AD7811YRUZ Datasheet AD7811YRUZ, AD7812YRUZ, AD7812YRZ | P1-P3

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AD7811/AD7812

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

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Fax: 781/326-8703 © Analog Devices, Inc., 2014

2.7 V to 5.5 V, 350 kSPS, 10-Bit

4-/8-Channel Sampling ADCs

FEATURES

10-Bit ADC with 2.3 ␮s Conversion Time

The AD7811 has Four Single-Ended Inputs that

Can Be Configured as Three Pseudo Differential

Inputs with Respect to a Common, or as Two Inde-

pendent Pseudo Differential Channels

The AD7812 has Eight Single-Ended Inputs that Can

Be Configured as Seven Pseudo Differential Inputs

with Respect to a Common, or as Four Independent

Pseudo Differential Channels

Onboard Track and Hold

Onboard Reference 2.5 V ⴞ 2.5%

Operating Supply Range: 2.7 V to 5.5 V

Specifications at 2.7 V–3.6 V and 5 V ⴞ 10%

DSP-/Microcontroller-Compatible Serial Interface

High Speed Sampling and Automatic Power-Down Modes

Package Address Pin on the AD7811 and AD7812 Allows

Sharing of the Serial Bus in Multipackage Applications

Input Signal Range: 0 V to V

REF

Reference Input Range: 1.2 V to V

Qualified for Automotive Applications

GENERAL DESCRIPTION

The AD7811 and AD7812 are high speed, low power, 10-bit

A/D converters that operate from a single 2.7 V to 5.5 V supply.

The devices contain a 2.3 µs successive approximation A/D

converter, an on-chip track/hold amplifier, a 2.5 V on-chip refer-

ence and a high speed serial interface that is compatible with the

serial interfaces of most DSPs (Digital Signal Processors) and

microcontrollers. The user also has the option of using an exter-

nal reference by connecting it to the V

REF

pin and setting the

EXTREF bit in the control register. The V

REF

pin may be tied

to V

. At slower throughput rates the power-down mode may

be used to automatically power down between conversions.

The control registers of the AD7811 and AD7812 allow the

input channels to be configured as single-ended or pseudo

differential. The control register also features a software convert

start and a software power-down. Two of these devices can

share the same serial bus and may be individually addressed in

a multipackage application by hardwiring the device address pin.

The AD7811 is available in a small, 16-lead 0.3" wide, plastic

dual-in-line package (mini-DIP), in a 16-lead 0.15" wide, Small

Outline IC (SOIC) and in a 16-lead, Thin Shrink Small Out-

line Package (TSSOP). The AD7812 is available in a small,

20-lead 0.3" wide, plastic dual-in-line package (mini-DIP), in a

20-lead, Small Outline IC (SOIC) and in a 20-lead, Thin Shrink

Small Outline Package (TSSOP).

PRODUCT HIGHLIGHTS

1. Low Power, Single Supply Operation

Both the AD7811 and AD7812 operate from a single 2.7 V

to 5.5 V supply and typically consume only 10 mW of power.

The power dissipation can be significantly reduced at

lower throughput rates by using the automatic power-

down mode e.g., 315 µW @ 10 kSPS, V

= 3 V—see

Power vs. Throughput.

2. 4-/8-Channel, 10-Bit ADC

The AD7811 and AD7812 have four and eight single-ended

input channels respectively. These inputs can be configured

as pseudo differential inputs by using the Control Register.

3. On-chip 2.5 V (±2.5%) reference circuit that is powered

down when using an external reference.

4. Hardware and Software Control

The AD7811 and AD7812 provide for both hardware and

software control of Convert Start and Power-Down.

FUNCTIONAL BLOCK DIAGRAMS

REV. C

CHARGE

REDISTRIBUTION

DAC

CLOCK

OSC

AD7811

CONVST

AGND

COMP

REF

DOUT

DGND

IN1

IN2

IN3

IN4

DIN

RFS

TFS

SCLK

BUF

CONTROL

LOGIC

MUX

REF

SERIAL

PORT

1.23V

REF

CHARGE

REDISTRIBUTION

DAC

CLOCK

OSC

AD7812

AGND

REF

DOUT

DGND

DIN

RFS

TFS

SCLK

BUF

CONTROL

LOGIC

MUX

REF

SERIAL

PORT

IN1

IN2

IN3

IN4

IN5

IN6

IN7

IN8

CONVST

COMP

1.23V

REF

–2–

REV. B

AD7811/AD7812–SPECIFICATIONS

Parameter Y Version Unit Test Conditions/Comments

DYNAMIC PERFORMANCE f

= 30 kHz Any Channel, f

SAMPLE

= 350 kHz

Signal to (Noise + Distortion) Ratio

58 dB min V

REF

Internal or External

Total Harmonic Distortion (THD)

