ANALOGICTECH AAT3110-5

AAT3110
MicroPower™ Regulated Charge Pump
General Description
Features
The AAT3110 ChargePump™ is a MicroPower
switched-capacitor voltage converter that delivers
a regulated output. No external inductor is required
for operation. Using three small capacitors, the
AAT3110 can deliver up to 150mA to the voltage
regulated output. The AAT3110 features very low
quiescent current and high efficiency over a large
portion of its load range making this device ideal
for battery-powered applications. Furthermore, the
combination of few external components and small
package size keeps the total converter board area
to a minimum in space restricted applications. The
AAT3110 operates in an output-regulated voltage
doubling mode. The regulator uses a pulse-skipping technique to provide a regulated output from a
varying input supply. The AAT3110 contains a thermal management circuit to protect the device
under continuous output short circuit conditions.
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The AAT3110 ChargePump™ is a member of
AnalogicTech's Total Power Management IC product family.
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Step-up type voltage converter
Input Range
• AAT3110-5: 2.7V to 5V
• AAT3110-3.3: 2.3V to 3.3V
MicroPower consumption: 13µA
5V, 3.3V Regulated ±4% output
5V Output Current
• 100mA with VIN ≥ 3.0V
• 50mA with VIN ≥ 2.7V
3.3V Output Current
• 150mA with VIN ≥ 2.7V
• 100mA with VIN ≥ 2.3V
High Frequency 750 kHz operation
Shutdown mode draws less than 1µA
Short-circuit/over-temperature protection
2kV ESD Rating
SC70JW-8 or SOT23-6 package
Preliminary Information
The AAT3110 is available in a surface mount 6-pin
SOT23 or 8-pin SC70JW package and is rated
from -40 to 85°C.
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ChargePump™
Applications
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Cellular Phones
Portable Communication Devices
Handheld Electronics
Digital Cameras
PDAs
Battery Back Up Supplies
LED/Display Back Light Driver
Typical Operating Circuits
AAT3110
VOUT
VOUT
C+
GND
VIN
SHDN
C-
1uF
COUT
10uF
ON/OFF
VIN
CIN
10uF
3110.2001.9.0.92
1
AAT3110
MicroPower™ Regulated Charge Pump
Pin Descriptions
Pin #
SOT-23-6
SC70JW-8
Symbol
Function
1
1
VOUT
Regulated output pin. Bypass this pin to ground with at
least 6.8µF low ESR capacitor
2
2, 3, 4
GND
Ground connection
3
5
SHDN
4
6
C-
Flying capacitor negative terminal
5
7
VIN
Input supply pin. Bypass this pin to ground with at least
6.8µF low ESR capacitor
6
8
C+
Flying capacitor positive terminal
Shutdown input. Active low signal disables the converter.
Pin Configuration
SOT23-6
SHDN
3
C+
5
VIN
4
C-
VOUT
GND
GND
GND
1
2
8
7
2
2
6
1
GND
2
2
1
1
VOUT
SC70JW-8
3
6
4
5
C+
VIN
CSHDN
3110.2001.9.0.92
AAT3110
MicroPower™ Regulated Charge Pump
Absolute Maximum Ratings
Symbol
(TA=25°C unless otherwise noted)
Description
VIN
VOUT
VSHDN
tSC
TJ
TLEAD
VESD
VIN to GND
VOUT to GND
SHDN to GND
Output to GND Short-Circuit Duration
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
ESD Rating1 — HBM
Value
Units
-0.3 to 6
-0.3 to 6
-0.3 to 6
Indefinite
-40 to 150
300
2000
V
V
V
s
°C
°C
V
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.
Note 1: Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
Thermal Information
Symbol
Description
ΘJA
PD
Rating
Units
150
667
°C/W
mW
Maximum Thermal Resistance (SOT23-6 or SC70JW-8)
Maximum Power Dissipation (SOT23-6 or SC70JW-8)
Note 2: Mounted on an FR4 board.
Electrical Characteristics (TA = -40 to 85°C unless otherwise noted.
