Download datasheet for ACE708BN+H by Ace Technology Co. Ltd

Download datasheet for ACE708BN+H by Ace Technology Co. Ltd
ACE708
300mA Iout, 0.85V startup, 1.2MHz, Synchronous Boost Converter
Description
The ACE708 is a step-up converter that provides a boosted output voltage from a low voltage source.
Because of its proprietary design, it starts up at a very low input voltage down to 850mV, making it an
ideal choice for single cell alkaline/NiMH battery operations.
A switching frequency of 1.2MHz minimizes solution footprint by allowing the use of tiny, low profile
inductors and ceramic capacitors. The current mode PWM design is internally compensated, reducing
external parts count.
Features


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Up to 95% Efficiency
1.2MHz Switching Frequency allows small inductor and output cap
Input boost-strapping allows using small or no input cap
Low Vin Start-up Voltage down to 850mV Ideal for Single Alkaline Cell operations
Maximum Output Current up to 300mA
Low Noise PWM control
Internally Compensated Current Mode Control
Internal Synchronous Rectifier
Logic Control Shutdown (IQ<1uA)
Application
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One to Three Cell Battery Operated Devices
Medical Instruments
Bluetooth Headsets
Flash-Based MP3 Players
Noise Canceling Headphones
Absolute Maximum Ratings
Parameter
Max
Unit
SW Voltage
-0.3~6
V
EN, FB, OUT Voltage
-0.3~6
Junction to Ambient Thermal Resistance
190
Maximum Power Dissipation
0.45
V
O
C/ W
W
Operating Temperature Range
-40~150
O
Storage Temperature
-55~150
O
C
C
Note: Exceed these limits to damage to the device.
Exposure to absolute maximum rating conditions may affect device reliability.
VER 1.4
1
ACE708
300mA Iout, 0.85V startup, 1.2MHz, Synchronous Boost Converter
Packaging Type
SOT-23-5
5
1
SOT-23-5 Description
4
2
3
1
FB
2
GND
3
EN
4
SW
5
OUT
Ordering information
ACE708 XX + H
Halogen - free
Pb - free
BN : SOT-23-5
Block Diagram
VER 1.4
2
ACE708
300mA Iout, 0.85V startup, 1.2MHz, Synchronous Boost Converter
Detail Description
ACE708 is a low input voltage start up, current mode dc-dc step up converter. It’s operation can be best
understood by referring to the block diagram. Upon starting up, the low voltage startup circuitry drives SW
with on-off cycles, transferring energy from input to OUT by storing energy in the inductor during on-time
and releasing it to the output during off-time. When OUT reaches 2V, the startup circuit turns off and the
main controller takes over. The main control loop consists of a reference, a GM error amplifier, a PWM
controller, a current sense amplifier, an oscillator, a PWM logic control, and it is power stage including its
driver. The main control loop is a classic current mode control loop. The GM stage integrates the error
between FB and REF, and its output is used to compare with a triangular wave which the summing result
of the current sense amplifier output and a slope compensation voltage. The output of the comparator is
used to drive the power stage to reach regulation.
Application Information
Output Voltage selection
The output voltages can be set by connecting FB to OUT, to G or to the midpoint of a resistor divider
connected to OUT. See below table for details.
FB=G
VOUT=5.0V
FB=OUT
VOUT=3.3V
FB to resistor divider
VOUT=0.6V(1+R1/R2)
Inductor selection
With switching frequency up to 1MHz, small surface mount inductors can be used with values from
2.2uH to 4.7uH. For a given chosen inductor value and application conditions make sure the peak
inductor current does not exceed the maximum current rating of the selected vendor's inductor.
Input and output capacitor selection
The ACE708's bootstrap architecture allows the use of very small input capacitor. For applications that
only need to drive small output load current, the input capacitor is optional, because once output is started
up, the IC's is powered by OUT, a quiet power supply.
The output capacitor is used to stabilize the loop and provide ac current to the load. A low ESR ceramic
cap with values from 2.2uF to 22uF can be used. Smaller value capacitors are generally cheaper with
small footprints, while larger capacitor provides lower ripples and better transient load responses. Also,
when extreme low startup voltage is needed, larger output capacitors are needed for the part to startup
under heavy load condition.
VER 1.4
3
ACE708
300mA Iout, 0.85V startup, 1.2MHz, Synchronous Boost Converter
Electrical Characteristics
O
Test condition: Vin=1.8V, Vout=3.3V, T A=25 C, unless otherwise specified.
Parameter
Test Conditions
Minimum Input Voltage
0.7
Max Unit
V
Startup Voltage
0.85
1.1
Dropout Voltage, Vout≧2.8V
FB Feedback Voltage
Min
Typ
V
FB=OUT
3.3
V
FB=G
5
V
Vout=2.5 to 5V
0.6
V
FB Input Current
nA
5
V
Output Voltage Range
External divider
Quiescent Current at OUT
VFB=0.7V
35
Shutdown Supply Current at OUT
EN=G
0.1
NMOS Switch On Resistance
Isw=100mA
0.3
uA
Ω
PMOS Switch On Resistance
Isw=100mA
0.7
Ω
NMOS Switch Current Limit
2.5
50
uA
1
1
A
uA
EN Input Current
1
uA
EN Input Voltage for “Low”
0.3
V
SW Leakage Current
1
Vout=5.5V, Vsw=0 or 5.5V, EN=G
EN Input Voltage for “High”
0.6
V
Typical Application Circuit
SW
ACE708
OUT
EN
GND
FB
VER 1.4
4
ACE708
300mA Iout, 0.85V startup, 1.2MHz, Synchronous Boost Converter
Typical Performance Characteristics
O
Typical values are tested at TA=25 C, unless otherwise specified.
VER 1.4
5
ACE708
300mA Iout, 0.85V startup, 1.2MHz, Synchronous Boost Converter
Typical Performance Characteristics
O
Typical values are tested at TA=25 C, unless otherwise specified.
VER 1.4
6
ACE708
300mA Iout, 0.85V startup, 1.2MHz, Synchronous Boost Converter
Packing Information
SOT-23-5
VER 1.4
7
ACE708
300mA Iout, 0.85V startup, 1.2MHz, Synchronous Boost Converter
Notes
ACE does not assume any responsibility for use as critical components in life support devices or systems
without the express written approval of the president and general counsel of ACE Electronics Co., LTD.
As sued herein:
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and shoes failure to perform when properly used in
accordance with instructions for use provided in the labeling, can be reasonably expected to result in
a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can
be reasonably expected to cause the failure of the life support device or system, or to affect its safety
or effectiveness.
ACE Technology Co., LTD.
http://www.ace-ele.com/
VER 1.4
8
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