Page 1
AAT3110
MicroPower™ Regulated Charge Pump
General Description
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.
The AAT3110 is available in a surface mount 6-pin
SOT23 or 8-pin SC70JW package and is rated
from -40 to 85°C.
ChargePump
Features
• 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 V
• 50mA with V
• 3.3V Output Current
• 150mA with V
• 100mA with V
• 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
Applications
IN
≥ 2.7V
IN
IN
IN
≥ 3.0V
≥ 2.7V
≥ 2.3V
™
Preliminary Information
The AAT3110 ChargePump™ is a member of
AnalogicTech's Total Power Management IC product family.
Typical Operating Circuits
AAT3110
V
OUT
ON/OFF
C
OUT
10uF
V
OUT
GND
SHDN
• Cellular Phones
• Portable Communication Devices
• Handheld Electronics
• Digital Cameras
• PDAs
• Battery Back Up Supplies
• LED/Display Back Light Driver
C+
V
C-
IN
1uF
C
IN
10uF
V
IN
3110.2001.9.0.92 1
3110.2001.9.0.92 1
Page 2
Pin Descriptions
Pin #
SOT-23-6 SC70JW-8
AAT3110
MicroPower™ Regulated Charge Pump
Symbol Function
11V
OUT
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 Shutdown input. Active low signal disables the converter.
4 6 C- Flying capacitor negative terminal
57V
IN
Input supply pin. Bypass this pin to ground with at least
6.8µF low ESR capacitor
6 8 C+ Flying capacitor positive terminal
Pin Configuration
SOT23-6 SC70JW-8
V
OUT
GND
SHDN
1 2
1
2
3
6
C+
5
V
IN
4
C-
V
OUT
GND
GND
GND
1 2
1
2
3
45
8
C+
7
V
6
CSHDN
IN
2 3110.2001.9.0.92
Page 3
AAT3110
MicroPower™ Regulated Charge Pump
Absolute Maximum Ratings (T
=25°C unless otherwise noted)
A
Symbol Description Value Units
V
IN
V
OUT
V
SHDN
t
SC
T
J
T
LEAD
V
ESD
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.
VINto GND -0.3 to 6 V
V
to GND -0.3 to 6 V
OUT
SHDN to GND -0.3 to 6 V
Output to GND Short-Circuit Duration Indefinite s
Operating Junction Temperature Range -40 to 150 °C
Maximum Soldering Temperature (at leads, 10 sec) 300 °C
ESD Rating1— HBM 2000 V
Thermal Information
Symbol Description Rating Units
Θ
JA
P
D
Note 2: Mounted on an FR4 board.
Maximum Thermal Resistance (SOT23-6 or SC70JW-8) 150 °C/W
Maximum Power Dissipation (SOT23-6 or SC70JW-8) 667 mW
Electrical Characteristics (T
C
=1µF, CIN=10µF, C
FLY
OUT
=10µF)
= -40 to 85°C unless otherwise noted. Typical values are at TA=25°C,
A
AAT3110-5
Symbol Description Conditions Min Typ Max Units
V
IN
I
Q
V
OUT
I
SHDN
V
RIPPLE
η Efficiency V
f
OSC
V
IH
V
IL
I
IH
I
IL
t
ON
I
SC
Note 3: Under short-circuit conditions, the device may enter overtemperature protection mode.