Typical values are at TA=25°C,
CFLY=1µF, CIN=10µF, COUT=10µF)
AAT3110-5
Symbol
VIN
IQ
Description
Conditions
Min
Input Voltage
No Load Supply Current
VOUT=5.0V
2.7V < VIN < 5V, IOUT=0mA, SHDN=VIN
2.7V < VIN < 5V, IOUT ≤ 50mA
3.0V < VIN < 5V, IOUT ≤ 100mA
2.7V < VIN < 3.6V, IOUT =0mA, VSHDN=0
3.6V < VIN < 5V, IOUT =0mA, VSHDN=0
VIN = 3V, IOUT = 50mA
VIN = 3V, IOUT = 100mA
VIN = 3V, IOUT = 50mA
Oscillator Free Running
2.7
VOUT
Output Voltage
ISHDN
Shutdown Supply Current
VRIPPLE
η
fOSC
VIH
VIL
IIH
IIL
tON
ISC
Ripple Voltage
Efficiency
Frequency
SHDN Input Threshold High
SHDN Input Threshold Low
SHDN Input Current High
SHDN Input Current Low
VOUT Turn-on time
Short-circuit current3
4.8
4.8
Typ
Max
Units
13
5
5
0.01
VOUT
30
5.2
5.2
1
2.5
V
µA
V
V
25
30
83
750
mVP-P
1.4
SHDN = VIN
SHDN = GND
VIN = 3V, IOUT = 0mA
VIN = 3V, VOUT = GND, SHDN = 3V
0.3
1
1
-1
-1
0.2
300
µA
%
kHz
V
V
µA
µA
ms
mA
Note 3: Under short-circuit conditions, the device may enter overtemperature protection mode.
3110.2001.9.0.92
3
AAT3110
MicroPower™ Regulated Charge Pump
Electrical Characteristics (TA = -40 to 85°C unless otherwise noted.
Typical values are at TA=25°C,
CFLY=1µF, CIN=10µF, COUT=10µF)
AAT3110-3.3
Symbol
VIN
IQ
VOUT
ISHDN
VRIPPLE
η
fOSC
VIH
VIL
IIH
IIL
tON
ISC
4
Description
Conditions
Min
Input Voltage
No Load Supply Current
VOUT=3.3V
2.3V < VIN < 3.3V, IOUT=0mA
2.3V < VIN < 3.3V, IOUT=50mA
2.5V < VIN < 3.3V, IOUT=100mA
2.3V < VIN < 3.3V, IOUT =0mA, VSHDN=0
VIN = 2.3V, IOUT = 50mA
VIN = 2.3V, IOUT = 25mA
Oscillator Free Running
2.3
Output Voltage
Shutdown Supply Current
Ripple Voltage
Efficiency
Frequency
SHDN Input Threshold High
SHDN Input Threshold Low
SHDN Input Current High
SHDN Input Current Low
VOUT Turn-on time
Short-circuit current
3.17
3.17
Typ
10
3.30
3.30
0.01
20
71
750
Max
Units
VOUT
30
3.43
3.43
1
V
µA
V
V
µA
mVP-P
%
kHz
V
V
µA
µA
ms
mA
1.4
SHDN = VIN
SHDN = GND
VIN = 3V, IOUT = 0mA
VIN = 3V, VOUT = GND, SHDN = 3V
0.3
1
1
-1
-1
0.2
300
3110.2001.9.0.92
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics—AAT3110-5
(Unless otherwise noted, VIN = 3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC)
Supply Current vs. Supply Voltage
AAT3110-5
Output Voltage vs. Output Current
AAT3110-5
24
5.1
Supply Current (µA)
Output Voltage (V)
5.15
VIN=3.6
5.05
5
VIN=3.0
4.95
VIN=2.7
VIN=3.3
4.9
4.85
IOUT=0 A
CFLY=1µF
VSHDN=VIN
22
20
18
16
14
12
10
4.8
0
50
100
2.5
150
3
Supply Current vs VSHDN
AAT3110-5
95%
5
5.5
VIN=5.5V
20
VIN=3.3V
15
VIN=2.8V
25 mA
90%
IOUT=0µA
Efficiency (%)
Supply Current (µA)
4.5
Efficiency vs. Supply Voltage
AAT3110-5
