202213A.pdf

DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
General Description
Features/Performance
The AAT3604B is a micropower PMU optimized for maximum lithium-ion (polymer) battery life both in operational and standby mode. The total no load current into
VIN when all functions are enabled is only 70µA.
•VIN: 2.7V to 5.5V
• Minimum External Components
• Less than 1.1mm Height for all External Components
• Total Standby Mode Ground Current 1µA
(VO1, VO2, and VO3 enabled).
• 1.8V Enable Logic
• Core Voltage Switchover in Standby Mode
• LDO Input Current Minimized for 5µA Typical Load
• Buck Efficiency Optimized for 0.6mA Load
• Separate Enable Pins for Each Supply Output
• Over-Current Protection
• Over-Temperature Protection
• 24-Pin 4x4 QFN package
The AAT3604B is a highly integrated device which simplifies system level design for the user with minimal external components required. It contains a step-up (boost)
converter, a step-down (buck) converter, an LDO regulator and a single-cell Lithium Ion/Polymer battery charger
in a single PMU. The device also includes a load switch
for dynamic power path/sleep mode operation for processor core voltage, making it ideal for ultra low power
portable devices.
The battery charger is a complete, thermally protected
constant current/constant voltage linear charger. It
includes an integrated pass device, reverse blocking protection, high accuracy current and voltage regulation,
charge status indication, and charge termination. The
step-up DC/DC converter is a high efficiency boost converter capable of 27V maximum output voltage. It is the
ideal power solution to power OLED, LCD, and CCD applications. The step-up converter offers a true load disconnect feature which isolates the load from the power
source when EN1 is pulled low. This eliminates leakage
current and isolates the output while the device is disabled.
The step-down DC/DC converter is integrated with internal compensation and operates up to a switching frequency of 1.6MHz, thus minimizing the size of external
components while keeping switching losses low and efficiency high.
The LDO regulator offers 60dB power supply rejection
ratio (PSRR) and low noise operation, making it suitable
for powering noise-sensitive loads.
The AAT3604B is available in a space-saving, thermally
enhanced 24-pin QFN44 package.
Step-Up (Boost) Converter
• 6.0 to 10V @ 2mA Output
Step-Down (Buck) Converter
• 0.6V to VIN @ 25mA Output
LDO Regulator (AUX)
• 2.0 to 2.6V/5mA @ VIN = 3.6V
• PSRR: [email protected]
• Noise: 175µVrms
Battery Charger (3.0V)
• Lithium-Ion/Polymer Battery Charger
• Digitized Thermal Regulation
• Charge Current Programming up to 100mA
• Charge Current Termination Programming
• Automatic Trickle Charge for Battery Preconditioning
• Charge Status Indicator
Applications
•
•
•
•
3D Goggles
GPS Tracking Units
Remote Sensors
Spy Modules
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012
1
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Typical Application
NSR0620P2T5G
3.3μH
LIN
SW
10V
0µA - 2mA
9MΩ
Boost
EN1
HiV Enable
2.7V to 5.5V
2.2μF
+1.8V
Enable
1μF
FB1
1.0MΩ
VIN
EN2
13MΩ
Buck
2.2μH
LX2
PGND
PGND
1.8V/25mA
1μF
2.0MΩ
1.0MΩ
VO2
FB2
Main
VCORE Select
+2.4V Enable
VSEL
EN3
VO5
4.7μF
Aux
13MΩ
VO3
LDO
FB3
USB
2.4V/5mA
1.4MΩ
1μF
1.0MΩ
AGND
USB Input
VCORE
Reverse Blocking
BAT
STAT
ISET
Lithium-Ion
Charger
RSET
2
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Pin Descriptions
Pin #
Symbol
1
2
3
4
5
6
7
8
9
10, 11, 12
13
14
15
16
17
18
19
20
21
22
23
24
EP
FB1
AGND
EN2
EN1
USB
FB2
BAT
ISET
STAT
N/C
VSEL
AGND
EN3
FB3
VO3
VO5
VO2
SW
PGND
LX2
VIN
LIN
EP
Function
Boost converter feedback voltage.
System small signal ground.
Active high buck converter enable.
Active high boost converter enable input.
USB source for battery charger. Should be decoupled with 2.2µF or greater capacitor.
Buck converter feedback voltage.
Battery connection.
Battery charge current set. Programs the charge current by terminating with a resistor to ground.
Battery charge status output.
No connection.
Core voltage select logic input. VSEL = 0, VO5 = VO3; VSEL = 1, VO5 = VO2.
System small signal ground.
Active high nano power LDO regulator enable.
Nano power LDO regulator feedback.
Nano power linear regulator output voltage. Should be decoupled with 1µF or greater output capacitor.
Core voltage.
Buck converter output voltage.
Boost switch node.
Power ground.
Buck converter switch node.
Input voltage. Should be decoupled with 2.2µF or greater capacitor.
Boost switched power input voltage.
Exposed pad; connect to ground plane.
Pin Configuration
QFN44-24
(Top View)
VO2
SW
PGND
LX2
VIN
LIN
19
20
21
22
23
24
FB1
AGND
EN2
EN1
USB
FB2
1
18
2
17
3
16
4
15
5
14
6
13
VO5
VO3
FB3
EN3
AGND
VSEL
12
11
9
10
8
7
N/C
N/C
N/C
STAT
ISET
BAT
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012
3
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Absolute Maximum Ratings1
Symbol
Description
VIN, BAT
LIN
USB
VSW
VLX21
VFB1 ,VFB2,VFB3
VSEL, EN1-EN3,
STAT, ISET
TJ
TLEAD
Value
Input Voltage and Bias Power to PGND
Boost Inductor Source to PGND
USB Battery Charger Input
SW to PGND
LX1 to GND
FB1, FB2, FB3 to GND
6.0
32
7.5
-0.3 to 30
-0.3 to 6
-0.3 to VINB + 0.3
Logic Levels
-0.3 to VINB + 0.3
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec.)
Units
V
-40 to 150
300
°C
Value
Units
2
50
W
°C/W
Thermal Information
Symbol
PD
ΘJA
Description
Maximum Power Dissipation
Thermal Resistance2
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions
specified is not implied.
2. Mounted on a FR4 board.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Electrical Characteristics
Buck Converter
TA = 0°C to 70°C, unless otherwise noted. Typical values are TA = 25°C, VIN = 3.6V.
