensor, Internal/

External Reference, and I2C Interface

6.0 Ordering Information

Temperature Range

–40°C ≤ TA ≤ +125°C NS

Package

Number

Specified

Power

Supply

Voltage

Order Number Device Marking

ADC128D818CIMT

ADC128D818CIMTX

ADC128D81

8CIMT MO-153 +3.0V to

+5.5V

6.0 Connection Diagram

30096302

7.0 Pin Descriptions

Number

Name(s)

ESD

Structure Type Description

1 VREF Analog Input

ADC external reference.

ADC128D818 allows two choices for sourcing VREF:

internal or external. If the +2.56V internal VREF is used,

leave this pin unconnected. If the external VREF is used,

source this pin with a voltage between +1.25V and V+. At

Power-On-Reset (POR), the default setting is the internal

VREF.

Bypass with the parallel combination of 1 μF (electrolytic

or tantalum) and 0.1 μF (ceramic) capacitors.

2 SDA Digital I/O Serial Bus Bidirectional Data. NMOS open-drain output.

Requires external pull-up resistor to function properly.

3 SCL Digital Input Serial Bus Clock. Requires external pull-up resistor to

function properly.

4 GND GROUND Internally connected to all of the circuitry.

5V+POWER

+3.0V to +5.5V power. Bypass with the parallel

combination of 1 μF (electrolytic or tantalum) and

0.1 μF (ceramic) bypass capacitors.

6 INT Digital Output Interrupt Request. Active Low, NMOS, open-drain.

Requires external pull-up resistor to function properly.

7 - 8 A0 - A1 Tri-Level Inputs Tri-Level Serial Address pins that allow 9 devices on a

single I2C bus.

9 - 16 IN7 - IN0 Analog Inputs

The full scale range will be controlled by the internal or

external VREF. These inputs can be assigned as single-

ended and/or pseudo-differential inputs.

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ADC128D818

8.0 Block Diagram

30096303

9.0 Product Highlights

The maximum number of channels that can be enabled for each input mode are shown in the table below. Unusued channels may

be disabled through software.

TABLE 1. Input Modes

Modes of

Operation

Single-Ended Inputs Pseudo-Differential

Inputs

Internal Temperature

Measurement

Cycle Time with Maximum

Number of Channels Enabled

(ms - typ).

0 7 - 1 88

1 8 - - 96

2 - 4 1 52

3 4 2 1 76

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ADC128D818

TABLE 2. Conversion Modes

Conversion Modes Description

Continuous Enabled channels are measured continuously.

Low Power

Enabled channels are measured, then the device is automatically placed into shutdown

mode. This cycle is repeated every 728 ms.

One-Shot

When One-Shot Register (address 09h) is programmed while the device is in shutdown or

deep shutdown mode, the device will initiate a single conversion and comparison cycle, after

which the device returns to the respective mode it was in.

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ADC128D818

10.0 Absolute Maximum Ratings (Note

1, Note 2)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

Supply Voltage (V+): 6.0V

Voltage on SCL, SDA, A0, A1, INT: –0.3V to 6.0V

Voltage on IN0-IN7, VREF: –0.3V to (V+ + 0.3)V

and ≤ 6.0V

Input Current at Any Pin (Note 3): ±5 mA

Package Input Current (Note 3): ±30 mA

Maximum Junction Temperature

(TJMAX): (Note 4)150°C

ESD Susceptibility (Note 6)

Human Body Model: 3,000V

Machine Model: 300V

Charged Device Model: 1,000V

Storage Temperature –65°C to +150°C

For soldering specifications,

see product folder at www.national.com and

www.national.com/ms/MS/MS-SOLDERING.pdf

11.0 Operating Ratings (Note 1, Note 2)

Supply Voltage (V+): 3.0V to 5.5V

Voltage on SCL, SDA, A0, A1, INT: –0.05V to 5.5V

Voltage on IN0-IN7, VREF: –0.05V to (V+ + 0.05)V and

≤ 5.5V

Temperature Range for Electrical

Characteristics:

TMIN = –40°C

TMAX = 125°C

Operating Temperature Range: –40°C ≤ TA ≤ +125°C

Junction to Ambient Thermal

Resistance (θJA): (Note 5)130°C/W

12.0 DC Electrical Characteristics

The following specifications apply for +3.0 VDC ≤ V+ ≤ +5.5 VDC , External VREF = +2.56V, unless otherwise specified. Boldface

limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C (Note 7).

Symbol Parameter Conditions Min

(Note 9)

Typical

(Note 8)

Max

(Note 9)

Units

POWER SUPPLY CHARACTERISTICS

V+Supply Voltage 3.0 3.3 or 5.0 5.5 V

VREF

External Reference Voltage 1.25 2.56 V+ V

Internal Reference Voltage 2.56 V

23 ppm/°C

I+

Supply Current (see the "Power

Management" section for more

information).

Interface Inactive, V+ = 5.5V, Mode 2 0.74 mA

Interface Inactive, V+ = 3.6V, Mode 2 0.56 mA

Shutdown Mode, V+ = 5.5V 0.65 mA

Shutdown Mode, V+ = 3.6V 0.48 mA

Deep Shutdown Mode (Note 10). 10 µA

TEMPERATURE-to-DIGITAL CONVERTER CHARACTERISTICS

Temperature Error –40°C ≤ TA ≤ +125°C ±3 °C

–25°C ≤ TA ≤ +100°C ±2 °C

Resolution 0.5 °C

ANALOG-to-DIGITAL CONVERTER CHARACTERISTICS

n Resolution 12-bit with full-scale at VREF = 2.56V. 0.625 mV

INL Integral Non-Linearity

External VREF = 1.25V, Pseudo-

Differential, V+ = 3.0V to 3.3V. (Note

10)

–1 0.36 1LSb

External VREF = 2.56V, Pseudo-

Differential –2 1.58 4LSb

External VREF = 5.0V, Pseudo-

Differential, V+ = 5.0V to 5.5V.

DNL Differential Non-Linearity (Note 13)-1 ±0.25 1LSb

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ADC128D818

Symbol Parameter Conditions Min

(Note 9)

Typical

(Note 8)

Max

(Note 9)

Units

TUE Total Unadjusted Error (Note 11)

Internal VREF, Single-Ended,

V+ = 3.0V to 3.6V. –0.5 0.5 % of FS

Internal VREF, Single-Ended,

V+ = 4.5V to 5.5V (Note 12).

Internal VREF, Pseudo-Differential,

V+ = 3.0V to 3.6V or V+ = 4.5V to 5.5V

(Note 12).

