BELLING BL8534 High efficiency low noise pfm step-up dc/dc converter Datasheet

BL8534
High Efficiency Low Noise PFM Step-up DC/DC Converter
DESCRIPTION
FEATURES
BL8534 series are CMOS-based PFM stepup 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 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.
•
•
•
•
•
•
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.
•
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
APPLICATIONS
BL8534 integrates stable reference circuits
and trimming technology, so it can afford high
precision and low temperature-drift coefficient
of the output voltage.
•
•
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,
SOT-23-5 and TO-92 packages that are PB
free. And in 5-pin packages, such as SOT-235, the device can be switch on or off easily by
CE pin, to minimize the standby supply
current.
•
TYPICAL APPLICATION
ELECTRICAL CHARACTERISTICS
LC3000CC3TR33
BL8534
Output Voltage(V)
4
BL8534
3
2
VIN=1.2V
VIN=1.5V
VIN=2V
1
VIN=2.5V
VIN=3V
0
0
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1
200
400
600
Output Current(mA)
800
BL8534
ORDERING INFORMATION
BL8534 □
1 □
2 □
3 □
4
Code
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
1
□
2
□
3
□
4
□
MARKING DESCRIPTION
Product Classification
BL8534CB3TR□□ Product Classification
Marking
Marking
LD: Product Code
LD: Product Code
LDXZZ X: Output Voltage
LDXZZ X: Output Voltage
ZZ: Date Code
Product Classification
Marking
LDXX LD: Product Code
XX: Output Voltage
YY: LOT NO.
YYBZZ
B: FAB Code
ZZ: Date Code
BL8534CB5TR□□
ZZ: Date Code
BL8534CC3TR□□ Product Classification
BL8534CHBG□□
Marking
LDXX LD: Product Code
XX: Output Voltage
YY: LOT NO.
YYBZZ
B: FAB Code
ZZ: Date Code
LD: Product Code;
X: Output voltage for SOT-23-3 and SOT-23-5;
XX: Output voltage for SOT-89-3 and TO-92. 25 stands for 2.5V, 60 stands for 6.0V;
Z: The Year of manufacturing, ”7” stands for year 2007, ”8” stands for year 2008;
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.
Output Voltage Code For SOT-23-3 and SOT-23-5
Vout
2.5V
Code
5
Vout
3.0V
Code
0
Vout
3.8V
Code
8
Vout
4.5V
Code
5
2.7V
7
3.3V
3
4.0V
0
5.0V
0
2.8V
8
3.6V
6
4.2V
2
6.0V
0
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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)
Power Dissipation
SOT-23-3
SOT-23-5
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
Min
Input Voltage Range
Inductor
Input Capacitor
Output Capacitor
Ambient Temperature
0.8
10
0
47
-40
Recommended
Max.
Unit
Vout
100
V
≥10
85
BLOCK DIAGRAM
BL8534
Note: CE pin is only available on 5 pins packages.
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3
µH
µF
µF
°C
BL8534
PIN DESCRIPTION
CE
Chip Enable (Active high)
Vss
Ground
OUT
Output, Power supply for internal
LX
Switching Pin
NC
Not Connected
ELECTRICAL CHARACTERISTICS
SYMBOL ITEM
Vout_rt
Rated Output
Voltage
Iin
Input Current
Vstart
Start-up Voltage
Vhold
Hold-on Voltage
IDD
Rswon
ILXleak
Quiescent
Current drawn
From Power
Source
Switch ON
Resistance
LX Leakage
Current
CE “H”
Threshold
Voltage
CE “L”
VCEL
Threshold
Voltage
Oscillator
Fosc_max
Frequency
Minimum Off
TOFF_MIN
Time
Oscillator Duty
Maxdty
Cycle
VCEH
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TEST CONDITIONS
Iout=0mA,
Vout=Vout*0.6
Iout=1mA,
VS:0→2V
Iout=1mA,
VS:2→0V
REFERENCE DATA
Min
2.45
2.646
2.94
3.234
3.528
3.92
4.9
5.88
0.6
Without external
components, Vout
=Vout_rt×1.05
Max
2.55
2.754
3.06
3.366
3.672
4.08
5.1
6.12
15
20
uA
0.8
0.9
V
0.7
4
VCE:0→2V
0.5
7
5
0.3
70
4
uA
V
VCE: 2→0V
LX on “L” side
uA
Ω
0.8
LX on “L” side
Vout=Vout_rt*0.96
V
V
0.8
Vout=VLx=6V
(VCE=0V in 5 pins
packages)
UNIT
Typ
2.5
2.7
3.0
3.3
3.6
4.0
5.0
6.0
V
150
KHz
1.4
uS
75
80
%
BL8534
DETAILED DESCRIPTION
The BL8534 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 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.