Symbol
Description
VIN
VO2
Input Voltage
Output Voltage Range
Maximum Output Current1
Output Voltage Tolerance
Efficiency
Input Current
Quiescent Current
System Shutdown Current
P-Channel Peak Current Limit
High Side Switch On-Resistance
Low Side Switch On-Resistance
IOUTMAX
VO2
η
IIN
IQ
ISYSSHDN
ILIM
RDS(ON)L
RDS(ON)H
∆VO2/
VO2*∆VIN
IFB2
FOSC
Line Regulation
FB Leakage Current
Maximum Switching Frequency
Over-Temperature Shutdown
TSD
Threshold
Over-Temperature Shutdown
THYS
Hysteresis
Active High Enable Logic Input
VEN2(L)
Enable Threshold Low
VEN2(H)
Enable Threshold High
IEN2
Enable Input Low Current
Conditions
Max
Units
4.5
VIN
750
1
1
V
V
mA
%
%
µA
µA
µA
mA
Ω
Ω
VIN = 2.7V to 4.5V
0.1
%/V
VO2 = 1.0V
1
1.6
nA
MHz
140
°C
25
°C
VIN = 2.7 to 4.5V @ VOUT = 1.8V
IO2 = 0mA to 5mA, VIN = 2.7V to 4.5V, TA = 25°C
IO2 = 1.0mA, VO2 = 1.8V
VO2 = 1.8V, IOUT = 0.6mA
No Load
EN2 = 0V, VIN = 2.7V to 4.2V
Min
Typ
2.7
0.6
25
-3.0
+3.0
85
350
25
2.0
0.4
1.4
VIN = 4.2V, VEN2 = GND
1
V
V
µA
LDO Regulator
TA = 0°C to 70°C, unless otherwise noted. Typical values are TA = 25°C, VIN = 3.6V, COUT = 0.1µF
Symbol
Description
Conditions
VIN
VO3
∆VOUT
IO3MAX
VDO
ISC
IQ
∆VO3/∆VIN
Input Voltage
Output Voltage Range
Output Voltage Tolerance
Maximum Output Current
Dropout Voltage1
Short-Circuit Current
Ground Current
Line Regulation
External Resistor Programmable
IO3 = 0 to 100µA, VIN = 2.7V to 4.5V
VO3 = 2.0V, VIN = 3.6V
IOUT = 100μA
VOUT < 0.4V
VIN = 2.7V to 3.6V, No Load
VIN = 2.7 to 4.5V
Load Regulation
IO3 = 0μA to 100μA
0.05
%
100Hz
100Hz to 100kHz @ 1mA
60
175
dB
µVRMS
∆VO3(LOAD)/VO3
PSRR
Power Supply Rejection Ratio
eN
Output Noise
Active High LDO Enable Input
VEN3(L)
Enable Threshold Low
VEN3(H)
Enable Threshold High
IEN3
Enable Input Low Current
Min
Typ
2.7
2.0
-3
5
17
12
1.5
0.02
Max
Units
4.5
2.6
+3
V
V
% VOUT
mA
mV
mA
µA
%
3.5
0.4
1.4
VIN = 4.2V, VEN3 = GND
1
V
V
µA
1. The AAT3604B is guaranteed to meet performance specification from 0°C to +70°C and is assured by design, characterization and correlation with statistical process controls.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012
5
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Electrical Characteristics (continued)
Boost Converter
VIN = 3.6V, VOUT = 27V, TA = 0°C to 70°C unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Conditions
Boost
VIN
VOUT
VOUT
VPK
IOUT
Input Voltage Range
Output Voltage Adjustment Range
Output Voltage Tolerance
Peak to Peak Output Voltage Ripple
Load Current Range
IOUT = 0 to 200μA
Load Current Range
VIN = 2.7V to 4.5V, VOUT = 6V to 10V
IOUT
IPG
IQ
ISHDN
RDS(ON)L
η
ΔVOUT
Load Regulation
ΔVOUT
Line Regulation
FOSC(MAX)
Typical Maximum Switching Frequency
FOSC(MIN)
Typical Minimum Switching Frequency
Active High Enable Input (EN)
VEN1(L)
Enable Threshold Low
VEN1(H)
Enable Threshold High
IEN1
Enable Input Low Current
100
50
VIN = 2.7V to 4.5V, VOUT = 6V to 27V
Fixed Peak Cycle by Cycle Inductor
Current Limit
Quiescent Supply Current (No Switching)
Shutdown Current
NMOS On-Resistance
Typ
Max
Units
4.5
27
+3
200
V
V
%
mV
µA
2
mA
2.7
6
-3
VIN = 2.7V to 4.5V
1
Efficiency
Min
VFB = 1.5V
EN1 = GND, VIN = 2.7V to 4.2V
TA = 25°C, VIN = 3.6V
IOUT = 50μA, L = 10µH, VIN = 3.6V VOUT = 27V
IOUT = 2mA, L = 3.3µH, VIN = 3.6V, VOUT = 10V
IOUT = 0 to 200μA
VIN = 2.7V to 4.5V
TA = 25°C, IOUT = 200µA
TA = 25°C, IOUT = 1µA
600
mA
16
1.0
0.6
73
85
0.1
0.1
0.12
0.5
µA
µA
Ω
%
%
%
%
MHz
kHz
0.4
1.4
VIN = 4.2V, VEN5 = GND
1
V
V
µA
VCORE Select
VIN = 3.6V, TA = 0°C to 70°C unless otherwise noted. Typical values are at TA = 25°C.
Symbol
VSEL Logic
RSWA
RSWB
IVO5
VSELL
VSELH
ISEL
Description
and Switch Characteristics
Resistance from VO2 to VO5
Resistance from VO3 to V05
VO5 Load Current
Low Threshold
High Threshold
VCORE Select Logic Input Current
Conditions
Min
VSEL = High
VSEL = Low
Typ
Max
5
35
25
0.4
1.4
VIN = 4.2V, VSEL= GND
1.0
Units
Ω
Ω
mA
V
V
µA
1. The AAT3604B is guaranteed to meet performance specification from 0°C to +70°C and is assured by design, characterization and correlation with statistical process controls.
