Advanced Power
Electronics Corp.
FEATURES
Very Low Supply Current is 22uA (typ.)
Maximum Shutdown Current <1uA
Output Voltage is Available form 2.5V to 5.0V
by 0.1V Steps
Output Voltage Accuracy ±5%
Output Current up to 100mA
Low Ripple and Low Noise
Very Low Start-up Voltage
High Efficiency (Vout = 5V TYP. 87%)
Few External Components
Internal Soft-Start
Low Profile: SOT-23-5L Pb-Free
APE2902
DESCRIPTION
The APE2902 is a high efficiency VFM Step-up DC/DC
converter for small, low input voltage or battery powered
systems with ultra low quiescent supply current. The
APE2902 accept a positive input voltage from start-up
voltage to V
OUT
and convert it to a higher output voltage in
the 2.5 to 5V range.
The APE2902 combine ultra low quiescent supply
current and high efficiency to give maximum battery life. The
high switching frequency and the internally limited peak
inductor current permits the use of small, low cost inductors.
Only three external components are needed an inductor a
diode and an output capacitor.
The APE2902 is suitable to be used in battery powered
equipment where low noise, low ripple and ultra low supply
current are required. Operating shutdown function is outside
controlling. If EN connects to GND, the IC was been shut
down and then the supply current is lower to 1uA.The
APE2902 is available in very small package: SOT-23-5L.
Typical applications are pagers, cameras & video
camera, cellular telephones, wireless telephones, palmtop
computer, battery backup supplies, battery powered
equipment.
MICROPOWER VFM STEP-UP DC/DC CONVERTER
TYPICAL APPLICATION
VIN
1
L1
47uH
D1
B140
2
1
2
VOUT
C1
100uF
C2
0.1uF
U1
NC
EN
SW
GND
OUT
C4
0.1uF
C3
47uF
Enable Input
APE2902
ORDER/MARKING INFORMATION
APE2902XX-XX
Vout
Package Type
22 : 2.2V
Y5 : SOT-23-5L
25 : 2.5V
Y5R : SOT-23-5L
26 : 2.6V
27 : 2.7V
:
:
50 : 5.0V
t&XYW
WW : 01~26(A~Z)
27~52(A~Z)
Year : 8 = 2008
A = 2010
Identification Code
Identification Code see page8.
Data and specifications subject to change without notice
1
200907313
Advanced Power
Electronics Corp.
ABSOLUTE MAXIMUM RATINGS
(T
A
= 25
VIN Supply Voltage(V
IN
) …………………………… 5.5 V
SW Voltage(V
SW
) …………………………………… 5.5 V
OUT Voltage(V
OUT
) …………………………………
5.5 V
EN Pin Voltage(V
EN
) ………………………………… 5.5 V
Power Dissipation(P
D
) ……………………………… ( T
J
-T
A
) / R
thja
W
Storage Temperature Range(T
ST
) ………………… -40°C To 150°C
Operating Junction Temperature Range(T
OP
) …… -20°C To + 100°C
Thermal Resistance from Junction to Case(Rth
JC
)
Thermal Resistance from Junction to Ambient(Rth
JA
)
o
APE2902
C)
110°C/W
250°C/W
Note : Rth
JA
is measured with the PCB copper area of approximately 1 in2(Multi-layer).
PACKAGE INFORMATION
Top View
NC
EN
5
4
Top View
GND
SW
5
4
AP2902Y5
1
2
3
AP2902Y5R
1
2
3
SW
GND
VOUT
SOT-23-5L
EN
VOUT
NC
SOT-23-5L
ELECTRICAL SPECIFICATIONS
( V
IN
=1.8V, I
OUT
=10mA, T
A
=25
o
C, unless otherwise specified)
Parameter
Output Voltage Accuracy
Start-up Voltage(V
IN
-V
F
)(Note 1)
Hold-on Voltage
Supply Current
Shutdown Current
Internal Switch R
DSON
Internal Leakage Current
Maximum Oscillator Frequency
Oscillator Duty On
Enable Input Threshold
Enable Input Current
SYM
△V
OUT
V
START-UP
V
HOLD
I
SUPPLY
I
SD
R
SW(DSON)
I
SW(leak)
F
OSC
D
ON
V
ENH
V
ENL
I
ENH
I
ENL
η
To be measured on SW pin
Driver ON
Driver OFF
V
EN
=V
IN
V
EN
=0V
Vout=2.5V~3.0V, I
OUT
=50mA
EFFICIENCY
Vout=3.1V~4.0V, I
OUT
=50mA
Vout=4.1V~5.0V, I
OUT
=50mA
Note 1: The minimum input voltage for the IC start-up is strictly a function of the VF catch diode.
TEST CONDITION
I
OUT
=1mA, V
IN
=rising from 0 to 2V
I
OUT
=1mA, V
IN
=falling from 2 to 0V
No Load
V
EN
=0V
I
SW
=150mA
V
SW
=4V, Forced V
OUT
=3.8V
MIN
-5
-
0.6
-
-
-
-
-
-
0.75
-
-
-
-
-
-
TYP
-
0.8
-
22
-
850
-
150
77
-
-
-
-
82
83
87
MAX
5
1.2
-
-
1
-
0.5
-
-
-
0.2
0.1
-0.1
-
-
-
UNITS
%
V
V
uA
uA
mΩ
uA
KHz
%
V
uA
%
%
%
2
Advanced Power
Electronics Corp.
