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PDF AAT2784 Data sheet ( Hoja de datos )
| Número de pieza | AAT2784 | |
| Descripción | 3-Channel Step-Down DC/DC Converter | |
| Fabricantes | Advanced Analogic Technologies | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AAT2784 (archivo pdf) en la parte inferior de esta página. Total 21 Páginas | ||
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SystemPowerTM
PRODUCT DATASHEET
AAT2784
3-Channel Step-Down DC/DC Converter
General Description
The AAT2784 is a 3-channel 1.8MHz step-down con-
verter for applications where power efficiency and solu-
tion size are critical. The input voltage range is 2.7V to
5.5V and the outputs are adjustable from 0.6V to VIN.
Channel 3 delivers up to 1.5A output current and chan-
nels 1 and 2 deliver up to 300mA each. The AAT2784
uses a high switching frequency to minimize the size of
external components. The AAT2784 requires a minimum
of external components to realize a high efficiency triple-
output buck converter minimizing solution cost and PCB
footprint.
Each of the 3 regulators has an independent enable pin,
adjustable output voltage and operates with low no load
quiescent current, providing high efficiency over the
entire load range.
The AAT2784 is available in a Pb-free 16 pin TDFN34
package, and is rated over the -40°C to +85°C operating
temperature range.
Typical Application
Features
• VIN Range: 2.7 to 5.5V
• Output Voltage Range: 0.6V to VIN
• Output Current:
▪ Channel 3: 1.5A
▪ Channel 1: 300mA
▪ Channel 2: 300mA
• Highly Efficient Step-Down Converters
• Low RDS(ON) Integrated Power Switches
• 100% Duty Cycle
• 1.8 MHz Switching Frequency
• Internal Soft Start
• Fast 150μs Turn-On Time
• Over-Temperature Protection
• Current Limit Protection
• TDFN34-16 Package
• -40°C to 85°C Temperature Range
Applications
• Cellular and Smart Phones
• Digital Cameras
• Handheld Instruments
• Mass Storage Systems
• Microprocessor / DSP Core / IO Power
• PDAs and Handheld Computers
• Portable Media Players
• USB Devices
• Wireless LAN
VIN : 2.7 – 5.5V
C1
10μF
C2
10μF
AAT2784
LX1
IN
FB1
VP 1_ 2
EN 1
LX 2
FB2
L1
4.7μH
L2
4.7μH
EN2
PGND
VP3
EN 3
AGND
LX3
FB3
PGND
L3
1.5μH
VOUT1: 3.3V
300mA
R1
267 k
VOUT2: 3.3V
300mA
R2
59.0k
C3
4. 7μF
R3
267k
R4
59.0k
C4
4.7μF
VOUT3: 1.2V
1.5A
R5
59 . 0k
R6
59 . 0k
C5
10μF
2784.2007.11.1.1
www.analogictech.com
1
1 page  
SystemPowerTM
Typical Characteristics
Efficiency vs. Output Current
(Channels 1 and 2; VOUT = 3.3V)
100
90 VIN = 3.6V
80
70 VIN = 4.2V
60 VIN = 5.0V
50
40
30
20
0.1
1
10 100
Output Current (mA)
1000
Efficiency vs. Output Current
(Channel 3; VOUT = 1.2V)
100
90
80 VIN = 4.2V
70
60
50
40
30
20
10
0
0.1
1
VIN = 2.7V
VIN = 3.6V
10
100
1000
Output Current (mA)
10000
Switching Frequency vs. Input Voltage
10
8
6
4
2
0
-2
-4
-6
-8
-10
2.3
Channel 3
Channels 1 and 2
2.8 3.3 3.8 4.3 4.8 5.3 5.8
Input Voltage (V)
PRODUCT DATASHEET
AAT2784
3-Channel Step-Down DC/DC Converter
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.1
Load Regulation
(Channels 1 and 2; VOUT = 3.3V)
VIN = 5.0V
VIN = 4.2V
VIN = 3.6V
1 10 100
Output Current (mA)
1000
Load Regulation
(Channel 3; VOUT = 1.2V)
1
0.8
0.6 VIN = 4.2V
0.4
0.2
0
-0.2 VIN = 3.6V
-0.4
-0.6
VIN = 2.7V
-0.8
-1
0.1
1
10 100
Output Current (mA)
1000
10000
Output Error vs. Temperature
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
-40
Channel 3
Channels 1 and 2
-15 10 35 60
Temperature (°C)
85
2784.2007.11.1.1
www.analogictech.com
5
5 Page 
SystemPowerTM
Functional Block Diagram
PRODUCT DATASHEET
AAT2784
3-Channel Step-Down DC/DC Converter
VP3
FB3
EN3
Error
Amp
Comp.
Control
Logic
Logic
OT OSC
LX 3
PGND3
VP1_2
FB2
EN2
AGND
IN
Error
Amp
Comp.
Control
Logic
Logic
OSC
LX2
PGND2
FB1
EN1
Error
Amp
Comp.
Voltage
Ref
Control
Logic
Logic
LX1
PGND1
Functional Description
The AAT2784 is a high performance power management
IC comprised of 3 buck converters. Each channel has an
independent enable pin. Operating at a switching fre-
quency of 1.8MHz, the converter requires a minimum of
small external components, reducing the solution cost
and PCB footprint.
All converters operate with an input voltage range of
2.7V to 5.5V. The output voltage range is 0.6V to VIN
and is adjustable with an external resistor divider.
Channel 3 power devices are sized for 1.5A output cur-
rent. Channels 1 and 2 power devices are sized for
300mA output current while maintaining over 85% effi-
ciency at full load. Peak efficiency is above 95%. Light
load efficiency is maintained at greater than 80% down
to 85% of full load current. All channels have excellent
transient response, load and line regulation. Transient
response time is typically less than 20μs.
Soft start limits the current surge seen at the input and
eliminates output voltage overshoot. The enable inputs,
when pulled low, force the respective converter into a
low power non-switching state consuming less than 1μA
of current.
For overload conditions, the peak input current is limit-
ed. Also, thermal protection completely disables switch-
ing if internal dissipation becomes excessive, thus pro-
tecting the device from damage. The junction over-
temperature threshold is 140˚C with 15˚C of hysteresis.
Under-voltage lockout (UVLO) guarantees sufficient VIN
bias and proper operation of all internal circuits prior to
activation.
Control Loop
The AAT2784 is a peak current mode step-down con-
verter. The current through the P-channel MOSFET (high
side) is sensed for current loop control, as well as short-
2784.2007.11.1.1
www.analogictech.com
11
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet AAT2784.PDF ] | |
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