Input Voltage V
No Load Supply Current 2.7V < VIN< 5V, I
Output Voltage
Shutdown Supply Current
Ripple Voltage
=5.0V 2.7 V
OUT
=0mA, SHDN=V
2.7V < V
IN
< 5V, I
3.0V < VIN< 5V, I
2.7V < VIN< 3.6V, I
= 3V, I
= 3V, I
< 5V, I
IN
= 50mA 25
OUT
= 100mA 30
OUT
= 50mA 83 %
OUT
3.6V < V
V
IN
VIN= 3V, I
IN
OUT
≤ 50mA 4.8 5 5.2 V
OUT
≤ 100mA 4.8 5 5.2 V
OUT
=0mA, V
OUT
=0mA, V
OUT
IN
=0 0.01 1
SHDN
=0 2.5
SHDN
OUT
13 30 µA
mV
Frequency Oscillator Free Running 750 kHz
SHDN Input Threshold High 1.4 V
SHDN Input Threshold Low 0.3 V
SHDN Input Current High SHDN = V
IN
-1 1 µA
SHDN Input Current Low SHDN = GND -1 1 µA
V
Turn-on time VIN= 3V, I
OUT
Short-circuit current
3
VIN= 3V, V
= 0mA 0.2 ms
OUT
= GND, SHDN = 3V 300 mA
OUT
V
µA
P-P
3110.2001.9.0.92 3
Page 4
AAT3110
MicroPower™ Regulated Charge Pump
Electrical Characteristics (T
C
=1µF, CIN=10µF, C
FLY
OUT
=10µF)
= -40 to 85°C unless otherwise noted. Typical values are at TA=25°C,
A
AAT3110-3.3
Symbol Description Conditions Min Typ Max Units
V
IN
I
Q
V
OUT
I
SHDN
V
RIPPLE
η Efficiency V
f
OSC
V
IH
V
I
IH
I
IL
t
ON
I
SC
Input Voltage V
No Load Supply Current 2.3V < VIN< 3.3V, I
Output Voltage
Shutdown Supply Current 2.3V < VIN< 3.3V, I
Ripple Voltage VIN= 2.3V, I
=3.3V 2.3 V
OUT
=0mA 10 30 µA
OUT
2.3V < V
2.5V < VIN< 3.3V, I
IN
IN
= 2.3V, I
< 3.3V, I
OUT
OUT
=50mA 3.17 3.30 3.43 V
OUT
=100mA 3.17 3.30 3.43 V
OUT
OUT
=0mA, V
=0 0.01 1 µA
SHDN
= 50mA 20 mV
= 25mA 71 %
Frequency Oscillator Free Running 750 kHz
SHDN Input Threshold High 1.4 V
SHDN Input Threshold Low 0.3 V
IL
SHDN Input Current High SHDN = V
IN
-1 1 µA
SHDN Input Current Low SHDN = GND -1 1 µA
V
Turn-on time VIN= 3V, I
OUT
Short-circuit current VIN= 3V, V
= 0mA 0.2 ms
OUT
= GND, SHDN = 3V 300 mA
OUT
OUT
V
P-P
4 3110.2001.9.0.92
Page 5
Typical Characteristics—AAT3110-5
(Unless otherwise noted, VIN= 3V, CIN=C
=10µF, C
OUT
AAT3110
MicroPower™ Regulated Charge Pump
=1µF, TA= 25ºC)
FLY
Output Voltage vs. Output Current
AAT3110-5
5.15
5.1
5.05
5
4.95
4.9
4.85
Output Voltage (V)
4.8
VIN=2.7
0 50 100 150
VIN=3.0
V
=3.6
IN
=3.3
V
IN
Output Current (mA)
Supply Current vs V
SHDN
AAT3110-5
30
I
25
20
15
10
5
Supply Current (µA)
0
012345
VIN=5.5V
VIN=3.3V
VIN=2.8V
V
Control Voltage (V)
SHDN
OUT
=0µA
Supply Current vs. Supply Voltage
AAT3110-5
24
I
=0 A
OUT
C
=1µF
FLY
V
SHDN=VIN
2.5 3 3.5 4 4.5 5 5.5
Supply Current (µA)
22
20
18
16
14
12
10
Supply Voltage (V)
Efficiency vs. Supply Voltage
AAT3110-5
95%
25 mA
90%
85%
80%
75%
50 mA
70%
65%
60%
Efficiency (%)
55%
50%
45%
2.70 3.00 3.50 4.00 4.50 5.00
100 mA
Supply Voltage (V)
Efficiency vs. Load Current
AAT3110-5
100%
90%
80%
70%
60%
50%
40%
30%
Efficiency (%)
