ETC AS2300

AS2300
0.85V Startup, 1.2MHz Synchronous
Step-Up Converter
DESCRIPTION
FEATURES
The AS2300 is a 1.2MHz constant frequency, current
„
High Efficiency: Up to 92%
mode PWM step-up converter. It can supply 3.3V
„
1.2MHz Constant Switching Frequency
output voltage at 100mA from a single AA Cell.
„
[email protected] Output from 1 Single AA Cell;
The device integrates a main switch and a
[email protected] Output from 2 AA cells
synchronous rectifier for high efficiency without an
„
Low Start-up Voltage: 0.85V
external Schottky diode. A switching frequency of
„
Integrated main switch and sync. rectifier.
1.2MHz allows the use of tiny, low profile inductors
„
2.5V to 5V Output Voltage Range
and ceramic capacitors. The current mode PWM
„
Automatic Pulse Skipping Mode Operation
operation
provides
„
Tiny External Components
excellent line and load transient characteristics. The
„
<1 µA Shutdown Current
AS2300 features Pulse Skipping Mode operation at
„
Anti-ringing Control Reduces EMI
light loads to avoid unacceptable ripple voltage.
„
Space Saving 6-Pin Thin SOT23 Package
with
internal
compensation
The AS2300 is offered in a low profile (1 mm) small
6-Pin SOT23 Package.
APPLICATIONS
ORDER INFORMATION
„
Cellular and Smart Phones
Part Number
Output Voltage
„
Microprocessors and DSP Core Supplies
AS2300EHT-adj
Adjustable
„
Wireless and DSL Modems
„
MP3 Player
„
Digital Still and Video Cameras
„
Portable Instruments
EVALUATION BOARD
Board Number
EV2300EH-00A
Dimensions
mm
50
mm
X x 50
mm
Y x 1.4
Z
“ANI” and “ANISEM” is Trademarks of ANISEM Semiconductor, Inc.
TYPICAL APPLICATION
100 EFFICIENCY vs
LOAD CURRENT
VIN=2.4V
90 VIN = 1.5V
EFFICIENCY (%)
80 70 60 50 40 30 VOUT = 3.3V
L = 4.7uH
20 10 0 10
100
1000
LOAD CURRENT (mA)
AS2300 Rev.1.6
08/25/2009
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© 2008 ANISEM All Rights Reserved.
1
AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER
ABSOLUTE MAXIMUM RATINGS(1)
PACKAGE REFERENCE
MARKING
VIN to GND… ………………………..….. -0.3V to 6V
VSW to GND …………………...…. -0.3V to VIN +0.3V
VEN, VFB Voltage ………………….…. -0.3V to +6.0V
Junction Temperature ……………….……….. 125°C
Lead Temperature (Soldering, 10sec.) …..…+300°C
Storage Temperature Range …….... -65℃ to 150°C
Part Number*
Package
Temperature
AS2300EHT-adj
TSOT23-6L
-40°C to 85°C
Recommended Operating Conditions(2)
Supply Voltage VIN……………….………1.0V to 5.0V
Output Voltage VOUT………….…….……2.5V to 5.0V
Operating Temperature …………….… -40°C to 85°C
ƟJA
ƟJC
Thermal Resistance (3)
TSOT23-6L……………….…220…….110…...°C/W
*For output voltage adjustable, add suffix –adj (eg. AS2300EHT-adj)
For fixed 3.3V output voltage, add suffix –3.3 (eg. AS2300EHT-3.3)
NOTEs:
1)
Exceeding these ratings may damage the device.
2)
The device is not guaranteed to function outside of its operating conditions.
3)
Measure on approximately 1’’square of 1 oz copper.
ELECTRICAL CHARACTERISTICS
VIN =1.2V, VOUT =3.3V, TA = 25°C Unless otherwise noted.
PARAMETER
CONDITIONS
Minimum Start-Up Voltage
Minimum Operating Voltage
MIN
ILOAD = 1mA
VEN = VIN
(Note 4)
Output Voltage Range
TYP
MAX
UNITS
0.85
1
V
0.5
0.65
V
5
V
1.268
V
2.5
Feedback Voltage
1.192
(Note 3)
1.230
Feedback Input Current
VFB = 1.25V
Quiescent Current(ISD)
VSHDN= 0V,No Include Switch Leakage
0.01
1
µA
Quiescent Current(Active)
Measured on VOUT
300
500
µA
NMOS Switch Leakage
VSW = 5V
0.1
5
µA
PMOS Switch Leakage
VSW = 0V
0.1
5
µA
NMOS Switch ON
VOUT = 3.3V
0.40
Ω
Resistance
VOUT = 5V
0.35
Ω
PMOS Switch ON
VOUT = 3.3V
0.70
Ω
Resistance
VOUT = 5V
0.60
Ω
850
mA
40
ns
80
85
%
Switching Frequency
0.9
1.2
1.5
MHz
EN Input Threshold
0.35
0.60
0.80
V
0.01
1
µA
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2
NMOS Current Limit
Current Limit Delay
600
Note 3
Max Duty Cycle
EN Input Current
1
VFB = 1.15V
VEN = 5.5V
nA
Note 3: Specification is guaranteed by design and not 100% tested in production.