6
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Electrical Characteristics (continued)
Lithium-Ion Charger
VUSB = 5V, TA = 0°C to 70°C unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Charger Characteristics
VUSB
USB Voltage Range
Under-Voltage Lockout (UVLO)
VUVLO
UVLO Hysteresis
IOP
Operating Current
ISHUTDOWN
USB Shutdown Current
ILEAKAGE
Reverse Leakage Current from BAT Pin
Voltage Regulation
VBAT_EOC
End of Charge Accuracy
∆VCH/VCH
Output Charge Voltage Tolerance
VMIN
Preconditioning Voltage Threshold
VRCH
Battery Recharge Voltage Threshold
Current Regulation
ICH
Charge Current Programmable Range
∆ICH/ICH
Charge Current Regulation Tolerance
VSET
ISET Pin Voltage
KI_A
Current Set Factor: ICH/ISET
Charging Device
RDS(ON)
Charging Transistor ON Resistance
Logic Control / Protection
VSTAT
Output Low Voltage
VOVP
Battery Over-Voltage Protection Threshold
ITK/ICHG
Pre-Charge Current
ITERM/ICH
Charge Termination Threshold Current
Conditions
Min
Typ
Max
Units
6.5
V
V
mV
mA
µA
µA
4.242
V
%
V
V
100
10
2
120
mA
%
V
mA/mA
2.5
Ω
4.0
Rising Edge
3.5
150
0.5
0.3
0.4
Charge Current = 25mA
VBAT = 4.25V
VBAT = 4V, USB Pin Open
4.158
Measured from VBAT_EOC
4.20
0.5
3.0
-0.1
5
VIN = 5.5V
STAT Pin Sinks 4mA
ISET = 25mA
0.4
4.4
10
10
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V
V
%
%
7
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Typical Characteristics – LDO Regulator
LDO Load Regulation vs. Output Current
Dropout Voltage vs. Temperature
(VOUT = 2.5V)
20
VBAT = 4.2V
VBAT = 3.6V
0.75
Dropout Voltage (mV)
Load Regulation (%)
1
(ILOAD = 100µA)
0.5
0.25
0
-0.25
-0.5
-0.75
-1
0.01
0.1
1
18
17
16
15
14
13
12
11
10
10
Load Current (mA)
19
0
0
-0.25
-0.5
-0.75
10
20
30
40
50
60
1.25
1
0.75
0.5
0.25
0
0
10
20
30
40
50
60
70
Temperature (°C)
LDO Output Voltage Noise
Power Supply Rejection Ratio, PSRR
70
100
60
80
50
PSRR (dB)
Noise (µVRMS)
70
1.5
(ILOAD = 1mA, Power BW = 100Hz to 100KHz)
40
30
20
60
40
20
10
1000
10000
Frequency (Hz)
8
60
1.75
70
Temperature (°C)
0
100
50
2
0.25
-1
0
40
Supply Current vs. Temperature
IOUT = 1µA
IOUT = 10µA
IOUT = 100µA
0.5
30
Temperature (°C)
Supply Current (µA)
Output Voltage Error (%)
1
20
Output Voltage Error vs. Temperature
0.75
10
0
10
100000
100
1000
10000
100000
Frequency (Hz)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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1000000
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Typical Characteristics – Buck Converter
Buck Efficiency vs. Load Current
Buck Load Regulation vs. Load Current
(VOUT = 1.8V)
(VOUT = 1.8V)
1
100
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
80
60
40
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
20
0
0.1
1
10
Efficiency (%)
Efficiency (%)
0.75
0.5
0.25
0
-0.25
-0.5
-0.75
-1
0.1
100
1
Load Current (mA)
10
100
Load Current (mA)
Buck Efficiency vs. Load Current
Buck Load Regulation vs. Load Current
(VOUT = 1.2V)
(VOUT = 1.2V)
1
100
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
80
60
40
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
20
0
0.1
1
10
Efficiency (%)
Efficiency (%)
0.75
0.5
0.25
0
-0.25
-0.5
-0.75
-1
0.1
100
1
Load Current (mA)
Supply Current vs. Temperature
(VIN = 3.6V; Switching)
26
25.2
25.75
25.1
Supply Current (µA)
Supply Current (µA)
(Switching)
25.5
25.25
25
24.75
24.5
2.75
3.0
3.25
3.5
3.75
Supply Voltage (V)
100
Load Current (mA)
Supply Current vs. Supply Voltage
24.25
2.5
10
4.0
4.25
4.5
25
24.9
24.8
24.7
24.6
24.5
0
10
20
30
40
50
60
70
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012
9
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Typical Characteristics – Buck Converter
Output Voltage Error vs. Temperature
0.5
1.25
0.25
0
-0.25
1
0.75
0.5
-0.5
0.25
-0.75
-1
0
10
20
30
40
Temperature (°C)
10
1.5
IOUT = 1µA
IOUT = 10µA
IOUT = 100µA
0.75
RDSON_N (Ω)
Output Voltage Error (%)
1
N-Channel RDS(ON) vs. Temperature
50
60
0
70
VIN = 3.0V
VIN = 3.6V
0
10
20
30
40
50
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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60
70
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Typical Characteristics – Boost Converter
Boost Efficiency vs. Load Current
Boost Load Regulation vs. Load Current
(VOUT = 27V)
(VOUT = 27V)
0.2
100
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
0.15
Efficiency (%)
Efficiency (%)
80
60
40
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
20
0
0.1
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
0.1
0.2
0.15
Load Current (mA)
0.2
Load Current (mA)
Boost Efficiency vs. Load Current
Boost Load Regulation vs. Load Current
(VOUT = 11V)
(VOUT = 11V)
2
100
80
60
40
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
20
0
0.01
0.1
1
Efficiency (%)
Efficiency (%)
1.5
1
0.5
0
-0.5
-1
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
-1.5
-2
0.01
10
0.1
Load Current (mA)
Output Voltage Error vs. Input Voltage
(VOUT = 27V)
1
Ouput Voltage Error (%)
1
Output Voltage Error (%)
10
Load Current (mA)
Output Voltage Error vs. Temperature
0.75
0.5
0.25
0
-0.25
-0.5
-0.75
-1
1
0
10
20
30
40
Temperature (°C)
50
60
70
0.75
0.5
0.25
0
-0.25
-0.5
IOUT = 10µA
IOUT = 100µA
IOUT = 200µA
-0.75
-1
2.5
3.0
3.5
4.0
4.5
4.0
4.5
Supply Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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11
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Typical Characteristics – Battery Charger
Trickle Charge to Full Charge Threshold
vs. Supply Voltage
3.1
3.01
3.075
3.008
Battery Voltage (V)
Battery Voltage (V)
Trickle Charge to Full Charge Threshold
vs. Temperature
3.05
3.025
3
2.975
2.95
2.925
2.9
3.006
3.004
3.002
3
2.998
2.996
2.994
2.992
0
10
20
30
40
50
60
2.99
4.5
70
Temperature (°C)
6.5
Charging Current vs. Temperature
Charging Current (mA)
Charging Current (mA)
6.0
30.05
31.2
30.8
30.4
30
29.6
29.2
4.0
4.25
4.5
4.75
5.0
5.25
5.5
5.75
6.0
6.25
30
29.95
29.9
29.85
29.8
29.75
6.5
Supply Voltage (V)
0
4.15
Battery Voltage (V)
4.2
4.199
4.198
4.197
4.196
4.195
20
30
40
Temperature (°C)
50
60
30
40
50
60
70
Recharge Voltage vs. Temperature
4.16
10
20
4.201
0
10
Temperature (°C)
End of Charge Voltage vs. Temperature
Battery Voltage (V)
5.5
Supply Voltage (V)
31.6
12
5.0
Charging Current vs. Supply Voltage
4.194
4.5
4.14
4.13
4.12
4.11
4.1
4.09
70
0
10
20
30
40
50
Temperature (°C)
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60
70
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Typical Characteristics – Battery Charger
Constant Charging Current vs. Supply Voltage
End of Charge Voltage Tolerance
vs. Temperature
34
0.2
33
0.15
End of Charge
Voltage Tolerance (%)
Charging Current (mA)
(ICH = 30mA)
32
31
30
29
0
-0.05
28
VBAT = 3.6V
