AD1403 View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

AD1403

Low Cost, Precision 2.5 V IC References

Analog Devices 

ApDp1l4yi0n3g/AthDe14A0D31A403/AD1403A

The AD1403 exhibits a worst-case shift of 7.5 mV over the en-

tire range of operating input voltage, 4.5 volts to 40 volts. Typi-

cally, the shift is less than 1 mV as shown in Figure 3.

THE AD1403A AS A LOW POWER, LOW VOLTAGE

PRECISION REFERENCE FOR DATA CONVERTERS

The AD1403A has a number of features that make it ideally

suited for use with A/D and D/A data converters used in com-

plex microprocessor-based systems. The calibrated 2.500 volt

output minimizes user trim requirements and allows operation

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 shows the AD1403 connected as a current source.

Total current is equal to the quiescent current plus the load

current. Most of the temperature coefficient comes from the

quiescent current term II, which has a typical TC of 0.13%/°C

(1300 ppm/°C). The load voltage (and hence current) TC is

much lower at ± 40 ppm/°C max (AD1403). Therefore, the

overall temperature coefficient decreases rapidly as the load cur-

rent is increased. Figure 9b shows the typical temperature coef-

ficient for currents between 1.5 mA and 10 mA. Use of an

AD1403A will not improve the TC appreciably.

Figure 9a. The AD1403 as a Precision Programmable

Current Source

Figure 8. Low Power, Low Voltage Reference for the

AD7524 Microprocessor-Compatible 8-Bit DAC

processor interface. The AD1403A and the AD7524 are speci-

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

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

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.

Figure 9b. Typical Temperature Coefficient of Current

Source

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

8-Pin Mini-DIP (N)

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

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