Datasheet ADR510 (Analog Devices) - 8

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ADR510 APPLICATIONS INFORMATION
The ADR510 is a 1.0 V precision shunt voltage reference
OUTPUT VOLTAGE TRIM
designed to operate without an external output capacitor Using a mechanical or digital potentiometer, the output voltage between the positive terminal and the negative terminal for of the ADR510 can be trimmed ±0.5%. The circuit in Figure 12 stability. An external capacitor can be used for additional illustrates how the output voltage can be trimmed using a filtering of the supply. 10 kΩ potentiometer. Note that trimming using other resistor As with all shunt voltage references, an external bias resistor values may not produce an accurate output from the ADR510. (RBIAS) is required between the supply voltage and the ADR510
VCC
(see Figure 2). RBIAS sets the current that is required to pass through the load (I
RBIAS
L) and the ADR510 (IQ). The load and the supply voltage can vary, thus R
VOUT
BIAS is chosen based on the
1
following conditions:
ADR510 3 POT 10kΩ R1
• R
2 470kΩ
2 BIAS must be small enough to supply the minimum IQ 01 0- current to the ADR510 even when the supply voltage is at 27 03 minimum value and the load current is at maximum value. Figure 12. Output Voltage Trim • RBIAS also needs to be large enough so that IQ does not
USING THE ADR510 WITH PRECISION DATA
exceed 10 mA when the supply voltage is at its maximum
CONVERTERS
value and the load current is at its minimum value. The compact ADR510 and its low minimum operating current Given these conditions, RBIAS is determined by the supply requirement make it ideal for use in battery-powered portable voltage (VS), the load and operating current (IL and IQ) of the instruments, such as the AD7533 CMOS multiplying DAC, that ADR510, and the ADR510 output voltage. use precision data converters. V − V S OUT Figure 13 shows the ADR510 serving as an external reference to R = (3) BIAS I + I the AD7533, a CMOS multiplying DAC. Such a DAC requires a L Q negative voltage input in order to provide a positive output
ADJUSTABLE PRECISION VOLTAGE SOURCE
range. In this application, the ADR510 is supplying a −1.0 V The ADR510, combined with a precision low input bias op amp reference to the REF input of the AD7533. such as the AD860x, can be used to output a precise adjustable
0 9
voltage. Figure 11 illustrates implementation of this application
+ MSB LSB
using the ADR510.
ADR510 – VDD 1 AD7533
Output of the op amp, V
1
OUT, is determined by the gain of
G
the circuit, which is completely dependent on the R2 and R1
N R2 3 2 1 15
resistors.
–VDD +
R2 V = 1 + (4)
VOUT = 0V TO 1.0V
OUT
–
3 R1 -01 70 32 An additional capacitor in parallel with R2 can be added to 0 Figure 13. ADR510 as a Reference for a 10-Bit CMOS DAC (AD7533) filter out high frequency noise. The value of C2 is dependent on the value of R2.
VCC RBIAS 1.0V AD860x VOUT = (1 + R2/R1) ADR510 R2 R1 C2 (OPTIONAL)
1 1 0 0- 27 03 Figure 11. Adjustable Precision Voltage Source Rev. B | Page 8 of 12 Document Outline FEATURES APPLICATIONS PIN CONFIGURATION GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS PARAMETER DEFINITIONS TEMPERATURE COEFFICIENT THERMAL HYSTERESIS APPLICATIONS INFORMATION ADJUSTABLE PRECISION VOLTAGE SOURCE OUTPUT VOLTAGE TRIM USING THE ADR510 WITH PRECISION DATA CONVERTERS PRECISE NEGATIVE VOLTAGE REFERENCE OUTLINE DIMENSIONS ORDERING GUIDE