Anpec APW7071 White led dc/dc step-up converter Datasheet

APW7071
White LED DC/DC Step-Up Converter
Features
General Description
•
2.4V to 6V Input Voltage Range
•
•
400mA, Internal Switch Current
Up to 1MHz Switching Frequency
•
70µA Typical No Load Quiescent Current
•
0.1µA Typical Shutdown Current
•
•
•
Internal Soft-start
Available in a Tiny 6-Pin SOT-23 Package
Up to 87% efficiency
The APW7071 is a high frequency step up DC/DC
converter in a small 6 leads SOT-23 package specially designed to drive white LEDs with a constant
current. The device can drive up to 4 LEDS in a series
from one Li-Ion cell. The APW7071 is ideal for LCD
panels requiring low current and high efficiency as well
as white LED applications for cellular phone backlighting.
•
Operating Output Capacitor down to 0.1µF
•
•
Over Voltage Protection included
Lead Free Available (RoHS Compliant)
Package Pin Out
V IN
Applications
•
Cellar Phones White LED Back Light
•
•
•
PDAs, Handheld Computers
Digital Still Cameras
MP3 Players
•
GPS Receivers
OVP SHDN
6
5
1
2
4
3
SW GND FB
SOT-23-6 (Top View)
APW7071
Ordering and Marking Information
APW7071
Package Code
C : SOT-23-6
Operating Junction Temp. Range
E : -40 to 85°C
Handling Code
TU : Tube
TR : Tape & Reel
Lead Free Code
L : Lead Free Device
Blank : Original Device
Lead Free Code
Handling Code
Temp. Range
Package Code
APW7071 C :
W71X
XXXXX - Date Code
Notes: ANPEC lead-free products contain molding compounds/die attach materials and 100% matte in plate
termination finish; which are fully compliant with RoHS and compatible with both SnPb and lead-free soldiering
operations. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J STD-020C for
MSL classification at lead-free peak reflow temperature.
ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and advise
customers to obtain the latest version of relevant information to verify before placing orders.
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
1
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APW7071
Block Diagram
OVP(5)
Under
Voltage
Lockout
VIN(6)
Thermal
Shutdown
SW(1)
OVP
+
400ns Min.
off-time
Error
Comparator
FB(3)
+
Vref=0.25V
Control
Logic
6us Max.
on-time
Gate
Driver
N-MOSFET
Current Limit
+
-
RSENSE
Soft
start
SHDN(4)
GND(2)
Pin Description
No
Name
1
SW
2
GND
3
FB
4
SHDN
5
OVP
6
Vin
Function
Switch Pin. Connect to inductor/diode here. Minimize trace area at this
pin to educe EMI.
Ground Pin.
Feedback Pin. Reference voltage is 0.25V. Connect cathode of
lowest LED and resistor here. Calculate resistor value according to
RFB = 0.25V/l LED
Shutdown Pin. Tie to 1.3V or higher to enable device, 0.4V or less to
disable.
Over voltage protection sense pin. Connect this pin to VOUT for over
voltage protection.
Supply voltage Pin.
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
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APW7071
Absolute Maximum Ratings
Symbol
Vin
FB
SHDN
SW
TJ
TSTG
Parameter
Supply voltage
Feedback Voltage
Shutdown Voltage
Switch Voltage
Junction Temperature Range
Storage Temperature Range
Rating
7
7
7
20
150
-40 to +150
Unit
V
V
V
V
°C
°C
Recommend Operating Conditions
Symbol
Vin
Vsw
L
Cin
Cout
Ta
Tj
Parameter
Min.
2.4
Vin
Input supply voltage
Switch voltage
Inductor
Input capacitor
Output capacitor
Operating ambient temperature
Operating junction temperature
Value
Typ.
Unit
Max.
6.0
18
V
V
µH
µF
µF
°C
°C
4.7
4.7
0.1
-40
-40
85
125
Electrical Characteristics
VIN=2.4V, EN=VIN, TA=-40°C to +85°C, typical values are at TA=+25°C (unless otherwise noted)
Symbol
Parameter
Test Condition
Supply Voltage and Current
Vin
Input Voltage Range
Iq
Isd
UVLO
Operating quiescent current
Shutdown current
Under-Voltage Lockout threshold
Under-Voltage Lockout
hysteresis
ENABLE
VIH
SHDN high level input voltage
VIL
SHDN low level input voltage
Ii
SHDN input leakage current
Power Switch and Current limit
Vsw
Maximum switching voltage
toff
Minimum off-time
ton
Maximum on-time
Rds,on
ILIM
MOSFET on-resistance
MOSFET leakage current
MOSFET current limit
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
Min.
