LC2MOS Complete/ 12-Bit/ 100 kHz/ Sampling ADCs
Description
FEATURES
Complete monolithic 12-bit ADCs with 2 μs track-and-hold amplifier 8 μs ADC On-chip reference Laser-trimmed clock Parallel, byte, and serial digital interface
72 dB SNR at 10 kHz input frequency (AD7870, AD7875)
57 ns data access time Low power: −60 mW typical Variety of input ranges
±3 V for AD7870 0 V to +5 V for AD7875 ±10 V for AD7876
GENERAL DESCRIPTION
The AD7870/AD7875/AD7876 are fast, complete, 12-bit analog-to-digital converters (ADCs).
These converters consist of a track-and-hold amplifier, an 8 μs successive approximation ADC, a 3 V buried Zener reference, and versatile interface logic.
The ADCs feature a self-contained internal clock which is laser trimmed to guarantee accurate control of conversion time.
No external clock timing components are required; the on-chip clock may be overridden by an external clock if required.
The parts offer a choice of three data output formats: a single, parallel, 12-bit word; two 8-bit bytes or serial data.
Fast bus access times and standard control inputs ensure easy interfacing to modern microprocessors and digital signal processors.
All parts operate from ±5 V power supplies.
The AD7870 and AD7876 accept input signal ranges of ±3 V and ±10 V, respectively, while the AD7875 accepts a unipolar 0 V to +5 V input range.
The parts can convert full power signals up to 50 kHz.
The AD7870/AD7875/AD7876 feature dc accuracy specifications, such as linearity, full-scale and offset error.
In addition, the AD7870 and AD7875 are fully specified for dynamic performance parameters including distortion and signal-tonoise ratio.
LC2MOS Complete, 12-Bit, 100 kHz, Sampling ADCs
AD7870/AD7875/AD7876
FUNCTIONAL BLOCK DIAGRAM
AGND
REF OUT
VIN
VDD
AD7870/AD7875/
INPUT
AD7876
SCALING
TRACK-AND-HOLD
3V REFERENCE
12-BIT DAC
COMP
CLK
12/8/CLK CONVST
CLOCK
CONTROL LOGIC
PARALLEL AND SERIAL INTERFACE
SAR + COUNTER
07730-001
CS RD BUSY/INT DB11 DB0
Figure 1.
DGND VSS
The parts are available in a 24-pin, 0.
3 inch-wide...
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