Technology
Description
ACE705
High efficiency, Low supply current, step-up
DC/DC Controller
The ACE705 series are CMOS-based PFM step-up DC-DC Controller with low supply current and high
output voltage accuracy. Quiescent current drawn from power source is as low as 6uA. It is capable of
delivering 500mA output current at 4.0V output with 2V input Voltage. Only four external components are
necessary: An inductor, a Schottky diode, an output filter capacitor and a NMOSFET or a NPN transistor
All of these features make ACE705 series be suitable for the portable devices, which are supplied by a
single battery to four-cell batteries.
ACE705 has a drive pin (EXT) for external transistor. So it is possible to load a large output current with
a power transistor which has a low saturation voltage.
ACE705 integrates stable reference circuits and trimming technology, so it can afford high precision and
low temperature-drift coefficient of the output voltage.
ACE705 is available in SOT-23-3 and SOT-23-5 packages which are PB free. And in SOT-23-5 the
device can be switch on or off easily by CE pin, to minimize the standby supply current.
Features
•
•
•
•
•
•
•
•
•
•
Deliver 500mA at 4.0V Output voltage with 2.0V input Voltage
The converter output voltage can be adjusted from 2.5V½6.0V(In 0.1V step)
Output voltage accuracy -----------±2％
Low temperature-drift coefficient of the output voltage------------------±100ppm/℃
Only four external components are necessary: An inductor, a Schottky diode an output filter
capacitor and a NMOSFET or a NPN transistor
High power conversion efficiency---90％
Low quiescent current drawn from power source------------------------------------- 6uA
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
Input voltage range
Input voltage
CE pin voltage
EXT pin output current
Maximum power dissipation, Pd T=25℃
SOT-23-5
SOT-23-3
Maximum junction temperature
Operating free-air temperature range
Storage temperature range
Symbol
Max
Unit
-0.3~12
V
V(EXT) -0.3~Vout+0.3 V
-0.3~Vout+0.3 V
0.7
A
0.25
0.15
150
-20~80
-40~125
W
℃
℃
℃
VER 1.2
1
Technology
Packaging Type
SOT-23-3
3
ACE705
High efficiency, multi-funtion step-up
DC/DC Controller
SOT-23-5
5
4
1
2
1
2
3
Pin
SOT-23-3 SOT-23-5
Function
V
SS
(GND)
1
4
Ground pin
V
OUT
2
2
Output pin, power supply for internal circuits
Ext
3
5
Switching pin
NC
3
CE
1
Chip enable pin (active high)
Ordering information
Selection Guide
ACE705 X XX XX + H
Halogen - free
Pb - free
BN : SOT-23-5
BM : SOT-23-3
Output Voltage :
2.5V / 3.0V ….. 6.0V
Function Description :
1 : Without Enable circuit
2 : With Enable circuit
VER 1.2
2
Technology
Block Diagram
ACE705
High efficiency, multi-funtion step-up
DC/DC Controller
ACE705
Recommended Work Conditions
Item
Input voltage range
Inductor
Min Nom Max Unit
0.8
Vout V
10 27 100
μH
Input capacitor
0
≧10
μF
Output capacitor
47 100 220
μF
Vout pin filter capacitor
1
nF
Operating junction temperature -20
85
O
C
*Suggestion: Use tantalum type capacitor to reduce the ripple of the output voltage. Use 1nF filter ceramic type
capacitor to connect Vout pin and GND pin. The filter capacitor is recommended as close as possible to Vout pin
and GND pin.
Electrical Characteristics
Default condition (unless otherwise provided): Vin=0.6xVout, Iout=10mA.Temperature=25℃. Use external
circuit in test circuit list.
