2.7 V to 5.5 V, 350 kSPS, 10-Bit a 4-/8-Channel Sampling ADCs AD7811/AD7812 The control registers of the AD7811 and AD7812 allow the FEATURES input channels to be configured as single-ended or pseudo 10-Bit ADC with 2.3 s Conversion Time differential. The control register also features a software convert The AD7811 has Four Single-Ended Inputs that start and a software power-down. Two of these devices can Can Be Configured as Three Pseudo Differential share the same serial bus and may be individually addressed in Inputs with Respect to a Common, or as Two Inde- a multipackage application by hardwiring the device address pin. pendent Pseudo Differential Channels The AD7811 is available in a small, 16-lead 0.3 wide, plastic The AD7812 has Eight Single-Ended Inputs that Can dual-in-line package (mini-DIP), in a 16-lead 0.15 wide, Small Be Configured as Seven Pseudo Differential Inputs Outline IC (SOIC) and in a 16-lead, Thin Shrink Small Out- with Respect to a Common, or as Four Independent line Package (TSSOP). The AD7812 is available in a small, Pseudo Differential Channels 20-lead 0.3 wide, plastic dual-in-line package (mini-DIP), in a Onboard Track and Hold 20-lead, Small Outline IC (SOIC) and in a 20-lead, Thin Shrink Onboard Reference 2.5 V 2.5% Small Outline Package (TSSOP). Operating Supply Range: 2.7 V to 5.5 V Specifications at 2.7 V3.6 V and 5 V 10% PRODUCT HIGHLIGHTS DSP-/Microcontroller-Compatible Serial Interface 1. Low Power, Single Supply Operation High Speed Sampling and Automatic Power-Down Modes Both the AD7811 and AD7812 operate from a single 2.7 V Package Address Pin on the AD7811 and AD7812 Allows to 5.5 V supply and typically consume only 10 mW of power. Sharing of the Serial Bus in Multipackage Applications The power dissipation can be significantly reduced at Input Signal Range: 0 V to V REF lower throughput rates by using the automatic power- Reference Input Range: 1.2 V to V DD down mode e.g., 315 W 10 kSPS, V = 3 Vsee Qualified for Automotive Applications DD Power vs. Throughput. GENERAL DESCRIPTION The AD7811 and AD7812 are high speed, low power, 10-bit 2. 4-/8-Channel, 10-Bit ADC A/D converters that operate from a single 2.7 V to 5.5 V supply. The AD7811 and AD7812 have four and eight single-ended The devices contain a 2.3 s successive approximation A/D input channels respectively. These inputs can be configured converter, an on-chip track/hold amplifier, a 2.5 V on-chip refer- as pseudo differential inputs by using the Control Register. ence and a high speed serial interface that is compatible with the 3. On-chip 2.5 V (2.5%) reference circuit that is powered serial interfaces of most DSPs (Digital Signal Processors) and down when using an external reference. microcontrollers. The user also has the option of using an exter- 4. Hardware and Software Control nal reference by connecting it to the V pin and setting the REF The AD7811 and AD7812 provide for both hardware and EXTREF bit in the control register. The V pin may be tied REF software control of Convert Start and Power-Down. to V . At slower throughput rates the power-down mode may DD be used to automatically power down between conversions. FUNCTIONAL BLOCK DIAGRAMS C REF V V AGND DGND C REF REF IN DD DD AGND DGND REF IN 1.23V 1.23V REF AD7812 REF AD7811 CLOCK CLOCK OSC OSC BUF BUF DOUT DOUT V DIN DIN IN1 CHARGE CHARGE SERIAL SERIAL V RFS REDISTRIBUTION IN2 REDISTRIBUTION RFS PORT PORT DAC DAC V TFS IN3 TFS V IN4 SCLK V SCLK IN1 MUX V IN5 V IN2 MUX V IN6 V IN3 CONTROL CONTROL V IN7 LOGIC V LOGIC V /3 IN4 DD V /3 COMP DD V COMP IN8 A0 CONVST A0 CONVST REV. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or Tel: 781/329-4700 World Wide Web Site: (V = 2.7 V to 3.6 V, V = 5 V 10%, GND = 0 V, V = V DD DD REF DD EXT . All specifications 40 C to +105 C unless otherwise noted.) AD7811/AD7812SPECIFICATIONS Parameter Y Version Unit Test Conditions/Comments DYNAMIC PERFORMANCE f = 30 kHz Any Channel, f = 350 kHz IN SAMPLE 1 Signal to (Noise + Distortion) Ratio 58 dB min V Internal or External REF 1 Total Harmonic Distortion (THD) 66 dB max 1 Peak Harmonic or Spurious Noise 80 dB typ 1, 2 Intermodulation Distortion fa = 29 kHz, fb = 30 kHz Second Order Terms 67 dB max Third Order Terms 67 dB max 1, 2 Channel-to-Channel Isolation 80 dB typ f = 20 kHz IN DC ACCURACY Any Channel Resolution 10 Bits Minimum Resolution for Which No Missing Codes are Guaranteed 10 Bits 1 Relative Accuracy 1 LSB max 1 Differential Nonlinearity 1 LSB max 1 Gain Error 2 LSB max 1 Gain Error Match 0.75 LSB max 1 Offset Error 2 LSB max 1 Offset Error Match 0.75 LSB max ANALOG INPUT Input Voltage Range 0 V min V V max REF 2 Input Leakage Current 1 A max 2 Input Capacitance 20 pF max 2 REFERENCE INPUTS V Input Voltage Range 1.2 V min REF V V max DD Input Leakage Current 3 A max Input Capacitance 20 pF max ON-CHIP REFERENCE Nominal 2.5 V Reference Error 2.5 % max Temperature Coefficient 50 ppm/C typ 2 LOGIC INPUTS V , Input High Voltage 2.4 V min V = 5 V 10% INH DD V , Input Low Voltage 0.8 V max V = 5 V 10% INL DD V , Input High Voltage 2 V min V = 3 V 10% INH DD V , Input Low Voltage 0.4 V max V = 3 V 10% INL DD Input Current, I 1 A max Typically 10 nA, V = 0 V to V IN IN DD Input Capacitance, C 8 pF max IN LOGIC OUTPUTS Output High Voltage, V I = 200 A OH SOURCE 4V min V = 5 V 10% DD 2.4 V min V = 3 V 10% DD Output Low Voltage, V I = 200 A OL SINK 0.4 V max High Impedance Leakage Current 1 A max High Impedance Capacitance 15 pF max CONVERSION RATE Conversion time 2.3 s max 1 Track/Hold Acquisition Time 200 ns max 2 REV. B