–0.3 0.5 % of FS

External VREF = 1.25V, Single-Ended,

V+ = 3.0V to 3.6V. –0.6 0.1 % of FS

External VREF = 2.56V, Single-Ended,

V+ = 3.0V to 5.5V.

External VREF = 1.25V, Pseudo-

Differential, V+ = 3.0V to 3.6V. –0.45 0.2 % of FS

External VREF = 2.56V, Pseudo-

Differential, V+ = 3.0V to 5.5V.

GE Gain Error

Internal VREF, V+ = 3.0V to 3.6V.

–0.25 0.45 % of FS

Internal VREF, V+ = 4.5V to 5.5V (Note

12)

External VREF = 1.25V or 2.56V,

V+ = 3.0V to 3.6V. –0.45 0.2 % of FS

External VREF = 2.56V or 5.0V,

V+ = 4.5V to 5.5V.

OE Offset Error

Internal VREF, Pseudo-

Differential, V+ = 4.5V to 5.5V (Note

12).

–0.15 0.2 % of FS

External VREF = 1.25V or 2.56V,

Single-Ended, V+ = 3.0V to 3.6V. –0.5 0.1 % of FS

External VREF = 2.56V or 5.0V, Single-

Ended, V+ = 4.5V to 5.5V

External VREF = 1.25V or 2.56V,

Pseudo-Differential, V+ = 3.0V to 3.6V. –0.2 0.15 % of FS

External VREF = 2.56V or 5.0V,

Pseudo-Differential, V+ = 4.5V to 5.5V

Continuous Conversion Mode Each Enabled Voltage Channel 12 ms

Internal Temperature Sensor 3.6 ms

Low Power Conversion Mode Enabled Voltage Channel(s) and

Internal Temperature Sensor 728 ms

MULTIPLEXER / ADC INPUT CHARACTERISTICS

RON On Resistance 2 10 kΩ

ION

Input Current (On Channel

Leakage Current) ±0.005 μA

IOFF Off Channel Leakage Current ±0.005 μA

DIGITAL OUTPUTS: INT

VOUT(0) Logical “0” Output Voltage IOUT = +5.0 mA at V+ = +4.5V,

IOUT = +3.0 mA at V+ = +3.0V 0.4 V

OPEN DRAIN SERIAL BUS OUTPUT: SDA

VOUT(0) Logical “0” Output Voltage IOUT = +3.0 mA at V+ = +4.5V, 0.4 V

IOH High Level Output Current VOUT = V+ 0.005 1μA

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ADC128D818

Symbol Parameter Conditions Min

(Note 9)

Typical

(Note 8)

Max

(Note 9)

Units

DIGITAL INPUTS: A0 and A1

VIN(1) Logical “1” Input Voltage 0.90 x V+ 5.5 V

VIM Logical Middle Input Voltage 0.43 x V+ 0.57 x V+

VIN(0) Logical “0” Input Voltage GND -

0.05

0.10 x V+ V

SERIAL BUS INPUTS: SCL and SDA

VIN(1) Logical “1” Input Voltage 0.7 × V+ 5.5 v

VIN(0) Logical “0” Input Voltage GND -

0.05 0.3 × V+V

VHYST Hysteresis Voltage V+ = +3.3V 0.67 V

V+ = +5.5V 1.45 V

ALL DIGITAL INPUTS: SCL, SDA, A0, A1

IIN(1) Logical “1” Input Current VIN = V+−1 – 0.005 µA

IIN(0) Logical “0” Input Current VIN = 0 VDC 0.005 1µA

CIN Digital Input Capacitance 20 pF

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ADC128D818

13.0 AC Electrical Characteristics

The following specifications apply for +3.0 VDC ≤ V+ ≤ +5.5 VDC , unless otherwise specified. Boldface limits apply for TA = TJ

= TMIN to TMAX; all other limits TA = TJ = 25°C.

Symbol Parameter Conditions Min Typical Max Units

(Note 9) (Note 8) (Note 9)

SERIAL BUS TIMING CHARACTERISTICS

t1SCL (Clock) Period 2.5 100 µs

t2Data In Setup Time to SCL High 100 ns

t3Data Out Stable After SCL Low 0 ns

t4SDA Low Setup Time to SCL Low (start) 100 ns

t5SDA High Hold Time After SCL High (stop) 100 ns

tTIMEOUT SCL or SDA time low for I2C bus reset 25 35 ms

30096326

FIGURE 1. Serial Bus Timing Diagram

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed

specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test

conditions.

Note 2: All voltages are measured with respect to GND, unless otherwise specified.

Note 3: If the input voltage at any pin exceeds the power supply ( that is, VIN < GND or VIN > V +) but is less than the absolute maximum ratings, then the current

at that pin should be limited to 5mA. The 30 mA maximum package input current rating limits the number of pins that can safely exceed the power supply with

an input current of 5mA to six pins. Parasitic components and/or ESD protection circuitry are shown in the Pin Descriptions table.

Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA and the ambient temperature, TA. The maximum

allowable power dissipation at any temperature is PD = (TJMAX − T A) / θJA.

Note 5: For the given θJA, the device is on a 2-layer printed circuit board with 1 oz. copper foil and no airflow.

Note 6: Human body model (HBM) is a charged 100pF capacitor discharged into a 1.5kΩ resistor. Machine model (MM) is a charged 200pF capacitor discharged

directly into each pin. Charged Device Model (CDM) simulates a pin slowly acquiring charge (such as from a device sliding down the feeder in an automated

assembler) then rapidly being discharged.

Note 7: Each input and output is protected by an ESD structure to GND, as shown in the Pin Descriptions table. Input voltage magnitude up to 0.3V above V+ or

0.3V below GND will not damage the ADC128D818. There are diodes that exist between some inputs and the power supply rails. Errors in the ADC conversion

can occur if these diodes are forward biased by more than 50mV. As an example, if V+ is 4.50 VDC, INx (where 0 ≤ x ≤ 7) must be ≤ 4.55 VDC to ensure accurate

conversions.

Note 8: Typicals are at TJ = TA = 25°C and represent most likely parametric norm.

Note 9: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).

Note 10: Limit is guaranteed by characterization.

Note 11: TUE (Total Unadjusted Error) includes Offset, Gain and Linearity errors of the ADC.

Note 12: The range is up to 7/8 of full scale.

Note 13: Limit is guaranteed by design.

Note 14: Timing specifications are tested at the Serial Bus Input logic levels: VIN(0) = 0.3 × V+ for a falling edge and VIN(1) = 0.7 × V+ for a rising edge if the SCL

and SDA edge rates are similar.

