a Low Cost, Precision

2.5 V IC References
AD1403/AD1403A*
FEATURES FUNCTIONAL BLOCK DIAGRAM
Improved, Lower Cost, Replacements for Standard
1403, 1403A
3-Terminal Device: Voltage In/Voltage Out
Laser Trimmed to High Accuracy: 2.500 V 6 10 mV
(AD1403A)
Excellent Temperature Stability: 25 ppm/8C (AD1403A)
Low Quiescent Current: 1.5 mA max
10 mA Current Output Capability
Low Cost
Convenient Mini-DIP Package

PRODUCT DESCRIPTION PRODUCT HIGHLIGHTS

The AD1403 and AD1403A are improved three-terminal, low 1. The AD1403A offers improved initial tolerance over the in-
cost, temperature compensated, bandgap voltage references that dustry-standard 1403A: ± 10 mV versus ± 25 mV at a lower
provide a fixed 2.5 V output voltage for inputs between 4.5 V cost.
and 40 V. A unique combination of advanced circuit design and 2. The three-terminal voltage in/voltage out operation of the
laser-wafer-trimmed thin-film resistors provides the AD1403/ AD1403/AD1403A provides a regulated output voltage with-
AD1403A with an initial tolerance of ± 10 mV and a tempera- out any external components.
ture stability of better than 25 ppm/°C. In addition, the low
quiescent current drain of 1.5 mA (max) offers a clear advan- 3. The AD1403/AD1403A provides a stable 2.5 V output volt-
tage over classical Zener techniques. age for input voltages between 4.5 V and 40 V making these
devices ideal for systems that contain a single logic supply.
The AD1403 or AD1403A is recommended as a stable refer-
ence for all 8-, 10- and 12-bit D-to-A converters that require an 4. Thin film resistor technology and tightly controlled bipolar
external reference. In addition, the wide input range of the processing provide the AD1403A with temperature stabilities
AD1403/AD1403A allows operation with 5 volt logic supplies, of 25 ppm/°C.
making these devices ideal for digital panel meter applications 5. The low 1.5 mA maximum quiescent current drain of the
and when only a single logic supply is available. AD1403 and AD1403A makes them ideal for CMOS and
The AD1403 and AD1403A are specified for operation over the other low power applications.
0°C to +70°C temperature range. The AD580 series of 2.5 volt
precision IC references is recommended for applications where
operation over the –55°C to +125°C range is required.

*Protected by U.S. Patent Numbers: 3,887,863, RE30,586.

REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
otherwise under any patent or patent rights of Analog Devices. Tel: 617/329-4700 Fax: 617/326-8703
AD1403/AD1403A–SPECIFICATIONS (V IN = 15 V, TA = +258C unless otherwise noted.)

Characteristic Symbol Min Typ Max Unit

Output Voltage
(IO = 0 mA) VO
AD1403 2.475 2.500 2.525 V
AD1403A 2.490 2.500 2.510
Temperature Coefficient of Output Voltage ∆VO/∆T ppm/°C
AD1403 10 40
AD1403A 10 25
Output Voltage Change, 0°C to +70°C ∆VO mV
AD1403 7.0
AD1403A 4.4
Line Regulation Regin mV
(15 V ≤ VIN ≤ 40 V) 1.2 4.5
(4.5 ≤ VIN ≤ 15 V) 0.6 3.0
Load Regulation Regload 10 mV
(0 mA < IO < 10 mA)
Quiescent Current II 1.2 1.5 mA
(IO = 0 mA)
Specifications subject to change without notice.

MAXIMUM RATINGS (TA = +25°C unless otherwise noted) ORDERING GUIDE

Rating Symbol Value Unit Initial Package

Model Tolerance Option*
Input Voltage VIN 40 V
AD1403 ± 25 mV N-8
Storage Temperature TSTG –25 to 100 °C
AD1403A ± 10 mV N-8
Junction Temperature TJ +175 °C *N Plastic DIP.
Operating Ambient
Temperature Range TA 0 to +70 °C

Figure 1. AD1403/AD1403A Connection Diagram Figure 2. Simplified AD1403 Schematic

–2– REV. A
 Typical Performance Curves– AD1403/AD1403A

Figure 3. Typical Change in VOUT vs. VIN Figure 6. Change in VOUT vs. Temperature
(Normalized to VOUT @ VlN = 15 V @ TC = 25°C) (Normalized to VOUT @ VIN = 15 V)

Figure 4. Change in Output Voltage vs. Load Current Figure 7. Change in VOUT vs. Temperature
(Normalized to VOUT @ VIN = 15 V, lOUT = 0 mA) (Normalized to VOUT @ VlN = 15 V, IOUT = 0 mA)