30
10
4
Supply Voltage (V)
Output Current (mA)
25
3.5
85%
80%
75%
70%
65%
50 mA
100 mA
60%
55%
50%
5
45%
2.70
0
0
1
2
3
4
3.00
3.50
4.00
4.50
5.00
Supply Voltage (V)
5
VSHDN Control Voltage (V)
Oscillator Frequency vs. Supply Voltage
AAT3110-5
100%
VIN = 2.7V
90%
Efficiency (%)
80%
70%
60%
VIN = 3.0V
VIN = 3.6V
50%
40%
VIN = 3.3V
30%
20%
10%
0%
0.01
0.1
1
10
Load Current (mA)
3110.2001.9.0.92
100
1000
Oscillator Frequency (kHz)
Efficiency vs. Load Current
AAT3110-5
1200
1100
1000
- 40º C
900
800
700
25º C
600
500
400
2.7
85º C
3.0
3.5
4.0
4.5
5.0
Supply Voltage (V)
5
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics—AAT3110-5
(Unless otherwise noted, VIN = 3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC)
Startup Time with 100 mA Load
AAT3110-5
Startup Time with 50 mA Load
AAT3110-5
SHDN
2V/DIV
SHDN
2V/DIV
VOUT
1V/DIV
VOUT
1V/DIV
50µS/DIV
50µS/DIV
Load Transient Response for 50mA
AAT3110-5
IOUT
0mA to
50mA
20mA/DIV
Load Transient Response for 100mA
AAT3110-5
IOUT
0mA to
100 mA
50mA/DIV
VIN=3.0V
VOUT
AC
COUPLED
20mV/DIV
VIN=3.0V
VOUT
AC
COUPLED
20mV/DIV
50µS/DIV
50µS/DIV
Output Ripple with IOUT=50 mA
AAT3110-5
VOUT
AC
Coupled
10 mV/DIV
VOUT
AC
Coupled
10 mV/DIV
VIN=3.0V
VIN=3.0V
2µS/DIV
6
Output Ripple with IOUT=100 mA
AAT3110-5
2µS/DIV
3110.2001.9.0.92
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics—AAT3110-5
(Unless otherwise noted, VIN = 3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC)
VIN vs. VIL
VIN vs. VIH
1.00
1.00
0.95
-40°C
0.95
0.90
0.90
25°C
0.80
0.80
VIL (V)
VIH (V)
-40°C
0.85
0.85
0.75
0.70
0.65
25°C
0.75
0.70
85°C
0.65
0.60
85°C
0.60
0.55
0.55
0.50
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0.50
5.5
2.0
2.5
3.0
VIN (V)
Normalized Output Voltage (%)
VSHDN Threshold (V)
0.95
0.90
VIH
0.80
0.75
0.70
VIL
0.60
0.55
0.50
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Normalized Output Voltage vs Temperature
1.00
0.65
4.0
VIN (V)
VSHDN Threshold vs. Supply Voltage
AAT3110-5
0.85
3.5
4.5
5.0
5.5
1.20%
IOUT=25mA
1.00%
0.80%
0.60%
0.40%
0.20%
0.00%
-0.20%
-0.40%
-0.60%
-50
-25
0
25
50
75
100
125
Temperature (C)
VIN (V)
3110.2001.9.0.92
7
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics—AAT3110-3.3
(Unless otherwise noted, VIN = 2.3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC)
Output Voltage vs. Output Current
AAT3110-3.3
Supply Current vs. Supply Voltage
AAT3110-3.3
24
3.35
Supply Current (µA)
Output Voltage (V)
3.4
VIN=3V
3.3
VIN=2.7V
3.25
3.2
VIN=2.3V
3.15
IOUT=0 A
CFLY=1µF
VSHDN=VIN
22
20
18
16
14
12
10
3.1
0
50
100
150
2.3
200
2.5
2.7
2.9
3.1
3.3