——

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ADC128D818

14.0 Typical Performance Characteristics The following typical performance plots apply for the

internal VREF = 2.56V, V+ = 3.3V, Pseudo-Differential connection, unless otherwise specified. Boldface limits apply for TA =

TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. (Note 14)

TUE vs. Code

30096346

TUE vs. Code (External VREF = 1.25V)

30096347

TUE vs. Code (External VREF = 2.56V)

30096348

TUE vs. Code (External VREF = 5V, V+ = 5V)

30096349

INL vs. Code (External VREF = 1.25V for 1 Unit)

30096350

INL vs. Code (External VREF = 1.25V for 28 Units)

30096371

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ADC128D818

INL vs. Code (External VREF = 2.56V for 1 Unit)

30096351

INL vs. Code (External VREF = 2.56V for 28 Units)

30096372

INL vs. Code (External VREF = 5V, V+ = 5V for 1 Unit)

30096352

INL vs. Code (External VREF = 5V, V+ = 5V for 28 Units)

30096373

DNL vs. Code (External VREF = 2.56V for 1 Unit)

30096354

DNL vs. Code (External VREF = 2.56V for 28 Units)

30096355

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ADC128D818

Offset Error vs. V+

30096356

Offset Error vs. Temperature

30096358

Gain Error vs. V+

30096360

Gain Error vs. Temperature

30096362

I+ vs. Temperature

30096364

I+ vs. V+ Typical

30096365

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ADC128D818

I+ vs. V+ for Voltage Conversion

30096366

I+ vs. V+ for Temperature Conversion

30096367

I+ vs. V+ in Shutdown Mode

30096368

I+ vs. V+ in Deep Shutdown Mode

30096369

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ADC128D818

15.0 Functional Description

15.1 GENERAL DESCRIPTION

The ADC128D818 provides 8 analog inputs, a temperature

sensor, a delta-sigma ADC, an external or internal VREF op-

tion, and WATCHDOG registers on a single chip. An I2C

Serial Bus interface is also provided. The ADC128D818 can

perform voltage and temperature monitoring for a variety of

systems.

The ADC128D818 continuously converts the voltage input to

12-bit resolution with an internal VREF of 0.625mV LSb

(Least Significant bit) weighting, yielding input range of 0V to

2.56V. There is also an external VREF option that ranges from

1.25V to V+. The analog inputs are intended to be connected

to several power supplies present in a variety of systems.

Eight inputs can be configured for single-ended and/or pseu-

do-differential channels. Temperature can be converted to a

9-bit two's complement word with resolutions of 0.5°C per

LSb.

The ADC128D818 provides a number of internal registers.

These registers are summarized in the "ADC128D818 Inter-

nal Registers" section.

The ADC128D818 supports Standard Mode (Sm, 100kbits/s)

and Fast Mode (Fm, 400kbits/s) I2C interface modes of op-

eration. ADC128D818 includes an analog filter on the I2C

digital control lines that allows improved noise immunity. The

device also supports TIMEOUT reset function on SDA and

SCL to prevent I2C bus lock-up. Two tri-level address pins

allow up to 9 devices on a single I2C bus.

At start-up, ADC128D818 cycles through each measurement

in sequence and continuously loops through the sequence

based on the Conversion Rate Register (address 07h) set-

ting. Each measured value is compared to values stored in

the Limit Registers (addresses 2Ah - 39h). When the mea-

sured value violates the programmed limit, the ADC128D818

will set a corresponding interrupt bit in the Interrupt Status

Registers (address 01h). An interrupt output pin, INT, is also

available and fully programmable.

15.2 SUPPLY VOLTAGE (V+)

The ADC128D818 operates with a supply voltage, V+, that

has a range between +3.0V to +5.5V. Care must be taken to

bypass this pin with a parallel combination of 1 µF (electrolytic

or tantalum) capacitor and 0.1 µF (ceramic) bypass capacitor.

15.3 VOLTAGE REFERENCES (VREF)

The reference voltage (VREF) sets the analog input range.

The ADC128D818 has two options for setting VREF. The first

option is to use the internal VREF, which is equal to 2.56V.

The second option is to source VREF externally via pin 1 of

ADC128D818. In this case, the external VREF will operate in

the range of 1.25V to V+. The default VREF selection is the

internal VREF. If the external VREF is preferred, use the Ad-

vanced Configuration Register (address 0Bh) to change this

setting.

VREF source must have a low output impedance and needs

to be bypassed with a minimum capacitor value of 0.1 µF. A

larger capacitor value of 1 µF placed in parallel with the

0.1 µF is preferred. VREF of the ADC128D818, like all ADC

converters, does not reject noise or voltage variations. Keep

this in mind if VREF is derived from the power supply. Any

noise and/or ripple from the supply that is not rejected by the

external reference circuitry will appear in the digital results.

The use of a reference source is recommended. The LM4040

and LM4050 shunt reference families as well as the LM4120

and LM4140 series reference families are excellent choices

for a reference source.

15.4 ANALOG INPUTS (IN0 - IN7)

The ADC128D818 allows up to 8 single-ended inputs or 4

pseudo-differential inputs as selected by the modes of oper-

ation. The input types are described in the next subsections.

15.4.1 Single-Ended Input

ADC128D818 allows a maximum of 8 single-ended inputs,

where the source's voltage is connected to INx (0 ≤ x ≤ 7).

The source’s ground should be connected to ADC128D818’s

GND pin. In theory, INx can be of any value between 0V and

(VREF-3LSb/2), where LSb = VREF/212.

To use the device single-endedly, refer to the "Modes of Op-

eration" section and to bits [2:1] of the Advanced Configura-

tion Register (address 0Bh). Figure 2 shows the appropriate

configuration for a single-ended connection.

30096331

FIGURE 2. Single-Ended Configuration

15.4.2 Pseudo-Differential Input

Pseudo-differential mode is defined as the positive input volt-

age applied differentially to the ADC128D818, as shown in

Figure 3. The input that is digitized is (ΔVIN = IN+ - IN-), where

(IN+ - IN-) is (IN0-IN1), (IN3-IN2), (IN4-IN5), or (IN7-IN6). Be

aware of this input configuration because the order is

swapped. In theory, ΔVIN can be of any value between 0V

and (VREF-3LSb/2),where LSb = VREF/212.

By using this pseudo-differential input, small signals common

to both inputs are rejected. Thus, operation with a pseudo-

differential input signal will provide better performance than

with a single-ended input. Refer to the "Modes of Operation"

section for more information.

