AAT AAT3110IGU-5.0-T1 Micropowerâ ¢ regulated charge pump Datasheet

AAT3110
MicroPower™ Regulated Charge Pump
General Description
Features
The AAT3110 ChargePump is a member of
AnalogicTech's Total Power Management IC™
(TPMIC™) product family. It 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 100mA 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 is available in a Pb-free, surfacemount 6-pin SOT23 or 8-pin SC70JW package and
is rated over the -40°C to +85°C temperature range.
ChargePump
SmartSwitch™
Step-Up Voltage Converter
Input Voltage Range:
— AAT3110-5: 2.7V to 5V
— AAT3110-4.5: 2.7V to 4.5V
MicroPower Consumption: 13µA
Regulated 5V, 4.5V ±4% Output
5V Output Current:
— 100mA with VIN ≥ 3.0V
— 50mA with VIN ≥ 2.7V
4.5V Output Current:
— 100mA with VIN ≥ 3.0V
— 50mA with VIN ≥ 2.7V
Peak Current 250mA for 100ms
High Frequency 750kHz Operation
Shutdown Mode Draws Less Than 1µA
Short-Circuit/Over-Temperature Protection
2kV ESD Rating
SC70JW-8 or SOT23-6 Package
Applications
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Cellular Phones
Digital Cameras
Handheld Electronics
LED/Display Backlight Driver
LEDs for Camera Flash
PDAs
Portable Communication Devices
Typical Application
AAT3110
VOUT
VOUT
C+
1µF
COUT
10µF
ON/OFF
GND
SHDN
VIN
VIN
C-
CIN
10µF
3110.2005.11.1.4
1
AAT3110
MicroPower™ Regulated Charge Pump
Pin Descriptions
Pin #
SOT23-6
SC70JW-8
Symbol
Function
1
1
VOUT
Regulated output pin. Bypass this pin to ground with a
6.8µF (min) low equivalent series resistance (ESR) capacitor.
2
2, 3, 4
GND
Ground connection.
3
5
SHDN
4
6
C-
5
7
VIN
Input supply pin. Bypass this pin to ground with a 6.8µF
(min) low-ESR capacitor.
6
8
C+
Flying capacitor positive terminal.
Shutdown input. Logic low signal disables the converter.
Flying capacitor negative terminal.
Pin Configuration
SOT23-6
VOUT
GND
SHDN
2
1
2
3
SC70JW-8
6
5
4
C+
VIN
C-
VOUT
GND
GND
GND
1
8
2
7
3
6
4
5
C+
VIN
CSHDN
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
Absolute Maximum Ratings1
TA = 25°C, unless otherwise noted.
Symbol
VIN
VOUT
VSHDN
tSC
TJ
TLEAD
VESD
Description
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 Rating2 — 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
Rating
Units
150
667
°C/W
mW
Thermal Information3
Symbol
ΘJA
PD
Description
Maximum Thermal Resistance
Maximum Power Dissipation
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. Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
3. Mounted on an FR4 board.
3110.2005.11.1.4
3
AAT3110
MicroPower™ Regulated Charge Pump
Electrical Characteristics
TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C, CFLY = 1µF, CIN = 10µF, COUT = 10µF.
