ОБЩЕЕ ОПИСАНИЕ

The ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550 devices are high precision, low power, low noise voltage references featuring ±0.02% B, C, and D grade maximum initial error, excellent temperature stability, and low output noise.

This family of voltage references uses an innovative core topology to achieve high accuracy while offering industry-leading temperature stability and noise performance. The low, thermally induced output voltage hysteresis and low long-term output voltage drift of the devices also improve system accuracy over time and temperature variations.

A maximum operating current of 950 μA and a maximum low dropout voltage of 300 mV allow the devices to function very well in portable equipment.

The ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550 series of references are each provided in an 8-lead SOIC and are available in a wide range of output voltages, all of which are specified over the extended industrial temperature range of −40°C to +125°C.

 

Регулирование линии

Line regulation refers to the change in output voltage in response to a given change in input voltage and is expressed in percent per volt, ppm per volt, or μV per volt change in input voltage. This parameter accounts for the effects of self heating.

 

Регулирование нагрузки

Load regulation refers to the change in output voltage in response to a given change in load current and is expressed in μV per mA,ppm per mA, or ohms of dc output resistance. This parameter accounts for the effects of self heating.

 

Solder Heat Resistance (SHR) Shift

SHR shift refers to the permanent shift in output voltage that is induced by exposure to reflow soldering and is expressed as a percentage of the output voltage. This shift is caused by changes in the stress exhibited on the die by the package materials when these materials are exposed to high temperatures. This effect is more pronounced in lead-free soldering processes due to higher reflow temperatures. SHR is calculated after three solder reflow cycles to simulate the worst case conditions when assembling a two-sided PCB with surface mount components with one additional rework cycle. The reflow cycles use the JEDEC standard reflow temperature profile.

 

Temperature Coefficient (TCVOUT)

The temperature coefficient relates the change in the output voltage to the change in the ambient temperature of the device, as normalized by the output voltage at 25°C. The TCVOUT for the ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550 A grade and B grade is fully tested over three temperatures: −40°C, +25°C, and +125°C. The TCVOUT for the C grade and D grade is fully tested over three temperatures: 0°C, +25°C, and +70°C. This parameter is specified using two methods. The box method is the most common method and accounts for the temperature coefficient over the full temperature range, whereas the bowtie method calculates the worst case slope from +25°C and is therefore more useful for systems which are calibrated at +25°C.

 

Input Capacitors

A 1 μF to 10 μF electrolytic or ceramic capacitor can be connected to the input to improve transient response in applications where the supply voltage may fluctuate. It is recommended to connect an additional 0.1 μF ceramic capacitor in parallel to reduce supply noise.

 

LOCATION OF REFERENCE IN SYSTEM

It is recommended to place the ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550 reference as close to the load as possible to minimize the length of the output traces and, therefore,the error introduced by the voltage drop. Current flowing through a PCB trace produces a voltage drop; with longer traces, this drop can reach several millivolts or more, introducing considerable error into the output voltage of the reference. A 1-inch long, 5 mm wide trace of 1-ounce copper has a resistance of approximately 100 mΩ at room temperature; at a load current of 10 mA, this resistance can introduce a full millivolt of error.