202052A.pdf

DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
General Description
Features
The AAT1219 is a high current synchronous boost converter with programmable low side MOSFET peak current
limit of 500mA to 2.5A. It is ideal for preventing input
current from overloading system power in PCI-E card
applications based on WCDMA/Edge/GPRS/TD-SCDMA
PCI-E card GSM high load pulse applications. With a suitable UltraCap or SuperCap, the AAT1219 ensures that
output voltage meets load power requirements when
large load pulses are applied. It is also ideal for CDMA/
Evdo-A/Evdo-B and other industry modem continuous
load current applications.
• VIN Range: 2.4V to VOUT + 0.25V
• VOUT Range
▪ Adjustable and Fixed Voltage Versions
▪ Adjustable: 3.0V to 5.0V
• Programmable NMOS Peak Current Limit: 500mA to
2.5A
• Startup Inrush Current Limit: 500mA
• Reverse Current Blocking
• True Load Disconnect when Shutdown
• Up to 95% Efficiency
• 1.2MHz Switching Frequency
• Low RDS(ON)
• Synchronous Boost Rectification and Internal
Compensation
• Output Ready Indicator
• Fault Protection
▪ Programmable Over-Voltage Protection
▪ Short-Circuit Protection
▪ Over-Temperature Protection
• Low-profile TDFN33-12 Package
The output voltage of the adjustable version of the
AAT1219 is programmed from 3.0V to 5.0V by an external resistive divider; the FB pin is left floating in the fixed
output voltage version. Optimized internal compensation
provides fast transient response with no external components. Light load switching frequency modulation and
low quiescent current maintain high efficiency performance for light load mode conditions.
The low-side power MOSFET peak current limit of 500mA
to 2.5A is set via an external resistor to protect the system power from overload. The high-side current limit
operates in a linear mode to limit inrush current to
500mA.
Reverse blocking is integrated to prevent current from
flowing back to the input. The AAT1219's true load disconnect function isolates the output from the input when the
device is disabled. Output over-voltage, short-circuit, and
over-temperature protection are also integrated to protect the AAT1219 from these fault conditions.
Applications
• PC Cards (PCMCIA) Modems
• PCI-E Modem Cards
▪ WCDMA/Edge/GPRS/TD-SCDMA
▪ CDMA/Evdo-A/Evdo-B
▪ Industry Modems
• USB Modems
The AAT1219 is available in a Pb-free, 12-pin, low-profile
TDFN33 package and is rated over the -40°C to 85°C
temperature range.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
1
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Typical Application
2.4V to
VOUT +0.25V
L1 4.7μH
LX
VIN
CIN
10μF
VOUT 3.8V
High Load Pulse
OUT
R1
316kΩ
AAT1219
R3
100kΩ
FB
R2
59kΩ
RDY
COUT1
22μF
COUT2
UltraCap
or SuperCap
EN
ISET
OVP
PGND
AGND
RSET
2.4V to
VOUT +0.25V
L1 4.7μH
LX
CIN
10μF
VIN
R1
287kΩ
AAT1219
R3
100kΩ
VOUT 3.5V
Continuous Load
OUT
COUT1
22μF
FB
R2
59kΩ
RDY
EN
ISET
AGND
OVP
PGND
RSET
40.2kΩ
Pin Descriptions
2
Pin #
Symbol
4
IN
1,2
LX
8
FB
10
OUT
11, 12
7
3
6
PGND
AGND
EN
RDY
9
ISET
5
OVP
Description
Battery input voltage. Supplies the IC at startup.
Switching node tied to drain of internal N-channel MOSFET and source of internal P-channel MOSFET. Connect this pin to the external power inductor.
Feedback input pin.This pin is connected to an external resistor divider which programs the output voltage
for adjustable version with feedback voltage of 0.6V.
Boost converter output voltage; connects to the P-channel synchronous MOSFET source. Bypass with ceramic
capacitor to GND.
Power ground.
Non-power signal ground pin.
Input enable pin. Logic high to enable the boost. Logic low to disable the IC.
System ready pin. Open drain, active low, initiated when the output capacitor is 95% charged.
Peak current limit programmable input. An external resistor from ISET to ground is adopted to program the
low-side MOSFET peak current limit between 500mA and 2.5A.