Symbol
Description
AAT3110-5
VIN
Input Voltage
IQ
No Load Supply Current1
VOUT
Output Voltage
ISHDN
Shutdown Supply Current
VRIPPLE
Ripple Voltage
η
Efficiency
fOSC
Frequency
VIH
SHDN Input Threshold High
VIL
SHDN Input Threshold Low
IIH
SHDN Input Current High
IIL
SHDN Input Current Low
tON
VOUT Turn-On Time
ISC
Short-Circuit Current2
AAT3110-4.5
VIN
Input Voltage
IQ
No Load Supply Current3
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 Current2
Conditions
Min
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 = 2.7V, IOUT = 50mA
VIN = 3V, IOUT = 100mA
VIN = 2.7V, IOUT = 50mA
Oscillator Free Running
2.7
4.8
4.8
Typ
Max
Units
13
5.0
5.0
0.01
VOUT
30
5.2
5.2
1
2.5
V
µA
25
30
92
750
-1
-1
VOUT = 4.5V
2.7V < VIN < 4.5V, IOUT = 0mA, SHDN = VIN
2.7V < VIN < 4.5V, IOUT ≤ 50mA
3.0V < VIN < 4.5V, IOUT ≤ 100mA
2.7V < VIN < 3.6V, IOUT = 0mA, VSHDN = 0
3.6V < VIN < 4.5V, IOUT = 0mA, VSHDN = 0
VIN = 2.7V, IOUT = 50mA
VIN = 3V, IOUT = 100mA
VIN = 2.7V, IOUT = 50mA
Oscillator Free Running
2.7
0.3
1
1
0.2
300
4.32
4.32
13
4.5
4.5
0.01
VOUT
30
4.68
4.68
1
2.5
25
30
83
750
0.3
1
1
-1
-1
0.2
300
%
kHz
V
V
µA
µA
ms
mA
V
µA
V
µA
mVP-P
1.4
SHDN = VIN
SHDN = GND
VIN = 3V, IOUT = 0mA
VIN = 3V, VOUT = GND, SHDN = 3V
µA
mVP-P
1.4
SHDN = VIN
SHDN = GND
VIN = 3V, IOUT = 0mA
VIN = 3V, VOUT = GND, SHDN = 3V
V
%
kHz
V
V
µA
µA
ms
mA
1. VOUT is pulled up to 5.5V to prevent switching.
2. Under short-circuit conditions, the device may enter over-temperature protection mode.
3. VOUT is pulled up to 5.0V to prevent switching.
4
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics — AAT3110-5V
Unless otherwise noted, VIN = 3V, CIN = COUT = 10µF, CFLY = 1µF, TA = 25°C.
Output Voltage vs. Output Current
Supply Current vs. Supply Voltage
22
5.1
Supply Current (µA)
Output Voltage (V)
5.15
VIN = 3.6V
5.05
5
VIN = 3.0V
4.95
VIN = 2.7V
VIN = 3.3V
4.9
4.85
50
100
18
16
14
12
10
8
2.5
4.8
0
IOUT = 0µA
CFLY = 1µF
VSHDN = VIN
20
150
3
Supply Current vs. VSHDN
95
IOUT = 0µA
5
5.5
20
VIN = 5.5V
15
VIN = 3.3V
25mA
90
25
Efficiency (%)
Supply Current (µA)
4.5
Efficiency vs. Supply Voltage
30
VIN = 2.8V
4
Supply Voltage (V)
Output Current (mA)
10
3.5
85
80
75
50mA
70
65
100mA
60
55
50
5
45
2.70
0
0
1
2
3
4
3.00
5
3.50
4.00
4.50
5.00
Supply Voltage (V)
VSHDN Control Voltage (V)
Efficiency vs. Load Current
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)
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100
1000
Oscillator Frequency (kHz)
Oscillator Frequency vs. Supply Voltage
1200
1100
1000
- 40°C
900
800
700
25°C
600
500
400
2.7
85°C
3.0
3.5
4.0
4.5
5.0
Supply Voltage (V)
5
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics — AAT3110-5V
Unless otherwise noted, VIN = 3V, CIN = COUT = 10µF, CFLY = 1µF, TA = 25°C.