VBAT = 3.9V
VBAT = 4.1V
27
26
25
4.0
0.1
0.05
4.5
5.0
5.5
6.0
6.5
Supply Voltage (V)
7.0
-0.1
-0.15
7.5
-0.2
0
10
20
30
40
50
60
70
Temperature (°C)
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DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Functional Block Diagram
LIN
SW
Boost
EN1
FB1
VIN
EN2
Buck
13MΩ
LX2
PGND
Main
VSEL
VO2
FB2
VO5
Aux
13MΩ
VO3
LDO
EN3
FB3
AGND
USB
STAT
ISET
Reverse Blocking
Lithium-Ion
Charger
Functional Description
The AAT3604B is a complete power management solution
for small low power portable devices. It seamlessly integrates an intelligent, stand-alone CC/CV (ConstantCurrent/Constant-Voltage), linear-mode lithium-ion/
polymer battery charger with a step-up (boost) converter,
a step-down (buck) converter, a low-dropout (LDO) regulator, and a voltage select function to switch the core voltage for an external processor. The AAT3604B can provide
charging current to the battery from a standard USB port.
An internal load switch controlled by the VSEL pin allows
the LDO or buck DC-DC converter to supply power to the
VCORE supply pin on an external processor.
14
BAT
Functional Description Lithium-Ion Polymer Battery Charger
The AAT3604B contains a low power battery charger
designed to charge lithium-ion polymer batteries with up
to 100mA of current from an external power source. It is
a stand-alone charging solution, with just three external
components required for complete functionality. The
charger precisely regulates battery charge voltage and
current for 4.2V lithium-ion polymer batteries. The
adapter/USB charge input constant current level can be
programmed up to 100mA for low power charging applications. The charger is rated for operation from 0°C to
+70°C. In the event of operating ambient temperatures
exceeding the power dissipation abilities of the device
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DATA SHEET
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Total Power Solution for Micro Power Applications
package for a given constant current charge level, the
charge control will enter into thermal limit. A status
monitor output pin is provided to indicate the battery
charge state by directly driving an external LED. Device
junction temperature and charge state are fully monitored for fault conditions. In the event of an over-voltage
or over-temperature fault, the device will automatically
shut down, protecting the charging device, control system, and the battery under charge.
Constant Current Charging
Charging Operation
Constant Voltage Charging
The charger has four basic modes for the battery charge
cycle: pre-conditioning/trickle charge; constant current/
fast charge; constant voltage; and end of charge (see
Figure 1).
Battery Preconditioning
Before the start of charging, the charger checks several
conditions in order to assure a safe charging environment. The input supply must be above the minimum
operating voltage, or under-voltage lockout threshold
(VUVLO), for the charging sequence to begin. When these
conditions have been met and a battery is connected to
the BAT pin, the charger checks the state of the battery.
If the cell voltage is below the preconditioning voltage
threshold (VMIN), the charge control begins preconditioning the cell. The battery preconditioning trickle charge
current is equal to the fast charge constant current
divided by 10. For example, if the programmed fast
charge current is 50mA, then the preconditioning mode
(trickle charge) current will be 5mA. Cell preconditioning
is a safety precaution for deeply discharged battery cells
and also aids in limiting power dissipation in the pass
transistor when the voltage across the device is at the
greatest potential.
Charge Complete Voltage
Preconditioning
Trickle Charge
Phase
Battery cell preconditioning continues until the voltage
on the BAT pin exceeds the preconditioning voltage
threshold (VMIN). At this point, the charger begins the
constant current charging phase. The charge constant
current (ICH) amplitude is programmed by the user via
the RSET resistor. The charger remains in the constant
current charge mode until the battery reaches the voltage regulation point, VBAT_EOC.
The system transitions to a constant voltage charging
mode when the battery voltage reaches the output
charge regulation threshold (VBAT_EOC) during the constant current fast charge phase. The regulation voltage
level is factory programmed to 4.2V (±0.5%). Charge
current in the constant voltage mode drops as the battery cell under charge reaches its maximum capacity.
End of Charge Cycle Termination
and Recharge Sequence
When the charge current drops to 10% of the programmed fast charge current level in the constant voltage mode, the device terminates charging and goes into
a sleep state. The charger will remain in a sleep state
until the battery voltage decreases to a level below the
battery recharge voltage threshold (VRCH). Consuming
very low current in sleep state, the charger minimizes
battery drain when it is not charging. This feature is particularly useful in applications where the input supply
level may fall below the battery charge or under-voltage
lockout level. In such cases where the charger input
voltage drops, the device will enter sleep state and automatically resume charging once the input supply has
recovered from the fault condition.
Constant Current
Charge Phase
Constant Voltage
Charge Phase
I = Max CC
Regulated Current
Constant Current Mode
Voltage Threshold
Trickle Charge and
Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
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DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
System Information Flowchart
Enable
No
Power on Reset
Yes
Power Input
Voltage
VIN > VUVLO
Yes
Shutdown
Yes
Fault Conditions
Monitoring
OV, OT
Charge
Control
No
Preconditioning
Test
VMIN > VBAT
Yes
Preconditioning
(Trickle Charge)
Yes
Constant
Current Charge
Mode
Yes
Constant
Voltage Charge
Mode
No
No
Recharge Test
VRCH > VBAT
Yes
Current Phase Test
VBAT_EOC > VBAT
No
Voltage Phase Test
IBAT > ITERM
No
Charge Completed
16
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DATA SHEET
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Total Power Solution for Micro Power Applications
Application Information
Protection Circuitry
USB Power Input
Over-Voltage Protection
Constant current charge levels up to 50mA may be programmed by the user when powered from a sufficient
input power source. The charger will operate from the
adapter input over a 4.0V to 6.5V range. The constant
current fast charge current for the adapter input is set
by the RSET resistor connected between ISET and ground.