Note 4: Minimum VIN operation after start-up is only limited by the battery’s ability to provide the necessary power as it enters a deeply discharged state..
AS2300 Rev.1.6
08/25/2009
AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER
TYPICAL PERFORMANCE CHARACTERISTICS
Vin=1.5V, Vout=3.3V,L=4.7uH, Cin=4.7uF, Cout=4.7uF; TA = +25°C; unless otherwise noted.
QUIESCENT CURRENT vs
SUPPLY VOLTAGE
ENABLE VOLTAGE vs
SUPPLY VOLTAGE
500
400
300
1.40
OSCILLATOR FREQUENCY (MHz)
1.00
ENABLE VOLTAGE (V)
0.80
0.60
0.40
200
0.20
100
ILOAD=50mA
0
0.00
2
2.5
3
3.5
1.20
1.15
1.10
ILOAD=150mA
2.5
3
3.5
1
3.40
VIN = 1.8V
EFFICIENCY (%)
70 60 50 40 30 3.35
60 50 40 30 VOUT = 3.3V
L = 4.7uH
20 VOUT = 5.0V
L = 4.7uH
20 10 10 0 1000
LOAD CURRENT (mA)
3.30
3.25
3.20
3.15
VIN=2.4V
3.10
3.05
0 100
5
3.45
80 70 4
3.50
VIN=3.6V
90 VIN = 1.5V
3
OUTPUT VOLTAGE vs
LOAD CURRENT
100 VIN=2.4V
90 2
SUPPLY VOLTAGE (V)
EFFICIENCY vs
LOAD CURRENT
100 EFFICIENCY (%)
1.25
SUPPLY VOLTAGE (V)
EFFICIENCY vs
LOAD CURRENT
10
1.30
1.00
2
SUPPLY VOLTAGE (V)
80 1.35
1.05
OUTPUT VOLTAGE(V)
QUIESCENT CURRENT (uA)
600
OSCILLATOR FREQUENCY vs
SUPPLY VOLTAGE
3.00
10
100
LOAD CURRENT (mA)
1000
0
100
200
300
400
500
LOAD CURRENT (mA)
OUTPUT VOLTAGE vs
SUPPLY VOLTAGE
5.50
5.40
5.30
OUTPUT VOLTAGE(V)
5.20
5.10
5.00
4.90
4.80
4.70
ILOAD=150mA
4.60
4.50
0
1
2
3
4
5
SUPPLY VOLTAGE (V)
AS2300 Rev.1.6
08/25/2009
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© 2008 ANISEM All Rights Reserved.
3
AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER
PIN FUNCTIONS
PIN NUMBER
PIN NAME
FUNCTION
Switch Pin. Connect inductor between SW and VIN. Optional Schottky diode is
1
connected between SW and VOUT. Keep these PCB trace lengths as short and wide as
SW
possible to reduce EMI and voltage overshoot. If the inductor current falls to zero, or EN
is low, an internal antiringing switch is connected from SW to VIN to minimize EMI.
2
GND
3
FB
Ground .
Feedback Input to the Error Amplifier. Connect resistor divider tap to this pin. The
output voltage can be adjusted from 2.5V to 5V by: VOUT = 1.23V • [1 + (R1/R2)]
Logic Controlled Shutdown Input. EN = High: Normal free running operation, 1.2MHz
4
EN
typical operating frequency. EN = Low: Shutdown, quiescent current <1uATypically, EN
should be connected to VIN through a 1M pull-up resistor.
Output Voltage Sense Input and Drain of the Internal Synchronous Rectifier
5
VOUT
MOSFET. Bias is derived from VOUT. PCB trace length from VOUT to the output filter
capacitor(s) should be as short and wide as possible. VOUT is held at VIN – 0.6V in
shutdown due to the body diode of the internal PMOS.
Battery Input Voltage. The device gets its start-up bias from VIN. Once VOUT
6
VIN
exceeds VIN, bias comes from VOUT. Thus, once started, operation is completely
independent from VIN. Operation is only limited by the output power level and
the battery’s internal series resistance.
