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PDF AAT2689 Data sheet ( Hoja de datos )
| Número de pieza | AAT2689 | |
| Descripción | PMIC Solution | |
| Fabricantes | Skyworks Solutions | |
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DATA SHEET
AAT2689
PMIC Solution for 12V Adapter Systems
with 2-Output High Performance Step-Down Converters
General Description
The AAT2689 provides two independently regulated DC
outputs, consisting of a high voltage step-down (Buck)
regulator and a low input voltage low dropout (LDO) regu-
lator. The PMIC is optimized for low cost 12V adapter
inputs, making the device the ideal system-on-a-chip
power solution for consumer communications equipment.
Channel 1 is a step-down (Buck) regulator with an input
voltage range of 6V to 24V providing up to 2500mA out-
put current. 490kHz fixed switching frequency allows
small L/C filtering components. Channel 1 utilizes volt-
age mode control configured for optimum performance
across the entire output voltage and load range.
Channel 2 is a low-dropout (LDO) regulator providing up
to 600mA output current. The device provides extremely
low output noise, low quiescent current and excellent
transient response.
The controller includes integrated cycle-by-cycle over-
current protection, soft-start and over-temperature dis-
able features. Independent input and enable pins pro-
vide maximum design flexibility.
The AAT2689 is available in the Pb-free 3x4mm 16-pin
TDFN package. The rated operating temperature range is
-40°C to 85°C.
Features
• 2-Output Step-Down Converters:
▪ Channel 1 (Buck): VIN1 = 6V to 24V
• VOUT1 adjustable from 1.5V to 5.5V
• IOUT1 up to 2.5A
• High Switching Frequency
• Voltage Mode Control
• PWM Fixed Frequency for Low-Ripple
▪ Channel 2 (LDO): VIN2 = 2.7V to 5.5V
• IOUT2 up to 600mA
• 1V Dropout Voltage at 600mA
• High Accuracy ±1.5%
• Small Solution Size
▪ System on a Chip
▪ Ultra-small External L/C
• Shutdown Current <35μA
• Independent Enable Pins
• Adjustable Over-Current Protection
• Over-Temperature Protection
• Internal Soft Start
• 3x4mm 16-Pin TDFN Low Profile Thermally Enhanced
Package
• -40°C to 85°C Temperature Range
Applications
• DSL and Cable Modems
• Notebook Computers
• Satellite Settop Box
• Wireless LAN Systems
Typical Application
VIN1
6.0V -24.0V
1
C4
0.1µF
D1
C6
2.2µF
C1 +
220µF
25V
EN1
C15
1µF
25V
VIN2
C5
2.2µF
TDFN34-16
BST1 LX1
VL1
IN1 RS1
OS1
AAT2689
EN1 FB1
IN2 COMP1
EN2 OUT2
GND
L1 4.7µH/5.3A
VOUT1
3.3V/2.5A
D2 R2 C7
2k 220nF
C8
330pF
R5
499
R3
27.4k
C9,C11
2x22µF
R1 24.3K
C2 470pF
C3 56pF
C10
2.2µF
VOUT2
1.8V/600mA
R4
6.04k
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202035A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 8, 2012
1
1 page  
DATA SHEET
AAT2689
Typical Characteristics
PMIC Solution for 12V Adapter Systems
with 2-Output High Performance Step-Down Converters
Step-Down Converter Efficiency vs. Load
(VOUT1 = 3.3V; L = 4.7µH)
100
90
80
70
60
50
40
30
20
10
0
0.1
1
VIN1 = 6V
VIN1 = 8V
VIN1 = 12V
VIN1 = 18V
VIN1 = 24V
10
100
1000
10000
Output Current (mA)
Step-Down Converter DC Regulation
(VOUT1 = 3.3V; L = 4.7µH)
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
0.1
VIN1 = 6V
VIN1 = 8V
VIN1 = 12V
VIN1 = 18V
VIN1 = 24V
1 10 100 1000
Output Current (mA)
10000
Step-Down Converter Line Regulation
(VOUT1 = 3.3V; L = 4.7µH)
1.00
0.75
0.50
0.25
0.00
-0.25
-0.50
-0.75
-1.00
6
IOUT1 = 0.1mA
IOUT1 = 1mA
IOUT1 = 1250mA
IOUT1 = 2500mA
8 10 12 14 16 18 20 22 24
Input Voltage (V)
Step-Down Converter Output Ripple
(VIN1 = 12V; VOUT1 = 3.3V; IOUT1 = 1mA)
12V
0V
3.31
3.30
3.29
0.4
0.2
0.0
Time (2µs/div)
Step-Down Converter Output Ripple
(VIN1 = 12V; VOUT1 = 3.3V; IOUT1 = 2.5A)
12V
0V
3.32
3.30
3.28
4.0
3.0
2.0
Time (1µs/div)
Step-Down Converter Load Transient Response
(IOUT1 = 1.875A to 2.5A; VIN1 = 12V;
VOUT1 = 3.3V; COUT1 = 2x22µF)
2.5A
3.0
2.5
1.875A
2.0
1.5
3.4
3.3
3.2
Time (100µs/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202035A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 8, 2012
5
5 Page 
DATA SHEET
AAT2689
PMIC Solution for 12V Adapter Systems
with 2-Output High Performance Step-Down Converters
Applications Information
Output 1 is a high voltage DC/DC Buck (step-down) con-
verter providing an output voltage from 1.5V to 5.5V.
