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參數(shù)資料
| 型號： | ADR440B |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Ultralow Noise, LDO XFET Voltage References with Current Sink and Source |
| 中文描述： | 超低噪聲，LDO的XFET電壓與電流吸入和源引用 |
| 文件頁數(shù)： | 14/20頁 |
| 文件大小： | 417K |
| 代理商： | ADR440B |
ADR440/ADR441/ADR443/ADR444/ADR445
THEORY OF OPERATION
The ADR44x series of references uses a new reference generation
technique known as XFET (eXtra implanted junction FET).
This technique yields a reference with low dropout, good
thermal hysteresis, and exceptionally low noise. The core of the
XFET reference consists of two junction field-effect transistors
(JFETs), one of which has an extra channel implant to raise its
pinch-off voltage. By running the two JFETs at the same drain
current, the difference in pinch-off voltage can be amplified
and used to form a highly stable voltage reference.
The intrinsic reference voltage is around 0.5 V with a negative
temperature coefficient of about –120 ppm/°C. This slope is
essentially constant to the dielectric constant of silicon, and it can
be closely compensated for by adding a correction term generated
in the same fashion as the proportional-to-temperature (PTAT)
term used to compensate band gap references. The advantage
of an XFET reference is its correction term, which is approx-
imately 20 times lower and requires less correction than that of a
band gap reference. Because most of the noise of a band gap
reference comes from the temperature compensation circuitry,
the XFET results in much lower noise.
Figure 33 shows the basic topology of the ADR44x series. The
temperature correction term is provided by a current source
with a value designed to be proportional to absolute temperature.
The general equation is
(
PTAT
P
OUT
I
R1
V
G
V
Δ
Rev. A | Page 14 of 20
)
×
=
(1)
where:
G
is the gain of the reciprocal of the divider ratio.
Δ
V
P
is the difference in pinch-off voltage between the two JFETs.
I
PTAT
is the positive temperature coefficient correction current.
ADR44x devices are created by on-chip adjustment of R2
and R3 to achieve the different voltage option at the
reference output.
I
PTAT
I
1
*
I
1
*EXTRA CHANNEL IMPLANT
V
OUT
= G (
Δ
V
P
– R1 × I
PTAT
)
R2
V
IN
V
OUT
GND
R3
R1
Δ
V
P
0
ADR44x
Figure 33. Simplified Schematic Device
POWER DISSIPATION CONSIDERATIONS
The ADR44x family of references is guaranteed to deliver load
currents to 10 mA with an input voltage that ranges from 3 V to
18 V. When these devices are used in applications at higher
currents, users should use the following equation to account for
the temperature effects of increases in power dissipation:
T
P
T
+
θ
×
=
A
JA
D
J
(2)
where:
T
J
and
T
A
are the junction and ambient temperatures,
respectively.
P
D
is the device power dissipation.
θ
JA
is the device package thermal resistance.
BASIC VOLTAGE REFERENCE CONNECTIONS
The ADR44x family requires a 0.1 μF capacitor on the input
and the output for stability. While not required for operation,
a 10 μF capacitor at the input can help with line voltage
transient performance.
NOTES
1. NC = NO CONNECT
2. TP = TEST PIN (DO NOT CONNECT)
Figure 34. Basic Voltage Reference Configuration
0
6
V
OUT
0.1μF
+
V
IN
10μF
0.1μF
TP
1
NC
3
4
TP
8
NC
7
TRIM
5
ADR440/
ADR441/
ADR443/
ADR444/
ADR445
TOP VIEW
(Not to Scale)
2
GND
NOISE PERFORMANCE
The noise generated by the ADR44x family of references is
typically less than 1.4 μV p-p over the 0.1 Hz to 10.0 Hz band
for ADR440, ADR441, and ADR443. Figure 26 shows the 0.1 Hz
to 10 Hz noise of the ADR441, which is only 1.2 μV p-p. The
noise measurement is made with a band-pass filter made of a
2-pole high-pass filter with a corner frequency at 0.1 Hz and a
2-pole low-pass filter with a corner frequency at 10.0 Hz.
TURN-ON TIME
Upon application of power (cold start), the time required for
the output voltage to reach its final value within a specified
error band is defined as the
turn-on settling time
. Two compo-
nents normally associated with this are the time for the active
circuits to settle and the time for the thermal gradients on the
chip to stabilize. Figure 20 and Figure 21 show the turn-on and
turn-off settling times for the ADR441.
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| ADR444BRZ-REEL7 | Ultralow Noise, LDO XFET Voltage References with Current Sink and Source |
| ADR445A | Ultralow Noise, LDO XFET Voltage References with Current Sink and Source |
| ADR445ARMZ | Ultralow Noise, LDO XFET Voltage References with Current Sink and Source |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADR440BR | 制造商:Analog Devices 功能描述:V-REF PRECISION 2.048V 10MA 8SOIC N - Bulk |
| ADR440BRZ | 功能描述:IC VREF SERIES PREC 2.048V 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電壓基準(zhǔn) 系列:XFET® 標(biāo)準(zhǔn)包裝:3,000 系列:- 基準(zhǔn)類型:旁路，精度 輸出電壓:3V 容差:±0.5% 溫度系數(shù):100ppm/°C 輸入電壓:- 通道數(shù):1 電流 - 陰極:82µA 電流 - 靜態(tài):- 電流 - 輸出:15mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-TSSOP（5 引線），SC-88A，SOT-353 供應(yīng)商設(shè)備封裝:SC-70-5 包裝:帶卷 (TR) 其它名稱:296-20888-2 |
| ADR440BRZ-REEL7 | 功能描述:IC VREF SERIES PREC 2.048V 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電壓基準(zhǔn) 系列:XFET® 標(biāo)準(zhǔn)包裝:2,000 系列:- 基準(zhǔn)類型:旁路，可調(diào)節(jié)，精度 輸出電壓:1.24 V ~ 16 V 容差:±0.5% 溫度系數(shù):- 輸入電壓:1.24 V ~ 16 V 通道數(shù):1 電流 - 陰極:100µA 電流 - 靜態(tài):- 電流 - 輸出:20mA 工作溫度:-40°C ~ 85°C 安裝類型:通孔 封裝/外殼:TO-226-3、TO-92-3（TO-226AA）成形引線 供應(yīng)商設(shè)備封裝:TO-92-3 包裝:帶卷 (TR) |
| ADR441 | 制造商:AD 制造商全稱:Analog Devices 功能描述:2.048 V High Precision, LDO XFET® References for High Performance Sigma-Delta and PulSAR® Converters |
| ADR441A | 制造商:AD 制造商全稱:Analog Devices 功能描述:Ultralow Noise, LDO XFET Voltage References with Current Sink and Source |
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