AD7812 Analog Devices Data Sheet Manual

2.7 V to 5.5 V, 350 k SPS, 10-Bit 4-/8-Channel Sampling ADCs

AD7811/AD7812

FEATURES The control registers of the AD7811 and AD7812 allow the 10-Bit ADC with 2.3
s Conversion Time input channels to be configured as single-ended or pseudo The AD7811 has Four Single-Ended Inputs that differential. The control register also features a software convert Can Be Configured as Three Pseudo Differential start and a software power-down. Two of these devices can Inputs with Respect to a Common, or as Two Inde- share the same serial bus and may be individually addressed in pendent Pseudo Differential Channels a multipackage application by hardwiring the device address pin. The AD7812 has Eight Single-Ended Inputs that Can The AD7811 is available in a small, 16-lead 0.3" wide, plastic Be Configured as Seven Pseudo Differential Inputs dual-in-line package (mini-DIP), in a 16-lead 0.15" wide, Small with Respect to a Common, or as Four Independent Outline IC (SOIC) and in a 16-lead, Thin Shrink Small Out- Pseudo Differential Channels line Package (TSSOP). The AD7812 is available in a small, Onboard Track and Hold 20-lead 0.3" wide, plastic dual-in-line package (mini-DIP), in a Onboard Reference 2.5 V  2.5% 20-lead, Small Outline IC (SOIC) and in a 20-lead, Thin Shrink Operating Supply Range: 2.7 V to 5.5 V Small Outline Package (TSSOP).

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

DSP-/Microcontroller-Compatible Serial Interface PRODUCT HIGHLIGHTS High Speed Sampling and Automatic Power-Down Modes 1. Low Power, Single Supply Operation Package Address Pin on the AD7811 and AD7812 Allows Both the AD7811 and AD7812 operate from a single 2.7 V Sharing of the Serial Bus in Multipackage Applications to 5.5 V supply and typically consume only 10 m W of power. Input Signal Range: 0 V to VREF The power dissipation can be significantly reduced at Reference Input Range: 1.2 V to VDD lower throughput rates by using the automatic power- down mode e.g., 315 µW @ 10 k SPS, VDD = 3 V—see

GENERAL DESCRIPTION

Power vs. Throughput.

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. 2. 4-/8-Channel, 10-Bit ADC The devices contain a 2.3 µs successive approximation A/D The AD7811 and AD7812 have four and eight single-ended converter, an on-chip track/hold amplifier, a 2.5 V on-chip refer- www.BDTIC.com/ADI input channels respectively. These inputs can be configured ence and a high speed serial interface that is compatible with the as pseudo differential inputs by using the Control Register.

serial interfaces of most DSPs (Digital Signal Processors) and

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

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

down when using an external reference.

nal reference by connecting it to the VREF pin and setting the

4. Hardware and Software Control

EXTREF bit in the control register. The VREF pin may be tied

The AD7811 and AD7812 provide for both hardware and

to VDD. At slower throughput rates the power-down mode may

software control of Convert Start and Power-Down.

be used to automatically power down between conversions.

FUNCTIONAL BLOCK DIAGRAMS

VDD CREF VDD AGNDREFIN DGND

CREF REFIN AGND DGND

REF AD7812

REF AD7811

CLOCK CLOCK OSC

BUF OSC BUF

DOUT DOUT

VIN1 DIN

CHARGE DIN CHARGE

SERIAL VIN2 SERIAL

REDISTRIBUTION RFS REDISTRIBUTION RFS

PORT PORT

DAC VIN3 DAC

TFS TFS

VIN4 SCLK

VIN1 SCLK MUX

MUX VIN6

VIN3 CONTROL CONTROL

VIN7 LOGIC

VIN4 LOGIC VDD/3

VDD/3 COMP

COMP VIN8

A0 CONVST

A0 CONVST

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