Startup Time with 100mA Load
Startup Time with 50mA Load
SHDN
(2V/div)
SHDN
(2V/div)
VOUT
(1V/div)
VOUT
(1V/div)
Time (50µs/div)
Time (50µs/div)
Load Transient Response for 50mA
IOUT
0mA to
50mA
(20mA/div)
Load Transient Response for 100mA
IOUT
0mA to
100 mA
(50mA/div)
VIN = 3.0V
VIN = 3.0V
VOUT
AC
Coupled
(20mV/div)
VOUT
AC
Coupled
(20mV/div)
Time (50µs/div)
Time (50µs/div)
Output Ripple with IOUT = 50mA
VOUT
AC
Coupled
(10 mV/div)
VOUT
AC
Coupled
(10 mV/div)
VIN = 3.0V
VIN = 3.0V
Time (2µs/div)
6
Output Ripple with IOUT = 100mA
Time (2µs/div)
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics — AAT3110-5V
Unless otherwise noted, VIN = 3V, CIN = COUT = 10µF, CFLY = 1µF, TA = 25°C.
Output Voltage vs. Input Voltage
(IOUT = 250mA)
Output Voltage (V)
5.2
-20°C
4.8
20°C
4.4
55°C
one shot
pulse
t = 100ms
4
3.6
3.2
3.2
3.4
3.6
3.8
4
4.2
Input Voltage (V)
3110.2005.11.1.4
7
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics — AAT3110-4.5V
Unless otherwise noted, VIN = 3V, CIN = COUT = 10µF, CFLY = 1µF, TA = 25°C.
Output Voltage vs. Output Current
Supply Current vs. Supply Voltage
4.54
18
Supply Current (µA)
Output Voltage (V)
3.6V
4.53
4.52
2.7V
3.0V
4.51
3.3V
4.5
4.49
0.1
1
10
100
17
16
No Load, Switching
15
14
13
12
No Load, No Switching
11
10
1000
2.5
Output Current (mA)
3
3.5
4
4.5
Supply Voltage (V)
Supply Current vs. VSHDN
Efficiency vs. Supply Voltage
30
85
80
25
Efficiency (%)
Supply Current (µA)
IOUT = 0µA
20
VIN = 5.5V
15
10
VIN = 2.8V
VIN = 3.3V
75
100mA
70
50mA
65
60
5mA
55
5
50
2.7
0
0
1
2
3
4
2.9
3.1
5
3.3
3.5
3.7
3.9
4.1
4.3
4.5
Supply Voltage (V)
VSHDN Control Voltage (V)
Oscillator Frequency vs. Supply Voltage
Oscillator Frequency (kHz)
Efficiency vs. Load Current
85
VIN = 2.7V
Efficiency (%)
80
75
VIN = 3.0V
70
VIN = 3.3V
65
60
0.1
1
10
Load Current (mA)
8
100
1000
1200
1100
1000
- 40°C
900
800
700
25°C
600
500
400
2.7
85°C
3.0
3.5
4.0
4.5
5.0
Supply Voltage (V)
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics — AAT3110-4.5V
Unless otherwise noted, VIN = 3V, CIN = COUT = 10µF, CFLY = 1µF, TA = 25°C.
Load Transient Response
Load Transient Response
(VIN = 2.7V)
(VIN = 3.0V)
IOUT
(100mA/div)
IOUT
(100mA/div)
VOUT
(20mV/div)
VOUT
(20mV/div)
Time (50µs/div)
Time (50µs/div)
Output Ripple
Output Ripple
(IOUT = 50mA @ VIN = 2.7V)
(IOUT = 100mA @ VIN = 3.0V)
VOUT
AC Coupled
(5mV/div)
VOUT
AC Coupled
(5mV/div)
Time (5µs/div)
Time (5µs/div)
Output Voltage vs. Input Voltage
for Pulsed High Current
Maximum Current Pulse (mA)
Maximum Current Pulse vs. Input Voltage
Output Voltage (V)
4.6
4.5
4.4
4.3
One-shot pulse duration = 50ms
IOUT = 250mA
4.2
4.1
4
3
3.2
3.4
3.6
3.8
Input Voltage (V)
3110.2005.11.1.4
4
4.2
600
500
400
300
200
One-shot pulse duration = 50ms
VOUT > 4.0V
100
0
3
3.2
3.4
3.6
3.8
4
4.2
Input Voltage (V)
9
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics — AAT3110-4.5V
Unless otherwise noted, VIN = 3V, CIN = COUT = 10µF, CFLY = 1µF, TA = 25°C.
