2.7 V to 5.25 V, Micropower, 8-Channel, a 125 kSPS, 12-Bit ADC in 16-Lead TSSOP AD7888 FUNCTIONAL BLOCK DIAGRAM FEATURES Specified for V of 2.7 V to 5.25 V DD Flexible Power/Throughput Rate Management AD7888 AIN1 Shutdown Mode: 1 A Max I/P T/H Eight Single-Ended Inputs MUX V DD AIN8 Serial Interface: SPI/QSPI/MICROWIRE/DSP Compatible 2.5V COMP 16-Lead Narrow SOIC and TSSOP Packages REF APPLICATIONS REF IN/REF OUT BUF Battery-Powered Systems (Personal Digital Assistants, Medical Instruments, Mobile Communications) CHARGE Instrumentation and Control Systems REDISTRIBUTION DAC High-Speed Modems SAR + ADC CONTROL LOGIC AGND AGND GENERAL DESCRIPTION SPORT The AD7888 is a high speed, low power, 12-bit ADC that oper- ates from a single 2.7 V to 5.25 V power supply. The AD7888 is capable of a 125 kSPS throughput rate. The input track-and- CS DIN DOUT SCLK hold acquires a signal in 500 ns and features a single-ended sampling scheme. The AD7888 contains eight single-ended analog inputs, AIN1 through AIN8. The analog input on each PRODUCT HIGHLIGHTS of these channels is from 0 to V . The part is capable of con- REF 1. Smallest 12-bit 8-channel ADC 16-lead TSSOP is the same verting full power signals up to 2.5 MHz. area as an 8-lead SOIC and less than half the height. The AD7888 features an on-chip 2.5 V reference that can be 2. Lowest Power 12-bit 8-channel ADC. used as the reference source for the A/D converter. The REF 3. Flexible power management options including automatic IN/REF OUT pin allows the user access to this reference. Alter- power-down after conversion. natively, this pin can be overdriven to provide an external refer- 4. Analog input range from 0 V to V (V ). ence voltage for the AD7888. The voltage range for this external REF DD reference is from 1.2 V to V . DD 5. Versatile serial I/O port (SPI/QSPI/MICROWIRE/DSP Compatible). CMOS construction ensures low power dissipation of typically 2 mW for normal operation and 3 W in power-down mode. The part is available in a 16-lead narrow body small outline (SOIC) and a 16-lead thin shrink small outline (TSSOP) package. SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corporation. 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 that Tel: 781/329-4700 www.analog.com may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781/326-8703(V = 2.7 V to 5.25 V, REFIN/REFOUT = 2.5 V External/Internal Reference unless AD7888SPECIFICATIONS DD otherwise noted f = 2 MHz (V = 2.7 V to 5.25 V) T = T to T , unless otherwise noted.) SCLK DD A MIN MAX 1 1 Parameter A Version B Version Unit Test Condition/Comment DYNAMIC PERFORMANCE 2, 3 Signal to Noise + Distortion Ratio (SNR) 71 71 dB typ f = 10 kHz Sine Wave, f = 125 kSPS IN SAMPLE 2 Total Harmonic Distortion (THD) 80 80 dB typ f = 10 kHz Sine Wave, f = 125 kSPS IN SAMPLE 2 Peak Harmonic or Spurious Noise 80 80 dB typ f = 10 kHz Sine Wave, f = 125 kSPS IN SAMPLE 2 Intermodulation Distortion (IMD) Second Order Terms 78 78 dB typ fa = 9.983 kHz, fb = 10.05 kHz, f = 125 kSPS SAMPLE Third Order Terms 78 78 dB typ fa = 9.983 kHz, fb = 10.05 kHz, f = 125 kSPS SAMPLE 2 Channel-to-Channel Isolation 80 80 dB typ f = 25 kHz IN Full Power Bandwidth 2.5 2.5 MHz typ 3 dB DC ACCURACY Any Channel Resolution 12 12 Bits 2 Integral Nonlinearity 2 1 LSB max 2 Differential Nonlinearity 2 1/+1.5 LSB max Guaranteed No Missed Codes to 11 Bits (A Grade) Guaranteed No Missed Codes to 12 Bits (B Grade) Offset Error 6 6 LSB max V = 4.75 V to 5.25 V (Typically 3 LSB) DD 4.5 4.5 LSB max V = 2.7 V to 3.6 V (Typically 2 LSB) DD 2 Offset Error Match 2 2 LSB typ 2 Gain Error 2 2 LSB max Typically 30 LSB with Internal Reference 2 Gain Error Match 3 3 LSB max ANALOG INPUT Input Voltage Ranges 0 to V 0 to V Volts REF REF Leakage Current 1 1 A max Input Capacitance 38 38 pF typ When in Track 4 4 pF typ When in Hold REFERENCE INPUT/OUTPUT REFIN Input Voltage Range 2.5/V 2.5/V V min/max Functional from 1.2 V DD DD Input Impedance 5 5 k typ Very High Impedance If Internal Reference Disabled REFOUT Output Voltage 2.45/2.55 2.45/2.55 V min/max REFOUT Tempco 50 50 ppm/C typ LOGIC INPUTS Input High Voltage, V 2.4 2.4 V min V = 4.75 V to 5.25 V INH DD 2.1 2.1 V min V = 2.7 V to 3.6 V DD Input Low Voltage, V 0.8 0.8 V max V = 2.7 V to 5.25 V INL DD Input Current, I 10 10 A max Typically 10 nA, V = 0 V or V IN IN DD 4 Input Capacitance, C 10 10 pF max IN LOGIC OUTPUTS Output High Voltage, V I = 200 A OH SOURCE V 0.5 V 0.5 V min V = 2.7 V to 5.25 V DD DD DD Output Low Voltage, V 0.4 0.4 V max I = 200 A OL SINK Floating-State Leakage Current 10 10 A max 5 Floating-State Output Capacitance 10 10 pF max Output Coding Straight (Natural) Binary CONVERSION RATE Throughput Time 16 16 SCLK Cycles Conversion Time + Acquisition Time. 125 kSPS with 2 MHz Clock 2 Track/Hold Acquisition Time 1.5 1.5 SCLK Cycles Conversion Time 14.5 14.5 SCLK Cycles 7.25 s (2 MHz Clock) REV. C 2