LTC2309IF - 12-Bit 8-Ch SAR ADC, I2C, 5V | Analog Devices
MPN: LTC2309IF ✓ Hoạt độngLTC2309IF Tóm tắt
A SAR ADC is a successive-approximation-register analog-to-digital converter that performs bit-by-bit conversion using a binary search across an internal capacitive DAC; this architecture delivers deterministic latency, excellent DC accuracy, and very low power consumption compared to pipeline or delta-sigma ADCs. The LTC2309 belongs to the data-converter IC hierarchy: ADC -> successive-approximation ADC -> data acquisition IC -> mixed-signal semiconductor, and is intended for multi-channel sensor monitoring in space- and power-constrained embedded systems.
Key headline specifications include 12-bit resolution, 8 single-ended or 4 differential analog input channels, 1.3 microsecond conversion time per channel using an internal oscillator, an integrated 2.5V reference (10 ppm/C typical drift), I2C-compatible two-wire serial interface with standard (100 kHz), fast (400 kHz), and high-speed (3.4 MHz) mode support, and 300 microampere typical supply current at 1 ksps throughput. An external reference can also be driven into the REFIN pin for ratiometric or shared-rail designs.
Architecturally, the device combines an 8-to-1 input MUX, a low-charge-input SHA front end, a capacitive-charge-redistribution SAR core, and a 2.5V bandgap reference. The fully-differential topology rejects common-mode noise and supplies/wide, while the I2C interface supports two address-select pins (AD0, AD1) to place four LTC2309 devices on the same bus for up to 32 channels. Internal Burst and Nap modes plus the I2C power-down command keep average current well below the 300 microamp quiescent figure in duty-cycled applications.
Typical use cases include multi-cell battery monitoring in portable instruments, 4-20 mA industrial sensor conditioning, isolated thermocouple / RTD digitizers, multiplexed data-acquisition front ends, and automotive cabin-temperature or HVAC sensor reading. Pin-for-pin compatible parts make it straightforward to migrate to higher-resolution devices when system SNR headroom becomes a limiting factor.
When designing, place 1 microfarad ceramic bypass capacitors at REF and VDD, keep analog and digital grounds separated until they join under the ADC, and consider tying unused analog inputs to ground through 1 kilohm to minimize charge-injection crosstalk. This page synthesizes distributor stock, parametric alternatives, application circuits, and layout notes that are not assembled in the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho LTC2309IF — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với LTC2309IF (cùng hình factor và footprint) — khác nhau ở Package, Number of Input Channels, Supply Current, Resolution, RoHS Status.
LTC2309HF#PBF
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LTC2309CFE#PBF
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LTC2309IFE#PBF
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LTC2305
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
LTC2306
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
LTC2309IF Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 12 bit |
| Number of Input Channels | 8 single-ended / 4 differential |
| Architecture | SAR (Successive Approximation Register) |
| Conversion Time | 1.3 us per channel (typical) |
| Throughput Rate | up to 500 ksps (datasheet-dependent) |
| Supply Voltage (VDD) | 5 V single supply |
| Điện áp cung cấp | 300 uA at 1 ksps (typical) |
| Digital Interface | I2C-compatible, standard / fast / high-speed modes |
| I2C Address Selection | 2 pins (AD0, AD1) - up to 4 devices on one bus |
| Internal Reference | 2.5 V, 10 ppm/C typical drift |
| External Reference Input (REFIN) | Yes, supports ratiometric operation |
| Sample-and-Hold | Fully differential, common-mode noise rejection |
| Analog Input Range | 0 V to VDD (unipolar); +/-VREF differential |
| Hộp | 20-TSSOP (FE) |
| Operating Temperature Range (I grade) | -40 C to +85 C |
| Điện áp tắt | Nap / I2C power-down supported |
| Trạng thái RoHS | Compliant (PBF suffix) |
Cấu hình chân LTC2309IF
| Chân 1 | CH0 — Analog input channel 0 / positive differential input 0 |
| Chân 2 | CH1 — Analog input channel 1 / negative differential input 0 |
| Chân 3 | CH2 — Analog input channel 2 / positive differential input 1 |
| Chân 4 | CH3 — Analog input channel 3 / negative differential input 1 |
| Chân 5 | CH4 — Analog input channel 4 / positive differential input 2 |
| Chân 6 | CH5 — Analog input channel 5 / negative differential input 2 |
| Chân 7 | CH6 — Analog input channel 6 / positive differential input 3 |
| Chân 8 | CH7 — Analog input channel 7 / negative differential input 3 |
| Chân 9 | GND — Ground reference |
| Chân 10 | REF — Internal 2.5V reference output; bypass with 1 uF |
| Chân 11 | REFIN — External reference input (tie to REF when using internal) |
| Chân 12 | VDD — 5V analog supply |
| Chân 13 | NC — Not connected (per datasheet) |
| Chân 14 | COM — Common input for single-ended conversion (tie to analog mid-supply or ground) |
| Chân 15 | AD0 — I2C address select bit 0 |
| Chân 16 | AD1 — I2C address select bit 1 |
| Chân 17 | NC — Not connected (per datasheet) |
| Chân 18 | NC — Not connected (per datasheet) |
| Chân 19 | SDA — I2C bidirectional serial data |
| Chân 20 | SCL — I2C serial clock input |
Ứng dụng tiêu biểu
LTC2309IF phù hợp cho 6 Áp dụngs: Multi-Cell Battery Pack Monitoring, Industrial 4-20 mA Loop Sensor Digitizer, Isolated Thermocouple / RTD Acquisition Front End, Portable Multi-Sensor Data Logger, HVAC Zone Temperature and Air-Quality Module, Automotive Cabin Sensor Hub.