20%
10%
0%
0.01 0.1 1 10 100 1000
VIN = 3.6V
VIN = 3.3V
Load Current (mA)
V
IN
VIN = 2.7V
= 3.0V
Oscillator Frequency vs. Supply Voltage
AAT3110-5
1200
1100
1000
- 40º C
900
800
700
25º C
600
500
85º C
Oscillator Frequency (kHz)
400
2.7 3.0 3.5 4.0 4.5 5.0
Supply Voltage (V)
3110.2001.9.0.92 5
Page 6
Typical Characteristics—AAT3110-5
(Unless otherwise noted, VIN= 3V, CIN=C
=10µF, C
OUT
AAT3110
MicroPower™ Regulated Charge Pump
=1µF, TA= 25ºC)
FLY
SHDN
2V/DIV
V
OUT
1V/DIV
0mA to
50mA
20mA/DIV
Startup Time with 50 mA Load
AAT3110-5
50µS/DIV
Load Transient Response for 50mA
AAT3110-5
I
OUT
VIN=3.0V
SHDN
2V/DIV
OUT
V
1V/DIV
I
OUT
0mA to
100 mA
50mA/DIV
Startup Time with 100 mA Load
AAT3110-5
50µS/DIV
Load Transient Response for 100mA
AAT3110-5
VIN=3.0V
V
OUT
AC
COUPLED
20mV/DIV
V
OUT
AC
Coupled
10 mV/DIV
50µS/DIV
Output Ripple with I
AAT3110-5
VIN=3.0V
2µS/DIV
=50 mA
OUT
V
OUT
AC
OUPLED
20mV/DIV
V
OUT
AC
Coupled
10 mV/DIV
50µS/DIV
Output Ripple with I
AAT3110-5
VIN=3.0V
2µS/DIV
=100 mA
OUT
6 3110.2001.9.0.92
Page 7
Typical Characteristics—AAT3110-5
(Unless otherwise noted, VIN= 3V, CIN=C
=10µF, C
OUT
AAT3110
MicroPower™ Regulated Charge Pump
=1µF, TA= 25ºC)
FLY
VIN vs. V
1.00
-40°C
25°C
85°C
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
(V)
IH
V
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
IH
VIN (V)
V
Threshold vs. Supply Voltage
SHDN
AAT3110-5
1.00
0.95
0.90
Threshold (V)
SHDN
V
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
V
IH
V
IL
2.0 2.5 3 .0 3.5 4.0 4 .5 5.0 5.5
VIN (V )
VIN vs. V
1.00
0.95
0.90
-40°C
25°C
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
(V)
IL
V
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
IL
85°C
VIN (V)
Normalized Output Voltage vs Temperature
1.20%
1.00%
0.80%
0.60%
0.40%
0.20%
0.00%
-0.20%
-0.40%
-0.60%
Normalized Output Voltage (%)
-50 -25 0 25 50 75 100 125
Temperature (C)
I
OUT
=25mA
3110.2001.9.0.92 7
Page 8
Typical Characteristics—AAT3110-3.3
5
t
(Unless otherwise noted, VIN= 2.3V, CIN=C
=10µF, C
OUT
AAT3110
MicroPower™ Regulated Charge Pump
=1µF, TA= 25ºC)
FLY
Output Voltage vs. Output Curren
AAT3110-3.3
3.4
3.35
3.3
3.25
3.2
3.15
Output Voltage (V)
3.1
0 50 100 150 200
VIN=2.3V
V
VIN=2.7V
Output Current (mA)
Supply Current vs V
SHDN
AAT3110-3.3
30
25
20
15
10
5
Supply Current (µA)
0
0 1 2 3 3.3
V
Control Voltage (V)
SHDN
VIN=3.3V
VIN=2.8V
I
IN
OUT
=3V
=0µA
Supply Current vs. Supply Voltage
AAT3110-3.3
24
I
=0 A
OUT
C
=1µF
FLY
V
SHDN=VIN
2.3 2.5 2.7 2.9 3.1 3.3
Supply Current (µA)
22
20
18
16
14
12
10
Supply Voltage (V)
Efficiency vs. Supply Voltage
AAT3110-3.3
80
70
60
50
40
30
20
I
Efficiency (%)
10
0
=100mA
OUT
22.533.