30096332

FIGURE 3. Pseudo-Differential Configuration

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ADC128D818

15.4.3 Modes of Operation

ADC128D818 allows 4 modes of operation, as summarized

in the following table. Set the desired mode of operation using

the Advanced Configuration Register (address 0Bh, bits

[2:1]).

TABLE 3. Modes of Operation

Ch. Mode 0 Mode 1 Mode 2 Mode 3

1 IN0 IN0

IN0 (+) &

IN1 (-) IN0

2 IN1 IN1

IN3 (+) &

IN2 (-) IN1

3 IN2 IN2

IN4 (+) &

IN5 (-) IN2

4 IN3 IN3

IN7 (+) &

IN6 (-) IN3

5 IN4 IN4

IN4 (+) &

IN5 (-)

6 IN5 IN5

IN7 (+) &

IN6 (-)

7 IN6 IN6

8 nc* IN7

Local

Temp Yes No Yes Yes

* nc = No Connect

15.5 DIGITAL OUTPUT (DOUT)

The digital output code for a 12-bit ADC can be calculated as:

DOUT = [ΔVIN / VREF] x 212

For the above equation, ΔVIN = INx - GND, where 0 ≤ x ≤ 7,

for the single-ended configuration, and ΔVIN = (IN+ - IN-) for

the pseudo-differential configuration. In theory, ΔVIN can be

of any value between 0V and (VREF-3LSb/2). Any ΔVIN val-

ue outside of this range will produce a digital output code of

0 or 4095. Figure 4 shows a theoretical plot of DOUT vs. ΔVIN

and some sample DOUT calculation using the equation above.

30096333

FIGURE 4. DOUT vs ΔVIN for a 12-bit ADC assuming VREF = 2.56V.

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ADC128D818

15.6 POWER MANAGEMENT

To understand the average supply current (I+), the conversion

rates must be introduced. ADC128D818 has three types of

conversion rates: Continuous Conversion Mode, Low Power

Conversion Mode, and One Shot Mode. In the Low Power

Conversion Mode, the device converts all of the enabled

channels then enters shutdown mode; this process takes ap-

proximately 728 ms to complete. (More information on the

conversion rate will be discussed in the "Conversion Rate

09h)" sections).

Each type of conversion produces a different average supply

current. The supply current for a voltage conversion will be

referred to as I+_VOLTAGE, a temperature conversion as

I+_TEMP, and the shutdown mode as I+_SHUTDOWN.

These values can be obtained from Typical Performance

Characteristics plots.

In general, I+ is the average supply current while

ADC128D818 is operating in the Low Power Conversion

Mode with all of the available channels enabled. Its plot can

be seen in the "Typical Performance Characteristic" section

and its equation is shown below.

30096345

FIGURE 5. I+ Equation

Where "a" is the number of local temperature available, and

"b" is the number of ENABLED voltage channel. Each mode

of operation has a different "a" and "b" values. The following

table shows the value for "a" and the maximum value for "b"

for each mode.

TABLE 4. "a" and "b" Values

a b (Max)

Mode 0 1 7

Mode 1 0 8

Mode 2 1 4

Mode 3 1 6

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ADC128D818

15.7 INTERFACE

The Serial Bus control lines include the SDA (serial data),

SCL (serial clock), and A0-A1 (Serial Bus Address) pins. The

ADC128D818 can only operate as a slave. The SCL line only

controls the serial interface, and all of other clock functions

within ADC128D818 are done with a separate asynchronous

internal clock.

When the Serial Bus Interface is used, a write will always

consists of the ADC128D818 Serial Bus Address byte, fol-

lowed by the Register Address byte, then the Data byte.

Figure 6 and Figure 7 are two examples showing how to write

to the ADC128D818.

There are two cases for a read:

1. If the Register Address is known to be at the desired

address, simply read the ADC128D818 with the Serial

Bus Address byte, followed by the Data byte read from

the ADC128D818. Examples of this type of read can be

seen in Figure 8 and Figure 9.

2. If the Register Address value is unknown, write to the

ADC128D818 with the Serial Bus Address byte, followed

by the desired Register Address byte. Then restart the

Serial Communication with a Read consisting of the

Serial Bus Address byte, followed by the Data byte read

from the ADC128D818. See Figure 10 and Figure 11 for

examples of this type of read.

The Serial Bus Address can be found in the next section, and

the Register Address can be found in the "Register Map" sec-

tion. For more information on the I2C Interface, refer to NXP's

"I2C-Bus Specification and User Manual", rev. 03.

15.7.1 Serial Bus Address

There are nine different configurations for the ADC128D818

Serial Bus Address, thus nine devices are allowed on a single

I2C bus. Examples to set each address bit low, high, or to

midscale can be found in the "Example Applications" section.

The Serial Bus Address can be set as follows:

TABLE 5. Serial Bus Address Table

A1 A0

Serial Bus

Address

[A6][A5][A4]...[A0]

Serial Bus

Address (hex)

LOW LOW 001_1101b 1Dh

LOW MID 001_1110b 1Eh

LOW HIGH 001_1111b 1Fh

MID LOW 010_1101b 2Dh

MID MID 010_1110b 2Eh

MID HIGH 010_1111b 2Fh

HIGH LOW 011_0101b 35h

HIGH MID 011_0110b 36h

HIGH HIGH 011_0111b 37h

15.7.2 Timeout

The ADC128D818 I2C state machine resets to its idle state if

either SCL or SDA is held low for longer than 35ms. This fea-

ture also ensures that ADC128D818 will automatically re-

lease SDA after driving it low continuously for 25-35ms, hence

preventing I2C bus lock-up. The TIMEOUT feature should not

be used when the device is operating in deep shutdown

mode.

15.7.3 Example Writes and Reads

30096309

FIGURE 6. Serial Bus Interface Write Example 1 - Internal Address Register Set Only.

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ADC128D818

30096308

FIGURE 7. Serial Bus Interface Write Example 2 - Internal Address Register Set with Data Byte Write.

30096310

FIGURE 8. Serial Bus Interface Read Example 1 - Single Byte Read with Preset Internal Address Register.

30096322

FIGURE 9. Serial Bus Interface Read Example 2 - Double Byte Read with Preset Internal Address Register.

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ADC128D818

30096324

FIGURE 10. Serial Bus Interface Read Example 3 - Single Byte Read with Internal Address Set using a Repeat Start.