Startup
SHDN
(1V/div)
ILOAD = 150mA @ VIN = 3.3V
ILOAD = 100mA @ VIN = 3.0V
VOUT
(2V/div)
ILOAD = 50mA @ VIN = 2.7V
Time (100µs/div)
10
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
Typical Characteristics — AAT3110
SHDN Input Threshold (high)
vs. Input Voltage
SHDN Input Threshold (low)
vs. Input Voltage
1.00
0.95
0.90
-40°C
0.85
25°C
0.80
0.75
0.70
85°C
0.65
0.60
0.55
0.50
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.00
SHDN Input Threshold (low) (V)
SHDN Input Threshold (high) (V)
Unless otherwise noted, VIN = 3V, CIN = COUT = 10µF, CFLY = 1µF, TA = 25°C.
0.95
0.90
-40°C
0.85
0.80
25°C
0.75
0.70
0.65
85°C
0.60
0.55
0.50
2.0
Input Voltage (V)
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Input Voltage (V)
VSHDN Threshold vs. Input Voltage
Normalized Output Voltage (%)
Normalized Output Voltage vs. Temperature
1.00
VSHDN Threshold (V)
0.95
0.90
VIH
0.85
0.80
0.75
0.70
VIL
0.65
0.60
0.55
0.50
2.0
2.5
3.0
3.5
4.0
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)
Input Voltage (V)
3110.2005.11.1.4
11
AAT3110
MicroPower™ Regulated Charge Pump
Functional Block Diagram
VIN
S1
S2
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. During the second
phase, switches S1 and S4 are turned off (open) and
switches 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 is 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
12
cycle stops and the charge pump circuit is temporarily placed in an idle state. When idle, the
AAT3110 has a quiescent current of 13µA or less.
The closed loop feedback 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.
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
Applications Information
External Capacitor Selection
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 ceramic capacitors are
used. In general, low ESR may be defined as less
than 100mΩ. 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 to their inherent high ESR characteristic.
Typically as a starting point, a capacitor value of
10µF should be used for CIN and COUT with 1µF for
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 be approximately 10 to 1. The compromise
for lowering the value of CIN, COUT, and the flying
capacitor CFLY is that 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 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
is high or if the value of CIN is too low. This situation
can be remedied by increasing the value of CIN.
3110.2005.11.1.4
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 is a very
important characteristic to consider when selecting
a capacitor. ESR is a resistance internal to a
capacitor that 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 than 0.1µF are typically made from NPO or
C0G materials. NPO and C0G 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.
Charge Pump Efficiency
The AAT3110 is a regulated output voltage doubling charge pump. The efficiency (η) can simply
13
AAT3110
MicroPower™ Regulated Charge Pump
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 VOUT × IOUT
V
=
= OUT
PIN
VIN × 2IOUT
2VIN
-or-
η(%) = 100
⎛ VOUT ⎞
⎝ 2VIN ⎠
For a charge pump with an output of 5.0V and a
nominal input of 3.0V, 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 the level of
VIN approaches VOUT. Refer to the Typical Characteristics section of this datasheet 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
14
charge pump switching cycle operation. The thermal limit system has 10°C of system hysteresis
before the charge pump can reset. Once the overcurrent event is removed from the output and the
junction temperature drops below 135°C, the
charge pump will become active again. The thermal protection system will cycle on and off if an output short-circuit condition persists. This will allow
the AAT3110 to operate indefinitely under short-circuit conditions without damaging 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 CIN, 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 30mVP-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 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
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
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 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 inrush 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
VOUT
(5V)
COUT2
1 µF
COUT1
22µF
+
VOUT
waveform. The low frequency break point for the
R/C filter will significantly depend on the capacitor
value selected.