APW7071
Typ. Max.
2.4
Iout=0, not switching,
VFB=0.3V
SHDN=GND
6
V
70
90
µA
0.1
1
2.3
µA
V
2.1
100
mV
1.3
0.1
0.4
1
V
V
µA
350
4
400
6
20
500
7.5
V
ns
µs
350
600
1
400
1000
10
450
mΩ
µA
mA
SHDN=GND or VIN
Vin=2.4V, Isw=200mA
Vsw=20V
3
Unit
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APW7071
Electrical Characteristics (Cont.)
Symbol
Parameter
OUTPUT
Vout
IFB
VFB
Test Condition
Min.
Adjustable output voltage range
Feedback input bias current
VFB=0.3V
2.4≦VIN≦6.0V
Feedback trip point voltage
OVP threshold
OVP hysteresis
APW7071
Typ. Max.
Vin
0.237
16
5
0.25
17
6
Unit
18
1
0.263
18
7
V
µA
V
V
V
Typical Application Circuit
D1
MSCD052
L1
Vin
Vout
4.7µH
2.7V~6V
C1
4.7µF
6
VIN
SW
1
C1
4.7µF
6
VIN
SW
1
off on
GND
4
SHDN
OVP
FB
5
2
3
off on
Fig.1 Typical 4LED application
Rev. A.1 - Feb., 2006
GND
4
SHDN
OVP
FB
5
3
R1
13
R1
13
Copyright  ANPEC Electronics Corp.
C2
1µF
0.1µF
2
Vout
10µH
2.4V~6V
C2
D1
MSCD052
L1
Vin
Fig.2 4LED application with
lower output voltage ripple
4
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APW7071
Typical Characteristics
(Circuit of Figure 1, VIN = 3.3V, ILED = 15mA, L1 = 4.7µH, CIN = 4.7µF, COUT = 0.1µF,4 LEDs,
TA = +25°C, unless otherwise noted.)
Efficiency vs LED Current
Efficiency vs Supply Voltage
90
90
88
88
Efficiency(%)
Vin=4.2V
86
Efficiency(%)
Vin=3.6V
84
Vin=2.7V
82
86
84
82
80
78
80
76
78
74
ILED=15mA
76
72
74
70
0.1
1
10
100
2
3
LED Current(mA)
4
5
6
Supply Voltage(V)
Switch Rds,on vs Supply Voltage
Switch Rds,on vs Temperature
0.7
0.6
0.6
0.5
Rds,on(Ω)
Rds,on(Ω)
0.5
0.4
0.3
0.4
0.3
0.2
0.2
0.1
0.1
Vin=3.3V
Ta=25°C
0
-40
0
2
3
4
5
6
Rev. A.1 - Feb., 2006
0
20
40
60
80
100
Temperature(°C)
Supply Voltage(V)
Copyright  ANPEC Electronics Corp.
-20
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APW7071
Typical Characteristics (Cont.)
Non-Switch Quiescent Current vs.
Supply Voltage
Non-Switch Quiescent Current vs.
Temperature
80
Non-Switch Quiescent Current(µA)
Non-Switch Quiescent Current(µA)
75
70
65
60
55
50
45
Ta=25°C
40
2
3
4
5
6
75
70
65
60
55
Vin=3.3V
50
-40
-20
0
20
40
60
80
100
Temperature(°C)
Supply Voltage(V)
Start-up Waveform
LED Current vs. Supply Voltage
LED Current(mA)
25
20
SHDN
2V/DIV
15
VOUT
5V/DIV
10
Input Current
100mA/DIV
L=4.7µH
5
Cout=0.1µF
4LED
0
1
2
3
4
5
6
1 ms/DIV
Supply Voltage(V)
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
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APW7071
Typical Characteristics (Cont.)