30096323

FIGURE 11. Serial Bus Interface Read Example 4 - Double Byte Read with Internal Address Set using a Repeat Start.

www.national.com 18

ADC128D818

15.8 USING THE ADC128D818

15.8.1 ADC128D818 Internal Registers

TABLE 6. ADC128D818 Internal Registers

Write

Address

(hex)

Default Value

[7:0] Register Description Register

Format

Configuration Register R/W 00h 0000_1000 Provides control and configuration 8-bit

Interrupt Status Register R 01h 0000_0000 Provides status of each WATCHDOG limit or

interrupt event 8-bit

Interrupt Mask Register R/W 03h 0000_0000 Masks the interrupt status from propagating to INT 8-bit

Conversion Rate Register R/W 07h 0000_0000 Controls the conversion rate 8-bit

Channel Disable Register R/W 08h 0000_0000 Disables conversion for each voltage or temperature

channel 8-bit

One-Shot Register W 09h 0000_0000 Initiates a single conversion of all enabled channels 8-bit

Deep Shutdown Register R/W 0Ah 0000_0000 Enables deep shutdown mode 8-bit

Advanced Configuration

operation 8-bit

Busy Status Register R 0Ch 0000_0010 Reflects the ADC128D818 'Busy' and 'Not Ready'

statuses 8-bit

Channel Readings

Registers R 20h - 27h - - - Report channels (voltage or temperature) readings 16-bit

Limit Registers R/W 2Ah - 39h - - - Set the limits for the voltage and temperature

channels 8-bit

Manufacturer ID Register R 3Eh 0000_0001 Reports the manufacturer's ID 8-bit

Revision ID Register R 3Fh 0000_1001 Reports the revision's ID 8-bit

15.8.2 Quick Start

1. Power on the device, then wait for at least 33ms.

2. Read the Busy Status Register (address 0Ch). If the 'Not

Ready' bit = 1, then increase the wait time until 'Not

Ready' bit = 0 before proceeding to the next step.

3. Program the Advanced Configuration Register (address

0Bh):

a. Choose to use the internal or external VREF (bit 0).

b. Choose the mode of operation (bits [2:1]).

4. Program the Conversion Rate Register (address 07h).

5. Choose to enable or disable the channels using the

Channel Disable Register (address 08h).

6. Using the Interrupt Mask Register (address 03h), choose

to mask or not to mask the interrupt status from

propagating to the interrupt output pin, INT.

7. Program the Limit Registers (addresses 2Ah – 39h).

8. Set the ‘START’ bit of the Configuration Register

(address 00h, bit 0) to 1.

9. Set the 'INT_Clear' bit (address 00h, bit 3) to 0. If needed,

program the 'INT_Enable' bit (address 00h, bit 1) to 1 to

enable the INT output.

The ADC128D818 then performs a round-robin monitoring of

enabled voltage and temperature channels. The sequence of

items being monitored corresponds to locations in the Chan-

nel Readings Registers (except for the temperature reading).

Detailed descriptions of the register map can be found at the

end of this datasheet.

15.8.3 Power On Reset (POR)

When power is first applied, the ADC128D818 performs a

power on reset (POR) on several of its registers, which sets

the registers to their default values. These default values are

shown in the table above or in the "Register Map" section.

Registers whose default values are not shown have power on

conditions that are indeterminate.

15.8.4 Configuration Register (address 00h)

The Configuration Register (address 00h) provides all control

to the ADC128D818. After POR, the 'START' bit (bit 0) is set

low and the 'INT_Clear' bit (bit 3) is set high.

The Configuration Register has the ability to start and stop the

ADC128D818, enable and disable the INT output, and set the

registers to their default values.

•Bit 0, ‘START’, controls the monitoring loop of the

ADC128D818. After POR, set this bit high to start

conversion. Setting this bit low stops the ADC128D818

monitoring loop and puts the ADC128D818 in shutdown

mode; thus, reducing power consumption. Even though

this bit is set low, serial bus communication is possible with

any register in the ADC128D818.

After an interrupt occurs, the INT pin will not be cleared if

the user sets this bit low.

•Bit 1, 'INT_Enable', enables the interrupt output pin, INT,

when this bit is set high.

•Bit 3, 'INT_Clear', clears the interrupt output pin, INT,

when this bit is set high. When this bit is set high, the

ADC128D818 monitoring function will stop. The content of

the Interrupt Status Register (address 01h) will not be

affected.

•Bit 7, ‘INITIALIZATION’, accomplishes the same function

as POR, that is, it initializes some of the registers to their

default values. This bit automatically clears after being set

high. Setting this bit high, however, does not reset the

Channel Readings Registers (addresses 20h - 27h) and

19 www.national.com

ADC128D818

the Limit Registers (addresses 2Ah - 39h). These registers

will be indeterminate immediately after power on. If the

Channel Readings Registers contain valid conversion

results and/or the Limit Registers have been previously

set, they will not be affected by this bit.

15.8.5 Interrupt Status Register (address 01h)

Each bit in this read-only register indicates whether the volt-

age reading > the voltage high limit or ≤ the voltage low limit,

or the temperature reading > the temperature high limit. For

example, if "IN0 High Limit" register (address 2Ah) were set

to 2V and if IN0 reading (address 20h) were 2.56V, then bit

'IN0 Error' would be 1, indicating that the voltage high limit has

been exceeded.

15.8.6 Interrupt Mask Register (address 03h)

This register masks the interrupt status from propagating to

the interrupt output pin, INT. For example, if bit 'IN0 Mask' =

1, then the interrupt output pin, INT, would not be pulled low

even if an error event occurs at IN0.

15.8.7 Conversion Rate Register (address 07h)

There are three options for controlling the conversion rate.

The first option is called the Low Power Conversion Mode,

where the device converts all of the enabled channels then

enters shutdown mode. This process takes approximately

728 ms to complete.

The second option is the Continuous Conversion Mode,

where the device continuously converts the enabled chan-

nels, thus never entering shutdown mode. A voltage conver-

sion takes 12.2 ms, and a temperature conversion takes 3.6

ms. For example, if operating in mode 2 and three voltage

channels were enabled, then each round-robin monitor would

take 40.2 ms (3 x 12.2ms + 3.6ms) to complete. Use the

"Channel Disable Register" (address 08h) to disable the de-

sired channel(s).

The third option is called the On-Shot mode, which will be

discussed in the next subsection.

15.8.8 One-Shot Register (address 09h)

The One-Shot register is used to initiate a single conversion

and comparison cycle when the device is in shutdown mode

or deep shutdown mode, after which the device returns to the

respective mode it was in. The obvious advantage of using

this mode is lower power consumption because the device is

operating in shutdown or deep shutdown mode.