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
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.
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.
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 inside BL8534 provides fixed
frequency and pulse width wave.
COMPONENTS SELECTION
boost DC-DC to operate in the continuous
current-mode condition.
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 ≥
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.
VOUT − VIN
VOUT
INDUCTOR SELECTION
Above all, we should define the minimum
value of the inductor that can ensure the
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D( 1 − D)2 RL
2f
Secondly, consider the ripple of the output
voltage,
5
BL8534
∆I =
CAPACITOR SELECTION
DVIN
Lf
I MAX =
Ignore ESR of capacitor,the ripple of output
voltage is:
VIN
DVIN
+
2
(1 − D) RL 2 Lf
r=
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.
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.
Consider ESR of capacitor , ripple will
increase:
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.
r' = r +
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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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 :
∆η ≈
∆VOUT
D
=
VOUT
RLOAD Cf
6
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
L=47uH
20
10
0
0
1
1.5
2
2.5
1
3
1.5
Input Voltage(V)
3
4
Output Voltage(V)
4
Output Voltage(V)
2.5
Output Voltage VS Output Current
Output Voltage VS Output Current
3
VIN=1.2V
2
VIN=1.5V
L=10uH
VIN=2V
1
VIN=2.5V
0
200
400
600
3
VIN=1.2V
2
VIN=1.5V
L=47uH
VIN=2V
1
VIN=2.5V
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%
Efficiency(%)
80%
Efficiency(%)
2
Input Voltage(V)
60%
VIN=1.2V
40%
VIN=1.5V
L=10uH
VIN=2V
20%
80%
60%
VIN=1.2V
L=47uH
40%
VIN=1.5V
VIN=2V
VIN=2.5V
20%
VIN=3V
VIN=2.5V
0%
VIN=3V
0%
1
10
100
1
1000
Load Current(mA)
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10
100
Load Current(mA)
8
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
Output Ripple VS Load Current
250
Output Ripple(mV)
Output Ripple(mV)
100
80
60
VIN=1.2V
L=10uH
VIN=1.5V
40
VIN=2V
VIN=2.5V
20
VIN=3V
150
VIN=1.2V
L=47uH
100
VIN=1.5V
VIN=2V
50
VIN=2.5V
VIN=3V
0
0
200
400
600
0
800
0
Load Current(mA)
1.0
0.8
0.6
0.4
L=47uH
0.2
L=10uH
0.0
0
5
10
15
20
Output Current(mA)
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100
200
300
400
500
Load Current(mA)
Minimum Start Up Voltage VS Output Current
Input Voltage(V)
200
9
600
700
BL8534
PACKAGE LINE
Package
SOT-23-3
Devices per reel
3000Pcs
Unit
mm
Devices per reel
3000Pcs
Unit
mm
Package dimension:
Package
SOT-23-5
Package specification:
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BL8534
PACKAGE LINE (Continued)
Package
SOT-89-3
Devices per reel
1000Pcs
Unit
mm
Devices per Bag
1000Pcs
Unit
mm
Package Dimension:
Package
TO-92
Package Dimension:
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