Supply Voltage (V)
Efficiency vs. Output Current
AAT3110-3.3
100.0%
90.0%
80.0%
70.0%
VIN=2.25V
60.0%
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%
0.01 0.1 1 10 100
I-Load (mA)
Oscillator Frequency vs. Supply Voltage
AAT3110-3.3
1200
1100
1000
- 40°C
900
800
25°C
700
85°C
600
500
Oscillator Frequency (kHz)
400
2.3 2.5 2.7 2.9 3.1 3.3
Supply Voltage (V)
8 3110.2001.9.0.928 3110.2001.9.0.92
Page 9
Typical Characteristics—AAT3110-3.3
(Unless otherwise noted, VIN= 2.3V, CIN=C
=10µF, C
OUT
AAT3110
MicroPower™ Regulated Charge Pump
=1µF, TA= 25ºC)
FLY
SHDN
2V/DIV
V
OUT
1V/DIV
I
OUT
0mA to
50mA
20mA/DIV
V
OUT
AC
COUPLED
20mV/DIV
Startup Time with 50 mA Load
AAT3110-3.3
100µS/DIV
Load Transient Response for 50mA
AAT3110-3.3
VIN=2.3V
C
=10µF
OUT
SHDN
2V/DIV
V
OUT
1V/DIV
I
OUT
0mA to
100mA
50mA/DIV
V
OUT
AC
COUPLED
20mV/DIV
Startup Time with 100 mA Load
AAT3110-3.3
100µS/DIV
Load Transient Response for 100mA
AAT3110-3.3
VIN=2.3V
C
=10µF
OUT
20µS/DIV
Output Ripple for 50mA Load
Output Ripple for 100mA Load
AAT3110-3.3
OUT
V
OUT
AC
Coupled
10mV/DIV
VIN=2.3V
2µs/DIV
3110.2001.9.0.92 9
V
AC
Coupled
10mV/DIV
VIN=2.3V
50µS/DIV
AAT3110-3.3
2µs/Div.
Page 10
Typical Characteristics—AAT3110-3.3
V
Th
h
ld
(V)
(Unless otherwise noted, VIN= 2.3V, CIN=C
=10µF, C
OUT
AAT3110
MicroPower™ Regulated Charge Pump
=1µF, TA= 25ºC)
FLY
VIN vs. V
IH
AAT3110-3.3
1.00
(V)
IH
V
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
-40°C
25°C
85°C
2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.3
VIN (V)
V
Threshold vs. Supply Voltage
SHDN
AAT3110-3.3
1.00
0.95
0.90
0.85
o
0.80
V
res
SHDN
0.75
0.70
0.65
0.60
0.55
0.50
IH
V
IL
2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.3
VIN (V)
VIN vs. V
IL
AAT3110-3.3
1.00
0.95
0.90
0.85
-40°C
0.80
0.75
(V)
IL
0.70
V
0.65
0.60
0.55
0.50
2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.3
25°C
85°C
VIN (V)
10 3110.2001.9.0.92
Page 11
Functional Block Diagram
V
IN
SHDN
AAT3110
MicroPower™ Regulated Charge Pump
S2
S1
CONTROL
-
+
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 C
mately 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 C
first phase. During the second phase, the flying
capacitor C
FLY
connected to V
flying capacitor C
connected to output through a switch. For each
cycle phase, charge from input node VINis 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 tem-
is charged to a level approxi-
FLY
is connected to GND during the
FLY
is switched so that the low side is
. The voltage at the high side of the
IN
is bootstrapped to 2×V
FLY
IN
and
C+
C-
V
REF
S4
GND
S3
V
OUT
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, V
OUT
, C
OUT
and I
OUT
.
For each phase of the switching cycle, the charge
transported from VINto V
can be approximated
OUT
by the following formula:
V
PHASE
FLY
×(2×V
IN-VOUT
)
≈ C
The relative average current that the charge pump
can supply to the output may be approximated by
the following expression:
I
OUT(AVG)
α C
FLY
×(2×V
IN-VOUT
)×F
SW
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.