The integrated high-side N-channel MOSFET device pro-
vides up to 2.5A output current. Input voltage range is
6.0V to 24.0V. The step-down converter utilizes constant
frequency (PWM-mode) voltage mode control to achieve
high operating efficiency while maintaining extremely
low output noise across the operating range. High
490kHz (nominal) switching frequency allows small
external filtering components, achieving minimum cost
and solution size. External compensation allows the
designer to optimize the transient response while achiev-
ing stability across the operating range.
Output 2 is a low voltage, low dropout (LDO) linear
regulator providing 1.8V with up to 600mA output cur-
rent. The input voltage range is 2.7V to 5.5V. The LDO
provides very low noise output which can be derived
directly from the Output 1 channel.
Channel 1 Regulator
Output Capacitor Selection
Two 22μF ceramic output capacitors are required to filter
the inductor current ripple and supply the load transient
current for IOUT = 2.5A. The 1206 package with 10V
minimum voltage rating is recommended for the output
capacitors to maintain a minimum capacitance drop with
DC bias.
Channel 1 Output Inductor Selection
The step-down converter utilizes constant frequency
(PWM-mode) voltage mode control. A 4.7μH inductor
value is selected to maintain the desired output current
ripple and minimize the converter’s response time to
load transients. The peak switch current should not
exceed the inductor saturation current, the MOSFET or
the external Schottky rectifier peak current ratings.
Channel 1 Rectifier Selection
Output Voltage and Current
Output 1 is set using an external resistor divider as
shown in Table 1. Minimum output voltage is 1.5V and
maximum output voltage is 5.5V. Typical maximum duty
cycle is 85%.
VOUT(V)
1.5
1.8
1.85
2.0
2.5
3.0
3.3
5.0
R4 = 6.04k
R3(k)
9.09
12.1
12.4
14.0
19.1
24.3
27.4
44.2
Table 1: Feedback Resistor Values
Alternately, the feedback resistor may be calculated
using the following equation:
R3
=
(VOUT
- 0.6)
0.6
·
R4
R3 is rounded to the nearest 1% resistor value.
When the high-side switch is on, the input voltage will be
applied to the cathode of the Schottky diode. The recti-
fier's rated reverse breakdown voltage must be chosen
at least equal to the maximum input voltage of the step-
down regulator.
When the high-side switch is off, the current will flow
from the power ground to the output through the
Schottky diode and the inductor. The power dissipation
of the Schottky diode during the time-off can be deter-
mined by the following equation:
PD = IOUT · VD ·
1 - VOUT
VIN
Where VD is the voltage drop across the Schottky diode.
Channel 1 Input Capacitor Selection
For low cost applications, a 100μF/25V electrolytic capac-
itor is selected to control the voltage overshoot across
the high side MOSFET. A small ceramic capacitor with
voltage rating at least 1.05 times greater than the max-
imum input voltage is connected as close as possible to
the input pin (Pin 14) for high frequency decoupling.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202035A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 8, 2012
11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet AAT2689.PDF ] | |
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