feature

Ultra-compact SC70 and TSOT package low temperature coefficient; 8-lead SOIC: 3 ppm/°C; 5-lead SC70: 9ppm/°C; 5-lead TSOT: 9ppm/°C; initial accuracy ±0.1%; no external capacitors required; low noise 10 microvolt pp (0.1 Hz to 10.0 Hz); wide operating range; ADR01 : 12.0 volts to 36.0 volts; ADR02: 7.0 volts to 36.0 volts; ADR03: 4.5 volts to 36.0 volts; ADR06: 5.0 volts to 36.0 volts; high output 10 mA current; Wide temperature range: –40°C to +125 °C ADR01/ADR02/ADR03 pin compatible with industry-standard REF01 /REF02/REF03; ADR01, ADR02, ADR03 and ADR06 SOICs for automotive applications.

application

Precision data acquisition systems; high-resolution converters; industrial process control systems; precision instruments; automatic battery monitoring; PCMCIA cards.

General Instructions

The ADR01, ADR02, ADR03, and ADR06 are precision 10.0V, 5.0V, 2.5V, and 3.0V bandgap voltage references featuring high accuracy, high stability, and low power consumption. The parts are packaged in tiny 5-wire SC70 and TSOT packages, as well as 8-wire SOIC versions. The SOIC versions of the ADR01, ADR02 and ADR03 are replacements for the industry standard REF01, REF02 and REF03. The small footprint and wide operating range make the adrx reference ideal for general purpose and space-constrained applications.

Temperature terminations can be used for temperature sensing and approximation with external buffers and a simple resistor network. There are trimming terminals on the device for trimming the output voltage.

The ADR01, ADR02, ADR03, and ADR06 are compact, low-drift voltage references that provide extremely stable output voltages over a wide supply voltage range. They are available in 5-wire SC70 and TSOT packages, as well as 8-wire SOIC packages, with a choice of A, B and C grades. All parts are specified over the extended industrial (–40°C to +125°C) temperature range. The ADR01, ADR02, ADR03, and ADR06 Class A 8-lead SOICs are available for automotive applications.

1. ADR01, ADR02 and ADR03 are compatible with REF01, REF02 and REF03 respectively. System-level compatibility is not guaranteed. The SOIC version of ADR01/ADR02/ADR03 is pin-to-pin compatible with the 8-lead SOIC version of REF01/REF02/REF03, respectively, with an additional temperature monitoring function.

Absolute Maximum Ratings

Rated at 25°C unless otherwise noted.

Stresses above the Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device under the conditions described in the operating section of this specification or any other conditions above is not implied. Long-term exposure to absolute maximum rating conditions may affect device reliability.

Thermal resistance

θJA is specified for worst-case, devices soldered in circuit boards intended for surface mount packages.

the term

Voltage drop (VDO)

Dropout voltage, sometimes referred to as mains voltage head chamber or mains output voltage difference, is the minimum voltage difference between the input and output required for the operation of a device, such as:

Because the leakage voltage depends on the current through the device, it is always specified for a given load current.

Temperature Coefficient (TCVO)

The temperature coefficient relates the change in the output voltage to the change in the ambient temperature of the device, normalized by the output voltage at 25°C. This parameter is expressed in ppm/°C and can be determined by the following equation:

Where: VOUT(25°C) is the output voltage at 25°C; VOUT(T1) is the output voltage at temperature 1; VOUT(T2) is the output voltage at temperature 2.

Output Voltage Hysteresis (ΔVOUT_HYS)

Output voltage hysteresis represents the change in output voltage after a device has been exposed to a specified temperature cycle. This can be expressed as a voltage change or a difference in parts per million from the nominal output as follows:

in:

VOUT (25°C) is the output voltage at 25°C; VOUT_TC is the output voltage after temperature cycling.

The thermal hysteresis effect is due to the packing force of the internal mold. This effect is more pronounced in some products in small packages.