FUNCTION BLOCK DIAGRAM
AS2300 Rev.1.6
08/25/2009
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4
AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER
OPERATION
The AS2300 is a synchronous step-up DC-DC
the main switch is turned off and the synchronous
converter. It utilizes internal MOSFETs to achieve
switch(PMOS) is turn on. This control topology
high efficiency over the full load current range. It
features cycle by cycle current limiting which can
operates at a fixed switching frequency of 1.2MHz,
prevent the main switch from overstress and
and uses the slope compensated current mode
prevent external inductor from saturation.
architecture. The device can operate with input
voltage even below 1 V and the typical start-up
PULSE SKIPPING MODE
voltage is 0.85V.
At very light load, the AS2300 automatically
switches into Pulse Skipping Mode to improve
LOW VOLTAGE START-UP
efficiency. During this mode, the PWM control will
The AS2300 can start up at supply voltage down to
skip some pulses to maintain regulation. If the load
0.85V. During start-up, the internal low voltage
increases and the output voltage drops, the device
start-up circuitry controls the NMOS switch to
will automatically switch back to normal PWM mode
maximum peak inductor current. The device leaves
and maintain regulation.
the start-up mode once the
VOUT
exceeds 2.3V. A
Comparator (VOUT GOOD Comp) monitors the output
ANTIRINGING CONTROL
voltage and allows the chip into normal operation
An antiringing circuitry is included to remove the
once the VOUT exceeds 2.3V. The device is biased by
high frequency ringing that appears on the SW pin
VIN during start-up while biased by VOUT once VOUT
when the inductor current goes to zero. In this case,
exceeds VIN then the operation will be independent
a ringing on the SW pin is induced due to remaining
of VIN
energy stored in parasitic components of switch and
inductor. The antiringing circuitry clamps the
SYNCHRONOUS RECTIFICATION
voltage internally to battery voltage and therefore
The AS2300 integrates a synchronous rectifier to
dampens this ringing.
improve efficiency as well as to eliminate the
external Schottky diode. The synchronous rectifier is
DEVICE SHUTDOWN
used to reduce the conduction loss contributed by
When EN is set logic high, the AS2300 is put into
the
The
operation. If EN is set logic low, the device is put
synchronous rectifier is realized by a P-ch MOSFET
into shutdown mode and consumes lower than 1 µA
with gate control circuitry that incorporates relatively
current. After start-up timing, the internal circuitry is
complicated timing concerns.
supplied by VOUT, however, if shutdown mode is
forward
voltage
of
Schottky
diode.
enabled, the internal circuitry will be supplied by
CURRENT MODE PWM CONTROL
battery again
The AS2300 is based on a slope compensated
current mode control topology. It operates at a fixed
frequency of 1.2MHz. At the beginning of each clock
cycle, the main switch (NMOS) is turned on and the
inductor current starts to ramp. After the maximum
duty cycle or the sense current signal equals to the
error amplifier (EA) output.
AS2300 Rev.1.6
08/25/2009
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© 2008 ANISEM All Rights Reserved.
5
AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER
APPLICATION INFORMATION
AS2300:
SETTING THE OUTPUT VOLTAGE
An external resistor divider is used to set the output
PART
voltage. The output voltage of the switching
NUMBER
L
MAX
RATED
SIZE
DCR
D.C.
WxLxH
(µH)
(mΩ)
Current(A)
(mm)
regulator (VOUT) is determined by the following
Sumida
4.7
108.7
1.15
equation:
CR43
10
182
1.04
4.7
72
1.32
Sumida
5.6
101
1.17
CDRH4D28
6.8
109
1.12
10
128
1.00
4.7
45
1.87
6.8
68
1.51
10
90
1.33
R1 ⎞
⎛
VOUT = 1.23V × ⎜1 +
⎟
⎝ R2 ⎠
Table 1 list the resistor selection for output voltage
setting.
VOUT
R1(Ω)
R2(Ω)
3.3V
1.02M
604K
5.0V
1.02M
332K
Table 1.Resistor selection for output voltage setting
Tokoy
D53LC
4.3x4.8x3.5
5.0x5.0x3.0
5.0x5.0x3.0
OUTPUT CAPACITOR SELECTION
The output capacitor is required to keep the output
INDUCTOR SELECTION
voltage ripple small and to ensure regulation loop
The high switching frequency of 1.2MHz allows for
stability. A 2.2µF to 10µF output capacitor is
small surface mount inductors. For most designs,
sufficient for most applications. If output capacitor is
the AS2300 operates with inductors of 4.7µH to
larger than 10µF, a phase lead capacitor must be
10µH.The equation below can help to select the
included to maintain enough phase margin. The
inductor, the maximum output current can be get by
output capacitor must have low impedance at the
this equation; where η is the efficiency, IPEAK is the
switching frequency. Ceramic capacitors with X5R or
peak current limit, f is the switching frequency, L is
X7R dielectrics are recommended due to their low
the inductance value and D is the duty cycle.
