Overview
The ADS1251U, produced by Texas Instruments, is a precision, wide dynamic range, delta-sigma Analog-to-Digital (A/D) converter. It operates with a 24-bit resolution and is capable of achieving high-resolution digital results at data rates up to 20kHz. The converter is powered by a single +5V supply and features a delta-sigma architecture that ensures 24 bits of no missing codes performance. It is particularly suited for high-resolution measurement applications due to its low noise and high effective resolution of 19 bits.
Key Specifications
| Parameter | Conditions | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Full-Scale Input Voltage | VIN - (-VIN) | ±VREF | V | ||
| Absolute Input Voltage | VIN or -VIN to GND | -0.3 | VDD | V | |
| Differential Input Impedance | CLK = 3.84kHz | 430 MΩ | Ω | ||
| CLK = 1MHz | 1.7 MΩ | Ω | |||
| CLK = 8MHz | 210 kΩ | Ω | |||
| Input Capacitance | 6 | pF | |||
| Input Leakage | At +25°C | 5 | 50 | pA | |
| At TMIN to TMAX | 1 nA | A | |||
| Data Rate | 20.8 kHz | kHz | |||
| Bandwidth -3dB | CLK = 8MHz | 4.24 kHz | kHz | ||
| Serial Clock (SCLK) | 8 MHz | MHz | |||
| System Clock Input (CLK) | 8 MHz | MHz | |||
| Integral Nonlinearity | Differential Input | ±0.0002 | ±0.0015 | % of FSR | |
| THD | 1kHz Input; 0.1dB below FS | 105 dB | dB | ||
| Noise | CLK = 8MHz, and VREF = 4.096 | 1.5 | 2.5 | ppm | |
| Voltage Reference (VREF) | 0.5 | 4.096 | V | ||
| Load Current | 32 μA | A | |||
| Logic Level: VIH | +4.0 | +VDD + 0.3 | V | ||
| Logic Level: VIL | -0.3 | +0.8 | V | ||
| Output Voltage (VOH) | IOH = –500μA | +4.5 | V | ||
| Output Voltage (VOL) | IOL = 500μA | 0.4 | V | ||
| Input Hysteresis | SCLK, CLK | 0.6 | V | ||
| Operating Voltage | +4.75 | +5 | +5.25 | VDC | |
| Quiescent Current | VDD = +5VDC | 1.5 | 2 | mA | |
| Operating Power | 7.5 | 10 | mW | ||
| Power-Down Current | 0.4 | 1 | μA | ||
| Operating Temperature Range | -40 | +85 | °C | ||
| Storage Temperature Range | -60 | +100 | °C |
Key Features
- 24-Bit Resolution: Ensures high-resolution digital results with no missing codes performance.
- Low Noise: Achieves an effective resolution of 19 bits with 1.5 ppm of rms noise.
- Differential Inputs: Supports differential analog input signals.
- External Reference: Allows for an external reference voltage between 0.5V and 5V.
- Power-Down Mode: Reduces power consumption to 0.4-1 μA in power-down mode.
- Sync Mode: Supports synchronous operation.
- Low Power Consumption: Operates at 8mW at 20kHz and 5mW at 10kHz.
Applications
- Cardiac Diagnostics: Suitable for high-resolution measurements in cardiac diagnostic equipment.
- Direct Thermocouple Interfaces: Can be used for precise temperature measurements.
- Blood Analysis: Applicable in medical devices for blood analysis.
- Infrared Pyrometers: Used in temperature measurement applications involving infrared pyrometers.
- Liquid/Gas Chromatography: Ideal for chromatography applications requiring high resolution.
- Precision Process Control: Utilized in industrial process control systems for precise measurements.
Q & A
- What is the resolution of the ADS1251U?
The ADS1251U has a 24-bit resolution with no missing codes performance. - What is the maximum data rate of the ADS1251U?
The maximum data rate is 20.8 kHz. - What is the operating voltage range of the ADS1251U?
The operating voltage range is from +4.75V to +5.25V. - What is the power consumption of the ADS1251U at 20kHz?
The power consumption is approximately 8mW at 20kHz. - Does the ADS1251U support differential inputs?
Yes, it supports differential analog input signals. - What is the effective resolution of the ADS1251U?
The effective resolution is 19 bits with 1.5 ppm of rms noise. - Can the ADS1251U operate in power-down mode?
Yes, it has a power-down mode that reduces power consumption to 0.4-1 μA. - What are some common applications of the ADS1251U?
Common applications include cardiac diagnostics, direct thermocouple interfaces, blood analysis, infrared pyrometers, liquid/gas chromatography, and precision process control. - What is the storage temperature range of the ADS1251U?
The storage temperature range is from -60°C to +100°C. - What type of package does the ADS1251U come in?
The ADS1251U is available in an SO-8 package.
