LHA7668/B-8
The LHA7668-8 is a low-power, low-noise, highly integrated analog front-end optimized for precision measurement applications. It integrates a low-noise 24-bit Σ-Δ analog-to-digital converter (ADC), configurable via registers to support up to 8 differential inputs or 15 single-ended / pseudo-differential inputs. The LHA7668-4 supports 4 differential pairs or 7 single-ended / pseudo-differential inputs. On-chip low-noise programmable gain amplifiers enable direct acquisition of small sensor signals.
A key advantage of the LHA7668-8/-4 is flexible selection among three power modes. Power consumption, output data rate and input-referred noise scale with the selected operating mode. Multiple digital filter options are provided to maximize user flexibility.
At an output data rate of 25 SPS (single-cycle settling), simultaneous 50 Hz and 60 Hz mains rejection is achieved; greater than 80 dB rejection performance is available at lower output data rates.
The LHA7668-8/-4 features a highly integrated signal chain. An on-chip precision low-noise, low-drift bandgap reference is implemented; an external buffered reference can also be adopted. Other key features include programmable matched excitation current sources, open-circuit detection current sources and bias voltage generators. The bias generator can set the common-mode voltage of single-ended channels to AVDD/2.
A low-side power switch allows the bridge sensor supply to be disabled between two conversions, minimizing overall system power consumption. Users may select either internal oscillator or external clock source.
An embedded automatic channel sequencer enables multiple channels to be enabled simultaneously, executing conversions sequentially across all active channels and simplifying host communication. Up to 16 channels can be enabled or disabled on demand, with independent configuration available per channel. Comprehensive analog input diagnostics (power supply check, reference voltage inspection, etc.) are supported, allowing alternating execution of conversion and diagnostic cycles.
The LHA7668-8/-4 supports independent configuration on a per-channel basis. Eight individual configuration sets are available on a single device, each with separate settings for gain, filter type, output data rate, buffer enable and reference selection.
Rich built-in diagnostic functions are integrated, including CRC error checking, signal chain verification and serial interface monitoring to enhance system reliability. Diagnostics require minimal external components, reducing PCB footprint, shortening design cycles and lowering BOM cost. According to IEC 61508, the safe failure fraction (SFF) exceeds 90% for typical applications, suitable for SIL safety diagnostic architectures.
The device operates from a single analog supply of 2.7 V ~ 5.5 V, or split bipolar supply ±1.8 V / ±2.5 V; digital interface supply ranges from 1.65 V to 5.5 V. Fully characterized over −40 ℃ to +125 ℃. The LHA7668-8/-4 is offered in 32-lead QFN and 24-lead TSSOP packages.
Product Features
- Three selectable power operating modes
- RMS noise (Gain = 128, typical)
- Low-power mode: 19 nV rms @ 1.17 SPS, Supply Current: 195 μA (LHA7668) / 183 μA (LHA7668B)
- Medium-power mode: 15 nV rms @ 2.34 SPS, Supply Current: 280 μA (LHA7668) / 260 μA (LHA7668B)
- Full-power mode: 20 nV rms @ 9.4 SPS, Supply Current: 810 μA (LHA7668) / 750 μA (LHA7668B)
- Up to 22 noise-free bits across all power modes (Gain = 1, 2, 4, 8)
- Output data rate
- Full-power: 9.38 SPS to 38,400 SPS
- Medium-power: 2.34 SPS to 9600 SPS
- Low-power: 1.17 SPS to 4800 SPS
- Rail-to-rail analog inputs
- Simultaneous 50 Hz / 60 Hz rejection at 25 SPS (single-cycle settling)
- Built-in diagnostic functions (support SIL safety certification)
- Crosspoint analog input multiplexer
- 8 fully differential or 15 pseudo-differential channels
- Programmable gain: 1 ~ 128
- On-chip voltage reference, maximum drift 10 ppm/℃
- Programmable matched excitation current sources
- Internal clock oscillator
- On-chip bias voltage generator
- Low-side power switch: turn off bridge sensor supply between conversions to minimize system power
- General-purpose output (GPO)
- Multiple digital filter options
- Integrated internal temperature sensor
- Self-calibration and system calibration
- Sensor open-circuit detection
- Automatic channel sequencer
- Per-channel independent configuration
- Power supplies: Single analog supply 2.7 V ~ 5.5 V; Split supply ±1.8 V or ±2.5 V
- Independent digital interface supply
- Temperature range: −40 ℃ to +125 ℃
- Packages: 32-lead QFN, 24-lead TSSOP
- 3-/4-wire serial interface
- SPI, QSPI™, MICROWIRE™ and DSP compatible
- Schmitt trigger on SCLK pin
- ESD rating: 4 kV
Application Scenario
- Temperature measurement
- Pressure measurement
- Industrial process control
- Instrumentation
- Smart transmitters
Room G2-1201,Artificial Intelligence Industrial Park, No. 88 JinjihuAvenue, Suzhou Industrial Park
Room 903,Hantang Building, No.1 Xinglong Street, OCT, NanshanDistrict,Shenzhen
Room 1306,Zhongkun Building, No. 59, Gaoliangqiao Xie StreetBeixiaguan Street, Haidian District, Beijing
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