This register is not a data register, and it is the write operation

that causes the one-shot conversion. The data written to this

address is irrelevant and is not stored. A zero will always be

read from this register.

15.8.9 Deep Shutdown Register (address 0Ah)

The ADC128D818 can be placed in deep shutdown mode,

thus reducing more power consumption. The procedures for

deep shutdown entrance are:

1. Enter shutdown by setting the ‘START’ bit of the

“Configuration Register’ (address 00h, bit 0) to 0.

2. Enter deep shutdown by setting the ‘DEEP SHUTDOWN’

bit (address 0Ah, bit 0) to 1.

3. A one-shot conversion can be triggered by writing any

values to register address 09h.

Deep Shutdown Exit Procedure:

1. Set the ‘DEEP SHUTDOWN’ bit to 0.

15.8.10 Channel Readings Registers (addresses 20h -

27h)

The channel conversion readings are available in registers

20h to 27h. Each register is 16-bit wide to accommodate the

12-bit voltage reading or 9-bit temperature reading. Conver-

sions can be read at any time and will provide the result of the

last conversion. If a conversion is in progress while a com-

munication is started, that conversion will be completed, and

the Channel Reading Registers will not be updated until the

communication is complete.

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ADC128D818

15.9 TEMPERATURE MEASUREMENT SYSTEM

The ADC128D818 delta-VBE type temperature sensor and

delta-sigma ADC perform 9-bit two's-complement conver-

sions of the temperature. This temperature reading can be

obtained at the Temperature Reading Register (address

27h). This register is 16-bit wide, and thus, all 9 bits of the

temperature reading can be read using a double byte read

(Figure 9 or Figure 11). The following figure and the table be-

low it show the theoretical output code (DOUT) vs. temperature

and some typical temperature-to-code conversions.

30096320

(Non-Linear Scale for Clarity)

FIGURE 12. 9-bit Temperature-to-Digital Transfer Function

Temp Digital Output (DOUT)

Binary [MSb...LSb] Decimal Hex

+125°C 0 _1111_1010 250 0_FA

+25°C 0_0011_0010 50 0_32

+0.5°C 0_0000_0001 1 0_01

+0°C 0_0000_0000 0 0_00

−0.5°C 1_1111_1111 511 1_FF

−25°C 1_1100_1110 462 1_CE

−40°C 1_1011_0000 432 1_B0

In general, the easiest way to calculate the temperature (°C)

is to use the following formulas:

If DOUT[MSb] = 0: +Temp(°C) = DOUT(dec) / 2

If DOUT[MSb] = 1: –Temp(°C) = [29 - DOUT(dec)] / 2

15.9.1 Temperature Limits

One of the ADC128D818 features is monitoring the temper-

ature reading. This monitoring is accomplished by setting a

temperature limit to the Temperature High Limit Register

(Thot , address 38h) and Temperature Hysteresis Limit Reg-

ister (Thot_hyst, address 39h). When the temperature reading

> Thot, an interrupt occurs. How this interrupt occurs will be

explained in the "Temperature Interrupt" section.

Each temperature limit is represented by an 8-bit, two's com-

plement word with an LSb (Least Significant bit) equal to

1°C. The table below shows some sample temperatures that

can be programmed to the Temperature Limit Registers.

In general, use the following equations to calculate the digital

code that represents the desired temperature limit:

If Temp Limit (°C) >= 0: Digital Code (dec) = Temp Limit(°C)

If Temp Limit (°C) < 0: Digital Code (dec) = 28 - |Temp Limit

(°C)|

Temp Limit Digital Code

Binary [MSb...LSb] Decimal Hex

+125°C 0111_1101 125 7D

+25°C 0001_1001 25 19

+1.0°C 0000_0001 1 01

+0°C 0000_0000 0 00

−1.0°C 1111_1111 255 FF

−25°C 1110_1111 231 E7

−40°C 1101_1000 216 D8

21 www.national.com

ADC128D818

15.10 INTERRUPT STRUCTURE

30096318

FIGURE 13. Interrupt Structure

Figure 13 shows the ADC128D818's Interrupt Structure. Note

that the number next to each bit name represents its register

address and bit number. For example, 'INT_Clear' (00h[3])

refers to bit 3 of register address 00h.

15.10.1 Interrupt Output (INT)

ADC128D818 generates an interrupt as a result of each of its

internal WATCHDOG registers on the voltage and tempera-

ture channels. In general, INT becomes active when all three

scenarios, as depicted in Figure 13, occur:

1. 'INT_Clear' (00h[3]) = 0.

2. 'INT_Enable' (00h[1]) = 1 to enable interrupt output.

3. The voltage reading > the voltage high limit or ≤ the

voltage low limit, or the temperature reading > Thot.

15.10.2 Interrupt Clearing

Reading the Interrupt Status Register (addresses 01h) will

output the contents of the register and clear the register.

When the Interrupt Status Register clears, the interrupt output

pin, INT, also clears until this register is updated by the round-

robin monitoring loop.

Another method to clear the interrupt output pin, INT, is setting

'INT_Clear' bit (address 00h, bit 3) = 1. When this bit is high,

the ADC128D818 round-robin monitoring loop will stop.

15.10.3 Temperature Interrupt

One of the ADC128D818 features is monitoring the temper-

ature reading. This monitoring is accomplished by setting a

temperature limit to the Temperature High Limit Register

(Thot , address 38h) and Temperature Hysteresis Limit Reg-

ister (Thot_hyst, address 39h). These limit registers have an

interrupt mode, shown in Figure 14, that operates the the fol-

lowing way: if the temperature reading > Thot, an interrupt will

occur and will remain active indefinitely until reset by reading

the Interrupt Status Register (address 01h) or cleared by the

'INT_Clear' bit.

Once an interrupt event has occurred by crossing Thot, then

reset, an interrupt will occur again once the next temperature

conversion has completed. The interrupts will continue to oc-

cur in this manner until the temperature reading is ≤ Thot_hyst

and a read of the Interrupt Status Register has occurred.

30096317

FIGURE 14. Temperature Response Structure

(Assuming the interrupt output pin, INT, is reset before the next temperature reading)

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ADC128D818

15.11 EXAMPLE APPLICATIONS

15.11.1 General Voltage Monitoring

30096341

FIGURE 15. Typical Analog Input Application

A typical application for ADC128D818 is voltage monitoring.

In this application, the inputs would most often be connected

to linear power supplies of 2.5V, 3.3V, ±5V and ±12V inputs.

