Datasheet ADR4520, ADR4525, ADR4530, ADR4533, ADR4540, ADR4550 (Analog Devices) - 31

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Data Sheet ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550 APPLICATIONS INFORMATION BASIC VOLTAGE REFERENCE CONNECTION SAMPLE APPLICATIONS
The circuit shown in Figure 94 illustrates the basic configuration
Bipolar Output Reference
for the ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ Figure 95 shows a bipolar reference configuration. By connecting ADR4550 family of voltage references. the output of the ADR4550 to the inverting terminal of an operational amplifier, it is possible to obtain both positive and
VIN
negative reference voltages. R1 and R2 must be matched as closely as possible to ensure minimal difference between the negative and positive outputs. Resistors with low temperature coefficients must also be used if the circuit is used in environments with large
BAND GAP VREF
temperature swings; otherwise, a voltage difference develops between the two outputs as the ambient temperature changes.
VIN 2 V 6 +5V IN VOUT
054
R1 GND
10203-
10kΩ
Figure 94. ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/ADR4550
1µF 0.1µF 0.1µF ADR4550
Simplified Schematic
R2 10kΩ INPUT AND OUTPUT CAPACITORS GND 4 +15V Input Capacitors ADA4000-1 –5V
A 1 μF to 10 μF electrolytic or ceramic capacitor can be connected to the input to improve transient response in applications where
R3 5kΩ
055
–15V
the supply voltage may fluctuate. An additional 0.1 μF ceramic 10203- capacitor should be connected in parallel to reduce supply noise. Figure 95. ADR4550 Bipolar Output Reference
Output Capacitors Boosted Output Current Reference
An output capacitor is required for stability and to filter out low Figure 96 shows a configuration for obtaining higher current level voltage noise. The minimum value of the output capacitor drive capability from the ADR4520/ADR4525/ADR4530/ is shown in Table 12. ADR4533/ADR4540/ADR4550 references without sacrificing
Table 12. Minimum C
accuracy. The op amp regulates the current flow through the
OUT Value
MOSFET until V
Part Number Minimum C
OUT equals the output voltage of the reference;
OUT Value
current is then drawn directly from V ADR4520, ADR4525 1.0 µF IN instead of from the reference itself, al owing increased current drive capability. ADR4530, ADR4533, 0.1 µF ADR4540, ADR4550
VIN U6 +16V
An additional 1 μF to 10 μF electrolytic or ceramic capacitor can be
R1 2 V 6 100Ω 2N7002
added in paral el to improve transient performance in response to
IN VOUT
sudden changes in load current; however, the designer should keep
AD8663 VOUT
in mind that doing so will increase the turn-on time of the device.
1µF 0.1µF ADR4520/ADR4525/ CL LOCATION OF REFERENCE IN SYSTEM ADR4530/ADR4533/ R 0.1µF ADR4540/ADR4550 C L L 200Ω
The ADR4520/ADR4525/ADR4530/ADR4533/ADR4540/
PART MINIMUM
ADR4550 reference should be placed as close to the load as possible
NUMBER CL GND 4
to minimize the length of the output traces and, therefore, the error
ADR4520, 1.0µF ADR4525
introduced by the voltage drop. Current flowing through a PCB
ADR4530, 0.1µF ADR4533,
trace produces an IR voltage drop; with longer traces, this drop 056
ADR4540, ADR4550
can reach several millivolts or more, introducing considerable 10203- error into the output voltage of the reference. A 1 inch long, 5 mm Figure 96. Boosted Output Current Reference wide trace of 1 ounce copper has a resistance of approximately Because the current-sourcing capability of this circuit depends only 100 mΩ at room temperature; at a load current of 10 mA, this on the I can introduce a ful mil ivolt of error. D rating of the MOSFET, the output drive capability can be adjusted to the application simply by choosing an appropriate MOSFET. In al cases, the VOUT pin should be tied directly to the load device to maintain maximum output voltage accuracy. Rev. A | Page 31 of 33 Document Outline Features Applications Pin Configuration General Description Revision History Specifications ADR4520 Electrical Characteristics ADR4525 Electrical Characteristics ADR4530 Electrical Characteristics ADR4533 Electrical Characteristics ADR4540 Electrical Characteristics ADR4550 Electrical Characteristics Absolute Maximum Ratings Thermal Resistance ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics ADR4520 ADR4525 ADR4530 ADR4533 ADR4540 ADR4550 Terminology Theory of Operation Long-Term Drift Power Dissipation Applications Information Basic Voltage Reference Connection Input and Output Capacitors Input Capacitors Output Capacitors Location of Reference in System Sample Applications Bipolar Output Reference Boosted Output Current Reference Outline Dimensions Ordering Guide Automotive Products