ADR02BRZ-REEL7 데이터 시트보기 (PDF) - Analog Devices
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ADR02BRZ-REEL7 Datasheet PDF : 21 Pages
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ADR01/ADR02/ADR03/ADR06
0.80
VIN = 15V
SAMPLE SIZE = 5
0.75
0.70
0.65
0.60
ΔVTEMP/ΔT ≈ 1.96mV/°C
0.55
0.50
0.45
0.40
–50 –25
0
25
50
75
TEMPERATURE (°C)
100 125
Figure 36. Voltage at TEMP Pin vs. Temperature
The TEMP function is provided as a convenience rather than a
precise feature. Because the voltage at the TEMP node is
acquired from the band gap core, current pulling from this pin
has a significant effect on VOUT. Care must be taken to buffer the
TEMP output with a suitable low bias current op amp, such as
the AD8601, AD820, or OP1177, all of which result in less than
a 100 µV change in ∆VOUT (see Figure 37). Without buffering,
even tens of microamps drawn from the TEMP pin can cause
VOUT to fall out of specification.
15V
VIN
U1
ADR01/
ADR02/
ADR03/
ADR06
VIN VOUT
VO
VTEMP
1.9mV/°C
V+
OP1177
U2 V–
TEMP TRIM
GND
Figure 37. Temperature Monitoring
LOW COST CURRENT SOURCE
Unlike most references, the ADR01/ADR02/ADR03/ADR06
employ an NPN Darlington in which the quiescent current
remains constant with respect to the load current, as shown in
Figure 23. As a result, a current source can be configured as
shown in Figure 38 where ISET = (VOUT − VL)/RSET. IL is simply
the sum of ISET and IQ. Although simple, IQ varies typically from
0.55 mA to 0.65 mA, limiting this circuit to general-purpose
applications.
Data Sheet
VIN
IIN
ADR01/
ADR02/ VOUT
ADR03/
ADR06
RSET
GND
IQ ≈ 0.6mA
RL
ISET = (VOUT – VL)/RSET
VL
IL = ISET + IQ
Figure 38. Low Cost Current Source
PRECISION CURRENT SOURCE WITH
ADJUSTABLE OUTPUT
Alternatively, a precision current source can be implemented
with the circuit shown in Figure 39. By adding a mechanical or
digital potentiometer, this circuit becomes an adjustable current
source. If a digital potentiometer is used, the load current is
simply the voltage across Terminal B to Terminal W of the
digital potentiometer divided by RSET.
IL
=
VREF ×
RSET
D
(1)
where D is the decimal equivalent of the digital potentiometer
input code.
+12V
U1
ADR01/
ADR02/
ADR03/
ADR06
VIN VOUT
TEMP TRIM
GND
0V TO (5V + VL)
B
AD5201 W
100kΩ
A
+12V
U2
V+
OP1177
–5V TO VL V–
RSET
1kΩ
VL
–12V
RL 1kΩ IL
Figure 39. Programmable 0 mA to 5 mA Current Source
To optimize the resolution of this circuit, dual-supply op amps
should be used because the ground potential of ADR02 can
swing from −5.0 V at zero scale to VL at full scale of the
potentiometer setting.
Rev. R | Page 16 of 20
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