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ADP1110AR-12 PDF 데이터시트 : 부품 기능 및 핀배열

부품번호 ADP1110AR-12
기능 Micropower/ Step-Up/Step-Down Switching Regulator; Adjustable and Fixed 3.3 V/ 5 V/ 12 V
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ADP1110AR-12 데이터시트, 핀배열, 회로
Micropower, Step-Up/Step-Down Switching
a Regulator; Adjustable and Fixed 3.3 V, 5 V, 12 V
ADP1110
FEATURES
Operates at Supply Voltages From 1.0 V to 30 V
Step-Up or Step-Down Mode
Minimal External Components Required
Low-Battery Detector
User-Adjustable Current Limiting
Fixed or Adjustable Output Voltage Versions
8-Pin DIP or SO-8 Package
APPLICATIONS
Cellular Telephones
Single-Cell to 5 V Converters
Laptop and Palmtop Computers
Pagers
Cameras
Battery Backup Supplies
Portable Instruments
Laser Diode Drivers
Hand-Held Inventory Computers
FUNCTIONAL BLOCK DIAGRAMS
SET
ADP1110
A2
VIN
GAIN BLOCK/
ERROR AMP
220mV
REFERENCE
A1 OSCILLATOR
A0
ILIM
SW1
Q1
COMPARATOR
R2
R1 300k
DRIVER
GND
SENSE
SW2
ADP1110 Block Diagram—Fixed Output Version
SET
ADP1110
GENERAL DESCRIPTION
The ADP1110 is part of a family of step-up/step-down switch-
ing regulators that operate from an input voltage supply as little
as 1.0 V. This very low input voltage allows the ADP1110 to be
used in applications that use a single cell as the primary power
source.
The ADP1110 can be configured to operate in either step-up or
step-down mode, but for input voltages greater than 3 V, the
ADP1111 would be a more effective solution.
An auxiliary gain amplifier can serve as a low battery detector or
as a linear regulator.
The quiescent current of 300 µA makes the ADP1110 useful in
remote or battery powered applications.
A2
VIN
GAIN BLOCK/
ERROR AMP
220mV
REFERENCE
A1 OSCILLATOR
A0
ILIM
SW1
Q1
COMPARATOR
DRIVER
GND
FB
SW2
ADP1110 Block Diagram—Adjustable Output Version
The 70 kHz frequency operation also allows for the use of
surface-mount external capacitors and inductors.
Battery protection circuitry limits the effect of reverse current to
safe levels at reverse voltages up to 1.6 V.
REV. 0
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
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1996




ADP1110AR-12 pdf, 반도체, 판매, 대치품
ADP1110-Typical Characteristics
1.4
1.2 VIN = +2V
1 VIN = +1.5V
0.8 VIN = +1.2V
0.6 VIN = +1V
0.4
VIN = +3V
VIN = +5V
0.2
0
0.1 0.2 0.4 0.5 0.6 0.8
1
ISWITCH CURRENT – A
1.2 1.25 1.4
Figure 2. Saturation Voltage vs. ISWITCH Current in Step-Up
Mode
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0.1
VIN = +12V
0.2 0.4 0.6 0.8
ISWITCH CURRENT – A
0.9
Figure 3. Switch ON Voltage vs. ISWITCH Current In Step-
Down Mode
1800
1600
1400
1200
1000
QUIESCENT CURRENT
800
600
400
200
0
1 3 6 9 12 15 18 21 24 27 30
INPUT VOLTAGE – V
Figure 4. Quiescent Current vs. Input Voltage
76
74
72
OSCILLATOR FREQUENCY
70
68
66
64
62
60
246
8 10 12 15 18 21 24 27 30
INPUT VOLTAGE – V
Figure 5. Oscillator Frequency vs. Input Voltage
1.9
1.7
1.5
1.3
1.1
0.9
0.7
0.5
0.3
0.1
1
STEP-DOWN WITH
V = +12V
10 100
RLIM
1000
Figure 6. Maximum Switch Current vs. RLIM
1.5
1.3
1.1
0.9
0.7
0.5
0.3
0.1
1
STEP-UP MODE
WITH V +5V
10 100
RLIM
1000
Figure 7. Maximum Switch Current vs. RLIM
–4– REV. 0

