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PDF ACE701 Data sheet ( Hoja de datos )
| Número de pieza | ACE701 | |
| Descripción | PFM STEP-UP DC/DC Converter | |
| Fabricantes | ACE Technology | |
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ACE701
Technology PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Description
The ACE701 series are CMOS-based PFM step-up DC-DC Converter. The converter can start up by
supply voltage as low as 0.8V, and capable of delivering maximum 200mA output current at 3.3V output
with 1.8V input Voltage. Quiescent current drawn from power source is as low as 5.5uA. All of these
features make ACE701 series be suitable for the portable devices, which are supplied by a single battery
to four-cell batteries.
To reduce the noise caused by the switch regulator, ACE701 is well considerated in circuit design and
manufacture. So that the interferer to other circuits by the device is reduced greatly.
ACE701 integrates stable reference circuits and trimming technology, so it can afford high precision and
low temperature-drift coefficient of the output voltage.
ACE701 is available in SOT-89-3、SOT-23-3、SOT-89-5 and SOT-23-5 packages which is PB free. And
in 5-pin packages, such as SOT-23-5 and SOT-89-5, the device can be switch on or off easily by CE pin,
to minimize the standby supply current.
Features
• Deliver 200mA at 3.3V Output voltage with 1.8V input Voltage
• Low start-up voltage (when the output current is 1mA)--------------------------0.8V
• The converter output voltage can be adjusted from 2.5V～6.0V(In 0.1V step)
• Output voltage accuracy -----------±2％
• Low temperature-drift coefficient of the output voltage------------------±100ppm/℃
• Only three external components are necessary: An inductor, a Schottky diode and an output filter
capacitor
• High power conversion efficiency---85％
• Low quiescent current drawn from power source------------------------------------- <5.5uA
Application
• Power source for PDA. DSC. MP3 Player. electronic toy and wireless mouse
• Power source for a single or dual-cell battery-powered equipments
• Power source for LED
Absolute Maximum Ratings
Parameter
Symbol Max Unit
Input supply voltage
Input voltage
CE pin voltage
VIN
VI(LX)
-0.3~12
-0.3~Vout+0.3
-0.3~Vout+0.3
V
V
Lx pin output current
Power Dissipation
SOT-89-3
SOT-23-5
SOT-23-3
Junction temperature
Storage temperature
Operating free-air temperature
TJ
TS
0.7 A
0.5
0.15
0.15
150
- 40 to 125
-20 ~ 80
W
OC
OC
OC
VER 1.2 1
1 page  
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ACE701
Technology PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
High-gain differential error amplifier guarantees stable output voltage at difference input voltage
and load. In order to reduce ripple and noise, the error amplifier is designed with high band-with.
Though at very low load condition, the quiescent current of chip do effect efficiency certainly. The four
main energy loss of Boost structure DC-DC converter in full load are the ESR of inductor, the voltage of
Schottky diode, on resistor of internal N-channel MOSFET and its driver. In order to improve the efficiency,
ACE701 integrates low on-resistor N-channel MOSFET and well design driver circuits. The switch energy
loss is limited at very low level.
Selection of the External Components
Thus it can be seen, the inductor and schottky diode affect the conversion efficiency greatly. The
inductor and the capacitor also have great influence on the output voltage ripple of the converter. So it is
necessary to choose a suitable inductor, a capacitor and a right schottky diode, to obtain high efficiency,
low ripple and low noise.
Before discussion，we define D≣Vout-Vin / Vout
(1)Inductor Selection
Above all, we should define the minimum value of the inductor that can ensure the boost DC-DC to
operate in the continuous current-mode condition.
Lmin≧D(1-D)2RL / 2f
The above expression is got under conditions of continuous current mode, neglect Schottky diode’s
voltage, ESR of both inductor and capacitor. The actual value is greater that it. If inductor’s value is less
than Lmin，the efficiency of DC-DC converter will drop greatly, and the DC-DC circuit will not be stable.
Secondly, consider the ripple of the output voltage,
ΔI=D‧Vin / Lf
Im ax=Vin / (1-D)2RL + DVin / 2Lf
If inductor value is too small, the current ripple through it will be great. Then the current through diode
and power switch will be great. Because the power switch on chip is not ideal switch, the energy of switch
will improve. The efficiency will fall.
Thirdly，in general, smaller inductor values supply more output current while larger values start up with
lower input voltage and acquire high efficiency.
An inductor value of 3uH to 1mH works well in most applications. If DC-DC converter delivers large
output current (for example: output current is great than 50mA), large inductor value is recommended in
order to improve efficiency. If DC-DC must output very large current at low input supply voltage, small
inductor value is recommended.
The ESR of inductor will effect efficiency greatly. Suppose ESR value of inductor is rL，Rload is load
resistor，then the energy can be calculated by following expression:
Δη≈ RL / Rload (1-D)2
VER 1.2 5
5 Page 
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ACE701
Technology PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Packing Information
SOT-23-3
VER 1.2 11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet ACE701.PDF ] | |
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