ACE703
Technology
Description
White LED PFM Step-Up DC-DC Converter
The ACE703 is a PFM step-up DC-DC converter specifically designed to drive white LEDs with a
constant current. It can deliver stable constant output current from 0mA to 500mA by adjusting the
external resistor.
The ACE703 can drive one or more LEDs in parallel connection, also it can drive two in series, several
in parallel connection from one or two battery cells. With overvoltage limit protection circuit interiorly, the
chip and the external circuits will be safe even if the load is not connected. The device also can deliver
steady constant output voltage from 2.5V to 6.0V by adjusting the external resistor.
The ACE703 integrates stable reference circuits and it uses trimming technology in the process, so it can
afford high precision and low temperature-drift coefficient output current or output voltage.
The ACE703 devices are available in SOT-89-5 package.
Features
•
•
•
•
•
•
•
•
•
Low start-up voltage (when the output current is 1mA)--------------------------0.8V
The converter can output constant voltage from 2.5V to 6.0V or it can output constant current from
0 to 500mA by adjusting the external resistor.
Output current accuracy -----------±10％
Low temperature-drift coefficient of the output current------------------±100ppm/℃
Only four external components are necessary: an inductor, a Schottky diode, an output filter capacitor
and a resistor.
High conversion efficiency (When Vin=2.5V, for 1W LED)----------80％
Application
Power source for white LED
Supply constant current
Power source for a single or dual-cell battery-powered equipments
Absolute Maximum Ratings
Parameter
Input supply voltage
LX pin voltage
CE pin voltage
IFB pin voltage
Lx pin output current
Power Dissipation P
D
@T=25
O
C
SOT-89-5
Junction temperature
Storage temperature
Operating free-air temperature
Symbol
Max
Unit
-0.3~10
V
-0.3 ~ Vout+0.3 V
-0.3 ~ Vout+0.3 V
-0.3 ~ Vout+0.3 V
1.5
A
0.5
150
- 40 to 125
-20 ~ 85
W
O
O
C
C
O
C
VER 1.2
1
Technology
Packaging Type
SOT-89-5
5
4
ACE703
White LED PFM Step-Up DC-DC Converter
1
2
3
Pin SOT-89-5
Function
IFB
1
Current feedback pin
V
OUT
2
Output pin, power supply for internal circuits
CE
3
Chip enable pin (active high)
L
X
4
Switching pin (Nch open drain)
GND
5
Ground pin
Ordering information
Selection Guide
ACE703 XX
XX +
H
Halogen - free
Pb - free
AN : SOT-89-5
Feedback Voltage
10…100mV / 20…200mV / 25…250 mV /
30…300 mV / 35…350 mV / 40…400 mV
VER 1.2
2
Technology
Block Diagram
ACE703
White LED PFM Step-Up DC-DC Converter
ACE703
Recommended Work Conditions
Item
Min Nom Max Unit
Input Voltage Range
0.8
Vout
V
Inductor
10
22
100
μH
Input capacitor
0
≧22
μF
Output capacitor
47
100 220
μF
Compensation capacitor
10
22
47
μF
Operating junction temperature -20
85
℃
*Suggestion: Tantalum capacitor is recommended to reduce the ripple of the output voltage
VER 1.2
3
Technology
Electrical Characteristics
ACE703
White LED PFM Step-Up DC-DC Converter
(Vin＝2.5V， V
CE
=Vout＝3.3V，R＝33Ω，TA=25°C, unless otherwise noted.)
Symbol
Item
Test conditions
V
IFB
Feedback voltage
Iout=100mA
Reference data
Min Typ. Max
80 100 120
180 200 220
230 250 270
280 300 320
330 350 370
380 400 420
0.8
0.6
0.7
20
100
700
1
<
0.1
300
70
0.6
350
75
80
0.9
0.3
500
0.5
400
80
30
150
0.9
Unit
mV
Vstart
Vhold
IDD2
*5
Inoload
*6
ILX
ILXleak
I
leak
Fosc
Maxdty
η
V
CEH
V
CEL
I
OM
Note:
Start-up voltage
Hold-on voltage
Quiescent current drawn from
power source
Current with no load
LX switching current
LX leakage current
Stand-by current
Oscillator frequency
Oscillator duty cycle
Efficiency
CE “H” threshold voltage
CE “L” threshold voltage
Maximum output current
Iout=1mA，
Vin：0→2V
Iout=1mA，
Vin：2→0V
LX hung in air, V
CE
=V
IFB
=
Vout=3.3V, Vin=2.5V
OUT pin and IFB pin without any
load, V
IFB
=0
Vlx=0.4V，V
IFB
=0
Vout=Vlx=V
IFB
=6V,
Vout=3.3V, V
CE
=0, LX、IFB hung in
air
V
IFB
=0，
On（Vlx “L”）side
Iout=300mA
V
CE
：0→2V
V
CE
：2→0V
V
IFB
=0，Vout≡3.3V
V
V
uA
uA
mA
uA
uA
kHZ
％
％
V
V
mA
0.6
1.Diode:schottky type, such as:1N5817,1N5819,1N5822
2.Inductor:22uH(R<0.5Ω)
3.Capacitor:100uF (Tantalum type)
4.Compensation capacitor:22uF (Tantalum type)
5.I
DD2
is quiescent current drawn from power source, It is the minimum current of the chip without any dynamic current
6.I
no load
is the current with no load in constant current application, it’s also the current consumed by the converter itself, including
the chip and external circuits, when Vin=2.5V,Vout=V
OM
VER 1.2
4
Technology
Typical Application
(1) Constant output current application
Vin
L
27uH
LX
ACE703
Power
Cin
47uF
CE
GND IFB
OUT
D 1N5819
ACE703
White LED PFM Step-Up DC-DC Converter
Iout
White LED
C1
22uF Tan
Cout
100uF Tan
Rc
(A) Drive only one white LED
ACE703
(B) Drive two white-LED in series and several in parallel connection
(2) Constant output voltage application
ACE703
VER 1.2
5
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