Over voltage protection pin.This pin is connected to an external resistor divider to set the over voltage
threshold.To disable the over voltage feature, short this pin to ground.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Pin Configuration
TDFN33-12
(Top View)
LX
LX
EN
IN
OVP
RDY
1
12
2
11
3
10
4
9
5
8
6
7
PGND
PGND
OUT
ISET
FB
AGND
Absolute Maximum Ratings1
Symbol
Description
LX, VIN, EN, RDY, FB Voltage to PGND
PGND Voltage to GND
Operating Junction Temperature Range
Storage Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
TJ
TS
TLEAD
Value
Units
-0.3 to 6.0
-0.3 to 0.3
-40 to 150
-65 to150
300
V
V
C
C
C
Value
Units
2
50
W
C/W
Thermal Information
Symbol
PD
JA
Description
Maximum Power Dissipation2
Maximum Thermal Resistance3
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.
Only one Absolute Maximum rating should be applied at any one time.
2. Mounted on 1.6mm thick FR4 circuit board.
3. Derate 25mW/C above 25 C ambient temperature.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
3
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Electrical Characteristics
VIN = 3.3V, CIN = 10μF, COUT = 22μF, L = 4.7μH, TA = 25°C unless otherwise noted.
Symbol
VIN
VOUT_RANGE
VOP
Input Operating Voltage Range
2.4
IQ
ISHDN
Quiescent Supply Current
Shutdown Current
VOVP
ILIMIT,P
ILIMIT,N
FOSC
DTYMAX
Logic
VEN(L)
VEN(H)
IEN
VRDY
Thermal
TSD
TSD(HYS)
Min
3.0
UVLO Threshold
∆VOUT/
∆IOUT
∆VOUT/
∆VOUT
RDS(ON)_N
RDS(ON)_P
Conditions
Minimum Start-Up Voltage
Output Voltage Range
VUVLO
VFB_ACC
4
Description
Feedback Voltage Accuracy
VIN Rising
Hysteresis
No Load, No Switching
EN = 0V, VIN = 5.5V
TA = 25°C, VFB = 600mV
TA = -40°C to +85°C, VFB = 600mV
Load Regulation
0A to 1.2A, VOUT = 3.8V
Line Regulation
NMOS Switch On Resistance
PMOS Switch On Resistance
Over-Voltage Protection Threshold
PMOS Current Limit
NMOS Current Limit
Switching Frequency
Maximum Duty Cycle
Logic Input Low Threshold for EN
Logic Input High Threshold for EN
Enable Input Low Current
RDY Threshold
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Typ
Max
Units
2.3
2.4
5.0
VOUT
+ 0.25
2.3
V
V
2.1
100
58
0.01
-2
-3
80
1
2
3
V
V
mV
μA
μA
%
%
0.5
%
VIN = 2.4V to VOUT
0.2
%/V
VOUT = 3.8V
VOUT = 3.8V
VOVP Rising, TA = 25°C
VOVP Hysteresis
VOUT = 0V
RSET = 100kΩ
250
300
600
20
500
1.0
1.2
90
mΩ
mΩ
mV
mV
mA
A
MHz
%
570
0.8
630
1.2
0.4
VIN = VOUT = 5.5V
VOUT Rising
VOUT Hysteresis
1.4
-1.0
1.0
95
10
140
15
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V
V
μA
% VOUT
% VOUT
C
C
o
o
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Typical Characteristics
L = 4.7μH, COUT = 22μF.