Long-term stability (ΔVOUT U LTD)

Long-term stability refers to the change in output voltage at 25°C after 1000 hours of operation at 25°C. This can also be expressed as a voltage change or a difference in parts per million from the nominal output as follows:

where VOUT(t0) is VOUT at 25°C at time 0; VOUT(t1) is VOUT at 25°C after 1000 hours of operation at 25°C.

Line conditioning

Line regulation is the change in output voltage in response to a given change in input voltage expressed as a percentage per volt, parts per million per volt, or microvolts per volt of input voltage change. This parameter accounts for the effect of self-heating.

load regulation

Load regulation refers to the response of the output voltage to a given change in load current, expressed in microvolts per milliamp, millionths per milliamp, or DC output resistance in ohms. This parameter accounts for the effect of self-heating.

Typical performance characteristics

application information

Overview

The ADR01/ADR02/ADR03/ADR06 are high precision, low drift 10.0V, 5.0V, 2.5V, and 3.0V voltage references available in ultra-small packages. The 8-lead SOIC versions of these devices are a replacement for the REF01/REF02/REF03 sockets with improved cost and performance.

These devices are standard bandgap references (see Figure 34). The bandgap cell contains two NPN transistors (Q18 and Q19) with a 2× difference in emitter area. The difference in their VBE produces a current proportional to the absolute temperature current (PTAT) in R14 and, when combined with the VBE of Q19, produces a nearly constant bandgap voltage VBG. The VO of ADR01, ADR02, ADR06, and ADR03 are precisely set to 10.0V, 5.0V, 2.5V, and 3.0V, respectively, through the internal op-amp and the feedback network of R5 and R6. Precision laser trimming of the resistors and other proprietary circuit techniques further improve the initial accuracy, temperature curvature, and drift performance of the ADR01/ADR02/ADR03/ADR06.

The PTAT voltage is available at the temperature pins of the ADR01/ADR02/ADR03/ADR06. It has a stable 1.96mv/°C temperature coefficient, so that users can estimate the temperature change of the device by knowing the voltage change at the temperature pin.

Apply ADR01/ADR02/ADR03/ADR06

Input and output capacitors

Although the ADR01/ADR02/ADR03/ADR06 are designed for stable operation without any external components, it is highly recommended to connect a 0.1µF ceramic capacitor to the output to improve stability and filter out low-level voltage noise. 1µF to 10µF electrolytic, tantalum, or ceramic capacitors can be added in parallel to improve transient performance during sudden changes in load current; however, designers should keep in mind that doing so will increase the turn-on time of the device.

A 1µF to 10µF electrolytic, tantalum, or ceramic capacitor can also be connected to the input to improve transient response in applications where the supply voltage may fluctuate. To reduce power supply noise, a 0.1µF ceramic capacitor should be connected in parallel. Install the input and output capacitors as close as possible to the device pins.

output adjustment

The output voltage can be adjusted beyond the rated voltage using the ADR01/ADR02/ADR03/ADR06 trimming terminals. This feature allows the system designer to make finer adjustments by setting the reference to voltages other than 10.0 V/5.0 V/2.5 V/3.0 V, adding a series resistance of 470 kΩ. Take that dummy - as shown in Figure 35, ADR01 can adjust from 9.70 V to 10.05 V, ADR02 can adjust from 4.95 V to 5.02 V, ADR06 can adjust from 2.8 V to 3.3 V, and ADR03 can adjust from 2.3 V to 2.8 V . As long as the resistance's temperature coefficient is relatively low, adjustment of the output does not significantly affect the temperature performance of the device.

temperature monitoring

As mentioned at the end of the overview section, the ADR01/ADR02/ADR03/ADR06 provide a temperature output that varies linearly with temperature (Pin 1 in Figure 1 and Pin 3 in Figure 2). This output can be used to monitor temperature changes in the system. At 25°C, the voltage of VTEMP is about 550mV and the temperature coefficient is about 1.96mV/°C (see Figure 36). A voltage change of 39.2 mV at the temperature pin corresponds to a temperature change of 20°C.