Supply Voltage (V)
Output Current (mA)
Efficiency vs. Supply Voltage
AAT3110-3.3
Supply Current vs VSHDN
AAT3110-3.3
30
80
70
Efficiency (%)
Supply Current (µA)
IOUT=0µA
25
20
VIN=3.3V
15
VIN=2.8V
10
5
60
50
40
30
IOUT=100mA
20
10
0
0
0
1
2
3
2
3.3
2.5
VSHDN Control Voltage (V)
Efficiency vs. Output Current
AAT3110-3.3
Oscillator Frequency (kHz)
90.0%
80.0%
VIN=2.25V
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%
0.01
0.1
1
I-Load (mA)
8
3.5
Oscillator Frequency vs. Supply Voltage
AAT3110-3.3
100.0%
70.0%
60.0%
3
Supply Voltage (V)
10
100
1200
1100
1000
- 40°C
900
800
25°C
700
600
85°C
500
400
2.3
2.5
2.7
2.9
3.1
3.3
Supply Voltage (V)
3110.2001.9.0.92
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics—AAT3110-3.3
(Unless otherwise noted, VIN = 2.3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC)
Startup Time with 100 mA Load
AAT3110-3.3
Startup Time with 50 mA Load
AAT3110-3.3
SHDN
2V/DIV
SHDN
2V/DIV
VOUT
1V/DIV
VOUT
1V/DIV
100µS/DIV
100µS/DIV
Load Transient Response for 50mA
AAT3110-3.3
IOUT
0mA to
50mA
20mA/DIV
Load Transient Response for 100mA
AAT3110-3.3
IOUT
0mA to
100mA
50mA/DIV
VIN=2.3V
COUT=10µF
VOUT
AC
COUPLED
20mV/DIV
VIN=2.3V
COUT=10µF
VOUT
AC
COUPLED
20mV/DIV
20µS/DIV
50µS/DIV
Output Ripple for 50mA Load
AAT3110-3.3
VOUT
AC
Coupled
10mV/DIV
VOUT
AC
Coupled
10mV/DIV
VIN=2.3V
VIN=2.3V
2µs/DIV
3110.2001.9.0.92
Output Ripple for 100mA Load
AAT3110-3.3
2µs/Div.
9
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics—AAT3110-3.3
(Unless otherwise noted, VIN = 2.3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC)
VIN vs. VIH
AAT3110-3.3
VIN vs. VIL
AAT3110-3.3
1.00
1.00
0.95
0.95
-40°C
0.90
0.90
0.85
25°C
0.80
VIL (V)
VIH (V)
0.85
0.75
0.70
-40°C
0.80
0.75
25°C
0.70
0.65
0.65
85°C
0.60
0.60
85°C
0.55
0.55
0.50
0.50
2.0
2.2
2.4
2.6
2.8
3.0
3.2 3.3
2.0
2.2
2.4
2.6
2.8
3.0
3.2 3.3
VIN (V)
VIN (V)
VSHDN Threshold vs. Supply Voltage
AAT3110-3.3
VSHDN Threshold (V)
1.00
0.95
0.90
0.85
0.80
VIH
0.75
0.70
0.65
VIL
0.60
0.55
0.50
2.0
2.2
2.4
2.6
2.8
3.0
3.2 3.3
VIN (V)
10
3110.2001.9.0.92
AAT3110
MicroPower™ Regulated Charge Pump
Functional Block Diagram
VIN
S2
S1
SHDN
CONTROL
C+
CVREF
S4
S3
VOUT
+
GND
Functional Description
Operation (Refer to block diagram)
The AAT3110 uses a switched capacitor charge
pump to boost an input voltage to a regulated output
voltage. Regulation is achieved by sensing the
charge pump output voltage through an internal
resistor divider network. A switched doubling circuit
is enabled when the divided output drops below a
preset trip point controlled by an internal comparator.
