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PDF AAT2504 Data sheet ( Hoja de datos )
| Número de pieza | AAT2504 | |
| Descripción | Adjustable 3-Channel Regulator | |
| Fabricantes | AAT | |
| Logotipo |  |
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General Description
The AAT2504 is a three-channel regulator consist-
ing of a step-down converter with an input voltage
range of 2.7V to 5.5V plus two low dropout (LDO)
linear regulators. The two LDOs have an input volt-
age range of 1.8V to 5.5V, making them well-suited
for post regulating from the step-down converter.
The step-down converter optimizes power efficiency
throughout the load range. Pulling the MODE/SYNC
pin high enables "PWM Only" operation, maintaining
constant frequency and low output ripple across the
operating range. Alternatively, the converter may be
synchronized to an external clock to the MODE/
SYNC pin. The step-down converter delivers up to
800mA of output current. The switching frequency is
2MHz, minimizing the size of external components.
The two LDOs (LDOA/LDOB) have independent
inputs and are capable of delivering up to 300mA
each. A Power-OK (POK) function provides an open
drain output signal when LDOA is within regulation.
Both LDOs feature low quiescent current and a low
dropout voltage. The output voltages for both LDOs
are adjustable to as low as 0.6V. The linear regula-
tors have independent Enable pins. Typical no load
quiescent current is a low 80µA when the step-
down converter and LDOs are enabled.
The AAT2504 is available in a Pb-free 3x4mm
QFN34-20 package and is rated over the -40°C to
+85°C temperature range.
Typical Application
AAT2504
Adjustable 3-Channel Regulator
Features
SystemPower™
• 800mA Buck Converter
— VIN Range: 2.7V to 5.5V
— VOUT Range: 0.9V to VIN, Adjustable
— High Efficiency: 95%
— 2MHz Switching Frequency
— Synchronizable to External Clock
— Internal Soft Start
• Two 300mA Linear Regulators
— VIN Range: 1.8V to 5.5V
— Low Dropout Voltage
— High Output Accuracy: ±1.5%
• Low Total Quiescent Current IQ (80μA)
• Independent Enable Pins
• Over-Temperature Protection
• QFN34-20 Package
• -40°C to +85°C Temperature Range
Applications
• Cellular Phones
• Digital Cameras
• Handheld Instruments
• Microprocessor/DSP Core/IO Power
• PDAs and Handheld Computers
VIN
MODE/SYNC
ENA
ENB
EN
LX
AAT2504 FB
L
VIN
VLDOA
VLDOB
VP
OUTA
POK
FBA
OUTB
FBB
PGND
AGND
100kΩ
POK
OUTB
R1B
2.2μF
R2B
R1A
R2A
OUTA
2.2μF
VOUT (Step-down)
R1
COUT
R2
2504.2007.06.1.0
1
1 page  
AAT2504
Adjustable 3-Channel Regulator
Electrical Characteristics (continued)1
VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol Description
Conditions
Step-Down Converter
VIN Input Voltage
VOUT
Output Voltage Tolerance
VOUT
VFB
ISHDN
ILX_LEAK
IFB
ILIM
RDS(ON)H
RDS(ON)L
ΔVLOADREG/
VOUT
ΔVLINEREG/
VIN
FOSC
TSD
THYS
VEN(L)
VEN(H)
IEN
VOUT Programmable Range
Feedback Threshold Voltage
Shutdown Current
LX Leakage Current
Feedback Leakage
Current Limit
High Side Switch On Resistance
Low Side Switch On Resistance
Load Regulation
Line Regulation
Oscillator Frequency
Over-Temperature Shutdown
Threshold
Over-Temperature Shutdown
Hysteresis
Enable Threshold Low
Enable Threshold High
EN Input Leakage
IOUT = 0 to 800mA;
VIN = 2.7V to 5.5V
EN = GND
VIN = 5.5, VLX = 0 - VIN
VFB = 1.0V
ILOAD = 10 to 800mA
VEN = 5V, VIN = 5V
Min Typ Max Units
2.7 5.5 V
-3.0 3.0 %
0.9 VIN
0.891 0.9 0.909
V
V
1.0 µA
1.0 µA
0.2 µA
1.2 A
280 mΩ
160 mΩ
0.2 %
0.2 %/V
1.6 2.0 2.4 MHz
140 °C
15 °C
0.6 V
1.4 V
-1.0 1.0 µA
1. The AAT2504 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured
by design, characterization, and correlation with statistical process controls.
2504.2007.06.1.0
5
5 Page 
Functional Block Diagram
FB
AAT2504
Adjustable 3-Channel Regulator
VIN VP
MODE/SYNC
EN
VLDOA
ENB
VLDOB
Voltage
Reference
Err.
Amp.
Control
Logic
Err.
Amp.
Voltage
Reference
DH
Logic
DL
Over-Current
Protection
90%
VREF
OUTB
LX
PGND
OUTA
ENA
FBA
POK
FBB AGND
Functional Description
The AAT2504 is a high performance power man-
agement IC comprised of a step-down converter
and two linear regulators. The step-down convert-
er operates in both fixed and variable frequency
modes for high efficiency performance. The switch-
ing frequency is 2MHz, minimizing the size of the
inductor. The converter requires only three external
power components (CIN, COUT, and L). Each LDO
can deliver up to 300mA. Each regulator has inde-
pendent input voltage and enable pins and oper-
ates with ceramic capacitors.
Switch-Mode Step-Down Converter
The switching regulator is a monolithic step-down
converter operating with input voltage range of 2.7V
to 5.5V. Power devices are sized for 800mA current
capability and achieves over 95% efficiency. The
internal oscillator operates at 2MHz, minimizing the
cost and size of external components. Light Load
2504.2007.06.1.0
operation maintains high efficiency under light load
conditions (typically <50mA) when MODE/SYNC is
grounded. The MODE/SYNC pin tied high allows
optional "PWM Only" operation. This maintains con-
stant frequency and low output ripple across all load
conditions. Alternatively, by connecting an external
clock to the AAT2504's MODE/SYNC pin, the inter-
nal clock is disabled. The external synchronization
must stay between 1MHz and 3MHz.
The current through the P-channel MOSFET (high
side) is sensed for current loop control, as well as
short-circuit and overload protection. A fixed slope
compensation signal is added to the sensed current
to maintain stability for duty cycles greater than
50%. The peak current mode loop appears as a
voltage-programmed current source in parallel with
the output capacitor.
The output of the voltage error amplifier programs
the current mode loop for the necessary peak
switch current to force a constant output voltage for
all load and line conditions. Internal loop compen-
11
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet AAT2504.PDF ] | |
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