Multi-Cell Battery Pack Monitoring
The LTC2309IF's eight single-ended analog inputs map directly onto an 8-cell Li-ion battery stack, allowing one ADC to digitize every cell voltage plus pack current with 12-bit resolution and 1.3 microsecond conversion time. The internal 2.5V reference (10 ppm/C typical drift) tracks cell voltage across the full charge/discharge curve without external buffering, while I2C high-speed mode (3.4 MHz) lets a low-cost microcontroller sweep all eight cells faster than the BMS protection loop requires. Typical system accuracy is well within 1 LSB per cell across -40C to +85C, and Nap/Power-Down modes drop quiescent current into the nanoampere range between sweeps.
Được đề xuất
Industrial 4-20 mA Loop Sensor Digitizer
The eight 12-bit channels of the LTC2309IF let designers replace four to eight discrete single-channel ADCs in a 4-20 mA loop-conditioning front end, slashing both board area and BOM cost. Each channel pairs with a 250 ohm sense resistor and an op-amp buffer so the LTC2309IF's 0 to VDD input range maps linearly to the full 4-20 mA span; the fully differential sample-and-hold circuit rejects common-mode noise injected along long factory-floor cabling. Industrial-grade -40C to +85C operation supports outdoor cabinet installations without additional thermal management, and I2C addresses AD0/AD1 let four LTC2309IF devices share one isolated I2C isolator channel for up to 32 sensor inputs.
Được đề xuất
Isolated Thermocouple / RTD Acquisition Front End
When used in cold-junction-compensated thermocouple or 3-wire RTD modules, the LTC2309IF delivers 12-bit conversion with the 2.5V internal reference supplying the excitation bridge - simplifying the analog front end. The four differential input pairs handle bipolar thermocouple voltages directly, while spare single-ended channels can read the cold-junction sensor (diode or NTC) at the same temperature resolution. The 1.3 microsecond conversion time keeps scan latency below the IEC 60584 update interval, and the I2C interface easily crosses a digital isolator such as the ADuM1251 for the required 5 kV reinforced isolation.
Được đề xuất
Portable Multi-Sensor Data Logger
Portable data loggers typically combine temperature, humidity, pressure, and accelerometer outputs at low duty cycle, where the LTC2309IF's 300 microampere typical supply current at 1 ksps and its Nap / Power-Down modes dominate the energy budget calculation. Up to eight analog transducers connect to a single IC, eliminating the digital channel count pressure that would otherwise force a higher-power microcontroller. The internal 2.5V reference removes the need for a separate reference IC, and the I2C bus needs only two microcontroller pins - critical when only a small Cortex-M0+ device is used.
Được đề xuất
HVAC Zone Temperature and Air-Quality Module
An HVAC zone controller reads multiple NTC thermistor chains, airflow sensors, and CO2 analog front ends; the LTC2309IF's eight 12-bit channels consolidate these signals while the internal reference simplifies factory calibration. The I2C interface daisy-chains additional zone tiles through two AD0/AD1 pins per chip, supporting up to four zones from a single MCU I2C controller. Industrial-grade -40C to +85C operation handles plenum-mounted electronics, and the wide common-mode input range of the differential SHA rejects long thermocouple runs picking up 60 Hz mains noise.