PFM Operation
OVP Waveform
VOUT(AC)
200mV/DIV
VOUT
5V/DIV
Vsw
10V/DIV
VFB
100mV/DIV
1 µs/DIV
20 ms/DIV
Burst Mode Operation
VOUT(AC)
200mV/DIV
Vsw
10V/DIV
VFB
100mV/DIV
2 µs/DIV
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
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APW7071
Function Descriptions
OPERATION
Over Voltage Protection (OVP)
The APW7071 operates in a pulse frequency modulation (PFM) scheme with constant peak current
control.The operation can be understood by referring
to the block diagram of Figure 1. The converter monitors the output voltage, and if the feedback voltage
falls below the reference voltage (typical 0.25V), the
internal switch turns on and the inductor current ramps
up. The switch turns off if the inductor current reaches
the internally set peak current (typical 400mA) or
maximum on-time detected. As the switch is turned
off, the inductor current ramps down to zero and
charge output capacitor through external Schottky
diode. The switch remains off for a minimum of 400
ns (typical), or until the feedback voltage drops below the reference voltage again. The operation frequency is up to 1MHz and is determined by the output current, current limit, inductor value, input voltage and output voltage. This regulation scheme is
inherently stable, allowing a wider selection range
OVP is integrated to prevent the output voltage
increase over the maximum switching voltage rating.
In some cases an LED may fail, this will result in
the feedback voltage always being zero. The device
will boost the output voltage higher and higher.
When the output voltage exceeds the OVP threshold voltage (typical 17V), the switch turns off. The
converter switch remains off until the output voltage
falls below the OVP threshold voltage.
Thermal Shutdown
A thermal shutdown function is integrated to shutdown device when junction temperature exceed
160°C. If thermal shutdown detected, converter
switch turn off until junction temperature falls bellow
120°C.
for the inductor and output capacitor.
Enable
Force SHDN pin greater than 1.3 V to enable the
device works in normal operation. Pulling SHDN pin
less than 0.4V to shut down reducing the shutdown
current to 0.1 µA (typical). The SHDN pin should
not be left floating.
Soft Start
The APW7071 limits this inrush current by increasing the current limit at start-up.
Under Voltage Lockout
Transients during powering on or instantaneous
glitches in the supply voltage can cause system
damage or failure. The undervoltage lockout circuit
turned the main switch off to prevent malfunction at
low input voltage.
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
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APW7071
Application Information
Setup the LED current
The LED current is controlled by the reference
voltage and resistor and R1 shows in Figure 1. The
Vin
C1
4.7µF
6
2
a. By an adjustable DC voltage
Uses a DC voltage to control the feedback voltage.
As the DC voltage increases, current starts flowing
down R3, R2 and R1. The loop will continue to
regulate the feedback voltage at 250mV. Thus the
current has to decrease through the LEDs by the
same amount of current as is being injected from
the DC voltage source. With a VDC from 0V to 3.
3V, the resistor values shown for R2 and R3 can
100Hz~300Hz
PWM
brightness
control
D1
MSCD052
L1
6
VIN
GND
4
SHDN
R1
13
c. By a filtered PWM signal
Brightness can be achieved by a filtered PWM
signal. The PWM signal above 5KHz is
recommended.
Vout
D1
MSCD052
L1
Vin
C2
1
3
FB
signal apply to SHDN
C1
4.7µF
6
VIN
SW
C2
1
0.1µF
2
GND
OVP
4
SHDN
FB
0.1µF
5
2
GND
4
R2
3
SHDN
R3
120K
Vout
4.7µH
2.7V~6V
SW
5
OVP
Fig. 4 Brightness Control by a PWM
4.7µH
2.7V~6V
C2
1
SW
Duty=100%, LED=20mA
Duty=0%, LED off
control the LED current from 0mA to 20mA.
C1
4.7µF
VIN
0.1µF
Brigtness control
Vin
Vout
4.7µH
2.7V~6V
current through the LEDs is given by the 250mV/R1.
D1
MSCD052
L1
OVP
FB
10K
R1
13
3.3V
PWM
brightness
0V
control
Duty=100%, LED off
Duty=0%, LED=20mA
Vadj=3.3V, LED off
Vadj=0V, LED=20mA
Fig. 3 Brightness Control by an
adjustable DC voltage
5
3
R2
10K
R3
120K
R4
10K
R1
13
C3
0.1uF
Fig. 5 Brightness Control by
a filtered PWM signal
b. By a PWM signal apply to SHDN
The PWM signal is applied to the SHDN pin of
the APW7071. The LEDs will switch between full
load to completely shut off. The average current
through the LEDs will increase proportionally to
the duty cycle of the PWM signal. Due to the soft
start function, the PWM signal should be 100Hz
to 300Hz.
