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PDF AAT1157 Data sheet ( Hoja de datos )
| Número de pieza | AAT1157 | |
| Descripción | DC/DC Converter | |
| Fabricantes | AAT | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AAT1157 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
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General Description
The AAT1157 SwitchReg™ is a member of
AnalogicTech's Total Power Management IC™
(TPMIC™) product family. The step-down switch-
ing converter is ideal for applications where fixed
frequency and low ripple are required over the full
range of load conditions. The 2.7V to 5.5V input
voltage range makes the AAT1157 ideal for single-
cell lithium-ion/polymer battery applications.
Capable of up to 1.2A with internal MOSFETs, the
current-mode controlled IC provides high efficiency
over a wide operating range. Fully integrated com-
pensation simplifies system design and lowers
external parts count. The device operates at a
fixed 1MHz switching frequency across all load
conditions.
The AAT1157 is available in the Pb-free, 16-pin
3x3mm QFN package and is rated over the -40°C
to +85°C temperature range.
AAT1157
1MHz 1.2A Buck DC/DC Converter
Features
SwitchReg™
• VIN Range: 2.7V to 5.5V
• Up to 95% Efficiency
• 110 mΩ RDS(ON) Internal Switches
• <1µA Shutdown Current
• 1MHz Buck Switching Frequency
• Fixed or Adjustable VOUT ≥ 0.8V
• Integrated Power Switches
• Current Mode Operation
• Internal Compensation
• Stable with Ceramic Capacitors
• Constant PWM Operation for Low Output
Ripple
• Internal Soft Start
• Over-Temperature Protection
• Current Limit Protection
• 16-Pin QFN 3x3mm Package
• -40°C to +85°C Temperature Range
Applications
www.DataSheet4U.com
• HDD MP3 Players
• Notebook Computers
• PDAs
• Point-of-Load Regulation
• Set Top Boxes
• Smart Phones
• Wireless Notebook Adapters
Typical Application
3.3V
C1
10µF
R1
100
C2
0.1µF
U1
AAT1157
12 VP
FB 4
11 VP
LX 15
10 VP
LX 14
7 EN
LX 13
9 VCC
N/C 16
6 N/C PGND 3
8 N/C PGND 2
5 SGND PGND 1
L1
3.0µH
2.5V
R3
187k
R4 C3-C4
59k 2x 22µF
1157.2005.11.1.4
1
1 page  
AAT1157
1MHz 1.2A Buck DC/DC Converter
Typical Characteristics
No Load Supply Current vs. Input Voltage
300
85°C
250
200
150
-40°C
100
25°C
50
0
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
2.0
1.0
0.0
-1.0
-2.0
-3.0
-4.0
1
DC Regulation
(VOUT = 2.5V)
VIN = 3.6V
VIN = 3.0V
VIN = 3.3V
10 100 1000
Output Current (mA)
10000
P-Channel RDSON vs. Input Voltage
200
180
160 100°C 120°C
140
120
100
80 85°C 25°C
60
40
20
0
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
N-Channel RDSON vs. Input Voltage
200
180
160 100°C 120°C
140
120
100
80
85°C 25°C
60
40
20
0
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-40
Output Voltage vs. Temperature
(VIN = 3.6V; VOUT = 2.5V; IOUT = 1.0A)
-20 0
20 40 60 80
Temperature (°C)
100
1.3
1.28
1.26
1.24
1.22
1.2
2.7
Frequency vs. Input Voltage
(VOUT = 1.8V)
3.1 3.5 3.9 4.3 4.7 5.1
Input Voltage (V)
5.5
1157.2005.11.1.4
5
5 Page 
Design Example
Specifications
IOUT 1.2A
IRIPPLE 330mA
VOUT 2.5V
VIN 3.0V to 4.2V
FS 1MHz
TAMB = 85°C
Maximum Input Capacitor Ripple:
IRMS = IO ·
VO · ⎛1- VO ⎞ = 0.59Arms
VIN ⎝ VIN ⎠
P = esr · IRMS2 = 5mΩ · 0.592 A = 1.7mW
AAT1157
1MHz 1.2A Buck DC/DC Converter
Inductor Selection:
L
=
VOUT
∆IPP ⋅ F
⋅
⎛⎝1
-
VOUT⎞
VIN ⎠
=
2.5V
0.33A ⋅ 1MHz
⋅
⎛⎝1 -
2.5V⎞
4.2V⎠
= 3.07µH
Select Sumida inductor CDRH5D28 3.0µH.
∆I =
VO
L⋅F
⋅
⎛⎝1
-
VO
VIN
⎞
⎠
=
2.5V
3.0µH ⋅ 1MHz
⋅ ⎛⎝1-
2.5V⎞
4.2V⎠
= 340mA
IPK
=
IOUT
+
∆I
2
=
1.2A
+
0.17A
=
1.37A
P = IO2 ⋅ DCR = (1.2A)2 ⋅ 31mΩ = 45mW
Output Capacitor Ripple Current:
IRMS =
1
2·
·
3
(VOUT) · (VIN - VOUT)
L · F · VIN
=
1·
2· 3
2.5V · (4.2V - 2.5V)
3.0µH · 1MHz · 4.2V
= 97.4mArms
Pesr = esr · IRMS2 = 5mΩ · (97.4mA)2 = 47.4µW
1157.2005.11.1.4
11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet AAT1157.PDF ] | |
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