3110.2001.9.0.92 11
Page 12
AAT3110
MicroPower™ Regulated Charge Pump
Applications Information
External Capacitor Selection
Careful selection of the three external capacitors
CIN, C
will affect turn on time, output ripple and transient
performance. Optimum performance will be
obtained when low ESR (<100mΩ) ceramic capaci-
tors are used for CINand C
al, 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.
Typically as a starting point, a capacitor value of
10µF should be used for C
C
FLY
output load conditions. Lower values for CIN, C
and C
cations. Applications drawing a load current of
10mA or less may use a CINand C
value as low as 1µF and a C
and C
10µF or more for heavy output load conditions.
C
FLY
C
FLY
by the same ratio to minimize output ripple. As a
basic rule, the ratio between CIN, C
should not exceed a ratio of 10 to 1. The compromise for lowering the value of CIN, C
ing capacitor C
be increased. In any case, if the external capacitor
values deviate greatly from the recommendation of
CIN= C
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 C
capacitor. However, if CINis 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
OUT
and C
is very important because they
FLY
OUT
IN
and C
and C
. In gener-
FLY
with 1µF
OUT
when the AAT3110 is used under maximum
may be utilized for light load current appli-
FLY
OUT
value of 0.1µF. C
may range from 1µF for light loads to
OUT
FLY
OUT
capacitor
may range from 0.01µF to 2.2µF or more. If
is increased, C
FLY
= 10µF and C
OUT
should also be increased
OUT
and C
OUT
and the fly-
OUT
FLY
is the output ripple voltage may
= 1µF, the AAT3110
FLY
IN
IN
is high, or if the value of C
is too low. This situa-
IN
tion can be remedied by increasing the value of CIN.
Capacitor Characteristics
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.
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.
12 3110.2001.9.0.92
Page 13
AAT3110
MicroPower™ Regulated Charge Pump
Applications Information
Charge Pump Efficiency
The AAT3110 is a regulated output voltage dou-
bling 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 = P
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=P
OUT/PIN
η(%) = 100(V
=(V
OUT
OUT×IOUT
/ 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 V
approaches V
. Refer to the Typical Char-
OUT
acteristics 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
OUT
)/(V
IN
/ P
×2I
IN
OUT
)=V
OUT
/2V
IN
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 C
I
and the level of VIN. Ripple observed at V
OUT
typically a sawtooth waveform in shape. The ripple
frequency will vary depending on the load current
I
and the level of VIN. As VINincreases the abili-
OUT
ty 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. C
and C
have an effect on output ripple. Since
FLY
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 50mV
5.0V, C
IN
When the AAT3110 is used in light output load
= 10µF and C
OUT
applications where I
tor C
value can be reduced. The reason for this
FLY
effect is when the charge pump is either under very
light load conditions the transfer of charge across
C
is greater during each phase of the switching
FLY
cycle. The result is higher ripple seen at the
charge pump output. This effect will be reduced by
decreasing the value of C
observed when decreasing the flying capacitor. If
the output load current rises above the nominal
level for the reduced C
ciency 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 C
capacitor. The nominal 10µF C
OUT
itor can be increased to 22µF or more. Larger values for the C
OUT
by nature have lower ESR and can improve both
high and low frequency components of the charge
and C
OUT
when VIN= 3.0V, V
P-P
FLY
< 10mA, the flying capaci-
OUT
FLY
, the load current
FLY
OUT
OUT
OUT
= 1µF.
. Caution should be
FLY
value, charge pump effi-
capac-
OUT
capacitor (22µF and greater) will
is
=
3110.2001.9.0.92 13
Page 14
Applications Information
AAT3110
MicroPower™ Regulated Charge Pump
and low frequency components of the charge pump
output ripple response. If a higher value tantalum
capacitor is used for C
to reduce low frequency
OUT
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 C
capacitor is the AAT3110 device
OUT
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 C
capacitor (see Figure 2). An R/C
OUT
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.
