AD7724

a FEATURES 13 MHz Master Clock Frequency 0 V to +2.5 V or ؎ 1.25 V Input Range Single Bit Output Stream 90 dB Dynamic Range Power Supplies AVDD, DVDD: 5 V␣ ؎ 5% DVDD1: 3 V ؎ 5% Logic Outputs 3 V/5 V Compatible On-Chip 2.5 V Voltage Reference 48-Lead LQFP Dual CMOS ⌺-⌬ Modulators AD7724 FUNCTIONAL BLOCK DIAGRAM REF1 REF2A 2.5V REFERENCE REF2B AD7724 AVIN(+) AVIN(–) ⌺-⌬ MODULATOR A ADATA SCLK BVIN(+) BVIN(–) ⌺-⌬ MODULATOR B BDATA XTAL OFF CLOCK CIRCUITRY XTAL1 XTAL2/MCLK DVAL MZERO GC BIP CONTROL LOGIC GENERAL DESCRIPTION STBY RESET This device consists of two seventh order sigma-delta modulators. Each modulator converts its analog input signal into a high speed 1-bit data stream. The part operates from a 5 V power supply and accepts a differential input range of 0 V to +2.5 V or ± 1.25 V centered about a common-mode bias. The analog inputs are continuously sampled by the analog modulators, eliminating the need for external sample-and-hold circuitry. The input information is contained in the output stream as a density of ones. The original information can be digitally reconstructed with an appropriate digital filter. The part provides an accurate on-chip 2.5 V reference for each modulator. A reference input/output function is provided to allow either the internal reference or an external system reference to be used as the reference source for the modulator. The device is offered in a 48-lead LQFP package and designed to operate from –40°C to +85°C. DVDD DVDD1 DGND...