See Table 1 for recommended RSET values for a desired
constant current charge level.
An over-voltage event is defined as a condition where
the voltage on the BAT pin exceeds the maximum battery charge voltage and is set by the over-voltage protection threshold (VOVP). If an over-voltage condition
occurs, the charge control will shut down the charger
until voltage on the BAT pin drops below VOVP. The part
will resume normal charging operation after the overvoltage condition is removed.
USB Input Charge Inhibit and Resume
Over-Temperature Shutdown
The charger has a UVLO and power on reset feature so
that if the input supply to the USB pin drops below the
UVLO threshold, the charger will suspend charging and
shut down. When power is re-applied to the USB pin or
the UVLO condition recovers, the system charge control
will assess the state of charge on the battery cell and will
automatically resume charging in the appropriate mode
for the condition of the battery.
Programming Charge Current
The fast charge constant current charge level is user
programmed with a set resistor placed between the ISET
pin and ground. The accuracy of the fast charge, as well
as the preconditioning trickle charge current, is dominated by the tolerance of the set resistor used. For this
reason, a 1% tolerance metal film resistor is recommended for the set resistor function. Fast charge constant current levels from 5mA to 100mA may be set by
selecting the appropriate resistor value from Table 1.
Nominal ICHARGE (mA)
Set Resistor Value (kΩ)
100
85
60
50
40
30
20
10
2.5
3.0
4.0
5.11
6.34
8.45
12.7
25.5
Table 1: RSET Values vs. Charge Current.
The AAT3604B has a thermal protection control circuit
which will shut down charging functions should the internal die temperature exceed the preset thermal limit
threshold. Once the internal die temperature falls below
the thermal limit, normal operation will resume the previous charging state.
Charge Status Output
The AAT3604B provides battery charge status via a status pin. This pin is internally connected to an N-channel
open drain MOSFET, which can be used to drive and
external LED. The status pin can indicate the following
conditions.
Event Description
Status
No battery charging activity
OFF
Blinking 1 Second,
50% Duty Cycle
On
Battery charging via USB port
Charging Completed
Table 2: LED Status Indicator.
The LED should be biased with as little current as necessary to create reasonable illumination; therefore, a ballast resistor should be placed between the LED cathode
and the STAT pin. LED current consumption will add to
the overall thermal power budget for the device package, hence it is good to keep the LED drive current to a
minimum. 2mA should be sufficient to drive most low
cost green or red LEDs. It is not recommended to exceed
8mA for driving an individual status LED.
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DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
The required ballast resistor values can be estimated
using the following formulas:
R1 =
(VADP - VF(LED))
ILED
Example:
R1 =
(5.5V - 2.0V)
= 1.75kΩ
2mA
Note: Red LED forward voltage (VF) is typically 2.0V @
2mA.
Capacitor Selection
Input Capacitor
In general, it is good design practice to place a decoupling capacitor between the USB pin and GND. An input
capacitor in the range of 2.2µF to 4.7µF is recommended. If the source supply is unregulated, it may be necessary to increase the capacitance to keep the input voltage above the under-voltage lockout threshold during
device enable and when battery charging is initiated. If
the AAT3604B's USB input is to be used in a system with
an external power supply source, such as a typical
AC-to-DC wall adapter, then a CIN capacitor in the range
of 10µF should be used. A larger input capacitor in this
application will minimize switching or power transient
effects when the power supply is “hot plugged” into an
adapter or USB port.
Output Capacitor
The AAT3604B only requires a 1µF ceramic capacitor on
the BAT pin to maintain circuit stability. This value should
be increased to 10µF or more if the battery connection is
made any distance from the charger output. If the
AAT3604B is to be used in applications where the battery
can be removed from the charger, such as with desktop
charging cradles, an output capacitor greater than 10µF
may be required to prevent the device from cycling on
and off when no battery is present.
18
Functional Description – LDO Regulator
The AAT3604B has an LDO regulator for applications
where output current load requirements range from no
load to 100uA. The advanced circuit design of the LDO
has been optimized for minimum quiescent or ground
current consumption, making it ideal for use in power
management systems for small battery operated devices.
The typical quiescent current level is just 1µA. The LDO
also demonstrates excellent power supply ripple rejection
(PSRR) and load and line transient response characteristics. The AAT3604B contains a truly high performance
LDO regulator especially well suited for circuit applications which are sensitive to load circuit power consumption and extended battery life. The LDO regulator output
has been specifically optimized to function with low cost,
low equivalent series resistance (ESR) ceramic capacitors. However, the design will allow for operation with a
wide range of capacitor types. The LDO has complete
short-circuit and thermal protection. The integral combination of these two internal protection circuits give the
AAT3604B a comprehensive safety system to guard
against extreme adverse operating conditions. Device
power dissipation is limited to the package type and
thermal dissipation properties. Refer to the Thermal
Considerations section of this datasheet for details on
device operation at maximum output load levels.
Output Voltage Programming
The output voltage may be programmed through a resistor divider network located from the output capacitor to
the FB3 pin to ground.
Applications Information
Input Capacitor
The CIN capacitor is shared with the boost converter and
buck converter. CIN should be located as close to the
device VIN pin as practically possible. Typically, a 2.2µF
or larger capacitor is recommended for CIN in most applications. CIN values greater than 2.2µF will offer superior
input line transient response and will assist in maximizing the highest possible power supply ripple rejection.
Ceramic, tantalum, or aluminum electrolytic capacitors
may be selected for CIN. There is no specific capacitor
ESR requirement for CIN. For LDO regulator output operation, ceramic capacitors are recommended for CIN due
to their inherent capability over tantalum capacitors to
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DATA SHEET
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Total Power Solution for Micro Power Applications
withstand input current surges from low-impedance
sources such as batteries in portable devices.
Output Capacitor
For proper load voltage regulation and operational stability, a capacitor is required between pins VO3 and GND.
The COUT capacitor connection to the LDO regulator
ground pin should be as direct as practically possible for
maximum device performance. The LDO has been specifically designed to function with very low ESR ceramic
capacitors. Although the AAT3604B is intended to operate with low ESR capacitors, it is stable over a very wide
range of capacitor ESR, thus it will also work with some
higher ESR tantalum or aluminum electrolytic capacitors.