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
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APW7071
Application Information (Cont.)
Inductor selection
Since the PFM peak current control scheme is
inherently stable, the inductor value does not affect
the stability of the regulator. The selection of the
inductor together with the nominal load current,
internal set peak current, input and output voltage of
the application determines the switching frequency
of the converter. For the LED application, inductor
values between 2.2 µH up to 10 µH are
recommended.
Recommended inductors
Part No.
LQH32CN4R7M23L
Value(µH)
4.7
Recommended output capacitor
Part No.
Value
GRM185R61C105KE44D 1.0µF/X5R/
0603/16V
Any
0.22µF
Any
0.1µF
Vender
Murata
Any
Any
Input capacitor selection
For good input voltage filtering, low ESR ceramic capacitors are recommended. A 4.7µF ceramic input
capacitor is sufficient for most applications. For better input voltage filtering the capacitor value can be
increased.
Vendor
Murata
Recommended input capacitor
LQH32CN100K53L
SH30184R7YSB
SH3018100YSB
10
4.7
10
Murata
Part No.
Value
Vender
GRM188R60J475KE19D 4.7µF/X5R/ Murata
0603/6.3V
GRM219R60J106KE19D 10µF/X5R/ Murata
0805/6.3V
ABC
ABC
Output capacitor selection
Diode selection
For better output voltage filtering, a low ESR output
capacitor is recommended. Ceramic capacitors have
a low ESR value, but depending on the application,
tantalum capacitors can be used. The selection of the
output capacitor value directly influences the output
voltage ripple of the converter which also influences
line regulation. The larger the output voltage ripple,
the larger the line regulation, which means that the
LED current changes if the input voltage changes. If a
certain change in LED current gives a noticeable
change in LED brightness, depends on the LED manufacturer and on the application. Applications requiring
good line regulation ±1%/V (typ) must use output ca-
To achieve high efficiency a Schottky diode must be
used. The current rating of the diode must meet the
peak current rating of the converter.
Recommended diode
Part No.
MSCD052
Rev. A.1 - Feb., 2006
Vender
Zowie
Layout considerations
Typical for all switching power supplies, the layout is
an important step in the design; especially at high
peak currents and switching frequencies. If the layout
is not carefully done, the regulator might show noise
problems and duty cycle jitter. The input capacitor
should be placed as close as possible to the input pin
for good input voltage filtering. The inductor and diode
should be placed as close as possible to the switch
pacitor values eqµAl or large than 1 µF.
Copyright  ANPEC Electronics Corp.
Reverse
Voltage
20
10
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APW7071
Application Information (Cont.)
Layout considerations (Conts.)()
pin to minimize the noise coupling into other circuits.
Since the feedback pin and network is a high impedance circuit, the feedback network should be routed
away from the inductor. The feedback pin and feedback network should be shielded with a ground plane
or trace to minimize noise coupling into this circuit.
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
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APW7071
Package Information
SOT-23-6
D
6
5
4
E
1
2
H
3
S1
e
D
A
α
A2
A1
Dim
A
A1
A2
b
D
E
e
H
L
L1
L2
α
S1
Millimeters
Min.
1.00
0.00
0.70
0.35
2.70
1.40
Max.
1.45
0.15
1.25
0.55
3.10
1.80
1.90 BSC
2.60
0.30
0.08
3.00
0.25
0.60 REF
0°
0.85
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
L2
10 °
1.05
12
L1
L
Inches
Min.
Max.
0.0394
0.0571
0.0000
0.0591
0.0276
0.0492
0.0138
0.0217
0.1063
0.1220
0.50551
0.0709
0.07480 BSC
0.1024
0.1181
000118
0.0031
0.0098
0.024 REF
0°
10 °
0.0335
0.0413
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APW7071
Physical Specifications
Terminal Material
Lead Solderability
Solder-Plated Copper (Solder Material : 90/10 or 63/37 SnPb)
Meets EIA Specification RSI86-91, ANSI/J-STD-002 Category 3.