Input Current vs. Input Voltage
Input Current vs. Input Voltage
(VOUT = 3.8V)
(VOUT = 5V)
150
110
145
108
140
Input Current (μA)
Input Current (μA)
112
106
104
102
100
98
96
94
135
130
125
120
115
110
92
105
90
100
2.4 2.6 2.8
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
3.0
3.2 3.4 3.6 3.8
Quiescent Current vs. Temperature
Efficiency vs. Output Current
(Measured from VOUT)
(VOUT = 3.3V)
100
100
90
90
80
60
50
40
30
VOUT = 5.5V
VOUT = 4.2V
VOUT = 3.3V
VOUT = 2.4V
20
10
-20
0
20
40
60
80
70
60
50
40
30
VIN = 2.4V
VIN = 2.7V
VIN = 3.0V
20
10
0
0.01
100
0.1
1
Efficiency vs. Output Current
100
1000
10000
Efficiency vs. Output Current
(VOUT = 3.8V)
(VOUT = 5.0V)
100
100
90
90
80
Efficiency (%)
80
Efficiency (%)
10
Output Current (mA)
Temperature (°C)
70
60
50
VIN = 2.4V
VIN = 2.6V
VIN = 2.8V
VIN = 3.0V
VIN = 3.3V
40
30
20
10
0
0.01
4.8 5.0
80
70
0
-40
4.6
Input Voltage (V)
Efficiency (%)
Quiescent Current (μA)
Input Voltage (V)
4.0 4.2 4.4
0.1
1
10
100
Output Current (mA)
1000
70
60
VIN = 2.4V
VIN = 2.8V
VIN = 3.0V
VIN = 3.3V
VIN = 3.6V
VIN = 4.0V
VIN = 4.2V
50
40
30
20
10
10000
0
0.01
0.1
1
10
100
1000
10000
Output Current (mA)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
5
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Typical Characteristics
L = 4.7μH, COUT = 22μF.
Load Regulation vs. Output Current
Load Regulation vs. Output Current
(VOUT = 3.8V)
(VOUT = 5.0V)
1.0
VIN = 2.4V
VIN = 2.6V
VIN = 2.8V
VIN = 3.0V
VIN = 3.3V
0.8
0.6
0.4
0.2
Load Regulation (%)
Load Regulation (%)
1.0
0.0
-0.2
-0.4
-0.6
-0.8
VIN = 2.4V
VIN = 2.8V
VIN = 3.0V
VIN = 3.3V
VIN = 3.6V
VIN = 4.0V
VIN = 4.2V
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
0.01
0.1
1
10
100
1000
-1.0
0.01
10000
0.1
1
Output Current (mA)
Feedback Voltage Error(%)
Feedback Voltage (V)
601.5
601.0
600.5
600.0
599.5
599.0
598.5
3.5
4.0
4.5
5.0
5.5
0.20
0.00
-0.20
-0.40
-40
-20
0
40
60
VEN(H) vs. Temperature
VEN(L) vs. Temperature
(VIN = 3.6V; VOUT = 5V)
(VIN = 3.6V; VOUT = 5V)
1.05
1.05
1
1
0.95
0.95
VEN(L) (V)
VEN(H) (V)
20
80
100
Temperature (°C)
0.9
0.85
0.8
0.9
0.85
0.8
-15
10
35
Temperature (°C)
6
10000
0.40
Input Voltage (V)
0.75
-40
1000
Feedback Voltage Error vs. Temperature
602.0
3.0
100
Output Current (mA)
Feedback Voltage vs. Input Voltage
598.0
2.5
10
60
85
0.75
-40
-15
10
35
60
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
85
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Typical Characteristics
L = 4.7μH, COUT = 22μF.
RDS(ON)_P vs. Input Voltage
RDS(ON)_N vs. Input Voltage
330
390
85°C
25°C
-40°C
85°C
25°C
-40°C
300
RDS(ON)_N (mΩ)
RDS(ON)_P (mΩ)
360
330
300
270
240
270
240
210
180
150
210
180
2.7
3.1
3.5
3.9
4.3
4.7
5.1
120
2.7
5.5
3.1
3.5
Input Voltage (V)
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Enable Threshold vs. Input Voltage
Switching Frequency vs. Temperature
Enable Threshold (V)
1.15
1.05
0.95
0.85
0.75
0.65
2.5
VEN(H)
VEN(L)
3.0
3.5
4.0
4.5
5.0
5.5
Switching Frequency (MHz)
(VIN = 3.6V; VOUT = 5V)
1.30
1.26
1.22
1.18
1.14
1.10
-40
-15
10
35
60
Line Transient
Load Transient
(VIN = 2.4V to 3.3V; VOUT = 3.8V; IOUT = 200mA; CFF = 0pF)
(VIN = 3.3V; VOUT = 3.8V; CFF = 47pF)
VIN
(0.5V/div)
VOUT
(200mV/div)
2.4
85
Temperature (°C)
Input Voltage (V)
3.8
500mA
VOUT
(100mV/div)
ILOAD
(0.25A/div)
3.8
50mA
0A
Time (40μs/div)
Time (100μs/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
7
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Typical Characteristics
L = 4.7μH, COUT = 22μF.
