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參數資料
| 型號： | ADM666A* |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | Tri-Mode: +3.3 V. +5 V. Adjustable Micropower Linear Voltage Regulators |
| 中文描述： | 三模式：3.3伏5五，調節微功率線性穩壓器 |
| 文件頁數： | 4/9頁 |
| 文件大小： | 331K |
REV. 0
–4–
ADM663A/ADM666A
GENERAL INFORMATION
The ADM663A/ADM666A contains a micropower bandgap
reference voltage source; an error amplifier, A1; three compara-
tors, C1, C2, C3, and a series pass output transistor. A P-chan-
nel FET and an NPN transistor are used on the ADM663A
while the ADM666A uses an NPN output transistor.
CIRCUIT DESCRIPTION
The internal bandgap reference is trimmed to 1.3 V
±
30 mV.
This is used as a reference input to the error amplifier A1. The
feedback signal from the regulator output is supplied to the
other input by an on-chip voltage divider or by two external re-
sistors. When V
SET
is at ground, the internal divider tap between
R1 and R2, provides the error amplifier’s feedback signal giving
a +5 V output. When V
SET
is at V
IN
,
the internal divider tap be-
tween R2 and R3 provides the error amplifier’s feedback signal
giving a +3.3 V output. When V
SET
is at more than 50 mV
above ground and less than 50 mV below V
IN
, the error ampli-
fier’s input is switched directly to the V
SET
pin, and external
resistors are used to set the output voltage. The external resis-
tors are selected so that the desired output voltage gives 1.3 V
at V
SET
.
Comparator C1 monitors the output current via the SENSE in-
put. This input, referenced to V
OUT(2)
, monitors the voltage
drop across a load sense resistor. If the voltage drop exceeds
0.5 V, then the error amplifier A1 is disabled and the output
current is limited.
The ADM663A has an additional amplifier, A2, which provides
a temperature proportional output, V
TC
. If this is summed into
the inverting input of the error amplifier, a negative temperature
coefficient results at the output. This is useful when powering
liquid crystal displays over wide temperature ranges.
The ADM666A has an additional comparator, C4, that com-
pares the voltage on the low battery input, LBI, pin to the inter-
nal +1.3 V reference. The output from the comparator drives an
open drain FET connected to the low battery output pin, LBO.
The low battery threshold may be set using a suitable voltage
divider connected to LBI. When the voltage on LBI falls below
1.3 V, the open drain output LBO is pulled low.
50mV
V
IN
ADM663A
SHDN
GND
V
TC
V
SET
V
OUT1
V
OUT2
SENSE
C2
1.3V
0.5V
C1
A2
A1
C3
D
E
C
O
D
E
R
V
IN
–50mV
0.9V
R2
R1
R3
Figure 1. ADM663A Functional Block Diagram
Both the ADM663A and the ADM666A contain a shutdown
(SHDN) input that can be used to disable the error amplifier
and hence the voltage output. The power consumption in shut-
down reduces to less than 9
μ
A.
50mV
V
IN
ADM666A
SHDN
GND
LBO
V
SET
V
OUT
SENSE
C2
1.3V
0.5V
C1
C4
A1
C3
D
E
C
O
D
E
R
V
IN
–50mV
1.3 V
LBI
R2
R1
R3
Figure 2. ADM666A Functional Block Diagram
Circuit Configurations
For a fixed +5 V output the V
SET
input is grounded and no ex-
ternal resistors are necessary. This basic configuration is shown
in Figure 3. For a fixed +3.3 V output, the V
SET
input is con-
nected to V
IN
as shown in Figure 4. Current limiting is not be-
ing utilized so the SENSE input is connected to V
OUT(2)
.
GND
ADM663A
ADM666A
SENSE
V
OUT(2)
V
IN
V
SET
SHDN
+5V
OUTPUT
+6V TO +16V
INPUT
Figure 3. A Fixed +5 V Output
GND
ADM663A
ADM666A
SENSE
V
OUT(2)
V
IN
V
SET
SHDN
+3.3V
OUTPUT
+4.5V TO +16V
INPUT
Figure 4. A Fixed +3.3 V Output
Output Voltage Setting
If V
SET
is not connected to GND or to V
IN
, the output voltage is
set according to the following equation:
V
OUT
=
V
SET
×
(
R
1
+
R
2)
R
1
where V
SET
= 1.30 V.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| ADM666AAN | 制造商:AD 制造商全稱:Analog Devices 功能描述:Tri-Mode: +3.3 V, +5 V, Adjustable Micropower Linear Voltage Regulators |
| ADM666AAR | 制造商:AD 制造商全稱:Analog Devices 功能描述:Tri-Mode: +3.3 V, +5 V, Adjustable Micropower Linear Voltage Regulators |
| ADM666AN | 制造商:Analog Devices 功能描述:Standard Regulator Pos 1.3V to 16V5V 0.04A 8-Pin PDIP 制造商:Analog Devices 功能描述:IC V REG ADJ +2/16.5V DIP8 666 |
| ADM666AR | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Tri-Mode: +3.3 V +5 V Adjustable Micropower Linear Voltage Regulators(332.03 k) |
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