4페이지










ADP1110AR-12 전자부품, 판매, 대치품
ADP1110
CALCULATING THE INDUCTOR VALUE
Selecting the proper inductor value is a simple three-step
process:
1. Define the operating parameters: minimum input voltage,
maximum input voltage, output voltage and output current.
2. Select the appropriate conversion topology (step-up, step-
down, or inverting).
3. Calculate the inductor value, using the equations in the
following sections.
INDUCTOR SELECTION–STEP-UP CONVERTER
In a step-up or boost converter (Figure 19), the inductor must
store enough power to make up the difference between the input
voltage and the output voltage. The power that must be stored
is calculated from the equation:
( ) ( )PL = VOUT +VD V IN(MIN ) IOUT
(Equation 1)
where VD is the diode forward voltage (0.5 V for a 1N5818
Schottky). Because energy is only stored in the inductor while
the ADP1110 switch is ON, the energy stored in the inductor
on each switching cycle must be must be equal to or greater
than:
PL
fOSC (Equation 2)
in order for the ADP1110 to regulate the output voltage.
When the internal power switch turns ON, current flow in the
inductor increases at the rate of:
I
L
(t
)
=
V IN
R'
1
e
R't
L

(Equation 3)
where L is in Henrys and R' is the sum of the switch equivalent
resistance (typically 0.8 at +25°C) and the dc resistance of
the inductor. If the voltage drop across the switch is small
compared to VIN, a simpler equation can be used:
IL
(t
)
= V IN
L
t
(Equation 4)
Replacing ‘t’ in the above equation with the ON time of the
ADP1110 (10 µs, typical) will define the peak current for a
given inductor value and input voltage. At this point, the
inductor energy can be calculated as follows:
EL
=
1
L
2
I
2PEAK
(Equation 5)
As previously mentioned, EL must be greater than PL/fOSC so
that the ADP1110 can deliver the necessary power to the load.
For best efficiency, peak current should be limited to 1 A or
less. Higher switch currents will reduce efficiency because of
increased saturation voltage in the switch. High peak current also
increases output ripple. As a general rule, keep peak current as low
as possible to minimize losses in the switch, inductor and diode.
In practice, the inductor value is easily selected using the equations
above. For example, consider a supply that will generate 12 V at
120 mA from a 4.5 V to 8 V source. The inductor power required
is from Equation 1:
( )PL = 12 V + 0.5 V 4.5 V 120 mA = 960 mW
On each switching cycle, the inductor must supply:
PL
f OSC
=
960 mW
70 kHz
=13.7 µJ
Assuming a peak current of 1 A as a starting point, (Equation 4)
can be rearranged to recommend an inductor value:
L = V IN t = 4.5V 10 µs = 45 µH
IL(MAX ) 1 A
Substituting a standard inductor value of 47 µH with 0.2 dc
resistance will produce a peak switch current of:
I PEAK
=
4.5V
1.0
–1.0 Ω •10 µs
1e 47 µH

= 862 mA
Once the peak current is known, the inductor energy can be
calculated from Equation 5:
EL
=
1
2
(47
µH
)
(862
mA)2
=
17.5
µJ
Since the inductor energy of 17.5 µJ is greater than the PL/fOSC
requirement of 13.7 µJ, the 47 µH inductor will work in this
application. By substituting other inductor values into the same
equations, the optimum inductor value can be determined.
When selecting an inductor, the peak current must not exceed
the maximum switch current of 1.5 A.
The peak current must be evaluated for both minimum and
maximum values of input voltage. If the switch current is high
when VIN is at its minimum, the 1.5 A limit may be exceeded at the
maximum value of VIN. In this case, the ADP1110’s current limit
feature can be used to limit switch current. Simply select a resistor
(using Figure 7) that will limit the maximum switch current to the
IPEAK value calculated for the minimum value of VIN. This will
improve efficiency by producing a constant IPEAK as VIN increases.
See the “Limiting the Switch Current” section of this data sheet for
more information.
Note that the switch current limit feature does not protect the
circuit if the output is shorted to ground. In this case, current is
only limited by the dc resistance of the inductor and the forward
voltage of the diode.
INDUCTOR SELECTION–STEP-DOWN CONVERTER
The step-down mode of operation is shown in Figure 20.
Unlike the step-up mode, the ADP1110’s power switch does not
saturate when operating in the step-down mode; therefore,
switch current should be limited to 800 mA in this mode. If the
input voltage will vary over a wide range, the ILIM pin can be
used to limit the maximum switch current. Higher switch
current is possible by adding an external switching transistor as
shown in Figure 22.
The first step in selecting the step-down inductor is to calculate
the peak switch current as follows:
IPEAK
= 2 IOUT
DC
V
V
IN
OUT +VD
V SW +V
D

(Equation 6)
where: DC = duty cycle (0.69 for the ADP1110)
VSW = voltage drop across the switch
VD = diode drop (0.5 V for a 1N5818)
IOUT = output current
VOUT = the output voltage
VIN = the minimum input voltage
REV. 0
–7–

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부품번호상세설명 및 기능제조사
ADP1110AR-12

Micropower/ Step-Up/Step-Down Switching Regulator; Adjustable and Fixed 3.3 V/ 5 V/ 12 V

Analog Devices
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