VIN
(4V/div)
0
VOUT
(5V/div)
0
IIN
(0.2A/div)
0
Soft Start
Output Ripple
(VIN = 3.6V; VOUT = 5V; IOUT = 100mA)
(VIN = 3.3V; VOUT = 3.8V; IOUT = 1mA)
ILX
(0.1A/div)
0A
VOUT
(20mV/div)
3.8V
Time (200μs/div)
Time (100μs/div)
Output Ripple
Maximum Output Current vs. Input Voltage
ILX
(0.1A/div)
0.55A
VOUT
(20mV/div)
3.8V
Time (0.8μs/div)
8
(VOUT = 3.8V; CFF = 0F)
Maximum Output Current (mA)
(VIN = 3.3V; VOUT = 3.8V; IOUT = 500mA)
2000
1800
1600
1400
1200
1000
800
2.4
2.6
2.8
3.0
3.2
3.4
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
3.6
3.8
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Functional Block Diagram
OUT
IN
UVLO
Over-Temperature
Protection
Internal Power
Select
Control Logic
DH
Reverse Current
Block
True Load
Disconnect
Start-up PMOS
Current Control
Mode
Control
OVP
EN
NMOS
Current
Control
ISET
PMOS
Comp
OVP
LX
0.575V
RDY
0.6V
NMOS
DL
Slope
Compensation
PGND
Functional Description
The AAT1219 synchronous step-up converter is targeted
for PC card GSM/GPRS/3G and WiMax modem card
applications. It includes two current limits to ensure fast,
controlled startup and continuous operation with the
PCMCIA specifications.
The high 1.2MHz switching frequency of the AAT1219
facilitates output filter component size reduction for
improved power density and reduced overall footprint. It
also provides greater bandwidth and improved transient
Error
Amp.
FB
AGND
response over other lower frequency step-up converters.
The compensation and feedback is integrated with only
three external components (CIN, COUT, L). Low RDS(ON) synchronous power switches provide high efficiency for
heavy load conditions. Switching frequency modulation
and low quiescent current maintains this high efficiency
for light load mode condition. In addition to the improved
efficiency, the synchronous rectifier has the added performance advantage of true load disconnect during shutdown (<1μA shutdown current), reverse current blocking, inrush current limit, and short-circuit protection.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
9
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
PWM/Light Load Control
True Load Disconnect and Shutdown
The AAT1219 is a fixed frequency PWM peak current
mode control step-up converter. For light load condition
(70 to 80mA and below), the converter remains in variable frequency (Light Load) mode to reduce the dominant switching losses. In addition to Light Load operation, a zero current comparator blocks reverse current in
the P-channel synchronous MOSFET and no noise control
removes the EMI effect caused by inductor current ring.
These controls, along with very low quiescent current,
help to maintain high efficiency over the complete load
range without increased output voltage ripple during
light load conditions.
A typical synchronous step-up (boost) converter has a
conduction path from the input to the output via the
parasitic body diode of the P-channel MOSFET when the
converter shuts down. The AAT1219 design uses a special power selection for the substrate to keep the parasitic body diode in off-state during shutdown and startup.
This enables the AAT1219 to provide true load disconnect
during shutdown and inrush current limit at startup.
Start-up and Inrush Current Limit
When the AAT1219's output voltage is less than the
input voltage at start-up, the device operates the limited
P-channel power MOSFET in a linear status to charge
large output capacitive loads. The fixed current limit of
the PMOS controls the maximum input inrush current to
500mA until output voltage is above input voltage. After
VOUT exceeds VIN, the converter enters step-up status
with internal circuitry power changed from VIN to VOUT.
Programmable NMOS Peak Current Limit
When the output voltage of the AAT1219 is in boost mode
with the output voltage greater than the input voltage,
the NMOS peak current limit takes over.During the inductor charge cycle, the current through the NMOS device is
sensed. When this current reaches the value set by the
RSET resistor, the low-side NMOS switch is turned off.The
NMOS current limit is an instantaneous peak current
measurement and should be set high enough to allow the
desired average current.The applications section discusses proper selection of RSET resistor values.