The TEMP function is provided for convenience rather than precise characterization. Since the voltage at the temperature node is obtained from the bandgap core, the current drawn from this pin has a significant effect on VOUT. Care must be taken to buffer the temperature output with an appropriate low bias current op amp such as the AD8601, AD820, or OP1177, all of which result in a change in ∏VOUT of less than 100µV (see Figure 37). Without buffering, even taking tens of microamps from the temperature pin will cause VOUT to be out of spec.

low cost current source

Unlike most references, the ADR01/ADR02/ADR03/ADR06 use an NPN Darlington, where the quiescent current remains constant with respect to the load current, as shown in Figure 23. Therefore, the current source can be configured as shown in Figure 38, where ISET=(VOUT−VL)/RSET. IL is just the sum of ISET and IQ. Although simple, the IQ typically varies from 0.55 mA to 0.65 mA, limiting the general-purpose application of this circuit.

Adjustable output precision current source

Alternatively, a precision current source can be implemented using the circuit shown in Figure 39. By adding a mechanical or digital potentiometer, the circuit becomes an adjustable current source. If a digital potentiometer is used, the load current is simply the voltage between terminals B and W of the digital potentiometer divided by RSET.

where D is the decimal equivalent of the digital potentiometer input code.

To optimize the resolution of this circuit, a dual-supply op amp should be used because the ground potential of the ADR02 can swing from -5.0 V at zero scale to VL at full scale set by the potentiometer.

Programmable 4mA to 20mA Current Transmitter

The device has the advantages of high accuracy, strong current handling capability, and small footprint, making it suitable as a reference source for many high-performance converter circuits. One such application is a multi-channel 16-bit, 4 mA to 20 mA current transmitter in the industrial control market (see Figure 40). Compared to traditional op amp and mosfet designs, the circuit employs a Hall current pump at the output for better efficiency, lower component count, and higher voltage compliance. In this circuit, if the resistors are matched as R1=R1′, R2=R2′, R3=R3′, the load current is:

where D is similarly the decimal equivalent of the DAC input code and N is the number of bits of the DAC.

According to Equation 2, R3' can be used to set the sensitivity. R3' can be as small as needed to achieve the current required for U4's output current drive capability. Change the machine, other resistors can be kept high to save power.

In this circuit, the AD8512 is capable of outputting 20 mA with a voltage compliance approaching 15.0 volts.

Howland current pumps produce a potentially infinite output impedance, which is ideal, but resistor matching is critical in this application. The output impedance can be determined using Equation 3. As the equation shows, if the resistors are perfectly matched, ZO is infinite. Or, if they don't match, ZO is positive or negative. If the latter is true, oscillations may occur. To do this, connect a capacitor C1 in the range of 1 pF to 10 pF between VP and the output terminals of U4 to filter any oscillations.

In this circuit, the ADR01 provides a stable 10.000 V reference voltage to the AD5544 four 16-bit DACs. The adjustable current has a resolution of 0.3 µA/step; the total worst-case INL error is only 4 lsb. This error equates to a 1.2 microampere or 0.006% system error, well below the requirements of most systems. The results are shown in Figure 41, measured at 25°C and 70°C; the total system error is 4 LSBs at 25°C and 70°C.

Precision Boost Output Regulator

Accurate voltage output with enhanced current capability can be achieved using the circuit shown in Figure 42. In this circuit, U2 adjusts the conduction of N1 to force VO to be equal to VREF, thereby making the load current provided by VIN. In this configuration, a load of 50ma can be achieved at a V In of 15.0v. MOSFETs generate moderate heat, and higher currents can be obtained by replacing larger devices. Also, for heavy capacitive loads with fast-edge input signals, buffers should be added at the output to enhance transient response.

Dimensions

automotive products

The ADR01W, ADR02W, ADR03W, and ADR06W models are available in controlled manufacturing to support the quality and reliability requirements of automotive applications. Note that specifications for these models may differ from commercial models; therefore, designers should carefully review the Specifications section of this data sheet. Only the automotive grade products shown are available for automotive applications. Please contact your local Analog Devices account representative for specific product ordering information and to obtain specific vehicle reliability reports for these models.