The charge pump switch cycling enables four internal switches at two non-overlapping phases. During
the first phase, switches S1 and S4 are switched on
(short) and switches S2 and S3 are off (open). The
flying capacitor CFLY is charged to a level approximately equal to input voltage VIN. On the second
phase, switches S1 and S4 are turned off (open), S2
and S3 are turned on (short). The low side of the flying capacitor CFLY is connected to GND during the
first phase. During the second phase, the flying
capacitor CFLY is switched so that the low side is
connected to VIN. The voltage at the high side of the
flying capacitor CFLY is bootstrapped to 2×VIN and
connected to output through a switch. For each
cycle phase, charge from input node VIN is transported from a lower voltage to a higher voltage. This
cycle repeats itself until the output node voltage is
high enough to exceed the preset input threshold of
the control comparator. When the output voltage
exceeds the internal trip point level, the switching
cycle stops and the charge pump circuit is tem3110.2001.9.0.92
porarily placed in an idle state. When idle, the
AAT3110 has a quiescent current of 13µA or less.
The closed loop feed back system containing the
voltage sense circuit and control comparator allows
the AAT3110 to provide a regulated output voltage to
the limits of the input voltage and output load current. The switching signal, which drives the charge
pump is created by an integrated oscillator within the
control circuit block. The free running charge pump
switching frequency is approximately 750kHz. The
switching frequency under an active load is a function of VIN, VOUT, COUT and IOUT.
For each phase of the switching cycle, the charge
transported from VIN to VOUT can be approximated
by the following formula:
VPHASE ≈ CFLY×(2×VIN-VOUT)
The relative average current that the charge pump
can supply to the output may be approximated by
the following expression:
IOUT(AVG) α CFLY×(2×VIN-VOUT)×FSW
The AAT3110 has complete output short circuit and
thermal protection to safeguard the device under
extreme operating conditions. An internal thermal
protection circuit senses die temperature and will
shut down the device if the internal junction temperature exceeds approximately 145°C. The charge
pump will remain disabled until the fault condition is
relieved.
11
AAT3110
MicroPower™ Regulated Charge Pump
Applications Information
is high, or if the value of CIN is too low. This situation can be remedied by increasing the value of CIN.
External Capacitor Selection
Capacitor Characteristics
Careful selection of the three external capacitors
CIN, COUT and CFLY is very important because they
will affect turn on time, output ripple and transient
performance. Optimum performance will be
obtained when low ESR (<100mΩ) ceramic capacitors are used for CIN and COUT and CFLY. In general, low ESR may be defined as less then 200mΩ . If
desired for a particular application, low ESR
Tantalum capacitors may be substituted; however
optimum output ripple performance may not be realized. Aluminum Electrolytic capacitors are not recommended for use with the AAT3110 due the their
inherent high ESR characteristic.
Ceramic composition capacitors are highly recommended over all other types of capacitors for use
with the AAT3110. Ceramic capacitors offer many
advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically
has very low ESR, is lower cost, has a smaller PCB
footprint and is non-polarized. Low ESR ceramic
capacitors help maximize charge pump transient
response. Since ceramic capacitors are non-polarized, they are not prone to incorrect connection
damage.
Typically as a starting point, a capacitor value of
10µF should be used for CIN and COUT with 1µF
CFLY when the AAT3110 is used under maximum
output load conditions. Lower values for CIN, COUT
and CFLY may be utilized for light load current applications. Applications drawing a load current of
10mA or less may use a CIN and COUT capacitor
value as low as 1µF and a CFLY value of 0.1µF. CIN
and COUT may range from 1µF for light loads to
10µF or more for heavy output load conditions.