10
When EN is set to logic low, the step-up converter is
forced into shutdown state with less than 1μA input current.
Short-Circuit Protection
When a short-circuit fault occurs and the AAT1219
detects that the VOUT voltage is lower than VIN minus
400mV, the internal control circuit changes the device
operation status from normal PWM regulation to startup
status with startup current limit active to limit the input
current. When the fault is removed, AAT1219 recovers to
normal operation automatically.
Over-Temperature Protection
An over-temperature event occurs when the AAT1219's
junction temperature exceeds the over-temperature protection threshold. In the case, the AAT1219's over-temperature protection circuitry completely disables switching and the PMOS current limit serves to control the
current level to avoid damage to the step-up converter.
When the over-temperature fault condition is removed,
the boost recovers regulation automatically.
Power Ready Indicator (RDY)
To indicate output voltage OK, an open-drain output RDY
pin is designed to pull down when the output voltage
increases to 95% of the nominal voltage level. The pin
will be pulled up when the output voltage drops below
87% of the nominal output level.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Application Information
RSET Selection for
Current Limit Programming
The current limit of the internal low-side NMOS power
switch is programmable from 500mA to 2.5A by an external resistor connected from ISET to ground. The resistor
value can be calculated using the following formula:
RSET =
R2 = 59kΩ
R1 (kΩ)
3.3
3.6
3.7
3.8
4.0
4.2
5.0
267
294
309
316
340
353
432
Table 2: 1% Standard Resistor Examples for
Different Output Voltages.
105
ILIM
When the inductor's peak current reaches the current
limit, the RDY indicator is pulled high. Table 1 gives standard 1% standard metal film resistor example values for
NMOS current limit programming.
NMOS Peak Current Limit (A)
RSET (kΩ)
0.5
0.6
0.7
0.8
0.9
1.0
1.25
1.5
1.75
2.0
2.25
2.5
200
165
143
124
110
100
78.7
66.5
56.2
49.9
44.2
40.2
Table 1: 1% Standard RSET Value Examples for
NMOS Current Limit Programming
Output Voltage Programming
The output voltage of the AAT1219 adjustable version
may be programmed from 3.0V to 5.5V with an external
resistor divider. Resistors R1 and R2 in Figure 2 program
the output voltage as shown by the following equation:
R1 =
VOUT (V)
R2 · VOUT
- R2
0.6
0.6V is the feedback reference voltage. To limit the bias
current required for the external feedback resistor string
while maintaining good noise immunity, the suggested
value for R2 is 59kΩ. Table 2 summarizes the resistor
values with R2 set to 59kΩ for good noise immunity and
6μA increased load current and gives some 1% standard
metal film resistor values for R1 at different output voltage settings.
Over-Voltage Protection
The AAT1219’s over-voltage protection function prevents
the output voltage from exceeding the programmed
over-voltage point via an external resistor divider when
output voltage has the possible risk of over-shoot.
Resistors R3 and R4 in Figure 2 program the over-voltage trip point. 100kΩ is a good resistance for R4 with
good noise immunity and reduced no load input current.
Calculate the value of R3 using the following formula:
R3 =
R4 · VOUT_OVP
- R4
0.6
As an example, for a 5.5V OVP setting, R3 is 820kΩ
when R4 is 100kΩ. If the over-voltage protection function is not used, connect the OVP pin to ground.
Inductor Selection
The AAT1219 is designed to operate with a 4.7μH inductor for all input/output voltage combinations. For high
efficiency, choose a ferrite inductor with a high frequency core material to reduce core loses. The inductor
should have low ESR (equivalent series resistance) to
reduce the I2R losses, and must be able to handle the
peak inductor current without saturating. To minimize
radiated noise, use a shielded inductor.
Input Capacitor
Select a low ESR ceramic capacitor with a value of at
least 10μF as the input capacitor. The input capacitor
should be placed as close to the VIN and PGND pins as
possible in order to minimize the stray resistance from
the converter to the input power source.