However, for best performance, ceramic capacitors are
recommended. The value of COUT typically ranges from
0.47µF to 10µF; however, 1µF is sufficient for most operating conditions.
If large output current steps are required by an application, then an increased value for COUT should be considered. The amount of capacitance needed can be calculated from the step size of the change in the output load
current expected and the voltage excursion that the load
can tolerate. The total output capacitance required can
be calculated using the following formula:
COUT =
∆I
· 15µF
∆V
Where:
ΔI = maximum step in output current
ΔV = maximum excursion in voltage that the load can
tolerate.
Note that use of this equation results in capacitor values
approximately two to four times the typical value needed
for the LDO at room temperature. The increased capacitor value is recommended if tight output tolerances must
be maintained over extreme operating conditions and
maximum operational temperature excursions. If tantalum or aluminum electrolytic capacitors are used, the
capacitor value should be increased to compensate for
the substantial ESR inherent to these capacitor types.
Capacitor Characteristics
Ceramic composition capacitors are highly recommended
over all other types of capacitors for use with the LDO.
Ceramic capacitors offer many advantages over their tan-
talum and aluminum electrolytic counterparts. A ceramic
capacitor typically has very low ESR, is lower cost, has a
smaller PCB footprint, and is non-polarized. Line and load
transient response of the LDO regulator is improved by
using low ESR ceramic capacitors. Since ceramic capacitors are non-polarized, they are less prone to damage if
incorrectly connected.
Equivalent Series Resistance
ESR is a very important characteristic to consider when
selecting a capacitor. ESR is the internal series resistance
associated with a capacitor that includes lead resistance,
internal connections, capacitor size and area, material
composition, and ambient temperature. Typically, capacitor ESR is measured in milliohms for ceramic capacitors
and can range to more than several ohms for tantalum
or aluminum electrolytic capacitors.
Ceramic Capacitor Materials
Ceramic capacitors less than 0.1µF are typically made
from NPO or C0G materials. NPO and C0G materials generally have tight tolerance and are very stable over temperature. Larger capacitor values are usually composed
of X7R, X5R, Z5U, or Y5V dielectric materials. Large
ceramic capacitors (i.e., greater than 2.2µF) are often
available in low-cost Y5V and Z5U dielectrics. These two
material types are not recommended for use with LDO
regulators since the capacitor tolerance can vary by
more than ±50% over the operating temperature range
of the device. A 2.2µF Y5V capacitor could be reduced to
1µF over the full operating temperature range. This can
cause problems for circuit operation and stability. X7R
and X5R dielectrics are much more desirable. The temperature tolerance of X7R dielectric is better than ±15%.
Capacitor area is another contributor to ESR. Capacitors,
which are physically large in size will have a lower ESR
when compared to a smaller sized capacitor of equivalent material and capacitance value. These larger devices
can also improve circuit transient response when compared to an equal value capacitor in a smaller package
size. Consult capacitor vendor datasheets carefully when
selecting capacitors for use with LDO regulators.
Feedback Resistor Selection
Resistors R1 and R2 of Figure 2 program the output to
regulate at a voltage higher than 1.0V. To limit the bias
current required for the external feedback resistor string
while maintaining good noise immunity, the minimum
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DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
suggested value for R6 is 1.0MΩ. VFB = 1.0V for the LDO.
Although a larger value will further reduce quiescent current, it will also increase the impedance of the feedback
node, making it more sensitive to external noise and
interference. Table 3 summarizes the resistor values for
various output voltages with R2 set to either 1.02MΩ for
reduced no load input current.
VO3
LDO
FB3
COUT
R1
R2
AGND
Figure 2: LDO Regulator External Feedback.
R1 =
VOUT
- 1 · R2
VFB
VOUT
R1 (Ω)
R2 (Ω)
2.0V
2.1V
2.2V
2.3V
2.4V
2.5V
2.6V
1.00M
1.10M
1.21M
1.30M
1.40M
1.50M
1.62M
1.00M
1.00M
1.00M
1.00M
1.00M
1.00M
1.00M
Table 3: LDO Feedback Resistor Values.
No-Load Stability
The LDO is designed to maintain output voltage regulation
and stability under operational no load conditions. This is
an important characteristic for applications where the
output current may drop to zero. An output capacitor is
required for stability under no-load operating conditions.
Refer to the Output Capacitor section of this datasheet for
recommended typical output capacitor values.
20
The DC/DC boost controller contains an integrated slew
rate controlled input disconnect MOSFET switch, and a
MOSFET power switch. A high voltage rectifier, power
inductor, output capacitor, and resistor divider network
are required to implement a DC/DC boost converter.
Control Loop
VIN
EN3
Functional Description – Boost Controller
The AAT3604B provides the benefits of current mode
control with a simple hysteretic feedback loop. The
device maintains exceptional DC regulation, transient
response, and cycle-by-cycle current limit without additional compensation components. The boost converter
modulates the power MOSFET switching current in
response to changes in output voltage. This allows the
voltage loop to directly program the required inductor
current in response to changes in the output load.
The switching cycle initiates when the N-channel MOSFET
is turned ON and current ramps up in the inductor. The
ON interval is terminated when the inductor current
reaches the programmed peak current level. During the
OFF interval, the input current decays until the lower
threshold, or zero inductor current, is reached. The lower
current is equal to the peak current minus a preset hysteresis threshold - which determines the inductor ripple
current. The peak current is adjusted by the controller
until the output current requirement is met.
The magnitude of the feedback error signal determines
the average input current. Therefore, the boost controller
implements a programmed current source connected to
the output capacitor and load resistor. There is no righthalf plane zero, and loop stability is easily achieved with
no additional compensation components. Increased load
current results in a drop in the output feedback voltage
(FB1) sensed through the feedback resistors (R1, R2).
The controller responds by increasing the peak inductor
current, resulting in higher average current in the inductor. Alternatively, decreased output load results in an
increase in the output feedback voltage (FB1 pin). The
controller responds by decreasing the peak inductor current, resulting in lower average current in the inductor.
The AAT3604B uses light load mode operation to reduce
switching losses and maintain high efficiency.
Operating frequency varies with changes in the input
voltage, output voltage, and inductor size. A small 10µH
(±20%) inductor is selected to maintain high efficiency
operation for 27V output at 200uA.
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DATA SHEET
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Total Power Solution for Micro Power Applications
Output Voltage Programming
The output voltage may be programmed through a resistor divider network located from the output capacitor to
the FB1 pin to ground. The range is 6V to 27V.
