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PDF AAT1185 Data sheet ( Hoja de datos )
| Número de pieza | AAT1185 | |
| Descripción | High Voltage Step-Down Controller | |
| Fabricantes | Skyworks | |
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General Description
The AAT1185 is a single output step-down (Buck) regu-
lator controller with an input range of 6V to 24V. The
output range is adjustable from 0.8V to 5.5V.
The device provides high and low-side pins to drive
external n-channel MOSFETs; allowing fully synchronous
operation for maximum efficiency and performance.
Alternately, the low-side MOSFET may be replaced with
a Schottky rectifier. Both high and low-side drive pins are
compatible with a wide range of external MOSFETs mak-
ing the device the ideal control solution for low power
and high power configurations.
Voltage mode control allows for optimum performance
across the entire output voltage and load range. The
490kHz fixed switching frequency allows wide range of
L/C filtering components, achieving smallest size and
maximum efficiency. External compensation allows the
designer to optimize the transient response.
The controller includes programmable over-current, inte-
grated soft-start and over-temperature protection.
The AAT1185 is available in the Pb-free, 14-pin TSOPJW
package. The rated operating temperature range is
-40°C to 85°C.
DATA SHEET
AAT1185
High Voltage Step-Down Controller
Features
VIN = 6.0V to 24.0V
VOUT Adjustable from 0.8V to 5.5V
IOUT from <1A up to 10A
Small Solution Size
Ultra-small External L/C
Synchronous or Non-Synchronous
Shutdown Current <30μA
High Switching Frequency
Voltage Mode Control
PWM Fixed Frequency for Lowest Noise
▪ Programmable Over-Current Protection
Over-Temperature Protection
Internal Soft Start
2.85x3mm TSOPJW-14 Package
-40°C to 85°C Temperature Range
Applications
• DSL and Cable Modems
• Notebook Computers
• Satellite Set Top Boxes
• Wireless LAN Systems
Typical Application
VIN
6V - 24V
C7
2.2μF
D1
BAS16
C3
470μF
25V
C5
10μF
25V
U1
BST
VCC
DH
AAT1185
HV LX
EN DL
RS
R1
3.32
R2
3.32
C8
0.1μF
Q1
Q2
PGND OS
COMP FB
TSOPJW-14
R4
20K
L1
3.9μH
R3
1.74K
C9
0.47μF
C10
33pF
C11
680pF
VOUT
3.3V/10A
R5 R6
1K 27.4K
C12
680pF
C13, C14
2×47μF
R7
6.04k
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012
1
1 page  
Typical Characteristics
Circuit of Figure 4, unless otherwise specified.
Step-Down Controller Efficiency vs. Load
(VOUT = 3.3V; L = 3.9µH)
100
90
80
70
60
50
40 VIN = 6V
30 VIN = 8V
20 VIN = 12V
VIN = 18V
10 VIN = 24V
0
0.1 1
10
100
1000
10000
Output Current (mA)
Step-Down Controller Line Regulation
(VOUT = 3.3V; L = 3.9µH)
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
6
IOUT = 0.1mA
IOUT = 100mA
IOUT = 1A
IOUT = 5A
IOUT = 8A
IOUT = 10A
8 10 12 14 16 18 20 22 24
Input Voltage (V)
Step-Down Controller Output Ripple
(VIN = 12V; VOUT = 3.3V; IOUT = 1mA)
12V
0V
3.31
3.30
3.29
1
0
-1
Time (1µs/div)
DATA SHEET
AAT1185
High Voltage Step-Down Controller
Step-Down Controller DC Regulation
(VOUT = 3.3V; L = 3.9µH)
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
0.1
VIN = 6V
VIN = 8V
VIN = 12V
VIN = 18V
VIN = 24V
1 10 100 1000
Output Current (mA)
10000
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-50
Step-Down Controller Output
Voltage Error vs. Temperature
(VIN = 12V; VOUT = 3.3V)
IOUT = 0.1mA
IOUT = 100mA
IOUT = 1A
IOUT = 5A
IOUT = 8A
IOUT = 10A
-25 0 25 50 75 100
Temperature (°C)
Step-Down Controller Output Ripple
(VIN = 12V; VOUT = 3.3V; IOUT = 10A)
12V
0V
3.32
3.30
3.28
12
10
8
Time (1µs/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012
5
5 Page 
The Buck regulator output will remain in a shutdown
state until the internal die temperature falls back below
the 135°C trip point. The combination and interaction
between the short circuit and thermal protection sys-
tems allows the Buck regulator to withstand indefinite
short-circuit conditions without sustaining permanent
damage.
Thermal Calculations
There are three types of losses associated with the
AAT1185 step-down converter: switching losses, con-
duction losses, and quiescent current losses. Conduction
losses are associated with the RDS(ON) characteristics of
the power output switching devices. Switching losses are
dominated by the gate charge of the power output
switching devices. At full load, assuming continuous con-
duction mode (CCM), a simplified form of the synchro-
nous step-down converter and LDO losses is given by:
PTOTAL
=
IOUT2 · (RDS(ON)H · VOUT + RDS(ON)L · [VIN - VOUT])
VIN
+ (tSW · FS · IOUT + IQ) · VIN
IQ1 is the step-down converter quiescent currents. The
term tSW is used to estimate the full load step-down con-
verter switching losses.
The power dissipation that relates to the RDS(ON) occurs in
the external high side and low side MOSFETs. Therefore,
the total package losses for AAT1185 reduce to the fol-
lowing equation:
PTOTAL = (tSW · FS · IOUT + IQ1) · VIN1
Since quiescent current, and switching losses all vary
with input voltage, the total losses should be investi-
gated over the complete input voltage range.
Given the total losses, the maximum junction tempera-
ture can be derived from the θJA for the TSOPJW-14
package, which is 140°C/W.
TJ(MAX) = PTOTAL · θJA + TAMB
DATA SHEET
AAT1185
High Voltage Step-Down Controller
Layout Considerations
The suggested PCB layout for the AAT1185 is shown in
Figures 5, 6, 7, and 8. The following guidelines should be
used to help ensure a proper layout.
1. The power input capacitors (C3 and C5) should be
connected as closely as possible to the high voltage
input pin (IN) and power ground.
2. C5, L1, Q1, C13, and C14 should be placed as close-
ly as possible to each other to minimize any para-
sitic inductance in the switched current path, which
generates a large voltage spike during the switching
interval. The connection of inductor to switching
node should be as short as possible.
3. The feedback trace or FB pin should be separated
from any power trace and connected as closely as
possible to the load point. Sensing along a high-
current load trace will degrade DC load regulation.
4. The resistance of the trace from the load returns to
PGND should be kept to a minimum. This will help to
minimize any error in DC regulation due to differ-
ences in the potential of the internal signal ground
and the power ground.
5. Connect unused signal pins to ground to avoid
unwanted noise coupling.
6. The critical small signal components, include feed-
back components and compensation components,
should be placed close to the FB1 and COMP1 pins.
The feedback resistors should be located as close as
possible to the FB1 pin with its ground tied straight
to the signal ground plane, which is separated from
the power ground plane.
7. C9 and R3 should be connected as closely as possi-
ble to the RS1 and OS1 pins and placed on the bot-
tom side of the layout to avoid noise coupling from
the inductor.
8. For good thermal coupling, a 4-layer PCB layout is
recommended and PCB vias are required from the
exposed pad (EP) for the MOSFETs paddle to the
middle plane and bottom plane.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet AAT1185.PDF ] | |
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