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 closely 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 to layout
design limitations, assure good ground connections by the use of large or multiple PCB vias.
Refer to the AAT3110 evaluation board for an example of good charge pump layout design (Figures 3
through 5).
C+
AAT3110-5
GND
CFLY
1µF
VIN
(2.7V to 5V)
VIN
+
ON/OFF
SHDN
C-
CIN
10µF
Figure 1: Application Using Tantalum Capacitor.
VOUT
(5V)
RFILTER
1.5Ω
VOUT
CFILTER
33µF
COUT
10µF
ON/OFF
C+
AAT3110-5
GND
SHDN
CFLY
1 µF
VIN
(2.7V to 5V)
VIN
C-
CIN
10µF
Figure 2: Application With Output Ripple Reduction Filter.
3110.2005.11.1.4
15
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
Solder Side Layout.
Typical Application Circuits
VOUT
(5V)
VOUT
COUT
10µF
C+
CFLY
1µF
AAT3110-5
GND
ON/OFF
SHDN
VIN
(2.7V to 5V)
VIN
CIN
10µF
C-
Figure 6: Typical Charge Pump Boost Converter Circuit.
CFLY
1µF
C-
VIN
(USB Port VOUT)
C+
VOUT
5V
100mA
VOUT
VIN
SHDN
CIN
10µF
AAT3110-5
COUT
10µF
GND
GND
(USB Port Return)
GND
Figure 7: 5V, 100mA Supply Powered From a USB Port.
16
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
VIN
VOUT
C+
Li-Ion Battery
2.7V to 4.2V
10µF
SHDN
ON/OFF
10µF
AAT3110-5
120
120
120
120
1µF
C-
Figure 8: 5V LED or Display Driver from a Li-Ion Battery Source.
VIN =
3.0V to 5V
VIN
CIN
10µF
SHDN
VOUT = 5V
IOUT = 200mA
VOUT
C+
AAT3110-5
(A)
SHDN
C-
CFLY
1µF
GND
VIN
VOUT
C+
AAT3110-5
(B)
SHDN
C-
CFLY
1µF
COUT
10µF
GND
Figure 9: 5V, 200mA Step-Up Supply from a 3V to 5V Source.
3110.2005.11.1.4
17
AAT3110
MicroPower™ Regulated Charge Pump
Ordering Information
Output Voltage
Package
Marking1
Part Number (Tape and Reel)2
4.5V
SOT23-6
EEXYY
AAT3110IGU-4.5-T1
5.0V
SOT23-6
ASXYY
AAT3110IGU-5.0-T1
4.5V
SC70JW-8
EEXYY
AAT3110IJS-4.5-T1
5.0V
SC70JW-8
ASXYY
AAT3110IJS-5.0-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
Package Information
SOT23-6
2.85 ± 0.15
1.90 BSC
2.80 ± 0.20
1.20 ± 0.25
0.15 ± 0.07
4° ± 4°
1.10 ± 0.20
0.075 ± 0.075
1.575 ± 0.125
0.95 BSC
10° ± 5°
0.40 ± 0.10 × 6
0.60 REF
0.45 ± 0.15
GAUGE PLANE
0.10 BSC
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on all part numbers listed in BOLD.
18
3110.2005.11.1.4
AAT3110
MicroPower™ Regulated Charge Pump
SC70JW-8
2.20 ± 0.20
1.75 ± 0.10
0.50 BSC 0.50 BSC 0.50 BSC
0.225 ± 0.075
2.00 ± 0.20
0.100
7° ± 3°
0.45 ± 0.10
4° ± 4°
0.05 ± 0.05
0.15 ± 0.05
1.10 MAX
0.85 ± 0.15
0.048REF
2.10 ± 0.30
All dimensions in millimeters.
3110.2005.11.1.4
19
AAT3110
MicroPower™ Regulated Charge Pump
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights,
or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice.
Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech
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830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
20
3110.2005.11.1.4
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