Soft Start / Enable
The input disconnect switch is activated when a valid
input voltage is present and the EN1 pin is pulled high.
The slew rate control on the P-channel MOSFET ensures
minimal inrush current as the output voltage is charged
to the input voltage, prior to switching of the N-channel
power MOSFET. Monotonic turn-on is guaranteed by the
built in soft-start circuitry. Soft-start eliminates output
voltage overshoot across the full input voltage range and
all loading conditions. Some applications may require the
output to be active when a valid input voltage is present.
In these cases, tie EN1 to VIN.
Current Limit and
Over-Temperature Protection
The switching of the N-channel MOSFET terminates when
current limit of 250mA (typical) is exceeded. This minimizes power dissipation and component stresses under
overload and short-circuit conditions. Switching resumes
when the current decays below the current limit. Thermal
protection disables the boost converter when internal dissipation becomes excessive. Thermal protection disables
both MOSFETs. The junction over-temperature threshold
is 140°C with 25°C of temperature hysteresis. Once an
over-temperature or over-current fault condition is
removed, the output voltage automatically recovers.
Under-Voltage Lockout
Internal bias of all circuits is controlled via the VIN input.
Under-voltage lockout (UVLO) guarantees sufficient VIN
bias and proper operation of all internal circuitry prior to
activation.
Application Information
Selecting DC/DC Boost Capacitors
The high output ripple inherent in the boost converter
necessitates low impedance output filtering. Multi-layer
ceramic (MLC) capacitors provide small size and adequate capacitance, low parasitic equivalent series resistance (ESR) and equivalent series inductance (ESL), and
are well suited for use with the AAT3604B boost regulator. MLC capacitors of type X7R or X5R are recommended to ensure good capacitance stability over the full
operating temperature range. The output capacitor is
sized to maintain the output load without significant voltage droop during the power switch ON interval, when the
output diode is not conducting. A ceramic output capacitor of 2.2µF is recommended. Typically, 30V rated
ceramic capacitors are required for the 27V boost output. Ceramic capacitors sized as small as 0603 are available which meet these requirements. MLC capacitors
exhibit significant capacitance reduction with applied
voltage. Output ripple measurements should confirm
that output voltage droop is acceptable.
The boost converter input current flows during both ON
and OFF switching intervals. The input ripple current is
less than the output ripple and, as a result, less input
capacitance is required. The CIN capacitor is shared with
the LDO regulator and buck converter. A ceramic input
capacitor from 2.2µF to 3.3µF is recommended. Minimum
6.3V rated ceramic capacitors are required at the input.
Ceramic capacitors sized as small as 0603 are available
which meet these requirements.
Large capacitance tantalum or solid-electrolytic capacitors
may be necessary to meet stringent output ripple and
transient load requirements. These can replace (or be
used in parallel with) ceramic capacitors. Both tantalum
and OSCON-type capacitors are suitable due to their low
ESR and excellent temperature stability (although they
exhibit much higher ESR than MLC capacitors). Aluminumelectrolytic types are less suitable due to their high ESR
characteristics and temperature drift. Unlike MLC capacitors, these types are polarized and proper orientation on
input and output pins is required. 30% to 70% voltage
derating is recommended for tantalum capacitors.
Selecting the Output Diode
To ensure minimum forward voltage drop and no recovery, high voltage Schottky diodes are considered the
best choice for the AAT3604B boost converter. The output diode is sized to maintain acceptable efficiency and
reasonable operating junction temperature under cycle
by cycle operating conditions. Forward voltage (VF),
reverse leakage and package thermal resistance (θJA)
are the dominant factors to consider in selecting a diode.
The diode’s published current rating may not reflect
actual operating conditions and should be used only as a
comparative measure between similarly rated devices.
20V rated Schottky diodes are recommended for outputs
less than 15V, while 30V rated Schottky diodes are recommended for outputs greater than 15V and 40V for
ouputs greater than 25V. The average diode current is
equal to the output current.
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DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
IAVG = IOUT
The average output current multiplied by the forward
diode voltage determines the loss of the output diode.
PLOSS_DIODE = IAVG · VF
= IOUT · VF
Diode junction temperature can be estimated.
TJ = TAMB + θJA · PLOSS_DIODE
The junction temperature should be maintained below
110ºC, but may vary depending on application and/or
system guidelines. The diode θJA can be minimized with
additional PCB area on the cathode. PCB heatsinking the
anode may degrade EMI performance. The reverse leakage current of the rectifier must be considered to maintain low quiescent (input) current and high efficiency
under light load. The rectifier reverse current increases
dramatically at high temperatures. For 27V outputs at
200uA, the Diodes, Inc. SD103BWS is recommended.
For less than 20V outputs, the Diodes, Inc. SD103CWS
can be used.
To ensure high reliability, the inductor temperature
should not exceed 100°C. Manufacturer’s recommendations should be consulted. Shielded inductors provide
decreased EMI and may be required in noise sensitive
applications. Unshielded chip inductors provide significant space savings at a reduced cost compared to shielded (wound and gapped) inductors. Chip-type inductors
have increased winding resistance when compared to
shielded, wound varieties. The Coiltronics SD3110-3R3-R
3.3µH inductor is recommended for a 10V output, the
Coilcraft LPO6610-103ML 10µH inductor is recommended
for a 19V output and the Sumida CDRH2D09NP-5R6MV
5.6µH inductor is recommended for 27V output.
Setting the Adjustable Output Voltage
The output voltage may be programmed through a resistor divider network located from the output to FB pin to
ground.
The output voltage of the boost switching regulator
(VOUT) is determined by the following equation:
VOUT = VFB 1 +
Selecting the Boost Inductor
An output inductor sized from 5.6µH to 10µH is recommended. The RMS current flowing through the boost
inductor is equal to the DC plus AC ripple components.
Under worst-case RMS conditions, the current waveform
is critically continuous. The resulting RMS calculation
yields worst-case inductor loss. The RMS value should be
compared against the manufacturer's temperature rise,
or thermal derating, guidelines.
IRMS =
IPEAK
3
R1 =
R1
R2
VOUT
- 1 · R2
VFB
Where VFB = 1.0V for the boost converter.
VIN
LIN
SW
VBOOST
R1
Boost
COUT
FB1
R2
For a given inductor type, smaller inductor size leads to
an increase in DCR winding resistance and, in most
cases, increased thermal impedance. Winding resistance
degrades boost converter efficiency and increases the
inductor operating temperature.
