datasheet for ACE701D237BN+H by Ace Technology Co. Ltd
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Description
The ACE701D 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 ACE701D 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, ACE701D is well considerate in circuit design and
manufacture. So that the interferer to other circuits by the device is reduced greatly.
ACE701D integrates stable reference circuits and trimming technology, so it can afford high precision
and low temperature-drift coefficient of the output voltage.
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
VIN
-0.3~12
V
-0.3~6.5
V
Lx Voltage
CE pin voltage
Lx pin output current
Power Dissipation
SOT-89-3
SOT-23-5
SOT-23-3L
TO-92
Operating Junction temperature
Storage temperature
Ambient Temperature
-0.3~Vout+0.3 V
0.7
TJ
TS
TA
500
250
250
500
125
A
mW
O
C
- 40 to 150
O
C
-40 to 85
O
C
Note: Exceed these limits to damage to the device.
Exposure to absolute maximum rating conditions may affect device reliability.
VER 1.3
1
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Packaging Type
SOT-89-3
SOT-23-5
5
1
2
3
1
SOT-23-3L
4
2
TO-92
3
3
1
2
123
SOT-89-3 SOT-23-5 SOT-23-3L TO-92 Description
Function
1
4
1
1
VSS(GND)
2
2
2
2
VOUT
3
5
3
3
LX(Ext)
Ground pin
Output pin, power supply for internal
circuits
Switching pin
3
NC
No connection
1
CE
Chip enable pin (active high)
Ordering information
ACE701D X XX XX + H
Halogen - free
Pb - free
AM : SOT-89-3
BN : SOT-23-5
BM : SOT-23-3L
EP : TO-92
Output Voltage : 2.5V / 3.0V ….. 6.0V
Function Description :
1 : Internal Tr. Driver, Without Enable circuit
2 : Internal Tr. Driver, With Enable circuit
3 : External Tr. Driver, Without Enable circuit
4 : External Tr. Driver, With Enable circui
VER 1.3
2
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Block Diagram
CE pin is only available on 5 pins packages.
Recommended Work Conditions
Item
Min Recommended Max Unit
Input Voltage Range
0.8
Inductor
10
27
Input capacitor
0
≧10
Output capacitor
47
100
Ambient Temperature
-40
Vout
V
100
μH
μF
220
μF
85
℃
VER 1.3
3
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Electrical Characteristics
Parameter
Symbol
Output Voltage
Test Conditions
Vout
Input Voltage
Vin
Input Current
Lin
Iout=0mA, Vin=Vout*0.6
Start-up voltage
Vstart
Iout=1mA, Vin:02V
Hold-on voltage
Quiescent current drawn from
power source
Switch ON Resistance
Vhold
Iout=1mA, Vin:20V
Without external components,
Vout=Vout x 1.05
Rswon
LX leakage current
ILXleak
Vout=Vlx=6V
CE “H” threshold voltage
VCEH
VCE: 02V
CE “L” threshold voltage
VCEL
VCE: 20V
Oscillator frequency
FOSC
LX on “L” side Vout=Vout * 0.96
Oscillator duty cycle
Maxdty
On (Vlx “L”) side
Efficiency
η
IDD
Min
Typ
Max
2.45
2.5
2.55
2.646
2.7
2.754
2.94
3.0
3.06
3.234
3.3
3.366
3.528
3.6
3.672
3.92
4.0
4.08
4.9
5.0
5.1
5.88
6.0
6.12
0.6
Unit
Vout
V
12
15
uA
0.8
0.9
V
0.7
4
V
7
0.5
uA
Ω
0.5
5
0.8
uA
V
0.3
400
70
V
75
V
Khz
80
85
%
%
Note :
1.
Diode: Schottky type, such as: 1N5817, 1N5819, 1N5822
2.
Inductor: 27uH(R<0.5Ω)
3.
Capacitor: 100uF (Tantalum type)
Typical Application Circuit
D 1N5819
Vin
Vout
L 27uH
LX
Cin 47uF
LX OUT
ACE701D
GND
Iout
Cout
100uF
Rload
Tan
VER 1.3
4
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Detailed Description
The ACE701D series are boost structure, voltage-type pulse-frequency modulation(PFM) step-up
DC-DC converter. Only three external components are necessary: an inductor, an output filter capacitor
and a schottky diode. And the converter’s low noise and low ripple output voltage can be adjusted from
2.5V to 5.0V, 0.1V step. By using the depletion technics, the quiescent current drawn from power source
is lower than 7uA. 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.
The PFM control circuit is the core of the ACE701D IC. This block controls power switch on duty cycle 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 ACE701D 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.
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,
ACE701D 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
VER 1.3
5
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
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 r L,Rload is load
resistor,then the energy can be calculated by following expression:
Δη≈ RL / Rload (1-D)2
For example: input 1.5V, output is 3.0V, Rload=20Ω, rL=0.5Ω, The energy loss is 10%.
Consider all above,inductor value of 47uH、ESR<0.5Ω is recommended in most applications. Large
value is recommended in high efficiency applications and smaller value is recommended
(2) Capacitor Selection
Ignore ESR of capacitor,the ripple of output voltage is:
R=ΔVout / Vout=D / Rload Cf
So large value capacitor is needed to reduce ripple. But too large capacitor value will slow down system
reaction and cost will improve. So 100uF capacitor is recommended. Larger capacitor value will be used
in large output current system. If output current is small (<10mA), small value is needed.
Consider ESR of capacitor,ripple will increase:
r'=r+Imax•RESR / Vout
When current is large, ripple caused by ESR will be main factor. It may be greater than 100mV。The ESR
will affects efficiency and increase energy loss. So low-ESR capacitor (for example: tantalum capacitor) is
recommend or connect two or more filter capacitors in parallel.
(3) Diode Selection
Rectifier diode will affects efficiency greatly,Though a common diode (such as 1N4148) will work well for
light load,it will reduce about 5%~10% efficiency for heavy load,For optimum performance, a Schottky
diode (such as 1N5817、1N5819、1N5822) is recommended.
(4) Input Capacitor
If supply voltage is stable, the DC-DC circuit can output low ripple, low noise and stable voltage without
input capacitor. If voltage source is far away from DC-DC circuit, input capacitor value greater than 10uF
is recommended.
VER 1.3
6
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Test Circuits
(1) Output voltage test circuit (Iload=1mA)
ACE701D
(2) Start-up voltage test circuit (Iload=1mA)
ACE701D
(3) Hold-on voltage test circuit (Iload=1mA)
ACE701D
VER 1.3
7
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
(4) Quiescent current test circuit
ACE701D
Note: Vout=Vout_nom*1.05, R=1KΩ, C=0.1uF
(5) Oscillator frequency and duty cycle test circuit
ACE701D
Oscillograph
Note: Vin=Vout*0.95, R=1KΩ
Electrical Characteristics
VER 1.3
8
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Typical Characteristic (Recommended operating conditions: Cin=47uF, Cout=47uF, Topt=25℃, unless otherwise noted)
VER 1.3
9
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Typical Characteristic(Recommended operating conditions: Cin=47uF, Cout=47uF, Topt=25℃, unless otherwise noted)
VER 1.3
10
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Packing Information
SOT-89-3
SOT-23-5
VER 1.3
11
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Packing Information
SOT-23-3L
VER 1.3
12
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
Packing Information
TO-92
VER 1.3
13
ACE701D
PFM STEP-UP DC/DC Converter with High Efficiency and Low Noise
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 1.3
14
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