These inputs should be attenuated with external resistors to

any desired value within the input range. The attenuation is

done with resistors R1 and R2 for the positive single-ended

voltage, and R3 and R4 for the positive pseudo-differential

voltage.

A typical single-ended application might select the input volt-

age divider to provide 1.9V at the analog input of the AD-

C128D818. This is sufficiently high for good resolution of the

voltage, yet leaves headroom for upward excursions from the

supply of about 25%. To simplify the process of resistor se-

lection, set the value of R2 first. Select a value for R2 between

10 kOhm and 100 kOhm. This is low enough to avoid errors

due to input leakage currents yet high enough to protect both

the inputs under and overdrive conditions as well as minimize

loading of the source. Finally, calculate R1 to provide a 1.9V

input using simple voltage divider derived formula:

R1 = [(VS1 - VIN2) / VIN2 ] x R2

Care should be taken to bypass V+ with decoupling 0.1 µF

ceramic capacitor and 1 µF tantalum capacitor. If using the

external reference option, VREF should be connected to a

voltage reference, such as the LM4140, and should also be

decoupled to the ground plane by a 0.1 µF ceramic capacitor

and a 1 µF tantalum capacitor. For both supplies, the 0.1 µF

capacitor should be located as close as possible to the AD-

C128D818.

Since SDA, SCL, and INT are open-drain pins, they should

have external pull-up resistors to ensure that the bus is pulled

high until a master device or slave device sinks enough cur-

rent to pull the bus low. A typical pull-up resistor, R, ranges

from 1.1 kOhm to 10 kOhm. Refer to NXP's "I2C-Bus Speci-

fication and User Manual" for more information on sizing R.

Because there are two tri-level address pins (A0 and A1), up

to 9 devices can share the same I2C bus. A trick to set these

serial addresses utilizes four GPO (general purpose output)

pins from the master device as shown in the example dia-

gram. A table showing how to program these GPO pins can

be seen below.

23 www.national.com

ADC128D818

TABLE 7. Setting Serial Bus Address using GPO

A1 A0 GPO1 GPO2 GPO3 GPO4

LOW LOW Z LOW Z LOW

LOW MID Z LOW HIGH LOW

LOW HIGH Z LOW HIGH Z

MID LOW HIGH LOW Z LOW

MID MID HIGH LOW HIGH LOW

MID HIGH HIGH LOW HIGH Z

HIGH LOW HIGH Z Z LOW

HIGH MID HIGH Z HIGH LOW

HIGH HIGH HIGH Z HIGH Z

Z = high impedance

15.11.2 Voltage Monitoring for Power Supplies

30096342

FIGURE 16. Power Supply Application

Figure 16 shows a more complete systems application using

a DC/DC converter. Such configuration can be used in a pow-

er supply application. The point to make with this example

diagram is the Serial Bus Address connections. The previous

example shows A0 and A1 connected to four GPOs, but this

example shows a simpler A0 and A1 connection using two

resistor dividers. This connection accomplishes the same

goal as the GPO connection, that is, it can set A0 and A1 high,

low, or to midscale.

For example, to set A0 high, don't populate RB_bottom; to set

A0 low, don't populate RB_top; and to set A0 to midscale,

leave RB_top and RB_bottom as is and set them equal to

each other. A typical RB value ranges from 1 kOhm to 10

kOhm.

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ADC128D818

15.11.3 Temperature Sensors

30096343

FIGURE 17. Temperature Sensor Applications

An external temperature sensor can be connected to any of

ADC128D818's eight single-ended input for additional tem-

perature sensing. One such temperature sensor can be

National's LM94022, a precision analog temperature sensor

with selectable gains. The application diagram shows

LM94022's gains (GS1 and GS0) both grounded indicating

the lowest gain setting. Four possible gains can be set using

these GS1 and GS0 pins.

According to the LM94022 datasheet, the voltage-to-temper-

ature output plot can be determined using the method of linear

approximation as follows:

V - V1 = (V2 - V1) / (T2 - T1) x (T - T1)

Where V is in mV, T is in °C, V1 and T1 are the coordinates

of the lowest temperature, and T2 and V2 are the coordinates

of the highest temperature.

For example, to determine the equation of a line over a tem-

perature range of 20°C to 50°C, first find V1 and V2 relative

to those temperatures, then use the above equation to find

the transfer function.

V - 925 mV = (760 mV - 925 mV) / (50C - 20°C) x (T - 20°C)

V = (-5.50 mV /°C) x T + 1035 mV

For more information and explanation of this example, refer

to the LM94022 datasheet.

25 www.national.com

ADC128D818

15.11.4 Bridge Sensors

30096344

FIGURE 18. Bridge Sensor Application

ADC128D818 is perfect for transducer applications such as

pressure sensors. These sensors measure pressure of gases

or liquids and produce a pressure-equivalent voltage at their

outputs. Figure 18 shows a typical connection of a pressure

sensor, represented by the bridge sensor.

Most pressure sensor has a low sensitivity characteristic,

which means its output is typically in the millivolts range. Be-

cause of that reason, an op-amp, such as an instrumentation

amplifier, can be used for the gain stage.

The positive aspect of this configuration is its ratiometric con-

nection. A ratiometric connection is when the ADC’s VREF

and GND are connected to the bridge sensor’s voltage refer-

ences. With a ratiometric configuration, external VREF accu-

racy can be ignored.

15.11.5 Layout and Grounding

Analog inputs will provide best accuracy when referred to the

GND pin or a supply with low noise. A separate, low-

impedance ground plane for analog ground, which provides

a ground point for the voltage dividers and analog compo-

nents, will provide best performance but is not mandatory.

Analog components such as voltage dividers should be lo-

cated physically as close as possible to the ADC128D818.