CFLY may range from 0.01µF to 2.2µF or more. If
CFLY is increased, COUT should also be increased
by the same ratio to minimize output ripple. As a
basic rule, the ratio between CIN, COUT and CFLY
should not exceed a ratio of 10 to 1. The compromise for lowering the value of CIN, COUT and the flying capacitor CFLY is the output ripple voltage may
be increased. In any case, if the external capacitor
values deviate greatly from the recommendation of
CIN = COUT = 10µF and CFLY = 1µF, the AAT3110
output performance should be evaluated to assure
the device meets the application requirements.
In applications where the input voltage source has
very low impedance, it is possible to omit the CIN
capacitor. However, if CIN is not used, circuit performance should be evaluated to assure desired
operation is achieved. Under high peak current
operating conditions that are typically experienced
during circuit start up or when load demands create
a large inrush current, poor output voltage regulation can result if the input supply source impedance
12
Equivalent Series Resistance (ESR): ESR is a
very important characteristic to consider when
selecting a capacitor. ESR is a resistance internal
to a capacitor, which is caused by the leads, internal connections, size or area, material composition
and ambient temperature. Typically capacitor ESR
is measured in milliohms for ceramic capacitors
and can range to more then several ohms for tantalum or aluminum electrolytic capacitors.
Ceramic Capacitor Materials: Ceramic capacitors
less then 0.1µF are typically made from NPO or
COG materials. NPO and COG materials typically
have tight tolerance and are very stable over temperature. Large capacitor values are typically composed of X7R, X5R, Z5U or Y5V dielectric materials. Large ceramic capacitors, typically greater
than 2.2µF are often available in low cost Y5V and
Z5U dielectrics. If these types of capacitors are
selected for use with the charge pump, the nominal
value should be doubled to compensate for the
capacitor tolerance which can vary more than ±50%
over the operating temperature range of the device.
A 10µF Y5V capacitor could be reduced to less than
5µF over temperature, this could cause problems
for circuit operation. 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 that are physically large will have a lower
ESR when compared to an equivalent material
smaller capacitor. These larger devices can improve
circuit transient response when compared to an
equal value capacitor in a smaller package size.
3110.2001.9.0.92
AAT3110
MicroPower™ Regulated Charge Pump
Applications Information
Charge Pump Efficiency
The AAT3110 is a regulated output voltage doubling charge pump. The efficiency (η) can simply
be defined as a linear voltage regulator with an
effective output voltage that is equal to two times
the input voltage. Efficiency (η) for an ideal voltage
doubler can typically be expressed as the output
power divided by the input power.
η = POUT / PIN
In addition, with an ideal voltage doubling charge
pump the output current may be expressed as half
the input current. The expression to define the
ideal efficiency (η) can be rewritten as:
η=POUT/PIN=(VOUT×IOUT)/(VIN×2IOUT)=VOUT/2VIN
η(%) = 100(VOUT / 2VIN)
For a charge pump with an output of 5 volts and a
nominal input of 3.0 volts, the theoretical efficiency
is 83.3%. Due to internal switching losses and IC
quiescent current consumption, the actual efficiency can be measured at 82.7%. These figures are
in close agreement for output load conditions from
1mA to 100mA. Efficiency will decrease as load
current drops below 0.05mA or when level of VIN
approaches VOUT. Refer to the Typical Characteristics section for measured plots of efficiency
versus input voltage and output load current for the
given charge pump output voltage options.
Short Circuit and Thermal Protection
In the event of a short circuit condition, the charge
pump can draw a much as 100mA to 400mA of current from VIN. This excessive current consumption
due to an output short circuit condition will cause a
rise in the internal IC junction temperature. The
AAT3110 has a thermal protection and shutdown
circuit that continuously monitors the IC junction
temperature. If the thermal protection circuit senses the die temperature exceeding approximately
145°C, the thermal shutdown will disable the
charge pump switching cycle operation. The thermal limit system has 10°C of system hysteresis
before the charge pump can reset. Once the over
current event is removed from the output and the
junction temperature drops below 135°C, the
charge pump will then become active again. The
3110.2001.9.0.92
thermal protection system will cycle on and off if an
output short circuit condition persists. This will
allow the AAT3110 to operate indefinitely a short
circuit condition without damage to the device.
