- LM5085 / LM25085 - Wide Input Range, Constant On-Time PFET Buck Switching Controller
- LM5088 / LM25088 - Wide Input Range, Emulated Current Mode Buck Controller
- Dual-Mode PWM Controller With Alternating Outputs
- Multi-Purpose 9-Output LED Driver
- 1A Switched Capacitor Flash LED Driver with I2C Compatible Interface
- LM315x Synchronous Simple Switcher® Controller Series
- LM2267X/LM22680 Simple Switcher® Step Down Regulator Series
- Versatile High Voltage Led Driver Controllers
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Overview: Voltage references are a key building block in data conversion systems, and understanding their specifications and how they contribute to error is necessary for selecting the right reference for the application. Figure 1 shows the application of a voltage reference in a simple analog-to-digital converter (ADC) and digital-to-analog converter (DAC). In each case, the reference voltage (VREF) acts as a very precise analog 'meter stick' against which the incoming analog signal is compared (as in an ADC) or the outgoing analog signal is generated (DAC). As such, a stable system reference is required for accurate and repeatable data conversion; and as the number of bits increases, less reference error can be tolerated. Monolithic voltage references produce an output voltage which is substantially immune to variations in ambient temperature as well as loading, input supply, and time. While many ADCs and DACs incorporate an internal reference, beyond 8 to10 bits it is rare to find one with sufficient precision as high-density CMOS technologies commonly used for data converters typically produce low-quality references. In most cases, the internal reference can be overdriven by an external one to improve performance. Terms such as "high precision" and "ultra-high precision" are common in reference datasheets but do little to help designers in their selection. This article seeks to provide an explanation of common reference specifications, rank their relative importance and show how a designer can use them in some simple calculations to narrow his or her search.
