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BL8534
High Efficiency Low Noise PFM Step-up DC/DC Converter
DESCRIPTION
FEATURES
BL8534 series are CMOS-based PFM step-up DCDC 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
20uA. All of these features make BL8534 series be
suitable for the portable devices, which are
supplied by a single battery to four-cell batteries.

Deliver 200mA at 3.3V Output voltage with
1.8V input Voltage
Low start-up voltage (when the output
current is 1mA)----------------------------------0.8V
Output voltage can be adjusted from 2.5V to
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
Low quiescent current drawn from power
source-------------------------------------------<20uA





To reduce the noise caused by the switch
regulator, BL8534 is well considerated in circuit
design and manufacture, so that the interferer to
other circuits by the device is reduced greatly.

BL8534 integrates stable reference circuits and
trimming technology, so it can afford high
precision and low temperature-drift coefficient of
the output voltage.
APPLICATIONS

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

BL8534 is available in SOT-89-3, SOT-23-3, SOT23-5 and TO-92 packages that are PB free. And in
5-pin packages, such as SOT-23-5, the device can
be switch on or off easily by CE pin, to minimize
the standby supply current.

TYPICAL APPLICATION
ELECTRICAL CHARACTERISTICS
D1
L1
VIN
BL8534CC3TR33
1N5819
4
VOUT
LX
47uH
VOUT
C1
47uF
OFF
Output Voltage(V)
LC3000
BL8534
ON
CE
GND
C2
100uF
GND
3
2
VIN=1.2V
VIN=1.5V
1
VIN=2V
VIN=2.5V
VIN=3V
0
0
200
400
Output Current(mA)
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1
600
800
BL8534
PIN CONFIGURATION
Product Classification
00: Product Code
ORDERING INFORMATION
BL8534 □1 □2 □3 □4
BL8534CB3TR□□
Code
□1
XX: Output Voltage
Product Classification
00: Product Code
□2
BL8534CB5TR□□
□3
XX: Output Voltage
Product Classification
LD: Product Code
XX: Output Voltage
YY: LOT NO.
B: FAB Code
ZZ: Date Code
Product Classification
LD: Product Code
XX: Output Voltage
YY: LOT NO.
B: FAB Code
□4
BL8534CC3TR□□
BL8534CHBG□□
ZZ: Date Code
CE
Chip Enable (Active high)
Vss
Ground
OUT
Output, Power supply for internal
LX
Switching Pin
NC
Not Connected
Z: The Year of manufacturing, ”9” stands for year
2009, ”0” stands for year 2010;
Z: The week of manufacturing. ”A” stands for week
1, ”Z” stands for week 26, ” A ” stands for week 27, ”
Z ” stands for week 52.
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Description
Temperature & Rohs:
C: -40~85C, Pb Free Rohs Std.
Package type:
B3: SOT-23-3
B5: SOT-23-5
C3: SOT-89-3
H: TO-92
Packing type:
TR: Tape & Reel (Standard)
BG: Bag (TO-92)
Output voltage
e.g. 25=2.5V
33=3.3V
60=6.0V
BL8534
ABSOLUTE MAXIMUM RATING
Parameter
Value
Max Input Voltage
CE Pin Voltage
Lx Pin Output Current
Lx Pin Voltage
Operating Junction Temperature (TJ)
Ambient Temperature (TA)
SOT-23-3
SOT-23-5
Power Dissipation
SOT-89-3
TO-92
Storage Temperature (Ts)
Lead Temperature & Time
-0.3V-10V
-0.3V-(Vout+0.3)
0.7A
10V
125C
-40C -85C
250mW
250mW
500mW
500mW
-40C -150C
260C, 10Sec
Note:
Exceed these limits to damage to the device.
Exposure to absolute maximum rating conditions may affect device reliability.
RECOMMENDED WORK CONDITIONS
Item
Input Voltage Range
Inductor
Input Capacitor
Output Capacitor
Ambient Temperature
Min
Recommended
0.8
10
0
47
-40
Max.
Unit
Vout
100
V
μH
μF
μF
C
≥10
85
BLOCK DIAGRAM
BL8534
Note: CE pin is only available on 5 pins packages.
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BL8534
ELECTRICAL CHARACTERISTICS
SYMBOL
ITEM
Vout_rt
Rated Output Voltage
Iin
Vstart
Vhold
Input Current
Start-up Voltage
Hold-on Voltage
Quiescent Current drawn
From Power Source
Switch ON Resistance
IDD
Rswon
ILXleak
LX Leakage Current
VCEH
VCEL
Fosc_max
TOFF_MIN
Maxdty
CE “H” Threshold Voltage
CE “L” Threshold Voltage
Oscillator Frequency
Minimum Off Time
Oscillator Duty Cycle
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TEST CONDITIONS
Iout=0mA，Vout=Vout*0.6
Iout=1mA，VS：02V
Iout=1mA，VS：20V
Without external components,
Vout =Vout_rt×1.05
REFERENCE DATA
Min
2.45
2.646
2.94
3.234
3.528
3.92
4.9
5.88
0.6
Typ
2.5
2.7
3.0
3.3
3.6
4.0
5.0
6.0
15
0.8
0.7
Max
2.55
2.754
3.06
3.366
3.672
4.08
5.1
6.12
20
0.9
4
7
0.8
Vout=VLx=6V
(VCE=0V in 5 pins packages)
VCE：02V
VCE： 20V
LX on “L” side, Vout=Vout_rt*0.96
0.8
LX on “L” side
70
4
0.5
V
uA
V
V
uA
Ω
5
0.3
350
1.4
75
UNIT
80
uA
V
V
KHz
uS
％
BL8534
DETAILED DESCRIPTION
The BL8534 series are boost structure, voltagetype 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 techniques, 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.
inside BL8534 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/℃。
The PFM control circuit is the core of the BL8534.
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
Though at very low load condition, the quiescent
current of chip do affect 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, BL8534 integrates low onresistor N-channel MOSFET and well design driver
circuits. The switch energy loss is limited at very
low level.
High-gain differential error amplifiers 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.
COMPONENTS SELECTION
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 ripple voltage 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
LMIN 
D( 1  D)2 RL
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 DCDC circuit will not be stable.
VOUT  VIN
VOUT
INDUCTOR SELECTION
Secondly, consider the ripple of the output
voltage,
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.
I 
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DVIN
Lf
BL8534
I MAX 
CAPACITOR SELECTION
VIN
DVIN