Output Ripple and Ripple Reduction
There are several factors that determine the amplitude and frequency of the charge pump output ripple, the values of COUT and CFLY, the load current
IOUT and the level of VIN. Ripple observed at VOUT is
typically a sawtooth waveform in shape. The ripple
frequency will vary depending on the load current
IOUT and the level of VIN. As VIN increases the ability of the charge pump to transfer charge from the
input to the output becomes greater, as it does, the
peak-to-peak output ripple voltage will also increase.
The size and type of capacitors used for VIN. COUT
and CFLY have an effect on output ripple. Since
output ripple is associated with the R/C charge time
constant of these two capacitors, the capacitor
value and ESR will contribute to the resulting
charge pump output ripple. This is why low ESR
capacitors are recommended for use in charge
pump applications. Typically, output ripple is not
greater than 50mVP-P when VIN = 3.0V, VOUT =
5.0V, COUT = 10µF and CFLY = 1µF.
When the AAT3110 is used in light output load
applications where IOUT < 10mA, the flying capacitor CFLY value can be reduced. The reason for this
effect is when the charge pump is either under very
light load conditions the transfer of charge across
CFLY is greater during each phase of the switching
cycle. The result is higher ripple seen at the
charge pump output. This effect will be reduced by
decreasing the value of CFLY. Caution should be
observed when decreasing the flying capacitor. If
the output load current rises above the nominal
level for the reduced CFLY value, charge pump efficiency can be compromised.
There are several methods that can be employed to
reduce output ripple depending upon the requirements of a given application. The most simple and
straightforward technique is to increase the value of
the COUT capacitor. The nominal 10µF COUT capacitor can be increased to 22µF or more. Larger values for the COUT capacitor (22µF and greater) will
by nature have lower ESR and can improve both
high and low frequency components of the charge
13
AAT3110
MicroPower™ Regulated Charge Pump
Applications Information
and low frequency components of the charge pump
output ripple response. If a higher value tantalum
capacitor is used for COUT to reduce low frequency
ripple elements, a small 1µF low ESR ceramic
capacitor should be added in parallel to the tantalum
capacitor (see Figure 1). The reason for this is tantalum capacitors typically have higher ESR than
equivalent value ceramic capacitors and are less
able to reduce high frequency components of the
output ripple. The only disadvantage to using large
values for the COUT capacitor is the AAT3110 device
turn-on time and in-rush current may be increased.
If additional ripple reduction is desired, an R/C filter
can be added to the charge pump output in addition to the COUT capacitor (see Figure 2). An R/C
filter will reduce output ripple by primarily attenuating high frequency components of the output ripple
waveform. The low frequency break point for the
R/C filter will significantly depend on the capacitor
value selected.
VOUT
(5V)
COUT2
1µF
COUT1
22µF
+
VOUT
High charge pump switching frequencies and large
peak transient currents mandate careful printed circuit board layout. As a general rule for charge
pump boost converters, all external capacitors
should be located as close as possible to the
device package with minimum length trace connections. Maximize the ground plane around the
AAT3110 charge pump and make sure all external
capacitors are connected to the immediate ground
plane. A local component side ground plane is recommended. If this is not possible due the layout
design limitations, assure good ground connections by the use of large or multiple pcb via's.
Refer to the following AAT3110 evaluation board for
an example of good charge pump layout design
(Figures 3 through 5).
