Overview
The LM12458, produced by Texas Instruments, is a highly integrated 12-bit + sign data acquisition system. This component operates on a single 5V supply and combines a fully-differential self-calibrating analog-to-digital converter (ADC) with extensive analog and digital functionality. It includes a built-in sample-and-hold circuit, an 8-channel multiplexer, and a 32-word conversion FIFO data buffer. The LM12458 is designed for high accuracy and reliability, making it suitable for various applications requiring precise data acquisition and processing.
Key Specifications
| Parameter | Conditions | Typical | Limits | Units |
|---|---|---|---|---|
| Integral Linearity Error (ILE) | After Auto-Cal | ±1/2 LSB | ±1 LSB (max) | LSB |
| Differential Non-Linearity (DNL) | 8-Bit + Sign and “Watchdog” Mode | ±3/4 LSB | ±1 LSB (max) | LSB |
| Zero Error | After Auto-Zero | ±0.2 LSB | ±1.75 LSB (max) | LSB |
| Full-Scale Error | 8-Bit + Sign and “Watchdog” Mode | ±0.2 LSB | ±2 LSB (max) | LSB |
| VA+ Supply Current (IA+) | CS = “1” | 3.1 mA | 5.5 mA (max) | mA |
| VD+ Supply Current (ID+) | CS = “1” | 0.55 mA | 1.2 mA (max) | mA |
| Internal Reference Output Voltage (VREFOUT) | 2.5 V | 2.5 ± 4% V (max) | V | |
| Logical “1” Input Voltage (VIN(1)) | VA+ = VD+ = 5.5V | 2.0 V | 2.0 V (min) | V |
| Logical “0” Input Voltage (VIN(0)) | VA+ = VD+ = 4.5V | 0.8 V | 0.8 V (max) | V |
Key Features
- 12-bit + sign, 8-bit + sign, and “watchdog” operating modes
- Single-ended or differential inputs
- Built-in sample-and-hold and 2.5V bandgap reference
- 8-channel multiplexer and 32-word conversion FIFO data buffer
- Instruction RAM and event sequencer for up to 32 consecutive conversions
- Programmable acquisition times and conversion rates
- Self-calibration and diagnostic mode
- 8- or 16-bit wide data bus microprocessor or DSP interface
- Internal clock-driven timers for programmable acquisition times
- External or internal reference voltage input for absolute or ratiometric operation
Applications
- Data Logging
- Instrumentation
- Process Control
- Energy Management
- Inertial Guidance
Q & A
- What is the resolution of the LM12458 ADC?
The LM12458 operates in 12-bit + sign, 8-bit + sign, and “watchdog” modes.
- What is the supply voltage range for the LM12458?
The supply voltage range is from 3.0V to 5.5V.
- Does the LM12458 have built-in sample-and-hold functionality?
- How many channels does the multiplexer support?
The LM12458 supports an 8-channel multiplexer.
- What is the purpose of the internal 2.5V bandgap reference?
The internal 2.5V bandgap reference is used for self-calibration and as a voltage reference for the ADC.
- Can the LM12458 operate in differential input mode?
- What is the function of the instruction RAM and event sequencer?
The instruction RAM and event sequencer allow for up to 32 consecutive conversions and store the conversion sequence.
- How can the acquisition times and conversion rates be programmed?
Programmable acquisition times and conversion rates are possible through the use of internal clock-driven timers.
- Does the LM12458 support self-calibration and diagnostic modes?
- What types of data bus interfaces does the LM12458 support?