Reflow Condition
(IR/Convection or VPR Reflow)
tp
TP
Critical Zone
T L to T P
Temperature
Ramp-up
TL
tL
Tsmax
Tsmin
Ramp-down
ts
Preheat
25
t 25 °C to Peak
Time
Classificatin Reflow Profiles
Profile Feature
Average ramp-up rate
(TL to TP)
Preheat
- Temperature Min (Tsmin)
- Temperature Max (Tsmax)
- Time (min to max) (ts)
Time maintained above:
- Temperature (T L)
- Time (tL)
Peak/Classificatioon Temperature (Tp)
Time within 5°C of actual
Peak Temperature (tp)
Ramp-down Rate
Sn-Pb Eutectic Assembly
Pb-Free Assembly
3°C/second max.
3°C/second max.
100°C
150°C
60-120 seconds
150°C
200°C
60-180 seconds
183°C
60-150 seconds
217°C
60-150 seconds
See table 1
See table 2
10-30 seconds
20-40 seconds
6°C/second max.
6°C/second max.
6 minutes max.
8 minutes max.
Time 25°C to Peak Temperature
Notes: All temperatures refer to topside of the package .Measured on the body surface.
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
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APW7071
Classificatin Reflow Profiles(Cont.)
Table 1. SnPb Entectic Process – Package Peak Reflow Temperature s
Package Thickness
Volume mm 3
Volume mm 3
<350
≥350
<2.5 mm
240 +0/-5°C
225 +0/-5°C
≥2.5 mm
225 +0/-5°C
225 +0/-5°C
Table 2. Pb-free Process – Package Classification Reflow Temperatures
Package Thickness
Volume mm 3
Volume mm 3
Volume mm 3
<350
350-2000
>2000
<1.6 mm
260 +0°C*
260 +0°C*
260 +0°C*
1.6 mm – 2.5 mm
260 +0°C*
250 +0°C*
245 +0°C*
≥2.5 mm
250 +0°C*
245 +0°C*
245 +0°C*
*Tolerance: The device manufacturer/supplier shall assure process compatibility up to and
including the stated classification temperature (this means Peak reflow temperature +0°C.
For example 260°C+0°C) at the rated MSL level.
Reliability test program
Test item
SOLDERABILITY
HOLT
PCT
TST
ESD
Latch-Up
Method
MIL-STD-883D-2003
MIL-STD-883D-1005.7
JESD-22-B, A102
MIL-STD-883D-1011.9
MIL-STD-883D-3015.7
JESD 78
Description
245°C , 5 SEC
1000 Hrs Bias @ 125 °C
168 Hrs, 100 % RH , 121°C
-65°C ~ 150°C, 200 Cycles
VHBM > 2KV, VMM > 200V
10ms , Itr > 100mA
Carrier Tape
t
D
P
Po
E
P1
Bo
F
W
Ko
Ao
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
D1
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APW7071
Carrier Tape(Cont.)
T2
J
C
A
B
T1
Application
SOT-23-5/6
A
B
C
J
178 ±1
72 ± 1.0
F
D
D1
Po
3.5 ± 0.05
1.5± 0.1
1.5± 0.1
4.0 ± 0.1
13.0 + 0.2 2.5 ± 0.15
T1
T2
W
P
E
8.4 ± 2
1.5 ± 0.3
8.0 ± 0.3
4 ± 0.1
1.75± 0.1
P1
Ao
Bo
Ko
t
3.2± 0.1
1.4± 0.1
0.2±0.033
2.0 ± 0.1 3.15 ± 0.1
(mm)
Cover Tape Dimensions
Application
SOT- 23-5/6
Carrier Width
8
Cover Tape Width
5.3
Devices Per Reel
3000
Customer Service
Anpec Electronics Corp.
Head Office :
No.6, Dusing 1st Road, SBIP,
Hsin-Chu, Taiwan, R.O.C.
Tel : 886-3-5642000
Fax : 886-3-5642050
Taipei Branch :
7F, No. 137, Lane 235, Pac Chiao Rd.,
Hsin Tien City, Taipei Hsien, Taiwan, R. O. C.
Tel : 886-2-89191368
Fax : 886-2-89191369
Copyright  ANPEC Electronics Corp.
Rev. A.1 - Feb., 2006
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