–66 dB max

Peak Harmonic or Spurious Noise

–80 dB typ

Intermodulation Distortion

1, 2

fa = 29 kHz, fb = 30 kHz

Second Order Terms –67 dB max

Third Order Terms –67 dB max

Channel-to-Channel Isolation

1, 2

–80 dB typ f

= 20 kHz

DC ACCURACY Any Channel

Resolution 10 Bits

Minimum Resolution for Which

No Missing Codes are Guaranteed 10 Bits

Relative Accuracy

± 1 LSB max

Differential Nonlinearity

± 1 LSB max

Gain Error

± 2 LSB max

Gain Error Match

± 0.75 LSB max

Offset Error

± 2 LSB max

Offset Error Match

± 0.75 LSB max

ANALOG INPUT

Input Voltage Range 0 V min

REF

V max

Input Leakage Current

± 1 µA max

Input Capacitance

20 pF max

REFERENCE INPUTS

REF

Input Voltage Range 1.2 V min

V max

Input Leakage Current ± 3 µA max

Input Capacitance 20 pF max

ON-CHIP REFERENCE Nominal 2.5 V

Reference Error ± 2.5 % max

Temperature Coefficient 50 ppm/°C typ

LOGIC INPUTS

INH

Input High Voltage 2.4 V min V

= 5 V ± 10%

INL

, Input Low Voltage 0.8 V max V

= 5 V ± 10%

INH

Input High Voltage 2 V min V

= 3 V ± 10%

INL

, Input Low Voltage 0.4 V max V

= 3 V ± 10%

Input Current, I

± 1 µA max Typically 10 nA, V

= 0 V to V

Input Capacitance, C

8 pF max

LOGIC OUTPUTS

Output High Voltage, V

SOURCE

= 200 µA

4V minV

= 5 V ± 10%

2.4 V min V

= 3 V ± 10%

Output Low Voltage, V

SINK

= 200 µA

0.4 V max

High Impedance Leakage Current ± 1 µA max

High Impedance Capacitance 15 pF max

CONVERSION RATE

Conversion time 2.3 µs max

Track/Hold Acquisition Time

200 ns max

= 2.7 V to 3.6 V, V

= 5 V ⴞ 10%, GND = 0 V, V

REF

= V

[EXT]. All specifications –40ⴗC to +105ⴗC

unless otherwise noted.)

–3–

REV. C

AD7811/AD7812

Parameter Y Version Unit Test Conditions/Comments

POWER SUPPLY

2.7 V min For Specified Performance

5.5 V max

Digital Inputs = 0 V or V

Normal Operation 3.5 mA max

Power-Down

Full Power-Down 1 µA max

Partial Power-Down (Internal Ref) 350 µA max See Power-Up Times Section

Power Dissipation V

= 3 V

Normal Operation 10.5 mW max

Auto Full Power-Down See Power vs. Throughput Section

Throughput 1 kSPS 31.5 µW max

Throughput 10 kSPS 315 µW max

Throughput 100 kSPS 3.15 mW max

Partial Power-Down (Internal Ref) 1.05 mW max

Full Power-Down 3 µW max

NOTES

See Terminology.

Sample tested during initial release and after any redesign or process change that may affect this parameter.

Specifications subject to change without notice.

TIMING CHARACTERISTICS

1, 2

Parameter Y Version Unit Conditions/Comments

POWER-UP

1.5 µs (max) Power-Up Time of AD7811/AD7812 after Rising Edge of CONVST

2.3 µs (max) Conversion Time

20 ns (min) CONVST Pulsewidth

25 ns (min) SCLK High Pulsewidth

25 ns (min) SCLK Low Pulsewidth

5 ns (min) RFS Rising Edge to SCLK Rising Edge Setup Time

5 ns (min) TFS Falling Edge to SCLK Falling Edge Setup Time

10 ns (max) SCLK Rising Edge to Data Out Valid

10 ns (min) DIN Data Valid to SCLK Falling Edge Setup Time

5 ns (min) DIN Data Valid after SCLK Falling Edge Hold Time

3, 4

20 ns (max) SCLK Rising Edge to D

OUT

High Impedance

100 ns (min) DOUT High Impedance to CONVST Falling Edge

NOTES

Sample tested to ensure compliance.

See Figures 16, 17 and 18.

These numbers are measured with the load circuit of Figure 1. They are defined as the time required for the o/p to cross 0.8 V or 2.4 V for V

= 5 V ± 10% and

0.4 V or 2 V for V

= 3 V ± 10%.

Derived from the measured time taken by the data outputs to change 0.5 V when loaded with the circuit of Figure 1. The measured number is then extrapolated back

to remove the effects of charging or discharging the 50 pF capacitor. This means that the time, t

, quoted in the Timing Characteristics is the true bus relinquish

time of the part and as such is independent of external bus loading capacitances.

Specifications subject to change without notice.

= 2.7 V to 5.5 V, V

REF

= V

[EXT] unless otherwise noted)

2.1V

200␮A

50pF

OUTPUT

200␮A

Figure 1. Load Circuit for Digital Output Timing Specifications

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AD7811YRUZ

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Description:

Analog to Digital Converters - ADC 10-Bit 4-Ch 350kSPS Serial

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AD7811YRUZ

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