PLOSS_INDUCTOR = IRMS2 · DCR
22
Figure 3: Boost Converter External Feedback.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Functional Description – Buck Converter
The buck converter is a high performance 25mA monolithic step-down converter. It minimizes external component size, enabling the use of a tiny 0603 inductor that is
only 1mm tall, and optimizes efficiency over the complete
load range. Apart from the small bypass input capacitor,
only a small L-C filter is required at the output. Typically,
a 2.2μH inductor and a 1μF ceramic capacitor are recommended (see table of values). Only three external power
components (CIN, COUT, and L) are required. The CIN capacitor is shared with the boost converter and LDO regulator.
Output voltage is set internally at 1.8V. At dropout, the
converter duty cycle increases to 100% and the output
voltage tracks the input voltage minus the RDS(ON) drop of
the P-channel high-side MOSFET. The input voltage range
is 2.7V to 5.5V. The converter efficiency has been optimized for all load conditions, ranging from no load to
5mA. The internal error amplifier and compensation provides excellent transient response, load, and line regulation. Soft start eliminates any output voltage overshoot
when the enable or the input voltage is applied.
Control Loop
The buck converter is a peak current mode step-down
converter. 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 compensation terminates the
transconductance voltage error amplifier output.
Soft Start / Enable
Soft start limits the current surge seen at the input and
eliminates output voltage overshoot. When pulled low,
the enable input forces the buck converter into a lowpower, non-switching state. The total input current during shutdown is less than 1μA.
Current Limit and
Over-Temperature Protection
For overload conditions, the peak input current is limited. To minimize power dissipation and stresses under
current limit and short-circuit conditions, switching is
terminated after entering current limit for a series of
pulses. Switching is terminated for seven consecutive
clock cycles after a current limit has been sensed for a
series of four consecutive clock cycles. Thermal protection completely disables switching when internal dissipation becomes excessive. The junction over-temperature
threshold is 140°C with 15°C of hysteresis. Once an
over-temperature or over-current fault conditions is
removed, the output voltage automatically recovers.
Applications Information
Inductor Selection
The step-down converter uses peak current mode control with slope compensation to maintain stability for
duty cycles greater than 50%. The output inductor value
must be selected so the inductor current down slope
meets the internal slope compensation requirements.
Table 1 displays suggested inductor values for various
output voltages. Manufacturer’s specifications list both
the inductor DC current rating, which is a thermal limitation, and the peak current rating, which is determined by
the saturation characteristics. The inductor should not
show any appreciable saturation under normal load conditions. Some inductors may meet the peak and average
current ratings yet result in excessive losses due to a
high DCR. Always consider the losses associated with the
DCR and its effect on the total converter efficiency when
selecting an inductor.
The 2.2μH LQM21P series inductor selected from Murata
has a 340mW DCR and a 600mA saturation current rating. At full load, the inductor DC loss is 8.5μW which
gives a 0.1% loss in efficiency for a 5mA, 1.8V output.
Input Capacitor
Select a 2.2μF to 4.7μF X7R or X5R ceramic capacitor for
the input since the CIN capacitor is shared with the boost
converter and LDO regulator.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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23
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Output Capacitor
Setting the Adjustable Output Voltage
The output capacitor limits the output ripple and provides holdup during large load transitions. A 1μF to
2.2μF X5R or X7R ceramic capacitor typically provides
sufficient bulk capacitance to stabilize the output during
large load transitions and has the ESR and ESL characteristics necessary for low output ripple.
The output voltage may be programmed through a resistor divider network located from the output to FB pin to
ground. An external resistor divider is used to set the
output voltage as shown in Figure 4.
The output voltage droop due to a load transient is dominated by the capacitance of the ceramic output capacitor.
During a step increase in load current, the ceramic output
capacitor alone supplies the load current until the loop
responds. Within two or three switching cycles, the loop
responds and the inductor current increases to match the
load current demand. The relationship of the output voltage droop during the three switching cycles to the output
capacitance can be estimated by:
COUT =
3 · ∆ILOAD
VDROOP · FS
Once the average inductor current increases to the DC
load level, the output voltage recovers. The above equation establishes a limit on the minimum value for the
output capacitor with respect to load transients. The
internal voltage loop compensation also limits the minimum output capacitor value to 1μF. This is due to its
effect on the loop crossover frequency (bandwidth),
phase margin, and gain margin. Increased output capacitance will reduce the crossover frequency with greater
phase margin.
The maximum output capacitor RMS ripple current is
given by:
IRMS(MAX) =
1
VOUT · (VIN(MAX) - VOUT)
L · FS · VIN(MAX)
2· 3
·
Dissipation due to the RMS current in the ceramic output
capacitor ESR is typically minimal, resulting in less than
a few degrees rise in hot-spot temperature.
The output voltage of the buck switching regulator (VOUT)
is determined by the following equation:
VOUT = VFB 1 +
R1 =
R1
R2
VOUT
- 1 · R2
VFB
Where VFB = 0.6V for the buck converter.
VIN
EN2
2.2μH
Buck
LX2
VO2
COUT
R1
R2
PGND
Figure 4: Buck Converter External Feedback.
Functional Description – VCORE Switch
An internal load switch controlled by the VSEL pin allows
the LDO regulator or buck DC-DC converter to supply
power to the VO5 output for a VCORE supply pin of an
external processor core voltage. The load switch is for
dynamic power path/sleep mode operation for ultra low
power portable devices. With VSEL low, the VO3 supply
is connected to VO5. When VSEL is high, the VO2 supply
is connected to VO5. The maximum output current is
25mA.
TJ(MAX) = PTOTAL · ΘJA + TAMB
24
FB2
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Ordering Information
Voltage
Package
Boost
Buck
LDO
Marking1
Part Number (Tape & Reel)2
QFN44-24
Adjustable
Adjustable
Adjustable
S9XYY
AAT3604BISK-T1
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
Package Information
QFN44-243
19
24
18
1
2.7 ± 0.05
R0.030Max
13
6
12
4.000 ± 0.050
0.300 × 45°
Pin 1 Identification
0.305 ± 0.075
0.5 BSC
7
2.7 ± 0.05
Top View
0.025 ± 0.025
Bottom View
0.214 ± 0.036
0.900 ± 0.050
4.000 ± 0.050
0.4 ± 0.05
Pin 1 Dot By Marking
Side View
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3.The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing
process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012
25
DATA SHEET
AAT3604B
Total Power Solution for Micro Power Applications
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes.
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Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper
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Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product
design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters.
Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
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26
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202213A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 26, 2012