ESR and high ripple current ratings.
⎛
V ×D ⎞
I OUT = η × ⎜ Ipeak − IN
⎟ × (1 − D )
2× f × L ⎠
⎝
Larger inductors mean less inductor current ripple
and usually less output voltage ripple. Larger
inductors also mean more load power can be
delivered. But large inductors are also with large
profile and costly. The inductor ripple current is
typically set for 20% to 40% of the maximum
inductor current. When selecting an inductor, the
DC current rating must be high enough to avoid
saturation at peak current. For optimum load
transient and efficiency, the low DCR should be
INPUT CAPACITOR SELECTION
The input capacitor reduces the surge current drawn
from the input and switching noise from the device. A
minimum 4.7µF input capacitor is needed for most
applications. The input capacitor impedance at the
switching frequency should be less than input source
impedance to prevent high frequency switching
current passing to the input. A low ESR input
capacitor sized for maximum RMS current must be
used.
Ceramic
capacitors
with X5R
or
X7R
dielectrics are highly recommended because of their
low ESR and small temperature coefficients.
selected. Table 2 lists some typical surface mount
inductors that meet target applications for the
AS2300 Rev.1.6
08/25/2009
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6
AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER
OUTPUT DIODE SELECTION
An Shottky diode should be included when the
conduction path exists from battery to output through
output voltage is above 4.5V. The Schottky diode is
the backgate of the P-ch MOSFET during shutdown.
optional for the output voltage not more than 4.5V,
A special application circuitry is provided to
but can improve efficiency by about 2% to 3%.
disconnect the load from the battery during
shutdown as below.
LOAD DISCONNECT IN SHUTDOWN
In conventional synchronous step-up converter, a
D1
MBR0520
4.7uH
INPUT
0.85V
Startup
OFF ON
6
VIN
VOUT
SI2305
5
1.02M
1%
AS2300
4.7uF
4
1
SW
FB
EN
3
510K
OUTPUT
3.3V/100mA
4.7uF
604K
1%
GND
2
510K
2N3904
SINGLE LITHIUM CELL to 5V APPLICATION
AS2300 Rev.1.6
08/25/2009
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© 2008 ANISEM All Rights Reserved.
7
AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER
PACKAGE DESCRIPTION
Package
6-Lead Plastic TSOT23-6L
AS2300 Rev.1.6
08/25/2009
www.anisem.com
ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2008 ANISEM All Rights Reserved.
8
AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER
© ANISEM Semiconductor Co., Ltd
ANISEM assume responsibility for use of any circuitry other than circuitry entirely embodied in an ANISEM product. No circuit patent licenses, copyrights,
mask work rights, or other intellectual property rights are implied. ANISEM 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. ANISEM warrants performance of its
semiconductor products to the specifications applicable at the time of sale in accordance with ANISEM’s standard warranty. Testing and other quality
control techniques are utilized to the extent ANISEM deems necessary to support this warranty. Specific testing of all parameters of each device is not
necessarily performed.
AS2300 Rev.1.6
08/25/2009
www.anisem.com
ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2008 ANISEM All Rights Reserved.
9
EV2300-1.0
1.2MHz, Sync. Boost Converter
FEATURES
GENERAL DESCRIPTION
High Efficiency: Up to 92%
The AS2300 is a 1.2MHz constant frequency,
1.2MHz Constant Switching Frequency
current mode PWM step-up converter. It can supply
[email protected] Output from 1 Single AA Cell;
3.3V output voltage at 100mA from a single AA Cell.
[email protected] Output from 2 AA cells
Low Start-up Voltage: 0.85V
The device integrates a main switch and a
Integrated main switch and sync. rectifier.
synchronous rectifier for high efficiency without an
2.5V to 5V Output Voltage Range
external Schottky diode. A switching frequency of
Automatic Pulse Skipping Mode Operation
1.2MHz allows the use of tiny, low profile inductors
Tiny External Components
and ceramic capacitors. The current mode PWM
<1 µA Shutdown Current
operation with internal compensation provides
Anti-ringing Control Reduces EMI
excellent line and load transient characteristics. The
Space Saving 6-Pin Thin SOT23 Package
AS2300 features Pulse Skipping Mode operation at
APPLICATIONS
light loads to avoid unacceptable ripple voltage.
Cellular and Smart Phones
The AS2300 is offered in a low profile (1 mm) small
Microprocessors and DSP Core Supplies
6-Pin SOT23 Package.
Wireless and DSL Modems
MP3 Player
Digital Still and Video Cameras
Portable Instruments
EV2300-1.0 EVALUATION BOARD
Figure1. High Performance Step-Up Converter
EV2300 Rev.1.0
6/25/2008
www.anisem.com
ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2008 ANISEM All Rights Reserved.
1