Microchip Targets Temperature Stability in New Cost-effective Vref IC

October 11, 2021 by Jake Hertz

When it comes to voltage references, not only are they important, but they must be stable, especially when it comes to temperature. Targeting just that, Microchip has released a new voltage reference IC.

One of the most important yet least talked about electrical components is the voltage reference (Vref). Many analog applications, including analog to digital converters (ADCs), digital to analog converters (DACs), sensors, and biasing circuitry, operates by comparing a given voltage to a known reference. 


An example diagram of an ADC voltage reference.

An example diagram of an ADC voltage reference. Image used courtesy of Analog Devices


As such, it's essential to have voltage references that are stable and reliable, ones that don't change with temperature, age, or process variations. 

Recently, Microchip announced the release of a new, high-reliability voltage reference for industrial and automotive applications. This article will talk about some of the challenges with achieving stable voltage references and how Microchip is looking to solve them.


Temperature Coefficient in Voltage References 

In a perfect world, a voltage reference will produce a stable voltage independent of changes in the environment. In the real world, however, imperfections and nonlinearities in the circuit elements cause the output of a voltage reference to exhibit temperature-induced variations at the output. 

To quantify the impact of the temperature-induced errors at the output, engineers use a temperature coefficient metric (or temperature drift). The temperature coefficient of a voltage reference defines the maximum voltage variation over a given temperature range and is calculated using a method called the "box method." 


\[TCV_o = \frac{V_{max} - V_{min}}{V_{nominal} (T_{max} - T_{min})} \times 10^6\]


The result of this method is a temperature coefficient defined in part per million per degree celsius (ppm/°C). 

Keeping this coefficient in mind, Microchip is leveraging it to create a more efficient and cost-effective voltage reference. 


The MCP1502

This week, Microchip announced its new voltage reference, the MPC1502, designed specifically for industrial and automotive applications. For this device, Microchip claims to have prioritized cost, reliability, and size.


Block diagram of the MCP1502.

Block diagram of the MCP1502. Image used courtesy of Microchip


An AEC-Q100 Grade 1 automotive-qualified device, the MCP1502 comes in a 6-pin SOT-23 package and claims to offer a maximum temperature coefficient of 7ppm/°C from -40C-125C, while being able to sink and source 20 mA of current. 

To achieve these specs, Microchip states that the device is built on a low drift band gap-based architecture that utilizes chopper-based amplifiers to reduce temperature drift significantly. 

At an initial accuracy of 0.1%, the MCP1502 offers a variety of output voltages from 1V to 4V. The device is also very cost-effective, with a starting price of $1.09, which could be a consideration when needing to include a Vref into a design. 


Future Applications 

With all things considered, Microchip feels that this new reference could find itself very useful in various applications. Amongst these applications, Microchip mentions precision data acquisition systems, electric vehicle battery management systems, industrial controls, and more. All in all, Vref's are a key part of many designs, and with companies like Microchip focusing on pushing this technology along to keep up with quickly changing factors, designs can continue to become more efficient and cost-effective.