V
OUT
(5V)
C
1µF
OUT2
C
OUT1
22µF
ON/OFF
+
OUT
AAT3110
GND
SHDN
Layout Considerations
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+V
VIN
C-
C
FLY
1µF
+
10µF
C
IN
V
IN
(2.7V to 5V)
Figure 1: Application using tantalum capacitor
R
FILTER
V
OUT
(5V)
C
FILTER
33µF
1.5 ohms
C
OUT
10µF
ON/OFF
OUT
AAT3110
GND
SHDN
C+V
VIN
C-
C
FLY
1µF
C
IN
10µF
V
IN
(2.7V to 5V)
Figure 2: Application with output ripple reduction filter
14 3110.2001.9.0.92
Page 15
AAT3110
MicroPower™ Regulated Charge Pump
Figure 3: Evaluation board Figure 4: Evaluation board Figure 5: Evaluation board
top side silk screen layout / component side layout component side layout
assembly drawing
Typical Application Circuits
V
OUT
(5V)
ON/OFF
C
OUT
10µF
OUT
AAT3110-5
GND
SHDN
C+V
V
C-
IN
Figure 6: Typical charge pump boost converter circuit
V
(USB Port Vout)
IN
C
IN
10µF
V
IN
SHDN
AAT3110-5
GND
(USB Port Return)
C
FLY
1µF
GND
C+C-
V
C
1µF
OUT
FLY
CIN
10µF
V
IN
(2.7V to 5V)
V
OUT
5V
100mA
C
OUT
10µF
GND
Figure 7: 5 Volt, 100mA supply powered from a USB port
3110.2001.9.0.92 15
Page 16
AAT3110
MicroPower™ Regulated Charge Pump
LI-Ion Battery
2.7V to 4.2V
ON/OFF
10µF
V
IN
AAT3110-5
SHDN
V
OUT
C+
C-
10µF 120 120 120 120
1µF
Figure 8: 5 Volt LED or Display Driver from a Li-Ion Battery Source
VIN =
3.0V to 5V
SHDN
C
IN
10µF
V
IN
AAT3110-5
SHDN
(A)
GND
V
OUT
C+
C
FLY
C-
1µF
V
OUT
= 200mA
I
OUT
= 5V
V
IN
V
OUT
C+
AAT3110-5
SHDN
(B)
C-
GND
C
1µF
Figure 9: 5 Volt, 200mA Step-Up Supply from a 3.0V to 5V Source.
FLY
C
OUT
10µF
16 3110.2001.9.0.92
Page 17
Ordering Information
AAT3110
MicroPower™ Regulated Charge Pump
Output Voltage Package Marking
3.3V 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
e1
e
L2
E
f
D
A2 A
t
L
C
GAUGE PLANE
Part Number
Bulk Tape and Reel
Dim
Millimeters Inches
Min Max Min Max
A 0.95 1.45 0.037 0.057
A1 0.05 0.15 0.002 0.006
A2 0.90 1.30 0.035 0.051
b 0.35 0.50 0.0137 0.019
c 0.08 0.20 0.0031 0.0078
D 2.84 3.00 0.1118 0.118
E 1.50 1.70 0.059 0.0669
E1 2.60 3.00 0.102 0.118
e 0.95 BSC 0.0374 BSC
e1 1.90 BSC 0.0748 BSC
f 0.50 BSC 0.0197 BSC
L 0.23 0.40 0.009 0.016
L1 0.10 BSC 0.039 BSC
L2 0.60 BSC 0.0236 BSC
t 0º 10º 0º 10º
A1
3110.2001.9.0.92 17
b
Page 18
SC70JW-8
AAT3110
MicroPower™ Regulated Charge Pump
eee
Dim
Millimeters Inches
Min Max Min Max
E 2.10 BSC 0.083 BSC
E1 1.75 2.00 0.069 0.079
E
L 0.23 0.40 0.009 0.016
A 1.10 0.043
A1 0 0.10 0.004
A2 0.70 1.00 0.028 0.039
D 2.00 BSC 0.079 BSC
b
D
c
A2
A
Θ1
L
E1
0.048REF
Θ
A1
e 0.50 BSC 0.020 BSC
b 0.15 0.30 0.006 0.012
c 0.10 0.20 0.004 0.008
Θ 08º08º
Θ1 4º 10º 4º 10º
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
Loading...