VOLTAGE VARIATION VS. TEMPERATURE AND LINE

Some confusion exists in the area of defining and specifying ref-
erence voltage error over temperature. Historically, references
are characterized using a maximum deviation per degree Centi-
grade; i.e., 10 ppm/°C. However, because of the inconsistent
nonlinearities in Zener references (butterfly or “S” type charac-
teristics), most manufacturers use a maximum limit error band
approach to characterize their references. This technique mea-
sures the output voltage at 3 to 5 different temperatures and
guarantees that the output voltage deviation will fall within the
guaranteed error band at these discrete temperatures. This ap-
proach, of course, makes no mention or guarantee of perfor-
mance at any other temperature within the operating
temperature range of the device.
The consistent Voltage vs. Temperature performance of a typi-
cal AD1403 is shown in Figure 6. Note that the characteristic is
quasi-parabolic, not the possible “S” type characteristics of clas-
sical Zener references. This parabolic characteristic permits a
maximum output deviation specification over the device’s full
Figure 5. Quiescent Current vs. Temperature operating temperature range, rather than just at 3 to 5 discrete
(VIN = 15 V, IOUT = 0 mA) temperatures.

REV. A –3–
Applying the AD1403/AD1403A
AD1403/AD1403A
The AD1403 exhibits a worst-case shift of 7.5 mV over the en- Figure 9a shows the AD1403 connected as a current source.
tire range of operating input voltage, 4.5 volts to 40 volts. Typi- Total current is equal to the quiescent current plus the load
cally, the shift is less than 1 mV as shown in Figure 3. current. Most of the temperature coefficient comes from the
quiescent current term II, which has a typical TC of 0.13%/°C
THE AD1403A AS A LOW POWER, LOW VOLTAGE (1300 ppm/°C). The load voltage (and hence current) TC is
PRECISION REFERENCE FOR DATA CONVERTERS much lower at ± 40 ppm/°C max (AD1403). Therefore, the
The AD1403A has a number of features that make it ideally overall temperature coefficient decreases rapidly as the load cur-

C551a–9–7/82
suited for use with A/D and D/A data converters used in com- rent is increased. Figure 9b shows the typical temperature coef-
plex microprocessor-based systems. The calibrated 2.500 volt ficient for currents between 1.5 mA and 10 mA. Use of an
output minimizes user trim requirements and allows operation AD1403A will not improve the TC appreciably.
from a single low voltage supply. Low power consumption
(1.5 mA quiescent current) is commensurate with that of CMOS-
type devices, while the low cost and small package complements
the decreasing cost and size of the latest converters.
Figure 8 shows the AD1403A used as a reference for the
AD7524 low-cost 8-bit CMOS DAC with complete micro-

Figure 9a. The AD1403 as a Precision Programmable

Current Source

Figure 8. Low Power, Low Voltage Reference for the Figure 9b. Typical Temperature Coefficient of Current
AD7524 Microprocessor-Compatible 8-Bit DAC Source
OUTLINE DIMENSIONS
processor interface. The AD1403A and the AD7524 are speci- Dimensions shown in inches and (mm).
fied to operate from a single 5 volt supply; this eliminates the
need to provide a +15 volt power supply for the sole purpose of 8-Pin Mini-DIP (N)
operating a reference. The AD7524 includes an 8-bit data regis-
ter, and address decoding logic; it may thus be interfaced di-
rectly to an 8- or 16-bit data bus. Only 300 µA of quiescent
current from the single +5 volt supply is required to operate the
AD7524 which is packaged in a small 16-pin DIP. The AD542 PRINTED IN U.S.A.
output amplifier is also low power, requiring only 1.5 mA quies-
cent current. Its laser-trimmed offset voltage preserves the ± 1/2
LSB linearity of the AD7524KN without user trims and it typi-
cally settles to ± 1/2 LSB in less than 5 microseconds. It will pro-
vide the 0 volt to –2.5 volt output swing from ± 5 volt supplies.

THE AD1403 AS A PRECISION PROGRAMMABLE

CURRENT SOURCE
The AD1403 is an excellent building block for precision current
sources. Its wide range of operating voltages, 4.5 V to 40 V,
along with excellent line regulation over that range (7.5 mV)
result in high insensitivity to varying load impedances. The low
quiescent current (II) of 1.5 mA (max) and the maximum speci-
fied maximum load current of 10 mA allows the user to pro-
gram current to any value between 1.5 mA and 10 mA.
–4– REV. A