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11
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Output Capacitor
The output capacitor provides energy to the load when
the high-side MOSFET is switched off. The output capacitance together with the boost switching frequency, duty
cycle, and load current value determine the output voltage ripple when the boost operation is in the continuous
PWM state.
∆VOUT =
IOUT · D
COUT · fSW
D is the duty ratio of low-side MOSFET turn-on time
divided by the switching period. It is calculated using the
equation
D=1-
VIN
VOUT
The output capacitor’s ESR increases the output ripple by
IOUT · ESR. The total output ripple is:
∆VOUT =
IOUT · D
COUT · fSW
+ IOUT · ESR
So the minimum output capacitor value is:
COUT_MIN =
(∆VOUT - IOUT · ESR) · fSW
D · IOUT
High Load Pulse Application
Together with a large value output capacitor or supercap,
the AAT1219 can support a higher load pulse in lower
input current limited applications such as GSM burst
mode in WCDMA, Edge, GPRS and TD-SCDMA applications. The large capacitance is determined by NMOS
peak current limit, inductor current ripple, VIN, VOUT, load
pulse high current level and elapsed time. It can be calculated as follows:
First calculate the AAT1219's load current from on the
expected ILIM based on an approximation of input current
equaling ILIM because the inductor current ripple is low
enough when compared to the input current:
IOUT_BOOST =
12
Second, calculate the maximum current the large capacitor COUT should provide:
ICOUT = ILOAD_PEAK - IOUT_BOOST
Finally, derive the COUT at a certain load on period TON:
COUT =
ICOUT · TON
∆VOUT
To consider the real tantalum capacitor having 20% tolerance, the selected capacitance should be 20% higher
than the calculated value.
Example: A 2A, 217Hz 12.5% duty cycle load pulse is
applied on 3.8V VOUT at 3.3V VIN. An input peak current
limit of 1.1A and a VOUT drop of less than 450mV are
required. Under these conditions, with 89% efficiency,
the AAT1219's output current is
IOUT_BOOST =
3.3 · 1 · 89%
= 0.85A
3.8
The maximum current necessary for the large capacitor
value is:
ICOUT = 2 - 0.85 = 1.15A
TON is 577μs for a 217Hz 12.5% duty cycle load pulse.
Considering 20% capacitance tolerance, the minimum
capacitance should be 1843μF. Figure 1 shows the
AAT1219 operating waveform under a 2A 577μs load
pulse with 6x330μF tantalum capacitor as COUT, as well
as a 22μF ceramic capacitor to closely filter the output
voltage.
Supercapacitors have large capacitance and can also be
used in this application. One supercapacitor has a maximum voltage of 1V or 2.5V depending on its electrode
material types (aqueous or organic). For higher voltage
applications, supercapacitors are connected in series. To
prevent any cell from charging over-voltage, a balance
resistor is required on a string of more than three cells.
VIN · ILIM · η
VOUT
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DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
VIN
1V/div
IIN
1A/div
VOUT
2V/div
IOUT
2A/div
RDY
2V/div
3.3V
Layout Guidance
3.8V
For best performance of the AAT1219, the following
guidelines should be followed when designing the PCB
layout:
1.
0V
2.
Time (1ms/div)
Figure 1: AAT1219 Operation Waveform
When 2A 577μs Load Pulse is Applied.
3.
Make the power trace as short and wide as possible,
including the input/output power lines and switching
node, etc.
Connect the analog and power grounds together
with a single short line and connect all low current
loop grounds to analog ground to decrease the
power ground noise on the analog ground and
achieve better load regulation.
For good power dissipation, the exposed pad under
the package should be connected to the top and bottom ground planes by PCB vias.
Evaluation Board Schematic
LX
VIN
4
L1
C1
10μF
VOUT
U1
AAT1219
1
4.7μH
2
VIN
GND
3
JP1
RSET
40.2K
9
OUT
10
LX
RDY
6
EN
FB
IN
R5 100k VIN
LX
ISET
OVP
8
5
RDY
R1
316k
FB
C3 R3
C21 C22
22μF
C23
C24
C25
R2
59k
AGND EP PGND PGND
7
12
11
R4
0
Figure 2: AAT1219 Evaluation Board Schematic.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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13
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Evaluation Board Layout
Figure 3: AAT1219 Evaluation Board
Top Side Layout.