C+
AAT3110
GND
ON/OFF
Layout Considerations
SHDN
CFLY
1µF
VIN
+
CIN
10µF
VIN
(2.7V to 5V)
C-
Figure 1: Application using tantalum capacitor
VOUT
(5V)
RFILTER
1.5 ohms
VOUT
CFILTER
33µF
COUT
10µF
C+
AAT3110
GND
CFLY
1µF
VIN
CIN
10µF
ON/OFF
SHDN
VIN
(2.7V to 5V)
C-
Figure 2: Application with output ripple reduction filter
14
3110.2001.9.0.92
AAT3110
MicroPower™ Regulated Charge Pump
Figure 3: Evaluation board
top side silk screen layout /
assembly drawing
Figure 4: Evaluation board
component side layout
Figure 5: Evaluation board
component side layout
Typical Application Circuits
VOUT
(5V)
VOUT
COUT
10µF
C+
CFLY
1µF
AAT3110-5
GND
VIN
CIN
10µF
ON/OFF
SHDN
VIN
(2.7V to 5V)
C-
Figure 6: Typical charge pump boost converter circuit
CFLY
1µF
CVIN
VIN
(USB Port Vout)
C+
VOUT
VOUT
5V
100mA
SHDN
CIN
10µF
AAT3110-5
COUT
10µF
GND
GND
(USB Port Return)
GND
Figure 7: 5 Volt, 100mA supply powered from a USB port
3110.2001.9.0.92
15
AAT3110
MicroPower™ Regulated Charge Pump
VIN
LI-Ion Battery
2.7V to 4.2V
10µF
C+
10µF
AAT3110-5
SHDN
ON/OFF
VOUT
120
120
120
120
1µF
C-
Figure 8: 5 Volt LED or Display Driver from a Li-Ion Battery Source
VIN =
3.0V to 5V
SHDN
CIN
10µF
VOUT = 5V
IOUT = 200mA
VOUT
VIN
C+
AAT3110-5
(A)
SHDN
C-
CFLY
1µF
GND
VOUT
VIN
C+
AAT3110-5
(B)
SHDN
C-
CFLY
1µF
COUT
10µF
GND
Figure 9: 5 Volt, 200mA Step-Up Supply from a 3.0V to 5V Source.
16
3110.2001.9.0.92
AAT3110
MicroPower™ Regulated Charge Pump
Ordering Information
Output Voltage
Package
3.3V
Part Number
Marking
Bulk
Tape and Reel
SOT-23-6
N/A
AAT3110IGU-3.3-T1
5.0V
SOT-23-6
N/A
AAT3110IGU-5-T1
3.3V
SC70JW-8
N/A
AAT3110IJS-3.3-T1
5.0V
SC70JW-8
N/A
AAT3110IJS-5-T1
Package Information
SOT-23-6
t
e1
Dim
e
L2
E
L
f
C
GAUGE PLANE
D
A2
A
A1
A2
b
c
D
E
E1
e
e1
f
L
L1
L2
t
Millimeters
Min
Max
0.95
1.45
0.05
0.15
0.90
1.30
0.35
0.50
0.08
0.20
2.84
3.00
1.50
1.70
2.60
3.00
0.95 BSC
1.90 BSC
0.50 BSC
0.23
0.40
0.10 BSC
0.60 BSC
0º
10º
Inches
Min
Max
0.037
0.057
0.002
0.006
0.035
0.051
0.0137 0.019
0.0031 0.0078
0.1118 0.118
0.059 0.0669
0.102
0.118
0.0374 BSC
0.0748 BSC
0.0197 BSC
0.009
0.016
0.039 BSC
0.0236 BSC
0º
10º
A
b
A1
3110.2001.9.0.92
17
AAT3110
MicroPower™ Regulated Charge Pump
SC70JW-8
e
e
e
Dim
E
b
D
0.048REF
c
A2 A
E
E1
L
A
A1
A2
D
e
b
c
Θ
Θ1
Millimeters
Min
Max
2.10 BSC
1.75
2.00
0.23
0.40
1.10
0
0.10
0.70
1.00
2.00 BSC
0.50 BSC
0.15
0.30
0.10
0.20
0
8º
4º
10º
Inches
Min
Max
0.083 BSC
0.069
0.079
0.009
0.016
0.043
0.004
0.028
0.039
0.079 BSC
0.020 BSC
0.006
0.012
0.004
0.008
0
8º
4º
10º
A1
Θ1
L
E1
Θ
Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone (408) 524-9684
Fax (408) 524-9689
18
3110.2001.9.0.92