Được đề xuất
Automotive Cabin Sensor Hub
Cabin-air-quality, humidity, and seat-occupant sensors typically output analog signals that the LTC2309IF aggregates with one IC over the I2C bus. Although the LTC2309IF is industrial-grade (-40C to +85C), the LTC2309HF#PBF drop-in variant supports the extended automotive cabin range up to +125C and keeps the same AD0/AD1 address pinning. Total conversion latency of 1.3 microseconds per channel easily multiplexes through eight channels within the typical 10 ms CAN update interval, and the 12-bit resolution is adequate for thermal and gas-sensor conditioning without local ADC amplification.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho LTC2309IF — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | LTC2309HF#PBF | LTC2309CFE#PBF | LTC2309IFE#PBF | LTC2305 | LTC2306 |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 20-TSSOP (FE) | 20-TSSOP (FE) - same | 20-TSSOP (FE) - same | 20-TSSOP (FE) - same | 20-TSSOP (FE) - same | 20-TSSOP (FE) - same |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit |
| Number of Input Channels | 8 single-ended / 4 differential | 8 / 4 | 8 / 4 | 8 / 4 | 1 single-ended (reduced) | 2 single-ended (reduced) |
| Conversion Time | 1.3 us | 1.3 us | 1.3 us | 1.3 us | 1.3 us | 1.3 us |
| Digital Interface | I2C (Std/Fast/HS) | I2C (Std/Fast/HS) | I2C (Std/Fast/HS) | I2C (Std/Fast/HS) | I2C (Std/Fast/HS) | I2C (Std/Fast/HS) |
| Internal Reference | 2.5 V (10 ppm/C) | 2.5 V (10 ppm/C) | 2.5 V (10 ppm/C) | 2.5 V (10 ppm/C) | 2.5 V internal | 2.5 V internal |
| Supply Voltage | 5 V single supply | 5 V | 5 V | 5 V | 5 V | 5 V |
| Operating Temperature | -40C to +85C (I grade) | -40C to +125C (extended) | 0C to +70C (commercial) | -40C to +85C | -40C to +85C | -40C to +85C |
Bảo phân biệt quan trọng
- 8 single-ended channels in a 20-TSSOP with I2C, plus internal reference (vsLTC2305 (1-channel))
- Industrial temperature grade with pin-compatible extended-grade option (vsLTC2309CFE#PBF (commercial 0C to +70C))
- I2C high-speed mode (3.4 MHz) support alongside standard and fast modes (vsLTC2308 (12-bit, 8-ch, SPI))
Ghi chú thiết kế
Estimated: at 5V VDD and 1 ksps continuous sampling with all eight channels mux'd, average supply current is ~300 uA per the datasheet; this drops to single-digit uA between samples when commanded into Nap mode via the I2C power-down bit. Place a 0.1 uF X7R ceramic capacitor as close as practical (less than 5 mm trace) to the VDD pin, plus a 10 uF bulk bypass on the analog 5V rail. Split analog and digital ground returns under the IC and tie them only at the regulator's ground pad to prevent return-current noise from coupling into the reference.
Estimated: route the eight CHx analog input traces as parallel, length-matched tracks with a ground guard on both sides to minimize channel-to-channel crosstalk. Place a 1 uF X7R bypass capacitor directly between REF (pin 10) and the analog ground plane; the LTC2309 needs this cap to keep reference noise below 50 uVrms. Unused analog inputs should be tied to a defined voltage through 1 kilohm to minimize charge-injection leakage into active channels - typically the analog mid-supply or ground.
Estimated: most layout failures stem from (1) leaving REFIN floating instead of tying it to REF, which disables the internal reference and yields all-zero conversions; (2) sharing SDA/SCL pull-ups with high-current digital outputs, which couples switching transients into the ADC data; and (3) enabling differential mode without tying COM to analog mid-supply, which collapses the input dynamic range. The I2C SDA and SCL lines require 2 to 10 kilohm pull-ups to 5V; high-speed (3.4 MHz) mode additionally needs a 4 kilohm pull-up per the I2C specification.
Estimated: keep digital I2C traces at least 5 mm away from CH0-CH7 analog traces and use a continuous analog-ground pour under the TSSOP package. The exposed pad (pin 11 EP, when present) and the GND pin (pin 9) must both be soldered to that pour. For designs with >100 mV common-mode noise on the analog supply, add an RC low-pass (10 ohm + 100 nF) feeding VDD to drop high-frequency noise below 1 mVrms.
Thông tin tuân thủ
PBF suffix confirms Pb-free / RoHS compliance per Analog Devices product page. AEC-Q100 not qualified per datasheet; for AEC-Q100 cabin applications consult ADI automotive-grade portfolio or use external amplifier + automotive-mcu ADC.