Figure 4: AAT1219 Evaluation Board
Bottom Side Layout
Component
Part Number
Description
Manufacturer
U1
R1
R2
R4
R5
RSET
C1
C21
L1
R3, C3, C22,
C23, C24, C25
AAT1219IWP-1-1.2
RC0603FR-07316KL
RC0603FR-0759KL
RC0603FR-070RL
RC0603FR-07100KL
RC0603FR-0740K2L
GRM21BR61C106K
GRM21BR60J226M
SD53-4R7
High Current Step-Up Converter with Adjustable Current Limit
Res 316kΩ 1/10W 1% 0603 SMD
Res 59kΩ 1/10W 1% 0603 SMD
Res 0Ω 1/10W 1% 0603 SMD
Res 100kΩ 1/10W 1% 0603 SMD
Res 40.2kΩ 1/10W 1% 0603 SMD
Cap Ceramic 10μF 0805 X5R 16V 10%
Cap Ceramic 22μF 0805 X5R 6.3V 20%
Inductor 4.7μH 2.1A SMD
Skyworks
Yageo
Murata
Coiltronics
Not Populated
Table 3: AAT1219 Evaluation Board Bill of Materials.
Manufacturer
Coiltronics
Sumida
Coilcraft
Part Number
L (μH)
Max DCR (mΩ)
Saturation
Current (A)
Size WxLxH
(mm)
SD3118
SD53
SD8328
CDRH4D14HPNP
CDRH4D22
CDRH8D28
LPS4018
LPS5030
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
162
45
24.7
140
82.6
19
125
83
1.31
2.1
3.6
1.4
2.2
3.4
1.9
2.0
3.1x3.1x1.8
5.2x5.2x3.0
8.3x9.5x3.0
4.6x4.6x1.5
5.0x5.0x2.4
8.3x8.3x3.0
4.0x4.0x1.7
4.8x4.8x2.9
Table 4: Surface Mount Inductors.
14
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DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Manufacturer
Part Number
Value (μF)
Voltage
Tolerance
Temp. Co.
ESR
(mΩ)
Case
Murata
GRM21BR60J226ME39
TAJD337M006R
TPSD337M006R0150
TAJD477M006R
TPSD477M006R0150
TAJD687M006R
TPSD687M006R0100
T491D337M006AT
T495D337M006ATE100
T491D477M006AT
T495D477M006ATE150
T491D687M006ZT
T495D687M006ZTE150
22
330
330
470
470
680
680
330
330
470
470
680
680
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
6.3
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
X5R
X5R
X5R
X5R
X5R
X5R
X5R
X5R
X5R
X5R
X5R
X5R
X5R
26
400
150
400
150
500
100
400
100
400
150
500
150
0805
7343
7343
7343
7343
7343
7343
7343
7343
7343
7343
7343
7343
AVX
KEMET
Table 5: Surface Mount Capacitors.
Manufacturer
Part Number
Capacitance (mF)
Rated Voltage (V)
ESR (mΩ)
Size WxLxH (mm)
Cap-xx
http://www.cap-xx.com/
GZ 215F
HS 203F
HS 211F
HS 206F
HW 207F
75
250
370
600
450
4.5
5.5
5.5
5.5
5.5
150
70
55
70
100
20x15x2.6
39x17x2.15
39x17x2.9
39x17x2.4
28.5x17x2.9
Table 6: Supercapacitors.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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15
DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Ordering Information
Package
Output Voltage
Feedback Voltage
Marking1
Part Number (Tape and Reel)2
TDFN33-12
Adjustable
0.6V
8VXYY
AAT1219IWP-1-1.2-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
TDFN33-123
Index Area
0.40 ± 0.05
Detail "A"
C0.3
0.45 ± 0.05
2.40 ± 0.05
3.00 ± 0.05
0.1 REF
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
0.23 ± 0.05
Pin 1 Indicator
(optional)
0.05 ± 0.05
0.23 ± 0.05
0.75 ± 0.05
Detail "A"
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.
16
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DATA SHEET
AAT1219
High Current Step-Up Converter with Adjustable Current Limit
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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