2
(1  D) RL 2 Lf
Ignore ESR of capacitor，the ripple of output
voltage is:
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.
r
VOUT
D

VOUT
RLOADCf
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.
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.
Consider ESR of capacitor，ripple will increase：
r' r 
I MAX RESR
VOUT
When current is large, ripple caused by ESR will
be main factor. It may be greater than 100mV。
The ESR will affect efficiency and increase energy
loss. So low-ESR capacitor (for example: tantalum
capacitor) is recommend or connects two or
more filter capacitors in parallel.
The ESR of inductor will affect efficiency greatly.
Suppose ESR value of inductor is rL，Rload is load
resistor，then the energy can be calculated by
following expression ：
DIODE SELECTION
 
rL
Rload (1  D) 2
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.
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
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BL8534
TEST CIRCUITS
BL8534
Figure 1: Output voltage test circuit (IOUT=1mA)
BL8534
Figure 2: Start-up voltage test circuit (IOUT =1mA)
BL8534
Figure 3: Hold-on voltage test circuit (IOUT =1mA)
BL8534
Figure 4: Quiescent current test circuit (VS=Vout_rt*1.05，R=1KΩ，C=0.1uF)
BL8534
Figure 5: Oscillator frequency and duty cycle test circuit (VS=Vout_rt*0.95，R=1KΩ)
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BL8534
TYPICAL PERFORMANCE CHARACTERISTICS
Recommended operating conditions: Cin=47uF, Cout=100uF, Topt=25C. (Unless otherwise noted)
And all the tests below are made on BL8534CC3TR33.
Quiescent Current VS Input Voltage
Quiescent Current VS Input Voltage
50
Quiescent Current(uA)
Quiescent Current(uA)
50
40
30
L=10uH
20
10
40
30
20
L=47uH
10
0
0
1.0
1.5
2.0
2.5
3.0
1.0
1.5
Input Voltage(V)
2.5
Output Voltage VS Output Current
4
Output Voltage(V)
4
3
2
VIN=1.2V
L=10uH
VIN=1.5V
1
VIN=2V
3
2
VIN=1.2V
L=47uH
VIN=1.5V
1
VIN=2V
VIN=2.5V
VIN=2.5V
0
200
400
600
VIN=3V
0
VIN=3V
0
0
800
200
400
600
800
Output Current(mA)
Output Current(mA)
Efficiency VS Load Current
Efficiency VS Load Current
100%
100%
80%
Efficiency(%)
Efficiency(%)
3.0
Input Voltage(V)
Output Voltage VS Output Current
Output Voltage(V)
2.0
60%
40%
VIN=1.2V
L=10uH
VIN=1.5V
20%
80%
60%
L=47uH
40%
VIN=1.2V
VIN=1.5V
VIN=2V
VIN=2.5V
VIN=3V
20%
VIN=2V
VIN=2.5V
0%
VIN=3V
0%
1
10
100
1000
Load Current(mA)
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1
10
Load Current(mA)
100
1000
BL8534
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
Recommended operating conditions: Cin=47uF, Cout=100uF, Topt=25C. (Unless otherwise noted)
And all the tests below are made on BL8534CC3TR33.
Output Ripple VS Load Current
250
100
90
80
70
60
50
40
30
20
10
0
L=10uH
0
200
Output Ripple(mV)
Output Ripple(mV)
Output Ripple VS Load Current
VIN=1.2V
VIN=1.5V
VIN=2V
VIN=2.5V
VIN=3V
400
600
0
L=47uH
L=10uH
15
20
Input Voltage(V)
Output Current(mA)
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VIN=1.2V
VIN=1.5V
VIN=2V
VIN=2.5V
VIN=3V
100
200
300
400
Load Current(mA)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
10
L=47uH
100
0
800
Minimum Start Up Voltage VS Output Current
5
150
50
Load Current(mA)
0
200
9
500
600
700
BL8534
PACKAGE LINE
Package
SOT-23-3
Devices per reel
3000Pcs
Unit
mm
3000Pcs
Unit
mm
Package dimension：
Package
SOT-23-5
Devices per reel
Package dimension：
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BL8534
PACKAGE LINE (Continued)
Package
SOT-89-3
Devices per reel
1000Pcs
Unit
mm
TO-92
Devices per Bag
1000Pcs
Unit
mm
Package dimension：
Package
Package dimension：
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