Parameter
Symbol
Test Conditions
Min Typ Max Unit
2.45 2.5 2.55
2.646 2.7 2.754
2.94 3.0 3.06
3.234 3.3 3.366
Output Voltage
Vout
V
3.528 3.6 3.672
3.92 4.0 4.08
4.9
5.0
5.1
5.88 6.0 6.12
Input Voltage
Vin
12
V
VER 1.2
3
Technology
Input Current * (no
load)
Quiescent current *
Chip leakage current
CE “H: threshold
voltage
CE “L” threshold
voltage
Oscillator frequency
CE ”H”
CE “L”
EXT “H” output current
Lin
I
DD
I
standby
V
CEH
V
CEL
F
OSC
I
CEH
I
CEL
I
EXTH
ACE705
25
8
1
uA
uA
uA
V
0.6
400
0.5
0.5
V
Khz
uA
uA
mA
High efficiency, multi-funtion step-up
DC/DC Controller
Iout=0mA, Vin=Vout*0.6
No external component,
Vout=Voutx1.05
V
CE
=0V
V
CE
:0 2V
V
CE
:2 0V
0.6
20
6
0.9
0.3
EXT “H” output current
Oscillator duty cycle
Efficiency
Note :
1.
2.
3.
4.
5.
I
EXTL
Duty
η
Vout=Vout*0.96 Test EXT pin
frequency
Vout=V
CE
=6V
Vout=V
CE
=6V
3.0V<=Vout<=3.9V
4.0V<=Vout<=4.9V
5.0V<=Vout<=6.9V
3.0V<=Vout<=3.9V
4.0V<=Vout<=4.9V
5.0V<=Vout<=6.9V
On(Vlx “L”) side
300
-0.5
-0.5
350
0
0
-21
-35
-41
23
25
31
75
90
mA
80
%
%
70
Diode: Schottky type, such as: 1N5817, 1N5819, 1N5822
Inductor: 27uH(R<0.5Ω)
Output Capacitor: 100uF (Tantalum type)
Vout pin filter capacitor: 1nF (Ceramic type)
Input capacitor: 47uF
Typical Application
(1) Application with external NMOSFET
Vin
L 27uH
EXT
Cin
47uF
CE
OFF
ON
ACE705
Cout
D 1N5817
Vout
OUT
Rload
GND
Cp
1nF
100uF Tan
Fig2
VER 1.2
4
Technology
(2) Application with external NPN transistor
ACE705
High efficiency, multi-funtion step-up
DC/DC Controller
ACE705
Fig3
Note: R
1
=330Ω, C
1
=10nF. (R
1
can be calculated by load. If load is light R
1
’s value can be added. If load is heavy R
1
’s value can
be smaller. )
Detailed Description
The ACE705 series are boost structure, voltage-type pulse-frequency modulation(PFM) step-up DC-DC
controller. Only four external components are necessary: an inductor, a schottky diode, an output filter
capacitor and a NMOSFET or a NPN transistor. The step-up DC-DC converter, constructed by ACE705,
can be adjusted from 2.5V to 6.0V, 0.1V step. By using the depletion technics, the quiescent current
drawn from power source is lower than 8uA. The high efficiency device consists of resistors for output
voltage detection and trimming, a start-up voltage circuit, an oscillator, a reference circuit, a PFM control
circuit, a switch protection circuit and a driver transistor.
ACE705 integrates PFM control system. This system controls fixed power switch on duty cycle
frequency to stabilize output voltage by calculating results of other blocks which sense input voltage,
output voltage, output current and load conditions. In PFM modulation system, the frequency and pulse
width is fixed. The duty cycle is adjusted by skipping pulses, so that switch on-time is changed based on
the conditions such as input voltage, output current and load. The oscillate block inside ACE705 provides
fixed frequency and pulse width wave.
The reference circuit provides stable reference voltage to output stable output voltage. Because internal
trimming technology is used, the chip output change less than ±2%. At the same time，the problem of
temperature-drift coefficient of output voltage is considered in design, so temperature-drift coefficient of
output voltage is less than 100ppm/℃。
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.
ACE705 has a drive pin (EXT) for external transistor. So it is possible to load a large output current with
a power transistor and a low saturation voltage. At very light load condition, the switch current and
quiescent current of chip will effect efficiency certainly. So in very light load condition, the efficiency will
drop. Therefore, it is recommended that user use ACE705 in the condition of load current as large as
several tens of mA to several hundreds of mA
VER 1.2
5
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