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Teilenummer | AAT1140 |
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Beschreibung | Fast Transient 600mA Step-Down Converter | |
Hersteller | Advanced Analog Technology | |
Logo | ||
Gesamt 19 Seiten SwitchRegTM
PRODUCT DATASHEET
AAT1140
Fast Transient 600mA Step-Down Converter
General Description
The AAT1140 SwitchReg is a 1.4MHz step-down con-
verter with an input voltage range of 2.7V to 5.5V and
output voltage as low as 0.6V. It is optimized to react
quickly to a load variation.
The AAT1140 is available in fixed voltage versions with
internal feedback and a programmable version with
external feedback resistors. It can deliver 600mA of load
current while maintaining a low 35μA no load quiescent
www.DatacSuhrereet4nUt..coTmhe 1.4MHz switching frequency minimizes the
size of external components while keeping switching
losses low.
The AAT1140 is designed to maintain high efficiency
throughout the operating range, which is critical for por-
table applications.
The AAT1140 is available in a Pb-free SOT23-5 package
and is rated over the -40°C to +85°C temperature
range.
Features
• VIN Range: 2.7V to 5.5V
• VOUT Fixed or Adjustable from 0.6V to VIN
• 35μA No Load Quiescent Current
• Up to 98% Efficiency
• 600mA Max Output Current
• 1.4MHz Switching Frequency
• 120μs Soft Start
• Fast Load Transient
• Over-Temperature Protection
• Current Limit Protection
• 100% Duty Cycle Low-Dropout Operation
• <1μA Shutdown Current
• SOT23-5 Package
• Temperature Range: -40°C to +85°C
Applications
• Cellular Phones
• Digital Cameras
• Handheld Instruments
• Microprocessor / DSP Core / IO Power
• PDAs and Handheld Computers
• USB Devices
Typical Application (Fixed Output Voltage)
VIN
C2
4.7µF
U1
AAT1140
IN LX
EN
GND
OUT
L1
4.7µH
VOUT
C1
4.7µF
1140.2007.12.1.1
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SwitchRegTM
Typical Characteristics
Soft Start
(VIN = 3.6V; VOUT = 1.8V; Load = 3Ω)
8.0
7.0 EN
6.0
5.0
www.DataSheet44U.0.com
3.0
2.0
1.0
VOUT
IIN
Time (100μs/div)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Output Voltage Error vs. Temperature
(VIN = 3.6V; VO = 1.8V; IOUT = 400mA)
2.0
1.0
0.0
-1.0
-2.0
-40
-20
0 20 40 60
Temperature (°C)
80 100
Frequency vs. Input Voltage
2.0
1.0 VOUT = 1.8V
0.0
-1.0
VOUT = 2.5V
VOUT = 3.3V
-2.0
-3.0
-4.0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
PRODUCT DATASHEET
AAT1140
Fast Transient 600mA Step-Down Converter
Line Regulation
(VOUT = 1.8V)
0.40
0.30
0.20 IOUT = 10mA
0.10
0.00
-0.10
-0.20
-0.30
IOUT = 1mA
IOUT = 400mA
-0.40
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Input Voltage (V)
Switching Frequency vs. Temperature
(VIN = 3.6V; VOUT = 1.8V)
15.0
12.0
9.0
6.0
3.0
0.0
-3.0
-6.0
-9.0
-12.0
-15.0
-40
-20
0
20 40 60 80 100
Temperature (°C)
No Load Quiescent Current vs. Input Voltage
(VOUT = 3.0V, L = 6.8µH)
60
55 TA = 85°C
50 TA = 25°C
45
40
35
30
25 TA = -40°C
20
3.3 3.8 4.3 4.8 5.3
Input Voltage (V)
6
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1140.2007.12.1.1
6 Page SwitchRegTM
PRODUCT DATASHEET
AAT1140
Fast Transient 600mA Step-Down Converter
voltage ripple and the input capacitor RMS current ripple
are a maximum at 50% duty cycle.
The input capacitor provides a low impedance loop for
the edges of pulsed current drawn by the AAT1140. Low
ESR/ESL X7R and X5R ceramic capacitors are ideal for
this function. To minimize stray inductance, the capacitor
should be placed as closely as possible to the IC. This
keeps the high frequency content of the input current
localized, minimizing EMI and input voltage ripple.
www.DataTShheeetp4rUo.cpoemr placement of the input capacitor (C2) can be
seen in the evaluation board layout in Figure 2.
A laboratory test set-up typically consists of two long
wires running from the bench power supply to the evalu-
ation board input voltage pins. The inductance of these
wires, along with the low-ESR ceramic input capacitor,
can create a high Q network that may affect converter
performance. This problem often becomes apparent in
the form of excessive ringing in the output voltage dur-
ing load transients. Errors in the loop phase and gain
measurements can also result.
Figure 2: AAT1140 Evaluation Board
Component Side Layout.
Figure 3: Exploded View of Sample Layout.
Figure 4: AAT1140 Evaluation Board
Solder Side Layout.
12
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1140.2007.12.1.1
12 Page | ||
Seiten | Gesamt 19 Seiten | |
PDF Download | [ AAT1140 Schematic.PDF ] |
Teilenummer | Beschreibung | Hersteller |
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