PIN DESCRIPTIONS
PIN SYMBOL
SW
GND
OUT
EN
PIN DESCRIPTION
Switch Pin. Connect External Inductor & Diode here.
GND Pin
Output Voltage
APE2902
Chip Enable Pin
BLOCK DIAGRAM
OUT
-
V
REF
LIMITER AMP.
VFM
CONTROL
ERROR AMP.
Driver
Chip Enable
GND
EN
OPERATION
The APE2902 architecture is built around a VFM CONTROL logic core, switching
frequency is set through a built in oscillator. T
ON
time is fixed (Typ. 5uS) while T
OFF
time is
determined by the error amplifier output, a logic signal coming from the comparison made
by the Error Amplifier Stage between the signal coming from the output voltage divider
network and the internal Band-Gap voltage reference (Vref). T
OFF
reaches a minimum
(Typ. 1.7us) when heavy load conditions are met (Clock frequency 150KHz). An over
current conditions, through the internal power switch, causes a voltage drop V
SW
=R
DS(ON)
x I
SW
and the V
SW
limiter block forces the internal switch to be off, so narrowing T
ON
time
and limiting internal power dissipation. In this case the switching frequency may be higher
than the 150KHz set by the internal clock generator.
VFM control ensures very low quiescent current and high conversion efficiency even
with very light loads. Since the Output Voltage pin is also used as the device Supply
Voltage, the versions with higher output voltage present an higher internal supply voltage
that results in lower power switch R
DS(ON)
, slightly greater output power and higher
efficiency. Moreover, bootstrapping allows the input voltage to sag to 0.6V (at I
OUT
=1mA)
once the system is started. If the input voltage exceeds the output voltage, the output will
follow the input, however, the input or output voltage must not be forced above 5.5V.
3
+
SW
-
+
Advanced Power
Electronics Corp.
APPLICATION INFORMATION
Input/Output Capacitor Selection
APE2902
The Output Ripple Voltage, as well as the Efficiency, is strictly related to the behavior
of these elements. The output ripple voltage is the product of the peak inductor current
and the output capacitor Equivalent Series Resistance (ESR). Best performances are
obtained with good high frequency characteristics capacitors and low ESR. The best
compromise for the value of the Output Capacitance is 47µF Tantalum Capacitor; Lower
values may cause higher Output Ripple Voltage and lower Efficiency without
compromising the functionality of the device.
An Input Capacitor is required to compensate, if present, the series impedance
between the Supply Voltage Source and the Input Voltage of the Application.
Inductor Selection
A 47µH inductor is recommended for most APE2902 applications. However, the
inductance value is not critical, and the APE2902 will work with inductors in the 33µH to
120µH.
Diode Selection
Schottky diodes with higher current ratings usually have lower forward voltage drop,
larger diode capacitance and fast reverse recovery, it is the ideal choices for APE2902
applications. The forward voltage drop of a Schottky diode represents the conduction
losses in the system, while the diode capacitance (C
T
or C
D
) represents the switching
losses. For diode selection, both forward voltage drop and diode capacitance need to be
considered.
PCB layout guide
When laying out the PC board, the following suggestions should be taken to ensure
proper operation of the APE2902. These items are also illustrated graphically in below.
1. The power traces, including the G
ND
trace, the SW trace and the V
IN
trace should be
kept short, direct and wide to allow large current flow. Put enough multiply-layer pads
when they need to change the trace layer.
2. Do not trace signal line under inductor.
4
Advanced Power
Electronics Corp.
TYPICAL PERFORMANCE CHARACTERISTICS
APE2902
T
A
=25
℃
, Input Voltage vs. Output Voltage
3.50
IOUT=50mA, Output Voltage vs. Temperature
3.05
3.00
V
IN
=2.4V
Output Vlotage (V)
Output Voltage (V)
2.50
V
IN
=0.9V
V
IN
=1.2V
V
IN
=1.8V
V
IN
=1.5
3.00
V
IN
=2.4V
V
IN
=1.8V
VIN=1.2V
2.00
2.95
1.50
2.90
1.00
2.85
0.50
0.00
2.80
17
5
10
0
12
5
15
0
20
0
22
5
25
0
10
50
25
75
Output Current (m A)
Temperature (
℃
)
VIN=1.8V, Output Voltage vs. Temperature
3.10
3.00
1.0
0.9
0.8
Start-up Voltage vs. Output Current
Output Vlotage (V)
Start-up Vlotage (V)
2.90
2.80
2.70
2.60
2.50
2.40
2.30
25
50
-2
0
0
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
I
OUT
=50mA
I
OUT
=0mA
I
OUT
=100mA
I
OUT
=150mA
I
OUT
=200mA
I
OUT
=250mA
Temperature (
℃
)
10
0
75
Output Current (mA)
IOUT=1mA, Start-up Voltage vs. Temperature
1.0
0.9
IOUT=1mA, Hold-On Voltage vs. Temperature
0.4
0.4
Start-up Vlotage (V)
Hold-On Vlotage (V)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0.3
0.3
0.2
0.2
0.1
0.1
0.0
10
0
10
0
25
50
-2
0
-2
0
Temperature (℃)
Temperature (
℃
)
75
25
50
75
0
0
10
0
25
50
10
75
1
10
0
50
-2
0
25
75
0
0
5
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