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ADC128D818

15.12 REGISTER MAP

15.12.1 ADC128D818 Internal Registers

TABLE 8. ADC128D818 Internal Registers

Write

Address

(hex)

Default Value

[7:0] Register Description Register

Format

Configuration Register R/W 00h 0000_1000 Provides control and configuration 8-bit

Interrupt Status Register R 01h 0000_0000 Provides status of each WATCHDOG limit or

interrupt event 8-bit

Interrupt Mask Register R/W 03h 0000_0000 Masks the interrupt status from propagating

to INT 8-bit

Conversion Rate Register R/W 07h 0000_0000 Controls the conversion rate 8-bit

Channel Disable Register R/W 08h 0000_0000 Disables conversion for each voltage or

temperature channel 8-bit

One-Shot Register W 09h 0000_0000 Initiates a single conversion of all enabled

channels 8-bit

Deep Shutdown Register R/W 0Ah 0000_0000 Enables deep shutdown mode 8-bit

Advanced Configuration

of operation 8-bit

Busy Status Register R 0Ch 0000_0010 Reflects ADC128D818 'Busy' and 'Not

Ready' statuses 8-bit

Channel Readings Registers R 20h - 27h - - - Report the channels (voltage or temperature)

readings 16-bit

Limit Registers R/W 2Ah - 39h - - - Set the limits for the voltage and temperature

channels 8-bit

Manufacturer ID Register R 3Eh 0000_0001 Reports the manufacturer's ID 8-bit

Revision ID Register R 3Fh 0000_1001 Reports the revision's ID 8-bit

15.12.2 Configuration Register — Address 00h

Default Value [7:0] = 0000_1000 binary

Bit Bit Name Read/Write Bit(s) Description

ALL MODES

0 Start Read/Write 0: ADC128D818 in shutdown mode

1: Enable startup of monitoring operations

1 INT_Enable Read/Write 1: Enable the interrupt output pin, INT

2 Reserved Read Only

3 INT_Clear Read/Write 1: Clear the interrupt output pin, INT, without affecting the contents of Interrupt Status

Registers. When this bit is set high, the device stops the round-robin monitoring loop.

4 Reserved Read Only

5 Reserved Read Only

6 Reserved Read Only

7 Initialization Read/Write

1: Restore default values to the following registers: Configuration, Interrupt Status,

Interrupt Mask, Conversion Rate, Channel Disable, One-Shot, Deep Shutdown,

Advanced Configuration, Busy Status, Channel Readings, Limit, Manufacturer ID,

Revision ID. This bit clears itself

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ADC128D818

15.12.3 Interrupt Status Register — Address 01h

Default Value [7:0] = 0000_0000 binary

Bit Bit Name Read/Write Bit(s) Description

MODE 0

0 IN0 Error Read Only 1: A High or Low limit has been exceeded

1 IN1 Error Read Only 1: A High or Low limit has been exceeded

2 IN2 Error Read Only 1: A High or Low limit has been exceeded

3 IN3 Error Read Only 1: A High or Low limit has been exceeded

4 IN4 Error Read Only 1: A High or Low limit has been exceeded

5 IN5 Error Read Only 1: A High or Low limit has been exceeded

6 IN6 Error Read Only 1: A High or Low limit has been exceeded

7 Hot Temperature Error Read Only 1: A High limit has been exceeded

MODE 1

0 IN0 Error Read Only 1: A High or Low limit has been exceeded

1 IN1 Error Read Only 1: A High or Low limit has been exceeded

2 IN2 Error Read Only 1: A High or Low limit has been exceeded

3 IN3 Error Read Only 1: A High or Low limit has been exceeded

4 IN4 Error Read Only 1: A High or Low limit has been exceeded

5 IN5 Error Read Only 1: A High or Low limit has been exceeded

6 IN6 Error Read Only 1: A High or Low limit has been exceeded

7 IN7 Error Read Only 1: A High or Low limit has been exceeded

MODE 2

0 IN0(+) & IN1(-) Error Read Only 1: A High or Low limit has been exceeded

1 IN3(+) & IN2(-) Error Read Only 1: A High or Low limit has been exceeded

2 IN4(+) & IN5(-) Error Read Only 1: A High or Low limit has been exceeded

3 IN7(+) & IN6(-) Error Read Only 1: A High or Low limit has been exceeded

4 Reserved Read Only

5 Reserved Read Only

6 Reserved Read Only

7 Hot Temperature Error Read Only 1: A High limit has been exceeded

MODE 3

0 IN0 Error Read Only 1: A High or Low limit has been exceeded

1 IN1 Error Read Only 1: A High or Low limit has been exceeded

2 IN2 Error Read Only 1: A High or Low limit has been exceeded

3 IN3 Error Read Only 1: A High or Low limit has been exceeded

4 IN4(+) & IN5(-) Error Read Only 1: A High or Low limit has been exceeded

5 IN7(+) & IN6(-) Error Read Only 1: A High or Low limit has been exceeded

6 Reserved Read Only

7 Hot Temperature Error Read Only 1: A High limit has been exceeded

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ADC128D818

15.12.4 Interrupt Mask Register — Address 03h

Default Value [7:0] = 0000_0000 binary

Bit Bit Name Read/Write Bit(s) Description

MODE 0

0 IN0 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

1 IN1 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

2 IN2 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

3 IN3 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

4 IN4 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

5 IN5 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

6 IN6 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

7 Temperature Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

MODE 1

0 IN0 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

1 IN1 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

2 IN2 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

3 IN3 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

4 IN4 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

5 IN5 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

6 IN6 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

7 IN7 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

MODE 2

0 IN0(+) & IN1(-) Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

1 IN3(+) & IN2(-) Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

2 IN4(+) & IN5(-) Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

3 IN7(+) & IN6(-) Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

4 Reserved Read Only

5 Reserved Read Only

6 Reserved Read Only

7 Temperature Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

29 www.national.com

ADC128D818

Bit Bit Name Read/Write Bit(s) Description

MODE 3

0 IN0 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

1 IN1 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

2 IN2 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

3 IN3 Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

4 IN4(+) & IN5(-) Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

5 IN7(+) & IN6(-) Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

6 Reserved Read Only

7 Temperature Mask Read/Write 1: Mask the corresponding interrupt status from propagating to the interrupt

output pin, INT

15.12.5 Conversion Rate Register — Address 07h

Default Value [7:0] = 0000_0000 binary

Bit Bit Name Read/Write Bit(s) Description

0 Conversion Rate Read/Write

Controls the conversion rate:

0: Low Power Conversion Mode

1: Continuous Conversion Mode

Note: This register must only be programmed when the device is in shutdown

mode, that is, when the 'START' bit of the 'Configuration Register' (address 00h)

= 0

1–7 Reserved Read Only

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ADC128D818

15.12.6 Channel Disable Register — Address 08h

Default Value [7:0] = 0000_0000 binary

•This register must only be programmed when the device

is in shutdown mode, that is, when the ‘START’ bit of the

“Configuration Register’ (address 00h) = 0.

•Whenever this register is programmed, all of the values in

the Channel Reading Registers and Interrupt Status

Registers will return to their default values.

Bit Bit Name Read/Write Bit(s) Description

MODE 0

0 IN0 Disable Read/Write 1: Conversions are skipped and disabled, value register reading will be 0, and